The project (WASP) leading to this publication, has received funding from the European Union&#8217;s Horizon 2020 Research and Innovation Program under grant agreement No. 825213.

1. Operation of the FIRA Oven
NOTE: A schematic of the FIRA oven, developed in-house, is shown in Figure 1A. The FIRA oven is composed of an array of six near-infrared halogen lamps (peak emission at wavelength of 1,073 nm) with an illumination power of 3,000 kW/m2 and a total output power of 9,600 kW. A hollow aluminum body provides an effective water-cooling system and it in turn allows rapid thermal energy dissipation (within seconds). It is kept in a nitrogen glovebox, and N2 is continuously flowed through the chamber via a gas inlet to keep it under an inert atmosphere, except during annealing. O2 can also be introduced when annealing metal oxide films to promote oxidation.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/61730/61730fig01.jpg" /> 
Figure 1: (A) Schematic showing cross-section of the FIRA oven. The oven chamber is continuously cooled by water flowing through the case and kept under an N2 atmosphere. (B) Picture of the FIRA oven. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61730/61730fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/61730/61730fig02.jpg" /> 
Figure 2: Interface of the FIRA software.&#160;The panel on the left shows the temperature profile, which displays the set point (input program), oven temperature, and pyrometer (substrate surface) temperature. The desired annealing program is inputted on the table on the right. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61730/61730fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<ol>
	<li>Programming of annealing cycles
	<ol>
		<li>Connect the FIRA oven to a computer, from which it can be controlled via a guide user interface (Figure 2) on an in-house software. Based on the experiment, select full-power mode or PID (proportional-integral-derivative) mode. In full-power mode, the IR lamps are either completely on or off, whereas in PID mode, the oven is held at a specific temperature for a certain amount of time by intensity modulation.</li>
		<li>Ensure Table is selected on the Table/Manual toggle and input a timebase that is longer than the total duration of the annealing and cooling processes.</li>
		<li>Full-power mode: Input the times at which the lamps should be on or off in the table on the right of the interface. In this way, single pulses as well as annealing cycles can be programed, allowing control of the pulse length and frequency. This is suitable for films that can be rapidly annealed, or for substrates that cannot tolerate sustained heating (e.g, ~1.5&#8211;2 s for perovskite films).</li>
		<li>PID mode: Input the time and temperature at which the oven should be irradiated in the table. Similar to the working principle of a traditional hotplate, the intensity of the heating source can be modulated. This is suitable for films that typically require longer annealing times (e.g., 15 min at 100 &#176;C for TBAI).</li>
		<li>Data acquisition: Download the temperature profile displayed on the left of the interface as a .txt or spreadsheet file by right-clicking on the profile and then click on Export File. 
		NOTE: The software is used for both data acquisition and system control, where the main raw data acquired is the temperature profile. On the temperature profile (Figure 2), the input program is represented by the &#8220;set point&#8221;. The oven temperature (measured by a K-type thermocouple) and substrate temperature (estimated by a pyrometer) are displayed in real time, giving insight into the thin film crystallization conditions. Please note that the oven temperature does not scale directly with traditional hot plate temperatures as the thermocouple is also directly exposed to IR radiation. Rather, it serves as a reference point for comparison between different FIRA annealing parameters.</li>
	</ol>
	</li>
	<li>General annealing process
	<ol>
		<li>Deposit the precursor via a suitable solution process: spin-coating26, dip-coating27, or doctor-blading28.</li>
		<li>Transfer the substrates into the FIRA oven chamber and close the oven lid. Ensure that nitrogen flow into the chamber is turned off by closing the gas inlet valve.</li>
		<li>Start and stop the annealing by clicking on START table and STOP table on the computer. Alternatively, connect the FIRA oven to a foot pedal, which can also be used to start and stop the program. As a result, annealing can be carried out without removing one&#8217;s hands from the glovebox, allowing for a much smoother and synchronized process.</li>
		<li>When the oven temperature reaches room temperature, remove the substrates from the oven chamber.</li>
	</ol>
	</li>
</ol>
2. MAPbI3 Perovskite Film Synthesis and Optimization on FTO Glass
<ol>
	<li>Perovskite Solution Preparation
	<ol>
		<li>Dissolve methylammonium iodide in anhydrous DMF:DMSO 2:1 v/v to obtain a 1.9 M solution.</li>
		<li>Add an equimolar amount of PbI2 to the solution and dilute with anhydrous DMF:DMSO 2:1 v/v to give a 1.4 M methylammonium lead iodide precursor solution. Heat at 80 &#176;C until complete dissolution and cool to room temperature. 
		NOTE: The solution is prepared and stored in an argon glovebox. The protocol can be paused here.</li>
	</ol>
	</li>
	<li>Perovskite film synthesis
	<ol>
		<li>Use FTO coated glass substrates of 1.7 cm x 2.5 cm.</li>
		<li>Clean the substrates via successive sonication in cleaning soap (2 vol % in deionized H2O), acetone and ethanol for 15 min each, then dry them with compressed air.</li>
		<li>Treat the substrates under UV/ozone in a plasma cleaner for 15 min.</li>
		<li>Input the desired annealing program as per section 1.1.</li>
		<li>Blow the substrate surface with a nitrogen gun to remove dust and other impurities.</li>
		<li>Spin-coat 50 &#181;L of the perovskite precursor at 4,000 rpm for 10 s, with an acceleration of 2000 rpm&#183;s-1.</li>
		<li>Immediately after deposition, transfer the substrate to the FIRA oven for annealing at a range of pulse times as desired (0&#8211;7 s used herein, optimized pulse is 2 s). Start the inputted annealing program by pressing START on the software or stepping on the foot pedal. A color change from yellow to black should be observed, indicating the formation of a 3D perovskite structure.</li>
		<li>Remove the substrate when the oven temperature reaches 25 &#176;C.</li>
		<li>Store the annealed films in a dry air box. 
		NOTE: The FIRA oven and the spin-coater are placed in the same nitrogen glovebox such that solution deposition and annealing can be carried out smoothly and under an inert atmosphere.</li>
	</ol>
	</li>
	<li>Material characterization
	<ol>
		<li>Capture optical images on a polarizing microscope equipped with a xenon light source and infinitely corrected objectives of 10x and 50x.</li>
		<li>Record absorbance spectra simultaneously with an optical fiber integrated into the microscope set-up and connected to a spectrometer (spectral range 300&#8211;1,100 nm). 
		NOTE: The above characterization can be done immediately after annealing, allowing for rapid screening of film quality. The measurements are taken in ambient air and temperature. More in-depth characterization such as scanning electron microscopy (SEM) and X-ray diffraction can be subsequently carried out (see section 3.7).</li>
	</ol>
	</li>
</ol>
3. FCG perovskite solar cell processing
<ol>
	<li>Substrate preparation and cleaning
	<ol>
		<li>Etch one side of the FTO glass substrates with Zn powder and 4 M HCl.</li>
		<li>Clean substrates via successive sonication in cleaning soap (2 vol % in deionized H2O) for 30 min and isopropanol for 15 min, and dry with compressed air.</li>
		<li>Treat under UV/ozone in a plasma cleaner for 5 min.</li>
	</ol>
	</li>
	<li>Compact TiO2 layer
	<ol>
		<li>Heat FTO glass substrates to 450 &#176;C on a sintering hot plate and keep them at this temperature for 15 min before solution deposition.</li>
		<li>Dilute 0.6 mL of titanium diisopropoxide bis(acetylacetonate) and 0.4 mL of acetylacetone in 9 mL of EtOH to give the precursor solution.</li>
		<li>Deposit the solution via spray pyrolysis with oxygen as the carrier gas (0.5 bar) at 45&#176; and a distance of ~20 cm. Leave an interval of 20 s between each spraying cycle.</li>
		<li>Leave the substrates at 450 &#176;C for 5 min more, then cool to room temperature. This gives a compact TiO2 layer of ~30 nm. 
		NOTE: The protocol can be paused here. If the next step is not carried out immediately, re-sinter the substrate at 450 &#176;C for 30 min before deposition of the mesoporous-TiO2 layer.</li>
	</ol>
	</li>
	<li>Mesoporous-TiO2 layer
	<ol>
		<li>Make a precursor solution by diluting TiO2 paste (particle size 30 nm) in EtOH at a concentration of 75 mg/mL. Stir the solution with a magnetic stirrer bar until complete dissolution.</li>
		<li>Spin-coat 50 &#181;L of the solution at 4,000 rpm for 10 s, with a ramp of 2,000 rpm&#183;s-1.</li>
		<li>Program an annealing cycle of 10 pulses, 15 s on and 45 s off in the table on the software.</li>
		<li>Place the substrates in the FIRA oven, and anneal under full power mode with the above annealing cycle by pressing Start Table or stepping on the foot pedal. This yields a 150&#8211;200 nm layer.</li>
		<li>Remove the samples when the oven temperature reaches 25 &#176;C. 
		NOTE: Ensure that the oven is at room temperature or below before starting annealing. With the above cycle, the oven temperature reaches ~600 &#176;C during annealing.</li>
	</ol>
	</li>
	<li>Perovskite layer
	<ol>
		<li>Make a solution of formamidinium iodide (1.12 M), PbI2 (1.4 M), CsI (0.21 M) and GAI (0.07 M) in anhydrous DMF:DMSO 2:1 v/v.</li>
		<li>Spin-coat 40 &#181;L of the solution at 4,000 rpm for 10 s.</li>
		<li>Program an annealing step of 1.6 s on full power mode on the software (this reaches ~90 &#176;C).</li>
		<li>Transfer the substrate to the FIRA oven and start annealing by pressing Start Table or stepping on the foot pedal. The surface should turn from yellow to black.</li>
		<li>Leave the samples in the oven for an additional 10 s for cooling before removal.</li>
	</ol>
	</li>
	<li>Tetrabutyl ammonium iodide (TBAI) post-treatment (optional)
	<ol>
		<li>Dissolve 3 mg of tetrabutyl ammonium iodide in 1 mL of isopropanol.</li>
		<li>Spin-coat the solution at 4,000 rpm for 20 s.</li>
		<li>Program an annealing step at 100 &#176;C for 15 min using PID mode.</li>
		<li>Transfer the substrate to the FIRA oven and anneal with the above program. Cool to 25 &#176;C before the next step.</li>
	</ol>
	</li>
	<li>Hole transporting material and top electrode
	<ol>
		<li>Dissolve spiro-OMeTAD in chlorobenzene (70 mM) and add 4-tert-butylpyridine (TBP), Lithium bis(trifluoromethylsulphonyl)imide) (Li-TFSI, 1.8 M in acetonitrile) and Tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)-cobalt(III) Tris(bis(trifluoromethylsulfonyl) imide) (FK209, 0.25 M in acetonitrile) such that the molar ratio of the additives with respect to spiro-OMeTAD are 3.3, 0.5, and 0.03 for TBP, Li-TFSI, and FK209 respectively.</li>
		<li>Deposit 50 &#181;L of the solution at 4,000 rpm for 20 s under dynamic spin-coating, adding the solution 3 s after the start of the program.</li>
		<li>Leave it to oxidize overnight in a dry air box.</li>
		<li>Deposit 80 nm of gold via thermal evaporation under vacuum. Use a shadow mask to pattern the electrodes.</li>
	</ol>
	</li>
	<li>Photovoltaic device testing and material characterization
	<ol>
		<li>Take photovoltaic measurements using a solar simulator equipped with a xenon arc lamp and a digital source meter. Specify the active area of the device with a black, non-reflective metal mask (0.1024 cm2 used herein). Measure the current-voltage curves under reverse and forward bias at a 10 mV/s scan rate under AM 1.5 G irradiation.</li>
		<li>Take X-ray diffraction patterns with a diffractometer in reflection-spin mode, using Cu K&#945; radiation and a Ni &#946; filter.</li>
		<li>Take scanning electron microscope images at an acceleration voltage of 3 kV.</li>
	</ol>
	</li>
</ol>
4. MAPbI3 films on ITO-PET substrate
<ol>
	<li>Cut ITO-PET and microscope glass slides into pieces of 1.7 cm x 2.5 cm.</li>
	<li>Clean the glass slides and ITO-PET as per steps 2.2.2&#8211;2.2.3.</li>
	<li>Attach the ITO substrates onto the glass slides with double-sided tape, ensuring they are as flat as possible.</li>
	<li>Prepare the MAPbI3 precursor as described in section 2.1. Blow the substrate surface with an N2 gun before spin-coating the solution and annealing the film with FIRA, as per steps 2.2.5&#8211;2.2.8, with a pulse time of 1.7 s.</li>
	<li>Carry out material characterization as described in sections 2.3 and 3.7.</li>
</ol>

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S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Morphology+of+polymer/fullerene+bulk+heterojunction+solar+cells.">Morphology of polymer/fullerene bulk heterojunction solar cells.</a> Journal of Materials Chemistry. 16 (1), 45-61 (2006).</li><li>Paquin, F., Rivnay, J., Salleo, A., Stingelin, N., Silva, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multi-phase+semicrystalline+microstructures+drive+exciton+dissociation+in+neat+plastic+semiconductors.">Multi-phase semicrystalline microstructures drive exciton dissociation in neat plastic semiconductors.</a> Journal of Materials Chemistry C. 3 (41), 10715-10722 (2015).</li><li>Diao, Y., Shaw, L., Bao, Z., Mannsfeld, S. C. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Morphology+control+strategies+for+solution-processed+organic+semiconductor+thin+films.">Morphology control strategies for solution-processed organic semiconductor thin films.</a> Energy &amp; Environmental Sciences. 7 (7), 2145-2159 (2014).</li><li>Slotcavage, D. J., Karunadasa, H. I., McGehee, 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=Light-induced+phase+segregation+in+halide-perovskite+absorbers.">Light-induced phase segregation in halide-perovskite absorbers.</a> ACS Energy Letters. 1 (6), 1199-1205 (2016).</li><li>Jiang, Q., 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=Surface+passivation+of+perovskite+film+for+efficient+solar+cells.">Surface passivation of perovskite film for efficient solar cells.</a> Nature Photonics. 13 (7), 460-466 (2019).</li><li>Yang, W. S., 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=Iodide+Management+in+formamidinium-lead-halide-based+perovskite+layers+for+efficient+solar+cells.">Iodide Management in formamidinium-lead-halide-based perovskite layers for efficient solar cells.</a> Science. 356 (6345), 1376-1379 (2017).</li><li>Almadhoun, M. N., Khan, M. A., Rajab, K., Park, J. H., Buriak, J. M., Alshareef, H. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=UV-Induced+ferroelectric+phase+transformation+in+PVDF+thin+films.">UV-Induced ferroelectric phase transformation in PVDF thin films.</a> Advanced Electronic Materials. 5 (1), 1800363 (2019).</li><li>Hooper, K., Smith, B., Baker, J., Greenwood, P., Watson, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spray+PEDOT:PSS+coated+perovskite+with+a+transparent+conducting+electrode+for+low+cost+scalable+photovoltaic+devices.">Spray PEDOT:PSS coated perovskite with a transparent conducting electrode for low cost scalable photovoltaic devices.</a> Materials Research Innovations. 19 (7), 482-487 (2015).</li></ol>

The authors have nothing to disclose.

Figure 9 shows the general process of perovskite film annealing with FIRA.
<img alt="Figure 9" class="xfigimg" src="/files/ftp_upload/61730/61730fig09.jpg" /> 
Figure 9: Schematic representation of perovskite film processing with FIRA.&#160;The wet film is deposited from the solution by spin-coating and subsequently transferred to the FIRA oven for annealing in ~2 s, giving the black perovskite stable phase. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61730/61730fig09large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
In the solidification process of a thin film from the solution, the desired final shape will depend on the application: films in energy devices for photocatalysis, battery electrodes, and solar cells can have different morphologies30,31,32,33. Therefore, identifying the optimal parameters for each substrate and wet film interface is a critical step in the protocol to follow. Typically, for PSCs we expect to have shiny and smooth films in order to minimize defects and to enhance the photophysical properties such as charge transport of carriers to give null non-radiative recombination34,35,36. For thin film processing, the main parameters are pulse time, the number of pulses, and the irradiation temperature, which are a balance between forming the desired morphology while being as rapid and energy efficient as possible. Insufficient energy would lead to incomplete solvent evaporation or crystallization, while excess energy would lead to degradation of the material. Therefore, it is crucial to systematically vary the annealing parameters and analyze the resulting film quality (as detailed in sections 2.2, 2.3, and 3.7) to find the optimal parameters for each thin film/substrate combination. Once this is completed, thin films can be synthesized rapidly and reliably. The method relies on its accuracy, for example, the minimum pulse time is 20 ms, allowing one to finely control the temperature ratio for crystal growth. Besides, one can have a wide window for optimization, aided by the data collection of images and absorption spectra for optical and morphological screening.
The FIRA method is still in development, and, as its name implies, it is currently based on IR irradiation. However, the latest version of FIRA includes UV-A radiation generated from a separate metal-halide lamp source. UV and IR can be used for combined wavelength photonic annealing and curing, providing additional functionality. For example, semiconductor curing with FIRA is a straightforward way to improve the wettability of substrates. Additionally, for a multi-layered approach in crystal growth, this selective wavelength annealing can be adapted depending on the material, and the pulse can be modulated depending on the desired shape16,32,37. Current investigations include annealing of an ITO electrode and a mesoscopic-TiO2 layer on paper (the latter using mixed IR/UV annealing, see Supplemental Figure 5 in the supplementary information). As shown in Supplemental Figure 6, a perovskite film can be successfully deposited on the FIRA-annealed ITO/TiO2 stack. This can be applied to a wide range of substrates and thin films in the future.
So far, the FIRA method is limited to the annealing of wet films that can be deposited via solution processes. It depends on the capability of the deposition method, and this is governed by solvent engineering and multi-layered growth based on solutions with approaching solvent polarities. Optimization is also required for each thin film as this is a novel method without a lot of previously reported protocols in literature, which may be time-consuming. Additionally, although FIRA can be used for flexible substrates such as PET and paper as there is rapid cooling from the case, a good contact between the substrate and the oven chamber must be ensured to avoid substrate melting. This may be difficult since flexible substrates are easily bent during processing, but this may be improved by attaching the substrates on a thin glass slide to ensure that they are completely flat and to allow ease of manipulation. However, it is important to note that the absorption of the film will change as the material transitions from non-absorbing (wet NIR-transparent perovskite precursor material) to dry (NIR-absorbing black perovskite) and this additional absorption can contribute to the damage of the substrate38.
Despite these limitations, FIRA still presents many advantages in comparison to the antisolvent method. Firstly, thin films can be synthesized much quicker. For example, the perovskite is formed in &#60;2 s while the mesoporous-TiO2 layer is formed in only 10 min, much shorter than the hours required in the conventional method. The elimination of the antisolvent and the shorter annealing times also mean that there is a much lower energetic and financial cost. Life cycle assessment (Figure 10) of the perovskite synthesis process shows that FIRA presents only 8% of the environmental impact and 2% of the fabrication cost of the antisolvent method. Additionally, it is compatible with flexible and large-area substrates. A total area of 10 x 10 cm2 can be irradiated at one time, and it has already been shown that devices of 1.4 cm2 active area as well as films of 100 cm2 can be synthesized this way. Finally, it is highly reproducible, versatile, and adaptable to fast throughput roll-to-roll manufacturing, as the deposition and annealing steps are carried out continuously in one place in a synchronized and smooth process.
<img alt="Figure 10" class="xfigimg" src="/files/ftp_upload/61730/61730fig10.jpg" /> 
Figure 10: A comparison of the relative cost and environmental impact of FIRA and anti-solvent methods determined by life cycle assessment.&#160;GWP = Climate change [kg CO2 eq], POP = Photochemical oxidation [kg C2H4 eq], AP = Acidification [kg SO2 eq], CED = Cumulative energy demand [MJ], HTC = Human Toxicity, cancer effects [CTUh], HTNC = Human Toxicity, non-cancer effects [CTUh], ET = Freshwater ecotoxicity [CTUe]. Reproduced with permission from12. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61730/61730fig10large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
Current investigations on FIRA are focused on optimization for thin film synthesis on flexible substrates such as paper and PET, as well as for the synthesis of other key component layers of PSCs such as the SnO2 compact layer, or carbon and ITO electrodes. Furthermore, the next step is to fabricate high-performing devices of &#62;5 cm2. Therefore, it can be said that FIRA represents a step toward an environmentally friendly and cost-efficient way to manufacture large-area, commercial PSCs.

Since their inception in 2009, solar cells based on lead halide perovskites have demonstrated unprecedented growth, with power conversion efficiencies (PCE) increasing from 3.8%1 to 25.2%2 in just over a decade of development. Recently, there has also been interest in the development of perovskite solar cells (PSCs) on flexible substrates such as polyethylene terephthalate (PET) as they are lightweight, cheap, applicable to roll-to-roll manufacturing and can be used to power flexible electronics3,4. In the past decade, the PCE of flexible PSCs has improved significantly from 2.62% to 19.1%5.
The majority of the current processing methods for PSCs involve deposition of the perovskite precursor solution, addition of an antisolvent (AS) such as chlorobenzene to induce nucleation and finally thermal annealing to evaporate the solvent and promote crystallization of the perovskite in the desired morphology6,7,8,9. This method requires moderate amounts of organic solvent (~100 &#181;L per 2 x 2 cm substrate) that is typically not reclaimed, is difficult to apply on large-area substrates and is not always reproducible. Additionally, the perovskite layer requires annealing at &#62;100 &#176;C for up to 120 min while the mesoporous-TiO2 electron transporting layer requires sintering at 450 &#176;C for at least 30 min, which not only leads to a large electronic cost and a potential bottleneck in the eventual upscaling of PSCs, but is also incompatible with flexible substrates which typically cannot sustain heating at &#8805;250 &#176;C10,11,12. Alternative manufacturing methods must, therefore, be found to commercialize this technology3,13,14.
Flash infrared annealing, first reported in 201511, is a low-cost, environmentally friendly and rapid method for the synthesis of compact and defect-tolerant perovskite and metal oxide thin films that eliminates the need for an antisolvent and is compatible with flexible substrates. In this method, freshly-spin-coated perovskite films are exposed to near-IR radiation (700&#8211;2,500 nm, peaking at 1,073 nm). Both TiO2 and perovskite have low absorbance in this region, whereas FTO is a strong NIR absorber and rapidly heats up, evaporating the solvent and indirectly annealing the active material11,15. A short 2 s pulse can heat the FTO substrate to 480 &#176;C, while the perovskite remains at ~70 &#176;C, promoting vertical evaporation of the solvent and lateral growth of crystals across the substrate. Heat is quickly dissipated via cooling from the external case, and within seconds, room temperature is reached.
The nucleation and crystallization processes, and thus the final morphology of the film, can be varied through FIRA parameters such as pulse length, frequency, and intensity, allowing for a much more reproducible and controllable crystal growth16. Assuming time-limited nucleation, the pulse length determines the nucleation density whereas the pulse intensity determines the energy provided for crystallization. Insufficient energy would result in incomplete solvent evaporation or crystallization, whereas excess energy would result in thermal degradation of the perovskite15. Optimization of these factors is, therefore, important for the formation of a homogeneous perovskite film, which can affect the optoelectronic properties of the final device.
Compared to the AS method, FIRA has a slower nucleation and faster crystal growth, leading to larger crystalline domains (~40 &#181;m for FIRA vs ~200 nm for AS)16. The lower nucleation rate could be due to a lower supersaturation or a limited nucleation phase as controlled by the duration of the pulse15. However, the difference in grain size does not affect charge carrier mobility and lifetime (mobility ~15 cm2/Vs for AS and ~19 cm2/Vs for FIRA)17 and gives films with similar structural and optical properties, as measured by X-ray diffraction (XRD) and photoluminescence (PL)12. In fact, reports suggest that larger grain sizes are favorable due to suppressed perovskite degradation at grain boundaries4. Compact, defect-tolerant, and highly crystalline perovskite films can be formed with both methods, giving devices with &#62;20% PCE18.
Additionally, the elimination of the antisolvent and the reduction in annealing time from hours to seconds make it much more cost-effective and environmentally friendly. With this method, a crystalline mesoscopic-TiO2 layer can also be manufactured, reducing the energy-intensive sintering step (at 450 &#176;C for 30 min, 1&#8211;3 h in total) to just 10 min16,18. TiO2 annealing times as short as seconds have also been previously reported using variations of this method19,20,21,22. As a result, a whole PSC can be fabricated in less than an hour18. This method is also compatible with industrial upscaling and commercialization as it can be adapted to large-area deposition and roll-to-roll processing for fast and synchronized throughput production15. Furthermore, the water-cooling system allows rapid heat dissipation, making it suitable for the fabrication of devices on flexible substrates such as PET.
FIRA can be used for any wet, thin film that can be deposited via a simple solution process and crystallized at different temperatures up to 1,000 &#176;C. The parameters can be optimized such that crystals in the desired morphology are formed. For example, it has been used for the synthesis of various perovskite compositions on glass and PET12,15,18, as well as the mesoscopic-TiO2 layer on glass, giving devices of &#62;20% PCE18. It also allows for the study of phase evolution against temperature, as the oven and substrate surface temperatures are measured to give a temperature profile of the crystallization process16,17.
This paper firstly discusses the protocol used for the optimization of annealing parameters to synthesize a compact, defect-tolerant, and homogeneous perovskite (MAPbI3) film, which simultaneously offers insight into perovskite morphology evolution against temperature/pulse time. Secondly, a protocol for the processing of perovskite solar cells with FIRA-annealed mesoscopic-TiO2 and perovskite layers is discussed. For this study, a perovskite composition based on formamidinium (80%), caesium (15%), and guanidinium (5%) cations was used (herein denoted FCG), and a tetrabutyl ammonium iodide (TBAI) post-treatment was carried out. Therefore, this paper aims to demonstrate the versatility of the FIRA method, its advantages over the conventional antisolvent method, and its potential to be applied in the eventual commercialization of perovskite solar cells20,21,22.
This protocol is divided into 4 sections: 1) A general description of the operation of the FIRA oven 2) Process for the optimization and synthesis of a MAPbI3 perovskite film on FTO glass 3) Processing of FCG perovskite solar cells and 4) Synthesis of MAPbI3 films on ITO-PET.

<table>
	<tbody>
		<tr>
			<td>4-tert-butylpyridine</td>
			<td>Sigma Aldrich</td>
			<td>142379</td>
			<td></td>
		</tr>
		<tr>
			<td>Acetonitrile, anhydrous</td>
			<td>ACROS Organics</td>
			<td>AC610220010</td>
			<td></td>
		</tr>
		<tr>
			<td>Acetylacetone</td>
			<td>Sigma Aldrich</td>
			<td>P7754</td>
			<td></td>
		</tr>
		<tr>
			<td>Caesium iodide</td>
			<td>Sigma Aldrich</td>
			<td>203033</td>
			<td></td>
		</tr>
		<tr>
			<td>Chlorobenzene, anhydrous</td>
			<td>ACROS Organics</td>
			<td>AC396971000</td>
			<td></td>
		</tr>
		<tr>
			<td>Digital source meter</td>
			<td>Metrohm</td>
			<td>PGSTAT302N Autolab</td>
			<td></td>
		</tr>
		<tr>
			<td>DMF, anhydrous</td>
			<td>ACROS Organics</td>
			<td>AC326871000</td>
			<td></td>
		</tr>
		<tr>
			<td>DMSO, anhydrous</td>
			<td>ACROS Organics</td>
			<td>AC326881000</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Sigma Aldrich</td>
			<td>459844</td>
			<td></td>
		</tr>
		<tr>
			<td>FIRA Software</td>
			<td>Labview</td>
			<td></td>
			<td>Developed in-house</td>
		</tr>
		<tr>
			<td>FK209</td>
			<td>Dyenamo</td>
			<td>DN-P04</td>
			<td></td>
		</tr>
		<tr>
			<td>Formamidinium iodide</td>
			<td>GreatCell Solar</td>
			<td>SKU MS150000</td>
			<td></td>
		</tr>
		<tr>
			<td>FTO glass</td>
			<td>Nippon Sheet Glass</td>
			<td>NSG 10</td>
			<td>Sheet resistance = 11-13 ohms/sq</td>
		</tr>
		<tr>
			<td>Guanidinium iodide</td>
			<td>Sigma Aldrich</td>
			<td>806056</td>
			<td></td>
		</tr>
		<tr>
			<td>Cleaning Soap</td>
			<td>Hellmanex III</td>
			<td>-</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrochloric acid</td>
			<td>Sigma Aldrich</td>
			<td>320331</td>
			<td></td>
		</tr>
		<tr>
			<td>Isopropanol</td>
			<td>Sigma Aldrich</td>
			<td>190764</td>
			<td></td>
		</tr>
		<tr>
			<td>ITO PET</td>
			<td>Sigma Aldrich</td>
			<td>639303</td>
			<td>Sheet resistance = 60 ohms/sq</td>
		</tr>
		<tr>
			<td>Lead iodide</td>
			<td>TCI</td>
			<td>L0279</td>
			<td></td>
		</tr>
		<tr>
			<td>Li-TFSI</td>
			<td>Sigma Aldrich</td>
			<td>544094</td>
			<td></td>
		</tr>
		<tr>
			<td>Mesoporous TiO2 paste, 3 nrd</td>
			<td>GreatCell Solar</td>
			<td>SKU MS002300</td>
			<td></td>
		</tr>
		<tr>
			<td>Methylammonium iodide</td>
			<td>GreatCell Solar</td>
			<td>SKU MS1010000</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope</td>
			<td>Zeiss</td>
			<td>Axio-Scope A1 Polarizing Microscope</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope lens</td>
			<td>Zeiss</td>
			<td>EC Epiplan-Apochromat</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope xenon light source</td>
			<td>Ocean Optics</td>
			<td>HPX-2000</td>
			<td></td>
		</tr>
		<tr>
			<td>Optical fibre</td>
			<td>Ocean Optics</td>
			<td>QP230-2-XSR</td>
			<td>230 &#956;m core</td>
		</tr>
		<tr>
			<td>Plasma cleaner</td>
			<td>Jetlight Company Inc.</td>
			<td>UVO-Cleaner Model no. 256-220</td>
			<td></td>
		</tr>
		<tr>
			<td>Polymer-planarised paper</td>
			<td>Arjowiggins</td>
			<td>Powercoat HD</td>
			<td></td>
		</tr>
		<tr>
			<td>Scanning electron microscope</td>
			<td>Zeiss</td>
			<td>Merlin Microscope</td>
			<td></td>
		</tr>
		<tr>
			<td>Sintering hot plate</td>
			<td>Harry Gestigkeit GMBH</td>
			<td>-</td>
			<td></td>
		</tr>
		<tr>
			<td>Solar simulator</td>
			<td>ABET Technologies</td>
			<td>Model 11016 Sun 2000</td>
			<td></td>
		</tr>
		<tr>
			<td>Spectrometer</td>
			<td>Ocean Optics</td>
			<td>Maya2000 Pro</td>
			<td>Spectral range: 300-1100 nm</td>
		</tr>
		<tr>
			<td>Spiro-OMeTAD</td>
			<td>Sigma Aldrich</td>
			<td>792071</td>
			<td></td>
		</tr>
		<tr>
			<td>Tetrabutyl ammonium iodide</td>
			<td>GreatCell Solar</td>
			<td>SKU MS106000</td>
			<td></td>
		</tr>
		<tr>
			<td>Thermal evaporator</td>
			<td>Kurt J. Lesker</td>
			<td>-</td>
			<td></td>
		</tr>
		<tr>
			<td>titanium diisopropoxide bis(acetylacetonate)</td>
			<td>Sigma Aldrich</td>
			<td>325252</td>
			<td></td>
		</tr>
		<tr>
			<td>X-ray diffractometer</td>
			<td>PANanalytical</td>
			<td>Empyrean diffractometer (theta-theta, 240 mm)</td>
			<td>equipped with a PIXcel-1D detector, Bragg-Brentano beam optics and parallel beam optics</td>
		</tr>
		<tr>
			<td>Zinc powder</td>
			<td>Sigma Aldrich</td>
			<td>324930</td>
			<td></td>
		</tr>
	</tbody>
</table>

flash infrared annealing for perovskite solar cell processing

Organic&#8211;inorganic perovskites have an impressive potential for the design of next generation solar cells and are currently considered for upscaling and commercialization. Currently, perovskite solar cells rely on spin-coating which is neither practical for large areas nor environmentally friendly. Indeed, one of the conventional and most effective lab-scale methods to induce perovskite crystallization, the antisolvent method, requires an amount of toxic solvent that is difficult to apply on larger surfaces. To solve this problem, an antisolvent-free and rapid thermal annealing process called flash infrared annealing (FIRA) can be used to produce highly crystalline perovskite films. The FIRA oven is composed of an array of near-infrared halogen lamps with an illumination power of 3,000 kW/m2. A hollow aluminum body enables an effective water-cooling system. The FIRA method allows the synthesis of perovskite films in less than 2 s, achieving efficiencies &#62;20%. FIRA has a unique potential for the industry because it can be adapted to continuous processing, is antisolvent-free, and does not require lengthy, hour-long annealing steps.

Optimization and synthesis of MAPbI3 films on FTO glass 
To assess perovskite film quality, microscope images, X-ray diffraction, and absorbance spectra were taken. The optimum pulse time should yield a compact, uniform, and pinhole-free film with large crystal grains. Figure 3 shows optical images of MAPbI3 films at pulse times ranging from 0 s to 7 s, while Figure 4 shows the XRD spectra of films annealed at selective pulse times. These pulse times represent the boundaries of the four distinct perovskite phases observed based on the various characterizations carried out. The phase evolution as a function of pulse time and temperature is shown in Figure 5, and a comparison of the top-view SEM images of films formed by both FIRA and antisolvent methods are found in supplementary information S1. XRD patterns for all pulses and corresponding absorbance spectra are found in supplementary information S2 and S3. Pulses from 0 to 1.6 s gave needle-like crystals or small crystalline domains separated by non-crystalline phases, as evidenced by the precursor peaks at 2&#952; = 6.59, 7.22, and 9.22&#176;29. For 1.8 to 3.8 s pulses, well-defined crystal grains were formed, and XRD patterns showed the formation of the MAPbI3 tetragonal I4/mcm phase. This is also confirmed by the absorption onset of 780 nm. However, longer pulse times led to thermal degradation of the perovskite, with complete degradation for pulses &#62;5 s, as shown by the evolution of the PbI2 peak at 2&#952; = 12.7&#176;. The optimized pulse was determined to be 2 s, giving crystal grains of ~30 &#181;m. Therefore, FIRA allows for a comprehensive study of the nucleation and crystallization processes based on temperature, as controlled by the pulse time. The parameters can also be varied and optimized for different thin films, showing the versatility of this method.
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/61730/61730fig03.jpg" /> 
Figure 3: Optical images of MAPbI3 perovskite films on FTO glass, annealed with pulses ranging from 0 s to 7 s.&#160;All images were taken at 10x magnification in transmission mode. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61730/61730fig03large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/61730/61730fig04.jpg" /> 
Figure 4: XRD spectra of MAPbI3 films annealed at selective pulse times.&#160;Labeled planes are representative of the tetragonal I4/mcm phase. Asterisked peaks represent diffractions from PbI2, while the blue rectangle represents those from the precursor solution. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61730/61730fig04large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/61730/61730fig05.jpg" /> 
Figure 5: Temperature profile showing perovskite phase evolution as a function of pulse length.&#160;The boundary of the different phases has been determined from the corresponding XRD analysis, shown in Figure 4. Adapted from15. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61730/61730fig05large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
FCG perovskite devices 
Figure 6A,B show the temperature profile and XRD pattern of the mesoscopic-TiO2 layer annealed with a FIRA cycle of 10 pulses, 15 s on and 45 s off. With FIRA, temperatures of ~600 &#176;C could be reached and the TiO2 layer can be synthesized in just 10 min, much shorter than the conventional method which requires sintering for 1 h to 3 h, peaking at 450 &#176;C. The resulting film shows no discernible difference to that sintered on a hot plate. As a result, the whole perovskite solar cell could be processed in less than an hour. The cross-sectional SEM image (Figure 6C) shows that the subsequent devices fabricated are very similar to those made via traditional methods, with layers of similar thickness and morphology. Additionally, FIRA-processed devices showed excellent performance (Figure 7), with the champion device showing PCE = 20.1%, FF = 75%, Voc = 1.1 V, and Jsc = 24.4 mA/cm2, comparable to devices fabricated with the antisolvent method. A large-area device with a 1.4 cm2 active area also gave PCE of 17%, showing FIRA is a promising alternative processing method for the manufacture of PSCs.
<img alt="Figure 6" class="xfigimg" src="/files/ftp_upload/61730/61730fig06.jpg" /> 
Figure 6: (A) Temperature profile of mesoporous TiO2 annealing in FIRA, with a cycle of 10 pulses of 15 s on and 45 s off. (B) X-ray patterns for TiO2 films annealed with a hotplate and FIRA, and a blank FTO substrate as reference. (C) Cross-sectional SEM images of perovskite solar cell architectures, processed by FIRA and antisolvent. Reproduced with permission from18. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61730/61730fig06large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 7" class="xfigimg" src="/files/ftp_upload/61730/61730fig07.jpg" /> 
Figure 7: Current-voltage curve for champion FCG perovskite devices.&#160;(A) FIRA-annealed mesoporous-TiO2 and perovskite layers. (B) Large area (1.4 cm2) device with FIRA-annealed mesoporous-TiO2 and perovskite layers. Reproduced with permission from18. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61730/61730fig07large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
MAPbI3 films on ITO-PET
Figure 8 shows optical images of MAPbI3 films annealed at pulses ranging from 1 s to 2 s. At shorter pulse times, there is incomplete crystallization, whereas at pulse times &#62;1.7 s, the PET substrate begins to melt (see Supplemental Figure 4). Thermal degradation of the perovskite is also observed for the 2 s pulse. At the optimized pulse time of 1.7 s, densely packed crystal domains of ~15 &#181;m were observed. Although there are small pinholes of 1&#8211;2 &#181;m, it is clear that FIRA can be used to form compact and uniform perovskite films on flexible polymers without melting the substrate, due to rapid cooling from the case, which is a significant advantage compared to hotplate annealing.
<img alt="Figure 8" class="xfigimg" src="/files/ftp_upload/61730/61730fig08.jpg" /> 
Figure 8: Optical images of MAPbI3 films annealed at various pulse times on ITO-PET.&#160;All images are taken in transmission mode and 10x magnification unless otherwise specified. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61730/61730fig08large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
Supplemental Figure 1: Top-view SEM comparison of FIRA and hotplate annealed perovskite films. (A) Top view of FIRA-annealed perovskite films for four annealing times, scale bar: 25 &#181;m. (B) Top view of a reference film made by the antisolvent method followed by annealing at 100 &#176;C for 1 h on a standard hotplate, scale bar: 1 &#181;m. Adapted from1. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61730/61730supfig01.jpg" target="_blank">Please click here to download this figure.</a>
Supplemental Figure 2: XRD spectra of MAPbI3 films on FTO glass, annealed with pulses of (A) 0&#8211;1.4 s (B) 1.6&#8211;3 s (C) 3.2&#8211;4.6 s (D) 4.8&#8211;7 s. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61730/61730supfig02.jpg" target="_blank">Please click here to download this figure.</a>
Supplemental Figure 3: Absorbance spectra of MAPbI3 films on FTO glass, annealed with pulses of (A) 0.2&#8211;1.8 s (B) 2&#8211;3.6 s (C) 3.8&#8211;7 s. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61730/61730supfig03.jpg" target="_blank">Please click here to download this figure.</a>
Supplemental Figure 4: Physical appearance of MAPbI3 films annealed on PET at various pulse lengths. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61730/61730supfig04.jpg" target="_blank">Please click here to download this figure.</a>
Supplemental Figure 5: Temperature profile and top-view SEM images of the pristine paper substrate, ITO electrode, and mesoporous-TiO2 layer processed with FIRA. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61730/61730supfig05.jpg" target="_blank">Please click here to download this figure.</a>
Supplemental Figure 6: Cross-sectional SEM image of perovskite deposited (via antisolvent method) on a FIRA-annealed ITO/TiO2 stack on a paper substrate. ITO np = ITO nanoparticles, pvk = perovskite. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61730/61730supfig06.jpg" target="_blank">Please click here to download this figure.</a>

Watch this Scientific Journal Video about Flash Infrared Annealing for Perovskite Solar Cell Processing at JoVE.com

Flash Infrared Annealing for Perovskite Solar Cell Processing

We describe a flash infrared annealing method used for the synthesis of perovskite and mesoscopic-TiO2 films. Annealing parameters are varied and optimized for processing on fluorine-doped tin oxide (FTO) glass and indium tin oxide-coated polyethylene terephthalate (ITO PET), subsequently giving devices power conversion efficiencies &#62;20%.

Organic&#8211;inorganic perovskites have an impressive potential for the design of next generation solar cells and are currently considered for upscaling ...

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7.6K Views.  Imperial College London. We describe a flash infrared annealing method used for the synthesis of perovskite and mesoscopic-TiO2 films. Annealing parameters are varied and optimized for processing on fluorine-doped tin oxide (FTO) glass and indium tin oxide-coated polyethylene terephthalate (ITO PET), subsequently giving devices power conversion efficiencies >20%.

Video: Flash Infrared Annealing for Perovskite Solar Cell Processing

Surface Renewal: An Advanced Micrometeorological Method for Measuring and Processing Field-Scale Energy Flux Density Data

Advanced micrometeorological methods have become increasingly important in soil, crop, and environmental sciences. For many scientists without formal training in atmospheric science, these techniques are relatively inaccessible. Surface renewal and other flux measurement methods require an understanding of boundary layer meteorology and extensive training in instrumentation and multiple data management programs. To improve accessibility of these techniques, we describe the underlying theory of surface renewal measurements, demonstrate how to set up a field station for surface renewal with eddy covariance calibration, and utilize our open-source turnkey data logger program to perform flux data acquisition and processing. The new turnkey program returns to the user a simple data table with the corrected fluxes and quality control parameters, and eliminates the need for researchers to shuttle between multiple processing programs to obtain the final flux data. An example of data generated from these measurements demonstrates how crop water use is measured with this technique. The output information is useful to growers for making irrigation decisions in a variety of agricultural ecosystems. These stations are currently deployed in numerous field experiments by researchers in our group and the California Department of Water Resources in the following crops: rice, wine and raisin grape vineyards, alfalfa, almond, walnut, peach, lemon, avocado, and corn.

Surface renewal is a micrometeorological method that is being used increasingly to determine energy fluxes, but its technical complexity makes it inaccessible to a broad audience. We describe the steps needed to set up and calibrate a surface renewal field station, to acquire and process data, and to correctly interpret results.

Advanced micrometeorological methods have become  increasingly important in soil, crop, and environmental sciences.  For many scientists without formal ...

A Whole Cell Bioreporter Approach to Assess Transport and Bioavailability of Organic Contaminants in Water Unsaturated Systems

Bioavailability of contaminants is a prerequisite for their effective biodegradation in soil. The average bulk concentration of a contaminant, however, is not an appropriate measure for its availability; bioavailability rather depends on the dynamic interplay of potential mass transfer (flux) of a compound to a microbial cell and the capacity of the latter to degrade the compound. In water-unsaturated parts of the soil, mycelia have been shown to overcome bioavailability limitations by actively transporting and mobilizing organic compounds over the range of centimeters. Whereas the extent of mycelia-based transport can be quantified easily by chemical means, verification of the contaminant-bioavailability to bacterial cells requires a biological method. Addressing this constraint, we chose the PAH fluorene (FLU) as a model compound and developed a water unsaturated model microcosm linking a spatially separated FLU point source and the FLU degrading bioreporter bacterium Burkholderia sartisoli RP037-mChe by a mycelial network of Pythium ultimum. Since the bioreporter expresses eGFP in response of the PAH flux to the cell, bacterial FLU exposure and degradation could be monitored directly in the microcosms via confocal laser scanning microscopy (CLSM). CLSM and image analyses revealed a significant increase of the eGFP expression in the presence of P. ultimum compared to controls without mycelia or FLU thus indicating FLU bioavailability to bacteria after mycelia-mediated transport. CLSM results were supported by chemical analyses in identical microcosms. The developed microcosm proved suitable to investigate contaminant bioavailability and to concomitantly visualize the involved bacteria-mycelial interactions.

A whole cell bioreporter assay with Burkholderia sartisoli RP037-mChe was developed to detect fractions of an organic contaminant (i.e., fluorene) available for bacterial degradation after active transport by mycelia bridging air-filled pores in a water unsaturated model system.

Bioavailability of contaminants is a prerequisite for their effective biodegradation in soil. The average bulk concentration of a contaminant, however, is ...

The Use of High-resolution Infrared Thermography (HRIT) for the Study of Ice Nucleation and Ice Propagation in Plants

Freezing events that occur when plants are actively growing can be a lethal event, particularly if the plant has no freezing tolerance. Such frost events often have devastating effects on agricultural production and can also play an important role in shaping community structure in natural populations of plants, especially in alpine, sub-arctic, and arctic ecosystems. Therefore, a better understanding of the freezing process in plants can play an important role in the development of methods of frost protection and understanding mechanisms of freeze avoidance. Here, we describe a protocol to visualize the freezing process in plants using high-resolution infrared thermography (HRIT). The use of this technology allows one to determine the primary sites of ice formation in plants, how ice propagates, and the presence of ice barriers. Furthermore, it allows one to examine the role of extrinsic and intrinsic nucleators in determining the temperature at which plants freeze and evaluate the ability of various compounds to either affect the freezing process or increase freezing tolerance. The use of HRIT allows one to visualize the many adaptations that have evolved in plants, which directly or indirectly impact the freezing process and ultimately enables plants to survive frost events.

The Use of High-resolution Infrared Thermography HRIT for the Study of Ice Nucleation and Ice Propagation in Plants

Here we present a protocol that allows one to visualize sites of ice formation and avenues of ice propagation in plants utilizing high resolution infrared thermography (HRIT).

Freezing events that occur when plants are actively growing can be a lethal event, particularly if the plant has no freezing tolerance. Such frost events ...

Experimental System of Solar Adsorption Refrigeration with Concentrated Collector

To improve the performance of solar adsorption refrigeration, an experimental system with a solar concentration collector was set up and investigated. The main components of the system were the adsorbent bed, the condenser, the evaporator, the cooling sub-system, and the solar collector. In the first step of the experiment, the vapor-saturated bed was heated by the solar radiation under closed conditions, which caused the bed temperature and pressure to increase. When the bed pressure became high enough, the bed was switched to connect to the condenser, thus water vapor flowed continually from the bed to the condenser to be liquefied. Next, the bed needed to cool down after the desorption. In the solar-shielded condition, achieved by aluminum foil, the circulating water loop was opened to the bed. With the water continually circulating in the bed, the stored heat in the bed was took out and the bed pressure decreased accordingly. When the bed pressure dropped below the saturation pressure at the evaporation temperature, the valve to the evaporator was opened. A mass of water vapor rushed into the bed and was adsorbed by the zeolite material. With the massive vaporization of the water in the evaporator, the refrigeration effect was generated finally. The experimental result has revealed that both the COP (coefficient of the performance of the system) and the SCP (specific cooling power of the system) of the SAPO-34 zeolite was greater than that of the ZSM-5 zeolite, no matter whether the adsorption time was longer or shorter. The system of the SAPO-34 zeolite generated a maximum COP of 0.169.

With solar energy as the driving force, a novel adsorption refrigeration system has been developed and experimentally investigated. Water vapor and zeolite formed the working pair of the adsorption system. This manuscript describes the setup of the experimental rig, the operation procedure, and the important results.

To improve the performance of solar adsorption refrigeration, an experimental system with a solar concentration collector was set up and investigated. The ...

Data Processing Methods for 3D Seismic Imaging of Subsurface Volcanoes: Applications to the Tarim Flood Basalt

The morphology and structure of plumbing systems can provide key information on the eruption rate and style of basalt lava fields. The most powerful way to study subsurface geo-bodies is to use industrial 3D&#160;reflection seismological imaging. However, strategies to image subsurface volcanoes are very different from that of oil and gas reservoirs. In this study, we process seismic data cubes from the Northern Tarim Basin, China, to illustrate how to visualize sills through opacity rendering techniques and how to image the conduits by time-slicing. In the first case, we isolated probes by the seismic horizons marking the contacts between sills and encasing strata, applying opacity rendering techniques to extract sills from the seismic cube. The resulting detailed sill morphology shows that the flow direction is from the dome center to the rim. In the second seismic cube, we use time-slices to image the conduits, which corresponds to marked discontinuities within the encasing rocks. A set of time-slices obtained at different depths show that the Tarim flood basalts erupted from central volcanoes, fed by separate pipe-like conduits.

Three-dimensional (3D) reflection seismology is a powerful method for imaging subsurface volcanoes. By using industrial 3D seismological data from the Tarim Basin, we illustrate how to extract the sills and the conduits of subsurface volcanoes from seismic data cubes.

The morphology and structure of plumbing systems can provide key information on the eruption rate and style of basalt lava fields. The most powerful way ...

Improving Infrared Spectroscopy Characterization of Soil Organic Matter with Spectral Subtractions

Soil organic matter (SOM) underlies numerous soil processes and functions. Fourier transform infrared (FTIR) spectroscopy detects infrared-active organic bonds that constitute the organic component of soils. However, the relatively low organic matter content of soils (commonly &#60; 5% by mass) and absorbance overlap of mineral and organic functional groups in the mid-infrared (MIR) region (4,000-400 cm-1) engenders substantial interference by dominant mineral absorbances, challenging or even preventing interpretation of spectra for SOM characterization. Spectral subtractions, a post-hoc mathematical treatment of spectra, can reduce mineral interference and enhance resolution of spectral regions corresponding to organic functional groups by mathematically removing mineral absorbances. This requires a mineral-enriched reference spectrum, which can be empirically obtained for a given soil sample by removing SOM. The mineral-enriched reference spectrum is subtracted from the original (untreated) spectrum of the soil sample to produce a spectrum representing SOM absorbances. Common SOM removal methods include high-temperature combustion (&#39;ashing&#39;) and chemical oxidation. Selection of the SOM removal method carries two considerations: (1) the amount of SOM removed, and (2) absorbance artifacts in the mineral reference spectrum and thus the resulting subtraction spectrum. These potential issues can, and should, be identified and quantified in order to avoid fallacious or biased interpretations of spectra for organic functional group composition of SOM. Following SOM removal, the resulting mineral-enriched sample is used to collect a mineral reference spectrum. Several strategies exist to perform subtractions depending on the experimental goals and sample characteristics, most notably the determination of the subtraction factor. The resulting subtraction spectrum requires careful interpretation based on the aforementioned methodology. For many soil and other environmental samples containing substantial mineral components, subtractions have strong potential to improve FTIR spectroscopic characterization of organic matter composition.

SOM underlies many soil functions and processes, but its characterization by FTIR spectroscopy is often challenged by mineral interferences. The described method can increase the utility of SOM analysis by FTIR spectroscopy by subtracting mineral interferences in soil spectra using empirically obtained mineral reference spectra.

Soil organic matter (SOM) underlies numerous soil processes and functions. Fourier transform infrared (FTIR) spectroscopy detects infrared-active organic ...

High-throughput, Microscale Protocol for the Analysis of Processing Parameters and Nutritional Qualities in Maize (Zea mays L.)

Maize is an important grain crop in the United States and worldwide. However, maize grain must be processed prior to human consumption. Furthermore, whole grain composition and processing characteristics vary among maize hybrids and can impact the quality of the final processed product. Therefore, in order to produce healthier processed food products from maize, it is necessary to know how to optimize processing parameters for particular sets of germplasm to account for these differences in grain composition and processing characteristics. This includes a better understanding of how current processing techniques impact the nutritional quality of the final processed food product. Here, we describe a microscale protocol that both simulates the processing pipeline to produce cornflakes from large flaking grits and allows for the processing of multiple grain samples simultaneously. The flaking grits, the intermediate processed products, or final processed product, as well as the corn grain itself, can be analyzed for nutritional content as part of a high-throughput analytical pipeline. This procedure was developed specifically for incorporation into a maize breeding research program, and it can be modified for other grain crops. We provide an example of the analysis of insoluble-bound ferulic acid and p-coumaric acid content in maize. Samples were taken at five different processing stages. We demonstrate that sampling can take place at multiple stages during microscale processing, that the processing technique can be utilized in the context of a specialized maize breeding program, and that, in our example, most of the nutritional content was lost during food product processing.

High-throughput, Microscale Protocol for the Analysis of Processing Parameters and Nutritional Qualities in Maize Zea mays L.

Here, we present a microscale protocol for processing grain samples and for incorporating this microscale approach into a high-throughput analytical pipeline. This is a higher throughput adaptation of currently available protocols.

Maize is an important grain crop in the United States and worldwide. However, maize grain must be processed prior to human consumption. Furthermore, whole ...

Protocol for Producing Three-Dimensional Infrared Video of Freezing in Plants

Freezing in plants can be monitored using infrared (IR) thermography, because when water freezes, it gives off heat. However, problems with color contrast make 2-dimensions (2D) infrared images somewhat difficult to interpret. Viewing an IR image or the video of plants freezing in 3 dimensions (3D) would allow a more accurate identification of sites for ice nucleation as well as the progression of freezing. In this paper, we demonstrate a relatively simple means to produce a 3D infrared video of a strawberry plant freezing. Strawberry is an economically important crop that is subjected to unexpected spring freeze events in many areas of the world. An accurate understanding of the freezing in strawberry will provide both breeders and growers with more economical ways to prevent any damage to plants during freezing conditions.
The technique involves a positioning of two IR cameras at slightly different angles to film the strawberry freezing. The two video streams will be precisely synchronized using a screen capture software that records both cameras simultaneously. The recordings will then be imported into the imaging software and processed using an anaglyph technique. Using red-blue glasses, the 3D video will make it easier to determine the precise site of ice nucleation on leaf surfaces.

Here, we present a protocol to image a strawberry plant freezing in 3 dimensions. Two infrared cameras positioned at slightly different angles are used to produce a red-blue anaglyph video to observe the freezing of the plant in 3 dimensions.

Freezing in plants can be monitored using infrared (IR) thermography, because when water freezes, it gives off heat. However, problems with color contrast ...

Fabrication of Anisotropic Polymeric Artificial Antigen Presenting Cells for CD8+ T Cell Activation

Artificial antigen presenting cells (aAPC) are a promising platform for immune modulation due to their potent ability to stimulate T cells. Acellular substrates offer key advantages over cell-based aAPC, including precise control of signal presentation parameters and physical properties of the aAPC surface to modulate its interactions with T cells. aAPC constructed from anisotropic particles, particularly ellipsoidal particles, have been shown to be more effective than their spherical counterparts at stimulating T cells due to increased binding and larger surface area available for T cell contact, as well as reduced nonspecific uptake and enhanced pharmacokinetic properties. Despite increased interest in anisotropic particles, even widely accepted methods of generating anisotropic particles such as thin-film stretching can be challenging to implement and use reproducibly.
To this end, we describe a protocol for the rapid, standardized fabrication of biodegradable anisotropic particle-based aAPC with tunable size, shape, and signal presentation for T cell expansion ex vivo or in vivo, along with methods to characterize their size, morphology, and surface protein content, and to assess their functionality. This approach to fabricating anisotropic aAPC is scalable and reproducible, making it ideal for generating aAPC for &#34;off-the-shelf&#34; immunotherapies.

Here, we present a protocol to quickly and reproducibly generate biologically inspired, biodegradable articifical antigen presenting cells (aAPC) with tunable size, shape, and surface protein presentation for T cell expansion ex vivo or in vivo.

Artificial antigen presenting cells (aAPC) are a promising platform for immune modulation due to their potent ability to stimulate T cells. Acellular ...

In Vitro Scratch Assay to Demonstrate Effects of Arsenic on Skin Cell Migration

Understanding the physiologic mechanisms of wound healing has been the focus of ongoing research for many years. This research directly translates into changes in clinical standards used for treating wounds and decreasing morbidity and mortality for patients. Wound healing is a complex process that requires strategic cell and tissue interaction and function. One of the many critically important functions of wound healing is individual and collective cellular migration. Upon injury, various cells from the blood, surrounding connective, and epithelial tissues rapidly migrate to the wound site by way of chemical and/or physical stimuli. This migration response can largely dictate the outcomes and success of a healing wound. Understanding this specific cellular function is important for translational medicine that can lead to improved wound healing outcomes. Here, we describe a protocol used to better understand cellular migration as it pertains to wound healing, and how changes to the cellular environment can significantly alter this process. In this example study, dermal fibroblasts were grown in media supplemented with fetal bovine serum (FBS) as monolayer cultures in tissue culture flasks. Cells were aseptically transferred into tissue culture treated 12-well plates and grown to 100% confluence. Upon reaching confluence, the cells in the monolayer were vertically scratched using a p200 pipet tip. Arsenic diluted in culture media supplemented with FBS was added to individual wells at environmentally relevant doses ranging 0.1-10 &#956;M. Images were captured every 4 hours (h) over a 24 h period using an inverted light microscope to observe cellular migration (wound closure). Images were individually analyzed using image analysis software, and percent wound closure was calculated. Results demonstrate that arsenic slows down wound healing. This technique provides a rapid and inexpensive first screen for evaluation of the effects of contaminants on wound healing.

In Vitro Scratch Assay to Demonstrate Effects of Arsenic on Skin Cell Migration

This study focuses on an in vitro model of wound healing (scratch assay) as a mechanism for determining how environmental contaminants such as arsenic influence cellular migration. The results demonstrate that this in vitro assay provides rapid and early indications of changes to cellular migration prior to in vivo experimentation.

Understanding the physiologic mechanisms of wound healing has been the focus of ongoing research for many years. This research directly translates into ...

Flash Infrared Annealing for Perovskite Solar Cell Processing

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Surface Renewal: An Advanced Micrometeorological Method for Measuring and Processing Field-Scale Energy Flux Density Data

A Whole Cell Bioreporter Approach to Assess Transport and Bioavailability of Organic Contaminants in Water Unsaturated Systems

The Use of High-resolution Infrared Thermography (HRIT) for the Study of Ice Nucleation and Ice Propagation in Plants

Experimental System of Solar Adsorption Refrigeration with Concentrated Collector

Data Processing Methods for 3D Seismic Imaging of Subsurface Volcanoes: Applications to the Tarim Flood Basalt

Improving Infrared Spectroscopy Characterization of Soil Organic Matter with Spectral Subtractions

High-throughput, Microscale Protocol for the Analysis of Processing Parameters and Nutritional Qualities in Maize (Zea mays L.)

Protocol for Producing Three-Dimensional Infrared Video of Freezing in Plants

Fabrication of Anisotropic Polymeric Artificial Antigen Presenting Cells for CD8+ T Cell Activation

In Vitro Scratch Assay to Demonstrate Effects of Arsenic on Skin Cell Migration