The authors acknowledge Peter Jonosson and the Lyons New Media Centre for the 3D printing of the chambers. This research was supported by 436100-2013 RGPIN, ER15-11-123, the McMaster Dean of Engineering Excellence Undergraduate Summer Research Award, and the Undergraduate Research Opportunities Program.

<ol>
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G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perovskite+solar+cells:+an+emerging+photovoltaic+technology.">Perovskite solar cells: an emerging photovoltaic technology.</a> Materials Today. 18 (2), 65-72 (2015).</li><li>Turak, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interfacial+degradation+in+organic+optoelectronics.">Interfacial degradation in organic optoelectronics.</a> RSC Advances. 3 (18), 6188 (2013).</li><li>Scholz, S., Kondakov, D., L&#252;ssem, B., Leo, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Degradation+Mechanisms+and+Reactions+in+Organic+Light-Emitting+Devices.">Degradation Mechanisms and Reactions in Organic Light-Emitting Devices.</a> Chemical Reviews. 115 (16), 8449-8503 (2015).</li><li>J&#248;rgensen, M., Norrman, K., Gevorgyan, S. A., Tromholt, T., Andreasen, B., Krebs, F. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stability+of+Polymer+Solar+Cells.">Stability of Polymer Solar Cells.</a> Advanced Materials. 24 (5), 580-612 (2012).</li><li>Habisreutinger, S. N., McMeekin, D. P., Snaith, H. J., Nicholas, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Research+Update:+Strategies+for+improving+the+stability+of+perovskite+solar+cells.">Research Update: Strategies for improving the stability of perovskite solar cells.</a> APL Materials. 4 (9), 091503 (2016).</li><li>Reese, M. O., Sigdel, A. K., Berry, J. J., Ginley, D. S., Shaheen, S. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simple+miniature+controlled-atmosphere+chamber+for+optoelectronic+characterizations.">A simple miniature controlled-atmosphere chamber for optoelectronic characterizations.</a> Solar Energy Materials and Solar Cells. 94 (7), 1254-1258 (2010).</li><li>Gevorgyan, S. A., Jorgensen, M., Krebs, F. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+setup+for+studying+stability+and+degradation+of+polymer+solar+cells.">A setup for studying stability and degradation of polymer solar cells.</a> Solar Energy Materials and Solar Cells. 92 (7), 736-745 (2008).</li><li>Park, J. -. S. S., Chae, H., Chung, H. K., Lee, S. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thin+film+encapsulation+for+flexible+AM-OLED:+a+review.">Thin film encapsulation for flexible AM-OLED: a review.</a> Semiconductor Science and Technology. 26 (3), 034001 (2011).</li><li>Ahmad, J., Bazaka, K., Anderson, L. J., White, R. D., Jacob, M. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Materials+and+methods+for+encapsulation+of+OPV:+A+review.">Materials and methods for encapsulation of OPV: A review.</a> Renewable &amp; Sustainable Energy Reviews. 27, 104-117 (2013).</li><li>Gevorgyan, S. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Round+robin+performance+testing+of+organic+photovoltaic+devices.">Round robin performance testing of organic photovoltaic devices.</a> Renewable Energy. 63, 376-387 (2014).</li><li>Osterwald, C. R., Hammond, R., Zerlaut, G., D'Aiello, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photovoltaic+module+certification+and+laboratory+accreditation+criteria+development.">Photovoltaic module certification and laboratory accreditation criteria development.</a> Solar Energy Materials and Solar Cells. 41, 629-636 (1996).</li><li>Turak, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Systematic+analysis+of+processing+parameters+on+the+ordering+and+performance+of+working+poly(3-hexyl-thiophene):[6,6]-phenyl+C(61)-butyric+acid+methyl+ester+solar+cells.">Systematic analysis of processing parameters on the ordering and performance of working poly(3-hexyl-thiophene):[6,6]-phenyl C(61)-butyric acid methyl ester solar cells.</a> Journal of Renewable and Sustainable Energy. 2 (5), 53103 (2010).</li><li>Qi, B., Wang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fill+factor+in+organic+solar+cells.">Fill factor in organic solar cells.</a> Physical Chemistry Chemical Physics. 15 (23), 8972-8982 (2013).</li><li>Lu, N., Li, L., Sun, P., Liu, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Short-circuit+current+model+of+organic+solar+cells.">Short-circuit current model of organic solar cells.</a> Chemical Physics Letters. 614, 27-30 (2014).</li><li>Qi, B., Wang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Open-circuit+voltage+in+organic+solar+cells.">Open-circuit voltage in organic solar cells.</a> Journal of Materials Chemistry. 22 (46), 24315-24325 (2012).</li><li>Xue, J., Uchida, S., Rand, B. P., Forrest, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=4.2%+efficient+organic+photovoltaic+cells+with+low+series+resistances.">4.2% efficient organic photovoltaic cells with low series resistances.</a> Applied Physics Letters. 84 (16), 3013-3015 (2004).</li><li>Hauch, J. A., Schilinsky, P., Choulis, S. A., Rajoelson, S., Brabec, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+impact+of+water+vapor+transmission+rate+on+the+lifetime+of+flexible+polymer+solar+cells.">The impact of water vapor transmission rate on the lifetime of flexible polymer solar cells.</a> Applied Physics Letters. 93 (10), 103306 (2008).</li><li>Norrman, K., Madsen, M. V., Gevorgyan, S. A., Krebs, F. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Degradation+Patterns+in+Water+and+Oxygen+of+an+Inverted+Polymer+Solar+Cell.">Degradation Patterns in Water and Oxygen of an Inverted Polymer Solar Cell.</a> Journal of the American Chemical Society. 132 (47), 16883-16892 (2010).</li><li>Dameron, A. A., Reese, M. O., Moriconie, T. J., Kempe, M. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Understanding+Moisture+Ingress+and+Packaging+Requirements+for+Photovoltaic+Modules.">Understanding Moisture Ingress and Packaging Requirements for Photovoltaic Modules.</a> Photovoltaics International. 5, 121-130 (2009).</li><li>Standard Test Method for Water Vapor Transmission Rate of Sheet Materials Using Dynamic Relative Humidity Measurement. ASTM E398 - 13 Available from: <a target="_blank" href="https://www.astm.org/Standards/E398">https://www.astm.org/Standards/E398</a> (2013)</li><li>Basha, R. K., Konno, K., Kani, H., Water Kimura, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Water+Vapor+Transmission+Rate+of+Biomass+Based+Film+Materials.">Water Vapor Transmission Rate of Biomass Based Film Materials.</a> Engineering in Agriculture, Environment and Food. 4 (2), 37-42 (2011).</li><li>Kim, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+correlation+study+between+barrier+film+performance+and+shelf+lifetime+of+encapsulated+organic+solar+cells.">A correlation study between barrier film performance and shelf lifetime of encapsulated organic solar cells.</a> Solar Energy Materials and Solar Cells. 101, 140-146 (2012).</li><li>Reese, M. O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pathways+for+the+degradation+of+organic+photovoltaic+P3HT:+PCBM+based+devices.">Pathways for the degradation of organic photovoltaic P3HT: PCBM based devices.</a> Solar Energy Materials and Solar Cells. 92 (7), 746-752 (2008).</li><li>Kempe, M. D., Reese, M. O., Dameron, A. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+the+sensitivity+limits+of+water+vapor+transmission+rate+measurements+using+electrical+calcium+test.">Evaluation of the sensitivity limits of water vapor transmission rate measurements using electrical calcium test.</a> Review of Scientific Instruments. 84 (2), 025109 (2013).</li><li>Reese, M. O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Consensus+stability+testing+protocols+for+organic+photovoltaic+materials+and+devices.">Consensus stability testing protocols for organic photovoltaic materials and devices.</a> Solar Energy Materials and Solar Cells. 95 (5), 1253-1267 (2011).</li><li>. Current landscape of standardisation efforts in organic and printed electronics 2015 - a VAMAS review Available from: <a target="_blank" href="https://www.researchgate.net/publication/278035615_Current_landscape_of_standardisation_efforts_in_organic_and_printed_electronics_2015_-_a_VAMAS_review">https://www.researchgate.net/publication/278035615_Current_landscape_of_standardisation_efforts_in_organic_and_printed_electronics_2015_-_a_VAMAS_review</a> (2015)</li></ol>

The authors have nothing to disclose.

The critical steps in recreating this experiment include the printing of the chambers to avoid cracks, gaps, or poor in-fill characteristics which can decrease the WVTR, sealing the chamber to prevent any ingress of moisture and oxygen by tightening the KF50 clamp to achieve a full sealing between the top and bottom chambers, using a vacuum-rated low-pressure epoxy around the contact pins or any feedthroughs to prevent any leaking, and creating a seal between the sample and the top chamber using a proper O-ring placement and sufficient pressure with the tightening screws on the retaining ring to prevent any leakage without cracking the sample. The O-ring should fit completely into the groove, without burrs or particulates, and should be compressed between 15 - 25% of its cross-section for an adequate seal10. It is also important to be careful when attaching the contact pins to the chamber body to both ensure good electrical contact and prevent paths for oxygen and moisture ingress through the low-pressure epoxy. An epoxy rated as a sealant for vacuum applications will provide an adequate seal. It is important to connect the contact pins to the measurement board to minimize any series resistance losses during the IV measurements. Store the chamber in an inert environment such as a glove box for at least 24 h before use to ensure that any moisture absorbed by the chamber has had time to escape from the material. This is especially important if the chamber has been stored for a more than a few days under ambient conditions in the open lab environment. It is not recommended to heat the chamber to accelerate the process of degassing, to avoid a softening of the chamber walls and the risk of collapsing the chamber structure.
Certain common problems can be encountered when recreating this experiment. As the chamber uses an O-ring seal pressed directly onto the tested sample, rather than a completely sealed chamber, it is possible to crack the sample when excessive force is used in mounting the retaining ring. Additionally, particulates on the O-ring or in the groove or burrs on any of the sealing joints can prevent a good seal, in addition to cracking the sample upon mounting10. A careful cleaning of the O-ring and the joints before mounting the ring is essential.
It is also important to avoid melting the chamber during the epoxy curing. After applying epoxy to secure the pogo pins in the bottom chamber, refrain from applying heat to speed up the drying process. This will result in melting the 3D-printed material, and hence in a disfiguration of the chamber.
The use of inadequate electrical connections between the contact pins and the test board is a significant problem. A poor solder, long wire connections, or a too thick gauge of wire can lead to a significant, avoidable decrease of the device performance due to resistance losses that occur along the electrical connections between the chamber and the test board. It is advised to always make an encapsulated organic device as a reference to check the quality of the connections outside of the chamber when wiring a new chamber. High resistance losses are likely if the device in the chamber shows orders of magnitude of less dark current or a significant slope around the short circuit current18 (i.e., Isc, around V = 0) and the open circuit voltage19 (i.e., Voc, around I = 0). These effects are shown in Figure 15, where the use of thick long wires to connect an unsupported chamber to the measurement board is compared to a support collar with embedded interconnects. As can be seen, the use of the support collar led to an increase in the dark current of two orders of magnitude (Figure 15a) and to an increase in the fill factor17 from 22.7% to 34.6%. It may be possible to further decrease the resistance losses through better soldering and wiring designs.
<img alt="Figure 15" class="xfigimg" src="/files/ftp_upload/56925/56925fig15.jpg" /> 
Figure 15: A HiRs IV comparison. These panels show electrical measurements for devices with poor and good contacts: (a) dark current-voltage measurements and (b) current-voltage measurements under illumination. The inset pictures represent the poor electrical contact configurations (the black border on the left-hand side) and the good electrical contact configurations (the red border on the right-hand side) to connect the contact pins from the chamber to the test measurement board. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56925/56925fig15large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
The use of a third helping-hand soldering station, clamps, and alligator clips to secure the solder cup and pogo pin will make soldering the contact pins easier, preventing any poor soldering of the contact pins. Ensure that the bead of the solder applied externally to the pin and cup is not too large; otherwise, it will not fit through the embedded holes in the bottom chamber. The solder must be placed on the outside of the pin, as soldering inside will cause the solder to enter the spring and render the pin unusable. Check the electrical connection across the pin and cup by using a multimeter.
When soldering external wires to the DHT22 temperature and humidity sensor, difficulties may be encountered as a result of the precision required due to how narrow the pins are, leading to a poor soldering of the wires to the sensor. Using a third helping-hand soldering station or any clamps and alligator clips will assist in securing the sensor and wires in place. Note that positioning the soldering iron too close to the base of the pin on the sensor for an extended period of time may burn the pin, causing it to fall off.
There are two main limitations to the general approach proposed here of using a 3D-printed atmospheric chamber. The first is that the WVTR is substantially higher for the 50% PLA-printed chamber than it would be for an equivalent chamber machined from metal. Therefore, in order to reduce the WVTR, two modifications exist for the chamber design that can increase the use time of the chamber: flowing inert gas and desiccant wells. To allow the flowing of inert gas, the bottom chamber with the gas ports configuration of the chamber design can be used. The WVTR was substantially decreased to less than 0.13 &#181;g/day in such a configuration. To accommodate desiccants, the bottom chamber has three wells around the feedthrough holes. These wells can be filled with standard moisture or oxygen getters to absorb any gases that enter the chamber. Reese et al.10 found that high-surface-area Getters of mixed Mg and drierite (both standard laboratory desiccants) were sufficient to decrease the WVTR for metal chambers to 0.5 &#181;g/day.
The second limitation is that the chamber, through the use of pogo pins and wiring connections to the measurement board, always shows higher contact resistance losses compared to an equivalent encapsulated device. Figure 12b shows this behavior for a device in the chamber compared to the same device encapsulated and contacted directly to the ZIF test board. This may have implications for the interpretation of the device&#39;s characteristics. Every effort must be made to limit the losses of this nature through proper wiring and soldering. As shown in Figure 15, it is possible to reduce losses significantly by improving the wiring connections between the chamber and the ZIF test board. Using a custom 3D-printed collar embedded with copper wires that fit directly into the ZIF test board, the device performance was improved significantly. Further improvements may be possible with better connection configurations or with other test boards.
An additional limitation is specific to the chamber designs described in this protocol but may be alleviated by researchers adopting designs for their own uses by changing the chamber configurations. Any organic device tested with the chambers as specified by the provided CAD files (as described in Figure 1) are limited in size to 40 mm in diameter. The total active area that can be illuminated is also limited by the size of the window in the top chamber. The 6-pixel design requires an oval shape for the top chamber opening which blocks two of the pixels, whereas the 4-pixel design has all pixels exposed within an 18 mm circle.
This protocol outlines an approach to build and test a small portable chamber, based on the original design by Resse et al.10. We have adapted this design, making it cheaper and more versatile by using 3D printing to produce the chamber components. The significance with respect to other protocols lies in its simplicity, adaptability, and accessibility. The use of 3D printing rather than machining allows for rapid, cost-effective adjustments to changing sample or environmental requirements while maintaining the utility of the basic design. In this contribution, we have proposed three variations of the chamber that can be produced, including different pixel layouts for the organic devices and ingress ports to flow various gases. The low cost and speed of the production using 3D printing can allow researchers to rapidly modify the design to suit their own purposes, including different pixel layouts, scaled device sizes, extra ports, and additional sensors.
The main rationale for using 3D printing for this chamber was to allow for an increased versatility of the chamber design to accommodate the specific needs of the users. This inherently implies that modifications can be easily made to suit a given purpose, from scaling up to a larger organic device or module designs, adding different measurement functionalities, to changing the organic device layout, giving a wide range of future applications. We propose two possible developments that will extend the use of these chambers even further. They include the ability to change the device layout and to control the temperature.
To change the device layout, as demonstrated above for the 4- and 6-pixel chamber configurations shown in Figure 1 and Figure 4, the chamber can be easily adapted to different organic device pixel layouts, using the CAD files available in the Supplementary Information. The location of the electrical feedthrough holes in the bottom chamber should be carefully re-designed to accommodate the appropriate organic device configuration. Note that the retaining ring overlaps with the corners of the organic device in order to secure it in the top chamber and, as such, electrical connections should not be placed in those areas. The top chamber has a hole to allow for the absorption/emission of light by the device. Any organic device tested with this chamber is, therefore, limited to active material in a region not outside of this area. The 6-pixel design requires an oval shape for the top chamber opening which blocks two of the pixels, whereas the 4-pixel design has all pixels exposed within an 18 mm circle. Care needs to be taken to ensure that the groove is deep enough to accommodate a new O-ring if necessary. Reese et al.10 indicate that the O-ring should be compressed between 15 - 25% of its cross-section for an adequate seal. Some CAD files for the top and bottom chambers without a specific design are also included in the Supplementary Information to aid any researcher in developing their own design.
As the chamber design is based on a standard vacuum fitting-a KF50-centering gasket-to ensure a good seal between the top and bottom chambers, it is well suited to accommodate devices smaller than 40 mm in diameter. Scaling up to larger sizes is possible, using other commercially available vacuum flange configurations such as the ISO series, which uses the same centering gasket design. Using a commercially available seal which is tested and certified makes it easy to repeatedly reassemble the chamber without any concern for the integrity of the seal10. If the design is to be changed to incorporate more space, be aware that increasing the size of the chamber also increases the transmission of water vapor and oxygen.
Any testing of the organic devices generally does not incorporate temperature control during the IV characterization14. As the organic device performance and stability is highly dependent upon the temperature6,7,8, this can lead to a significant problem in the comparability and reproducibility of reported laboratory test results14. Attempts to establish standard testing protocols for organic devices29,30 suggest that a temperature measurement and control should be built into any electronic test configuration. To address this problem, the atmospheric chambers have two modifications.
The first, a thermocouple probe feedthrough, is already implemented in the available designs as an additional contact pin at the center of the device (see the blue dots in Figure 4). Though it is placed at the center to minimize inaccuracies in pixel-to-pixel temperature readings from gradients across the device, the thermocouple may also be moved into the retaining ring so as not to interfere with the electrical measurements. The low thermal conductivity of PLA means that such a modification may require the use of metal for the retaining ring.
The second, for a method to control the temperature, is a thermoelectric cooling/heating ring applied to the top chamber. The ceramic cartridge heating/cooling ring can be applied to the exterior of the top chamber to emit or dissipate heat, as shown in Figure 16. The ring can be used for heating or cooling simply by reversing the side placed on the chamber. Due to the low thermal conductivity of PLA, this method is only effective for a highly thermally conductive top chamber material, such as metal.
<img alt="Figure 16" class="xfigimg" src="/files/ftp_upload/56925/56925fig16.jpg" /> 
Figure 16: An exploded view of the chamber with cooling. This panel shows an exploded view of a test chamber assembly with a cooling ring and the heat sink placement shown in blue. Note that for an optimal performance, the rod heat sinks should be placed all around the diameter of the ring, not just the two shown here for clarity. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56925/56925fig16large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
To dissipate heat effectively, a heat sink and fan must also be used during the operation. For an optimum performance, the heat sinks should be placed around the cooling ring to maximize the covered area. Any fan can be used, though stronger fans will provide a better performance. The application of the cooling ring and heat sinks can be done with a thermally conductive epoxy. While most epoxy can be removed with acetone, make sure the epoxy can be removed from the heat sinks and ring prior to the application if heating is required.

Organic and perovskite optoelectronic devices, solar cells, and light-emitting diodes based on &#960;-conjugated semiconducting organic molecules and organometal halides are a rapidly growing field of research. Organic light-emitting diodes (OLEDs) are already a major technological element in lighting and displays1, and organic photovoltaics have begun to achieve efficiencies that make them competitive with amorphous silicon2. The recent rapid advancement of perovskite-based devices for light absorbing and light-emitting applications3,4,5 suggests that low-cost, easily processed devices are likely to soon find widespread deployment. However, all of these technologies suffer from a sensitivity to atmospheric contaminants, particularly moisture and oxygen, which limits their effective lifetimes6,7,8,9.
For researchers studying such systems, it can be useful to have an adaptable, easy-to-use, portable, and reusable chamber to protect such sensitive materials or to expose them to contaminants in a controlled manner10,11. Though it is possible to use a glovebox for the characterization of air-sensitive devices, these large, expensive, and fixed-location, inert environments may be incompatible with the wide range of characterization that might be required. To provide a portable alternative, Reese et al.10 proposed a small metal chamber based on a standard vacuum flange suitable for the electrical and optical characterization of organic devices. We have adapted this design, making it cheaper and more versatile by using 3D-printing to produce the chamber components. The use of 3D-printing, rather than machining, allows for rapid, cost-effective adjustments to changing sample or environmental requirements while maintaining the utility of the basic design. In this contribution, we outline the procedure to make such a chamber, and use it to extract the current-voltage characteristics of an organic diode device.
A good encapsulation of organic and perovskite devices should have WVTRs of 10-3 - 10-6 g/m2/day for long-term device stability12,13, to ensure&#160;little water ingress into the organic device even in very harsh conditions. As this chamber is designed to be a controlled environment for testing purposes rather than a long-term storage or encapsulation method, the requirements for an effective chamber are not as strict. The chamber should be able to maintain the device properties within a reasonable timeframe to perform characterization experiments. The standard operating procedure of using PLA results in a chamber which can be used for several days or even weeks with an incorporated gas flow, without a significant loss of the device properties.
Changing the materials, or even the shape and size of the chamber body can drastically affect the penetration of contaminants from the air into the chamber. Therefore, the ingress of moisture and oxygen needs to be carefully monitored for each design to determine the efficacy of the chamber. We, additionally to the fabrication of the chamber, outline a simple procedure for determining the WVTR of the chamber, using a commercially available humidity sensor, to establish a timeframe for the use of the chamber for experimentation.
Such a simple, yet versatile chamber allows for multiple types of experiments to be performed. They can act as inert atmosphere environments outside the glovebox, suitable for electrical and optical characterizations through the electrical feedthrough ports and window. Their portability allows them to be used with standard electrical characterization equipment outside the lab where they were manufactured, which is useful in round robin testing for reliability14 or to obtain certified measurements of the device performance15. These chambers are also particularly useful for studying the effects of the introduction of contaminants for controlled degradation tests, with simple modifications. The use of 3D printing allows a significant, rapid adaptability to changing device layouts, sizes, or testing requirements.

<table>
	<tbody>
		<tr>
			<td>ORION DELTA DESKTOP 3D PRINTER RTP</td>
			<td>SeeMeCNC</td>
			<td>87999</td>
			<td>Known in Report As: 3D Printer</td>
		</tr>
		<tr>
			<td>1.75 mm PLA Filament</td>
			<td>SeeMeCNC</td>
			<td>50241</td>
			<td>Known in Report As: PLA</td>
		</tr>
		<tr>
			<td>Somos&#174; WaterShed XC 11122 chamber</td>
			<td>Somos</td>
			<td>printed at Custom Prototypes, Toronto.</td>
			<td>https://www.dsm.com/products/somos/en_US/products/offerings-somos-water-shed.html 
			Known in Report As: Water resistant polymer</td>
		</tr>
		<tr>
			<td>CURA</td>
			<td>CURA</td>
			<td></td>
			<td>https://ultimaker.com/en/products/cura-software 
			Known in Report As: slicing software</td>
		</tr>
		<tr>
			<td>Soldering iron with 600&#176; F tip</td>
			<td>Weller</td>
			<td>WTCPT</td>
			<td></td>
		</tr>
		<tr>
			<td>Xtralien X100 Source Measure Unit</td>
			<td>Ossila</td>
			<td>E561</td>
			<td>Known in Report As: SMU</td>
		</tr>
		<tr>
			<td>ZIF Test Board for Pixelated Anode Substrates</td>
			<td>Ossila</td>
			<td>E221</td>
			<td>Known in Report As: Zero insetion force/ZIF Test Board;</td>
		</tr>
		<tr>
			<td>BNC Cable</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Generic USB A - B</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Generic USB A - Micro</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>#12 O-Ring</td>
			<td></td>
			<td></td>
			<td>Source unkown 
			Known in Report As: o-ring</td>
		</tr>
		<tr>
			<td>116 Butyl O-Ring</td>
			<td>Global Rubber Products</td>
			<td>116 VI70</td>
			<td>Bought in-store 
			Known in Report As: o-ring</td>
		</tr>
		<tr>
			<td>Retaining ring</td>
			<td>McMaster</td>
			<td>NA</td>
			<td>3D printed in-house</td>
		</tr>
		<tr>
			<td>Bottom Chamber</td>
			<td>McMaster</td>
			<td>NA</td>
			<td>3D printed in-house</td>
		</tr>
		<tr>
			<td>Top Chamber</td>
			<td>McMaster</td>
			<td>NA</td>
			<td>3D printed in-house</td>
		</tr>
		<tr>
			<td>KF50 Cast Clamp (Aluminum)</td>
			<td>Kurt J. Lesker</td>
			<td>QF50-200-C</td>
			<td></td>
		</tr>
		<tr>
			<td>KF50 Centering Ring (Aluminum)</td>
			<td>Kurt J. Lesker</td>
			<td>QF50-200-BRB</td>
			<td></td>
		</tr>
		<tr>
			<td>Sn60/Pb40 Solder</td>
			<td>MG Chemicals</td>
			<td>4895-2270</td>
			<td></td>
		</tr>
		<tr>
			<td>#4-40 x 3/16&#34; machine screw</td>
			<td></td>
			<td></td>
			<td>Hardware store</td>
		</tr>
		<tr>
			<td>#4-40 IntThrd Brass TaperSingleVane Insert For Thermoplastic</td>
			<td>Fastenal</td>
			<td>11125984</td>
			<td>Fastenal requires to be affiliated with company/university 
			Known in Report As: #4-40 brass tapered threaded insert</td>
		</tr>
		<tr>
			<td>Varian Torr Seal Vacuum Equipment High Vacuum Epoxy</td>
			<td>Vacuum Products Canada Inc.</td>
			<td></td>
			<td>Known in Report As: low-pressure epoxy</td>
		</tr>
		<tr>
			<td>Smiths Interconnect/IDI Contact Probes HEADED RADIUS</td>
			<td>Mouser Electornics</td>
			<td>818-S-100-D-3.5-G</td>
			<td>Known in Report As: pogo pin</td>
		</tr>
		<tr>
			<td>Smiths Interconnect/IDI Contact Probes Receptacle Solder Cup</td>
			<td>Mouser Electornics</td>
			<td>818-R-100-SC</td>
			<td>Known in Report As: solder cup</td>
		</tr>
		<tr>
			<td>1/4&#34; Teflon Tubing</td>
			<td></td>
			<td></td>
			<td>Hardware store</td>
		</tr>
		<tr>
			<td>Teflon tape</td>
			<td></td>
			<td></td>
			<td>Hardware store</td>
		</tr>
		<tr>
			<td>1/4&#34; Tube x 1/8&#34; Male NPT Nickel Plated Brass Push-to-Connect Connector</td>
			<td>Fastenal</td>
			<td>442064</td>
			<td>Not the same ones used for this study, but are fuctionally equivalent 
			Known in Report As: push-to-connect pneumatic connector</td>
		</tr>
		<tr>
			<td>1/8&#34; NPT Tap and T-wrench</td>
			<td></td>
			<td></td>
			<td>Hardware store</td>
		</tr>
		<tr>
			<td>1/4&#34; Tube Push-to-Connect Manually Operated Valves</td>
			<td>Fluidline</td>
			<td>7910-56-00</td>
			<td>Known in Report As: manually operated push-to-connect valves</td>
		</tr>
		<tr>
			<td>Adafruit DHT22 Humidity Sensor (small)</td>
			<td>Digi-Key</td>
			<td>385</td>
			<td>Known in Report As: internal humidity sensor</td>
		</tr>
		<tr>
			<td>Adafruit DHT22 Humidity Sensor (large)</td>
			<td>Digi-Key</td>
			<td></td>
			<td>Known in Report As: external humidity sensor</td>
		</tr>
		<tr>
			<td>Arduino Uno</td>
			<td>Arduino</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Glovebox environment</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>10 kOhm Resistor</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Oscilla Xtralien Scientific Python IDE</td>
			<td>Oscilla</td>
			<td></td>
			<td>https://www.ossila.com/pages/xtralien-scientific-python 
			Known in Report As: Python IDE</td>
		</tr>
	</tbody>
</table>

a 3d-printed chamber for organic optoelectronic device degradation testing

In this manuscript, we outline the manufacture of a small, portable, easy-to-use atmospheric chamber for organic and perovskite optoelectronic devices, using 3D-printing. As these types of devices are sensitive to moisture and oxygen, such a chamber can aid researchers in characterizing the electronic and stability properties. The chamber is intended to be used as a temporary, reusable, and stable environment with controlled properties (including humidity, gas introduction, and temperature). It can be used to protect air-sensitive materials or to expose them to contaminants in a controlled way for degradation studies. To characterize the properties of the chamber, we outline a simple procedure to determine the water vapor transmission rate (WVTR) using relative humidity as measured by a standard humidity sensor. This standard operating procedure, using a 50% infill density of polylactic acid (PLA), results in a chamber that can be used for weeks without any significant loss of device properties. The versatility and ease of use of the chamber allows it to be adapted to any characterization condition that requires a compact-controlled atmosphere.

Current-voltage Measurements:
This chamber is designed to allow for the testing of an air-sensitive diode device, such as an organic or perovskite solar cell or a light-emitting diode. It can act as a reusable, temporary encapsulation or as a method of introducing contaminants to perform controlled degradation testing. The current density-voltage (JV) curves shown here were measured using a ZIF test board attached to an SMU under dark (i.e., no illumination) and illuminated conditions to extract the basic diode characteristics. By connecting the contact pins from the chamber to the ZIF board, each pixel can be individually addressed. In the example data below, the standard bottom chamber, without the gas ports, printed from 50% density PLA plastic was used to test an organic solar cell using the 6-pixel configuration. In these organic devices, &#34;pixel&#34; refers to the individual diode that can be measured using the measurement setup. Using the provided Python programs in the IV Measurement Code folder (found in the Supplementary Information), the following curves were attained for a single pixel from organic devices with a device architecture of ITO/PEDOT: PSS/P3HT: PCBM/Al. The details for producing the devices can be found elsewhere16.
Figure 12 represents the expected JV curves of one good working organic photovoltaic device in the dark and under illumination. Note that, to extract the current density (J), the current-voltage curves that are the outputs from the BasicIV.py Python program were divided by the measured diode area. For our diodes, this was around 1.2 mm2. Figure 12 shows the behavior of one diode within the chamber, with good pin contact with the electrode pads. All four pixels that are measurable in such a configuration show similar behavior. A working organic diode that is not degraded should show rectifying behavior, a low signal to noise, and an exponential increase in the current after an applied voltage of around 1 V in dark conditions; under illumination, it should have similar diode characteristics as in the dark, offset by the induced photocurrent2,16. For comparison, Figure 12 also shows the JV curves for one pixel from the same device, encapsulated using a microscope slide over the active area (i.e., the red outline area from Figure 4, sealed with low-pressure vacuum-sealing epoxy after the initial in-chamber tests). Notice that in the chamber, there is evidence of higher contact resistance as shown by the decrease of the fill factor17 [the curve becomes less &#34;square&#34; due to slope around the short circuit current (Jsc)18 and the open circuit voltage (Voc)]19. This can be attributed to the higher contact probe resistance of the device in the chamber compared to the device probed directly using the measurement board20. It should be possible to decrease the resistance losses significantly through better soldering and wiring designs. In the case of a degraded, non-functioning or poorly contacted organic device, we would not see a diode-like curve, as in Figure 12c. Such curves typically have a low measured current, no rectifying behavior, and a high signal-to-noise ratio, indicating &#34;noise&#34; or open contact. A short circuit, such as would occur if there was a direct contact between the top metal electrode and the ITO electrode on the bottom, would be shown by a straight line of a slope proportional to the resistance across the contact (Figure 12d).
<img alt="Figure 12" class="xfigimg" src="/files/ftp_upload/56925/56925fig12.jpg" /> 
Figure 12: An IV comparison. These panels show the current density-voltage (JV) measurement curves of a standard organic solar cell device inside the chamber and the same device encapsulated and contacted directly to the ZIF board through the built-in pins (a) under dark conditions (i.e., not under illumination) and (b) under illumination using a lab light source, showing expected diode behavior. (c) This panel shows an IV measurement curve of a standard organic solar cell device not under illumination showing degraded or non-contact behavior. (d) This panel shows an IV diode measurement curve of a short-circuited device not under illumination. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56925/56925fig12large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
Chamber Efficacy Tests: 
This chamber is intended to act as a temporary, reusable stable environment with controlled properties (including humidity, gas introduction, and temperature). To determine the efficacy of the atmospheric chambers, they were characterized in two ways: a water vapor transmission rate test using a humidity sensor and a device degradation test using the organic solar cell device used to demonstrate the current-voltage measurements in the previous section.
WVTR Tests:
One of the critical factors in the degradation of devices is the penetration of water into the device21,22. For long-term device stability, a good encapsulation of organic devices should have 10-4 - 10-6 g/m2/day of water ingress12,13. As this chamber is designed to be a controlled environment for testing purposes rather than a long-term storage or encapsulation method, the requirements for an effective chamber are not as strict. Rather, the chamber should be able to maintain the device properties within a reasonable timeframe for a given experimental condition. The primary method of characterizing water vapor ingress and the use time of the chamber is the water vapor transmission rate (WVTR)21.
The WVTR can take different meanings depending on the conditions under which it is measured and the units that are used23. For the purpose of this contribution, the WVTR is determined through a measure of relative humidity change24, similar to a gravimetric cup test23. Due to the complexity of the moisture ingress paths in the chamber, the mass change of the water vapor reaching the sensor shall be used, normalized by the per percentage difference (expressed as a fraction from 0 - 1) of the relative humidity across the boundary, adapted from the method of Basha et al.25.
(1)&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<img alt="Equation 1" src="/files/ftp_upload/56925/56925eq1.jpg" />
Here, <img alt="Equation 2" src="/files/ftp_upload/56925/56925eq2.jpg" /> represents the rate of change with respect to the time of the mass of water vapor contained in the chamber, and <img alt="Equation 3" src="/files/ftp_upload/56925/56925eq3.jpg" /> is the difference in relative humidity inside and outside the chamber. Such an approach yields units for the WVTR of the mass-per-unit time.
Implicit in this equation is the assumption that the rate of the water vapor ingress is proportional to the relative humidity difference between the inside and the outside of the chamber. This assumption leads to the following differential equation:
(2)&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<img alt="Equation 4" src="/files/ftp_upload/56925/56925eq4.jpg" />
Here, <img alt="Equation 5" src="/files/ftp_upload/56925/56925eq5.jpg" /> is the volume of the chamber (taken from the 3D models), and <img alt="Equation 6" src="/files/ftp_upload/56925/56925eq6.jpg" /> is the saturation density of the water vapor at the temperature recorded during the test.
Solving this equation and substituting it in the initial condition of 0% humidity in the chamber (ensured by leaving the chamber in the glovebox for &#62; 24 h), the governing equation of these experiments, as shown below, can be found.
(3)&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<img alt="Equation 7" src="/files/ftp_upload/56925/56925eq7.jpg" />
When conducting the humidity test, relative humidity readings were taken simultaneously from inside and outside the 3D-printed chamber. Once this data was compiled, it was plotted against time, t, as shown in Figure 13a. Linear regression was used to calculate the WVTR from the slope of the best fit line.
In this test, 50% print density PLA 3D-printed plastic was used. The test was run for a duration of 4 h, resulting in a WVTR of 270 &#181;g/day (R2 = 0.985). This is high compared to the requirements for a good organic device encapsulant12,13, but it is sufficient to minimize the device degradation for an electrical testing lasting several hours21 (see next section, Device Degradation Test). By contrast, a leaking chamber as shown in Figure 13b had a WVTR of 855 &#181;g/day (R2 = 0.99).
The rate at which moisture enters the chamber is governed by the diffusion coefficient of the most permeable material23. Assuming the same sealing conditions, different materials for the chamber walls will yield different values of WVTR. Results for a few representative materials and conditions are summarized in Table 1. The typical PLA chamber has a higher WVTR than an equivalent chamber machined out of metal10. Assuming a proportional relationship between the WVTR and device degradation, we can estimate the storage time before an 80% loss of the initial performance (T80)6,8 for a test device, using that chamber as a baseline for the moisture ingress of the seals. This can give a rough estimate of the usability time for a chamber in a given configuration. Under such conditions, the 50% density PLA chamber should be able to store a sample without any significant losses for around 3 days. This contrasts with a true encapsulation, where the significant performance was observed after more than two weeks of storage in ambient conditions.
It is also possible to extend the usable time window for a chamber by flowing an inert gas, such as N2. In such a configuration, the WVTR for the 50% PLA chamber decreased to below the detection limit of the sensor (see Figure 13b). With a minimum detection of a ~ 0.1% relative humidity change, that suggests a WVTR of less than 0.13 &#181;g/day, with a significant increase in the estimated storage time. However, previous studies10,27 have indicated that samples have a T90 of around 6 weeks in a glovebox. As this gas flow chamber configuration is comparable to an inert gas glovebox environment, this is a more likely upper bound for sample storage. To determine a more accurate measure of the WVTR for such low levels of water ingress, a more sensitive test such as the electrical calcium test28 should be used to give a better estimate.
If further testing of the chambers is desired, an oxygen sensor could be placed in the chamber and the oxygen levels could be monitored over time to give the oxygen transmission rate (OTR), which could be compared with the WVTR.
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Material</td>
			<td>DRHint (total test duration)</td>
			<td>WVTR (mg/day)</td>
			<td>Estimated device storage time (days)</td>
		</tr>
		<tr>
			<td>50% Density PLA</td>
			<td>1.80%</td>
			<td>271 &#177; 30</td>
			<td>3.3</td>
		</tr>
		<tr>
			<td>50% Density PLA (Leaking)</td>
			<td>4.70%</td>
			<td>855 &#177; 90</td>
			<td>1</td>
		</tr>
		<tr>
			<td>50% Density PLA with N2 Flow</td>
			<td>&#60;0.1%</td>
			<td>&#60;0.130</td>
			<td>&#62;7000</td>
		</tr>
		<tr>
			<td>Water resistant polymer</td>
			<td>9.00%</td>
			<td>3064 &#177; 300</td>
			<td>0.29</td>
		</tr>
		<tr>
			<td>Metal 1</td>
			<td>--</td>
			<td>90*</td>
			<td>10</td>
		</tr>
		<tr>
			<td>* corrected for external relative humidity</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td colspan="4">1 Reese,&#160; et al [10]</td>
		</tr>
	</tbody>
</table>
Table 1: The results for a few representative materials for the chamber walls and sealing conditions. This table illustrates the total change in internal relative humidity and water vapor transmission rate for chambers of various materials and in various conditions.
<img alt="Figure 13" class="xfigimg" src="/files/ftp_upload/56925/56925fig13.jpg" /> 
Figure 13: Water vapor transmission rate plots. (a) This panel shows a change of relative humidity used to determine the WVTR using equation 3. The dependent variable is the unitless natural logarithm of the ratio of the relative humidity (RH) of the internal and external sensors, plotted against time (see equation 3 in the Representative Results). The slope of the reduced square linear regression line is proportional to the WVTR, reported in Table 1 (R2 = 0.99). (b) This panel shows a change of the relative humidity for a 50% PLA 3D-printed chamber under various conditions. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56925/56925fig13large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
Device Degradation Test:
To test the degradation in the device performance under continuous operation, diodes were electrically stressed every 5 min from -5 to 5 V, to record the dark current response as a current-voltage curve. Figure 14 shows a comparison between the change in current at 4 V for a device tested inside the chamber versus a standard encapsulated diode. Due to the increased resistance, the device in the chamber has a slightly lower initial current than the encapsulated device. For both devices, an initial increase in the current is observed over the first 50 min period. After a maximum current is attained around 50 - 60 min, there is an inversion in the current curves and the current starts to decrease. This behavior is expected for this type of device, as the formation of a thin oxide interlayer at the top contact electrode initially improves the interface characteristics between the metal and the organic semiconductor6. This effect is much more pronounced in the device in the chamber, suggesting greater and faster oxidation. This underscores that the chamber is not intended to be a replacement for the encapsulation for long-term storage, but a portable controlled environment that can be used to measure changing device properties. Adding gas ports with flowing inert gases which decrease the WVTR would likely improve the stability of devices inside the chamber.
As the device is further stressed, the active layer begins to degrade due to a variety of interactions6,7,8,22. Both devices show around 0.3 - 0.4 &#181;A/min of loss-of-current as the measurement proceeds, though again, the chamber shows a higher rate of degradation. This underscores that the device inside the measurement chamber is behaving equivalently to the encapsulated device under electrical stress. As shown in Figure 14, the decay curves, based on the normalized current change over time, suggests a T80 for continuous use that is similar for the two devices (26 h vs. 30 h), though slightly longer for the encapsulated device.
<img alt="Figure 14" class="xfigimg" src="/files/ftp_upload/56925/56925fig14.jpg" /> 
Figure 14: Operational device degradation. (a) This panel shows a measured dark current at 4 V for IV measurements taken every 5 min for a standard organic solar cell device. (b) This panel shows normalized dark current decay curves at 4 V, I/Io, where Io is the initial current. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56925/56925fig14large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
In the raw data decay curve for the encapsulated organic device (Figure 14a), a sharp decline is observed between the first and second measurement over the course of 5 min. This decline is not observed for the organic device tested in the chamber. This is likely a result of the fact that it takes longer to assemble the organic device inside the chamber and attach it to the ZIF board whereas the encapsulated device can be directly measured immediately upon being removed from the glovebox environment.

Watch this Scientific Journal Video about A 3D-printed Chamber for Organic Optoelectronic Device Degradation Testing at JoVE.com

A 3D-printed Chamber for Organic Optoelectronic Device Degradation Testing

Here, we present a protocol for the design, manufacture, and use of a simple, versatile 3D-printed and controlled atmospheric chamber for the optical and electrical characterization of air-sensitive organic optoelectronic devices.

In this manuscript, we outline the manufacture of a small, portable, easy-to-use atmospheric chamber for organic and perovskite optoelectronic devices, ...

a-3d-printed-chamber-for-organic-optoelectronic-device-degradation

Nanyang Technological University

Research

JoVE Journal

Engineering

7.9K Views.  McMaster University. Here, we present a protocol for the design, manufacture, and use of a simple, versatile 3D-printed and controlled atmospheric chamber for the optical and electrical characterization of air-sensitive organic optoelectronic devices.

Video: A 3D-printed Chamber for Organic Optoelectronic Device Degradation Testing

Controlling the Size, Shape and Stability of Supramolecular Polymers in Water

For aqueous based supramolecular polymers, the simultaneous control over shape, size and stability is very difficult1. At the same time, the ability to do so is highly important in view of a number of applications in functional soft matter including electronics, biomedical engineering, and sensors. In the past, successful strategies to control the size and shape of supramolecular polymers typically focused on the use of templates2,3, end cappers4 or selective solvent techniques5. 
Here we disclose a strategy based on self-assembling discotic amphiphiles that leads to the control over stack length and shape of ordered, chiral columnar aggregates. By balancing electrostatic repulsive interactions on the hydrophilic rim and attractive non-covalent forces within the hydrophobic core of the polymerizing building block, we manage to create small and discrete spherical objects6,7. Increasing the salt concentration to screen the charges induces a sphere-to-rod transition. Intriguingly, this transition is expressed in an increase of cooperativity in the temperature-dependent self-assembly mechanism, and more stable aggregates are obtained. 
For our study we select a benzene-1,3,5-tricarboxamide (BTA) core connected to a hydrophilic metal chelate via a hydrophobic, fluorinated L-phenylalanine based spacer (Scheme 1). The metal chelate selected is a Gd(III)-DTPA complex that contains two overall remaining charges per complex and necessarily two counter ions. The one-dimensional growth of the aggregate is directed by &pi;-&pi; stacking and intermolecular hydrogen bonding. However, the electrostatic, repulsive forces that arise from the charges on the Gd(III)-DTPA complex start limiting the one-dimensional growth of the BTA-based discotic once a certain size is reached. At millimolar concentrations the formed aggregate has a spherical shape and a diameter of around 5 nm as inferred from 1H-NMR spectroscopy, small angle X-ray scattering, and cryogenic transmission electron microscopy (cryo-TEM). The strength of the electrostatic repulsive interactions between molecules can be reduced by increasing the salt concentration of the buffered solutions. This screening of the charges induces a transition from spherical aggregates into elongated rods with a length &gt; 25 nm. Cryo-TEM allows to visualise the changes in shape and size. In addition, CD spectroscopy permits to derive the mechanistic details of the self-assembly processes before and after the addition of salt. Importantly, the cooperativity -a key feature that dictates the physical properties of the produced supramolecular polymers- increases dramatically upon screening the electrostatic interactions. This increase in cooperativity results in a significant increase in the molecular weight of the formed supramolecular polymers in water.

The goal of this experiment is to determine and control the size, shape and stability of self-assembled discotic amphiphiles in water. For aqueous based supramolecular polymers such level of control is very difficult. We apply a strategy using both repulsive and attractive interactions. The experimental techniques applied to characterize this system are broadly applicable.

For aqueous based supramolecular polymers, the simultaneous control over shape, size and stability is very difficult1. At the same time, the ability to do ...

Characterization of Recombination Effects in a Liquid Ionization Chamber Used for the Dosimetry of a Radiosurgical Accelerator

Most modern radiation therapy devices allow the use of very small fields, either through beamlets in Intensity-Modulated Radiation Therapy (IMRT) or via stereotactic radiotherapy where positioning accuracy allows delivering very high doses per fraction in a small volume of the patient. Dosimetric measurements on medical accelerators are conventionally realized using air-filled ionization chambers. However, in small beams these are subject to nonnegligible perturbation effects. This study focuses on liquid ionization chambers, which offer advantages in terms of spatial resolution and low fluence perturbation. Ion recombination effects are investigated for the microLion detector (PTW) used with the Cyberknife system (Accuray). The method consists of performing a series of water tank measurements at different source-surface distances, and applying corrections to the liquid detector readings based on simultaneous gaseous detector measurements. This approach facilitates isolating the recombination effects arising from the high density of the liquid sensitive medium and obtaining correction factors to apply to the detector readings. The main difficulty resides in achieving a sufficient level of accuracy in the setup to be able to detect small changes in the chamber response.

A growing number of radiation therapy devices offer the advantage of delivering the dose through very small beams to the tumor, allowing for increased conformity and higher doses per fraction. Many different detectors can be used for the dosimetry of these small fields. In the present study, the effect of ion recombination is investigated for a liquid ionization chamber using a stereotactic radiation therapy system.

Most modern radiation therapy devices allow the use of very small fields, either through beamlets in Intensity-Modulated Radiation Therapy (IMRT) or via ...

Methods for Measuring the Orientation and Rotation Rate of 3D-printed Particles in Turbulence

Experimental methods are presented for measuring the rotational and translational motion of anisotropic particles in turbulent fluid flows. 3D printing technology is used to fabricate particles with slender arms connected at a common center. Shapes explored are crosses (two perpendicular rods), jacks (three perpendicular rods), triads (three rods in triangular planar symmetry), and tetrads (four arms in tetrahedral symmetry). Methods for producing on the order of 10,000 fluorescently dyed particles are described. Time-resolved measurements of their orientation and solid-body rotation rate are obtained from four synchronized videos of their motion in a turbulent flow between oscillating grids with R&#955; = 91. In this relatively low-Reynolds number flow, the advected particles are small enough that they approximate ellipsoidal tracer particles. We present results of time-resolved 3D trajectories of position and orientation of the particles as well as measurements of their rotation rates.

We use 3D printing to fabricate anisotropic particles in the shapes of jacks, crosses, tetrads, and triads, whose alignments and rotations in turbulent fluid flow can be measured from multiple simultaneous video images.

Experimental methods are presented for measuring the rotational and translational motion of anisotropic particles in turbulent fluid flows. 3D printing ...

Testing of Nanoparticle Release from a Composite Containing Nanomaterial Using a Chamber System

With the rapid development of nanotechnology as one of the most important technologies in the 21st century, interest in the safety of consumer products containing nanomaterials is also increasing. Evaluating the nanomaterial release from products containing nanomaterials is a crucial step in assessing the safety of these products, and has resulted in several international efforts to develop consistent and reliable technologies for standardizing the evaluation of nanomaterial release. In this study, the release of nanomaterials from products containing nanomaterials is evaluated using a chamber system that includes a condensation particle counter, optical particle counter, and sampling ports to collect filter samples for electron microscopy analysis. The proposed chamber system is tested using an abrasor and disc-type nanocomposite material specimens to determine whether the nanomaterial release is repeatable and consistent within an acceptable range. The test results indicate that the total number of particles in each test is within 20% from the average after several trials. The release trends are similar and they show very good repeatability. Therefore, the proposed chamber system can be effectively used for nanomaterial release testing of products containing nanomaterials.

Nanoparticle release is tested using a chamber system that includes a condensation particle counter, an optical particle counter and sampling ports to collect filter samples for microscopy analysis. The proposed chamber system can be effectively used for nanomaterial release testing with a repeatable and consistent data range.

With the rapid development of nanotechnology as one of the most important technologies in the 21st century, interest in the safety of consumer products ...

Scanning Light Scattering Profiler (SLPS) Based Methodology to Quantitatively Evaluate Forward and Backward Light Scattering from Intraocular Lenses

The scanning light scattering profiler (SLSP) methodology has been developed for the full-angle quantitative evaluation of forward and backward light scattering from intraocular lenses (IOLs) using goniophotometer principles. This protocol describes the SLSP platform and how it employs a 360&#176; rotational photodetector sensor that is scanned around an IOL sample while recording the intensity and location of scattered light as it passes through the IOL medium. The SLSP platform can be used to predict, non-clinically, the propensity for current and novel IOL designs and materials to induce light scatter. Non-clinical evaluation of light scattering properties of IOLs can significantly reduce the number of patient complaints related to unwanted glare, glistening, optical defects, poor image quality, and other phenomena associated with the unintended light scattering. Future studies should be conducted to correlate SLSP data with clinical results to help identify which measured light scatter is most problematic for patients that have undergone cataract surgery subsequent to IOL implantation.

Scanning Light Scattering Profiler SLPS Based Methodology to Quantitatively Evaluate Forward and Backward Light Scattering from Intraocular Lenses

This protocol describes the scanning light scattering profiler (SLSP) that enables the full-angle quantitative evaluation of forward and backward scattering of light from intraocular lenses (IOLs) using goniophotometer principles.

The scanning light scattering profiler (SLSP) methodology has been developed for the full-angle quantitative evaluation of forward and backward light ...

Subsurface Defect Localization by Structured Heating Using Laser Projected Photothermal Thermography

The presented method is used to locate subsurface defects oriented perpendicularly to the surface. To achieve this, we create destructively interfering thermal wave fields that are disturbed by the defect. This effect is measured and used to locate the defect. We form the destructively interfering wave fields by using a modified projector. The original light engine of the projector is replaced with a fiber-coupled high-power diode laser. Its beam is shaped and aligned to the projector&#39;s spatial light modulator and optimized for optimal optical throughput and homogeneous projection by first characterizing the beam profile, and, second, correcting it mechanically and numerically. A high-performance infrared (IR) camera is set up according to the tight geometrical situation (including corrections of the geometrical image distortions) and the requirement to detect weak temperature oscillations at the sample surface. Data acquisition can be performed once a synchronization between the individual thermal wave field sources, the scanning stage, and the IR camera is established by using a dedicated experimental setup which needs to be tuned to the specific material being investigated. During data post-processing, the relevant information on the presence of a defect below the surface of the sample is extracted. It is retrieved from the oscillating part of the acquired thermal radiation coming from the so-called depletion line of the sample surface. The exact location of the defect is deduced from the analysis of the spatial-temporal shape of these oscillations in a final step. The method is reference-free and very sensitive to changes within the thermal wave field. So far, the method has been tested with steel samples but is applicable to different materials as well, in particular to temperature sensitive materials.

This method aims at locating vertical subsurface defects. Here, we couple a laser with a spatial light modulator and trigger its video input to heat a sample surface deterministically with two anti-phased modulated lines while acquiring highly resolved thermal images. The defect position is retrieved from evaluating thermal wave interference minima.

The presented method is used to locate subsurface defects oriented perpendicularly to the surface. To achieve this, we create destructively interfering ...

Preparation of Liquid Crystal Networks for Macroscopic Oscillatory Motion Induced by Light

A strategy based on doped liquid crystalline networks is described to create mechanical self-sustained oscillations of plastic films under continuous light irradiation. The photo-excitation of dopants that can quickly dissipate light into heat, coupled with anisotropic thermal expansion and self-shadowing of the film, gives rise to the self-sustained deformation. The oscillations observed are influenced by the dimensions and the modulus of the film, and by the directionality and intensity of the light. The system developed offers applications in energy conversion and harvesting for soft-robotics and automated systems.
The general method described here consists of creating free-standing liquid crystalline films and characterizing the mechanical and thermal effects observed. The molecular alignment is achieved using alignment layers (rubbed polyimide), commonly used in the display manufacturing industry. To obtain actuators with large deformation, the mesogens are aligned and polymerized in a splay/bend configuration, i.e., with the director of the liquid crystals (LCs) going gradually from planar to homeotropic through the film thickness. Upon irradiation, the mechanical and thermal oscillations obtained are monitored with a high-speed camera. The results are further quantified by image analysis using an image processing program.

The goal of the protocol is to create liquid crystalline polymer films that can mechanically oscillate under continuous light irradiation. We describe in great detail the conception of free-standing films, from the liquid crystal alignment method to the photo-actuation. The experimental protocol applied to prepare this material is broadly applicable.

A strategy based on doped liquid crystalline networks is described to create mechanical self-sustained oscillations of plastic films under continuous ...

Atmospheric Pressure Fabrication of Large-Sized Single-Layer Rectangular SnSe Flakes

Tin selenide (SnSe) belongs to the family of layered metal chalcogenide materials with a buckled structure like phosphorene, and has shown potential for applications in two-dimensional nanoelectronics devices. Although many methods to synthesize SnSe nanocrystals have been developed, a simple way to fabricate large-sized single-layer SnSe flakes remains a great challenge. Herein, we show the experimental method to directly grow large-sized single-layer rectangular SnSe flakes on commonly used SiO2/Si insulating substrates using a straightforward two-step fabrication method in an atmospheric pressure quartz tube furnace system. The single-layer rectangular SnSe flakes with an average thickness of ~6.8 &#197; and lateral dimensions of about 30 &#181;m &#215; 50 &#181;m were fabricated by a combination of vapor transport deposition technique and nitrogen etching route. We characterized the morphology, microstructure, and electrical properties of the rectangular SnSe flakes and obtained excellent crystallinity and good electronic properties. This article about the two-step fabrication method can help researchers grow other similar two-dimensional, large-sized, single-layer materials using an atmospheric pressure system.

A protocol is presented demonstrating a two-step fabrication technique to grow large-sized single-layer rectangular shaped SnSe flakes on low-cost SiO2/Si dielectrics wafers in an atmospheric pressure quartz tube furnace system.

Tin selenide (SnSe) belongs to the family of layered metal chalcogenide materials with a buckled structure like phosphorene, and has shown potential for ...

A Standard and Reliable Method to Fabricate Two-Dimensional Nanoelectronics

Two-dimensional (2D) materials have attracted huge attention due to their unique properties and potential applications. Since wafer scale synthesis of 2D materials is still in nascent stages, scientists cannot fully rely on traditional semiconductor techniques for related research. Delicate processes from locating the materials to electrode definition need to be well controlled. In this article, a universal fabrication protocol required in manufacturing nanoscale electronics, such as 2D quasi-heterojunction bipolar transistors (Q-HBT), and 2D back-gated transistors are demonstrated. This protocol includes the determination of material position, electron beam lithography (EBL), metal electrode definition, et al. A step by step narrative of the fabrication procedures for these devices are also presented. Furthermore, results show that each of the fabricated devices has achieved high performance with high repeatability. This work reveals a comprehensive description of process flow for preparing 2D nano-electronics, enables the research groups to access this information, and pave the way toward future electronics.

The article aims to introduce a standard and reliable fabrication procedure for the development of future low dimensional nanoelectronics.

Two-dimensional (2D) materials have attracted huge attention due to their unique properties and potential applications. Since wafer scale synthesis of 2D ...

Method Development for Contactless Resonant Cavity Dielectric Spectroscopic Studies of Cellulosic Paper

The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of data that can be obtained from an individual sample and renders it difficult to produce statistically relevant data for unique and rare materials. Resonant cavity dielectric spectroscopy is a non-destructive, contactless technique which can simultaneously interrogate both sides of a sheeted material and provide measurements which are suitable for statistical interpretations. This offers analysts the ability to quickly discriminate between sheeted materials based on composition and storage history. In this methodology article, we demonstrate how contactless resonant cavity dielectric spectroscopy may be used to differentiate between paper analytes of varying fiber species compositions, to determine the relative age of the paper, and to detect and quantify the amount of post-consumer waste (PCW) recycled fiber content in manufactured office paper.

A protocol for the non-destructive analysis of the fiber content and relative age of paper.

The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of ...