Questa ricerca è gratitudine intrapresa con il sostegno della Ingegneria e Scienze Fisiche Research Council (EPSRC), finanziato attraverso una borsa di formazione dottorale. Open Access spese di produzione articolo (APC) sono stati finanziati da Research Councils UK (RCUK). Tutti i dati sono forniti integralmente nella sezione dei risultati della carta. I risultati rappresentativi sono stati precedentemente pubblicati dagli autori 42. Vorremmo ringraziare il Dott Senthilarasu Sundaram presso l&#39;Università di Exeter per il suo aiuto nella caratterizzazione delle prestazioni elettriche delle cellule.

1. formulazione dell&#39;inchiostro Nota: le formulazioni di inchiostro sono spesso tenuti segreti altamente sorvegliato dai produttori. Il successo formulazioni equilibrio getto, goccia formazione, bagnatura e il comportamento di essiccazione al fianco di prestazioni funzionali. Solitamente un materiale funzionale viene dispersa in un solvente ed almeno un altro componente per renderli Jettable. Questa sezione descrive lo sviluppo di un TiO2 inchiostro per un uso all&#39;interno di stampa a getto d&#39;inchiostro. Un piccolo lotto di inchiostro è stato preparato con il metodo seguente. Attenzione: la preparazione di inchiostro deve essere effettuata in una zona adeguatamente ventilato, per esempio, sotto una cappa aspirante, mentre indossa occhiali protettivi occhi e guanti in lattice. <ol><li> Preparare una soluzione acquosa 0,1 mM di acido cloridrico (HCl) per produrre un pH di circa 4. </li><li> Aggiungere 32 g della soluzione di acido per 8 g di un solvente compatibile con un punto di ebollizione più alto e più basso tensione superficiale dell&#39;acqua (quale dimetilformammide (DMF)). L&#39;aggiunta di un co-solvagisce ent come agente essiccante per indurre un flusso che circola all&#39;interno della gocciolina inchiostro evapora inchiostro, portando a un inserimento uniforme nanoparticelle sulla superficie della goccia 21. </li><li> Aggiungere 1,5 g di disperdente (45% soluzione attiva di glicole propilenico e tetrametil-5-decyne-4,7-diolo in acqua). </li><li> Aggiungere 10 g di glicole etilenico, come un umettante per evitare l&#39;essiccazione in corrispondenza degli ugelli. </li><li> Aggiungere 0,5 g di agente antischiuma (20% soluzione attiva di diolo acetilenico in methoxypolyethyleneglycol) per l&#39;inchiostro per evitare bolle d&#39;aria da sviluppare. </li><li> Eseguire un semplice test shake prendendo una aliquota dell&#39;inchiostro in un contenitore chiuso e agitare manualmente per 60 sec. Se si osserva la schiuma quindi aggiungere altri 0,5 g di antischiuma agente all&#39;inchiostro. </li><li> Mescolare la soluzione per 8 ore utilizzando una barra di agitazione magnetica per garantire l&#39;omogeneità a temperatura ambiente. </li><li> Aggiungere 1,5 g di biossido di titanio (TiO 2) nanoparticelle con una dimensione delle particelle primarie di 21 nm e la superficie di35 - 65 m 2 / g. </li><li> Sonicare miscela utilizzando una sonda ad ultrasuoni per 15 minuti ad una frequenza di 60 Hz. </li><li> Misurare le dimensioni delle particelle, utilizzando una tecnica di valutazione appropriato come dispersione della luce dinamica (DLS) secondo il protocollo del produttore, per garantire che essi scorrere facilmente attraverso le aperture degli ugelli. Effettuare misurazioni alle stesse condizioni (ad es., Lo stesso solvente, pH, concentrazione di disperdente) da utilizzare per l&#39;inchiostro da ciascun componente può influenzare la formazione di agglomerati all&#39;interno dell&#39;inchiostro. Per getto di successo, le particelle all&#39;interno del liquido deve essere 100 volte più piccola l&#39;apertura dell&#39;ugello. </li><li> Misurare la viscosità dell&#39;inchiostro, utilizzando una tecnica di valutazione appropriato come un viscosimetro rotazionale secondo il protocollo del produttore, per garantire getto affidabile dalla testina di stampa come stampa a getto di inchiostro richiede inchiostri a bassa viscosità compresa tra 2 e 20 centipoise (cP). Aumentare la viscosità attraverso la additisu materiali polimerici o materiali a base di cellulosa; tuttavia questi devono essere rimossi dopo la deposizione per liberare i siti per il colorante all&#39;interno del film stampato 22. </li><li> Misurare la tensione superficiale dell&#39;inchiostro, utilizzando una tecnica di valutazione appropriato come un tensiometro secondo il protocollo del produttore, per garantire getto affidabile. Le linee guida formulazione fluida Jettable per le stampanti a getto d&#39;inchiostro suggeriscono una tensione superficiale tra 28 e 33 mN / m per abilitare la stampa affidabile. </li></ol> La stampa a getto d&#39;inchiostro 2. <ol><li> Prima di stampare, immergere i substrati di vetro in una soluzione al 2% in peso di detersivo pulizia (una miscela di tensioattivi anionici e tensioattivi non ionici agenti attivi, agenti, alcali, costruttori detergenti non-fosfati e agenti sequestranti stabilizzanti, in base acquosa) in acqua deionizzata. Risciacquare accuratamente il bicchiere con acqua deionizzata non appena vengono rimossi dalla soluzione di pulizia per rimuovere tracce di contaminazione e detergente. </li&gt; <li> Misurare l&#39;energia superficiale del substrato, utilizzando una tecnica di valutazione appropriato come un tensiometro secondo il protocollo del produttore. Per una buona adesione, l&#39;energia superficiale del substrato non deve superare la tensione superficiale del liquido di oltre 10 - 15 mN / m. Modificare l&#39;energia superficiale del substrato utilizzando metodi come trattamento corona 23, il trattamento al plasma 24 e attacco chimico 25 se non è adatto. </li><li> Caricare il substrato nella stampante secondo il protocollo del produttore. </li><li> Lavare la testina di stampa con l&#39;inchiostro attraverso la porta situata sul lato della testa di spostare qualsiasi soluzione di aria o di pulizia all&#39;interno del serbatoio e ugelli. </li><li> Inserire la testina di stampa nella stampante. Collegare la testina di stampa con la scheda personalità testa. </li><li> Filtrare l&#39;inchiostro attraverso il filtro dimensione corretta appena prima di caricare nella cartuccia per rimuovere grandi aggregati di particelle che possono ostruire gli ugelli. Iltestina di stampa usata in questo lavoro ha ugelli con un diametro di 40 micron (ad esempio, Konica KM512.); Pertanto inchiostri non devono contenere particelle di diametro superiore a 400 nm. Passare le sospensioni attraverso un 5 micron, seguito da un filtro 1,2 micron fluoruro di polivinilidene (PVDF) per rimuovere eventuali particelle grandi. </li><li> Caricare l&#39;inchiostro nella siringa 150 ml situato sopra la testina di stampa, che fornisce l&#39;inchiostro alla testina di stampa. Attaccare il tappo ermetico in cima alla siringa e attivare la pompa del vuoto. </li><li> Eliminare l&#39;inchiostro attraverso gli ugelli premendo il pulsante &#39;purge&#39; che si trova sulla pompa del vuoto. </li><li> Attraverso il server di stampa sistema di informazione geografica (GIS), i parametri di forma d&#39;onda e la stampa di set-up. Si noti che la stampante possa stampare fino a una velocità di 1,5 metri al secondo, tuttavia per questo inchiostro una velocità di stampa di 0,3 metri al secondo è stato trovato per fornire rivestimento ottimale </li><li> Open GIS software di interfaccia utente e caricare il modello desiderato. </li><li> Print dalla cartuccia caricata secondo il protocollo del produttore. </li><li> Rimuovere il substrato dalla piastra e riscaldare i film stampati a 150 ° C per 30 minuti, seguita da 250 ° C per altri 30 min o su una piastra calda o in un forno. </li></ol> 3. Analisi delle Printed Cinema <ol><li> Utilizzare un microscopio ottico o un microscopio elettronico a scansione (SEM) per guardare la superficie dei film stampati a basso ingrandimento (100X) per analizzare la morfologia superficiale e ad alto ingrandimento (35,000X) analizzare la porosità dei film stampati. Verificare che le immagini mostrano una copertura uniforme, senza crepe e buona porosità. Per informazioni più dettagliate sul funzionamento del SEM si trova nelle seguenti riferimenti 26,27. </li><li> Misurare lo spessore dello strato stampato, utilizzando una tecnica di valutazione appropriato come un profiler superficie secondo il protocollo del produttore. Lo spessore e la porosità dello strato ingegno TiO 2hin DSSCs influenzano la quantità di colorante che può essere assorbita sulla superficie delle nanoparticelle, che influenzano quindi l&#39;efficienza globale di conversione elettrica della cella 18. È quindi un parametro importante per valutare. Utilizzare un profiler superficie (precisione di 1 nm) per misurare lo spessore dei film stampati. </li><li> Misurare la trasmittanza del film, utilizzando una tecnica di valutazione appropriata come lo spettrofotometro UV-visibile (UV-VIS) per determinare la quantità di luce visibile trasmette attraverso la pellicola stampata. Utilizzare il protocollo del produttore. </li></ol> 4. Rendere il cellulare <ol><li> Fare una soluzione colorante mescolando 20 ml di etanolo e 2 mg di colorante di rutenio in un bicchiere di vetro con un agitatore magnetico per 8 ore. </li><li> Immergere il vetro rivestito TiO 2 nella soluzione a temperatura ambiente (da 20 a 25 ° C) per 24 ore per permettere la tintura di assorbire sulla superficie delle particelle di TiO 2. </li><li> Rimuovere il TiO2 </sub&gt; vetro rivestito dalla soluzione e posto su carta velina per assorbire qualsiasi soluzione colorante in eccesso (con il TiO 2 rivolta verso l&#39;alto per evitare la contaminazione). </li><li> Posizionare il pre-taglio 60 micron di spessore distanziatore termoplastico tenuta sulla parte superiore del vetro conduttivo, intorno il rivestimento TiO 2. </li><li> Posizionare il ricoperto platino controelettrodo sopra il pre-taglio 60 micron di spessore distanziatore termoplastico di tenuta in modo che le superfici attive del anodo e il catodo di fronte all&#39;altra. Lasciare sufficiente sovrapposizione tra i due pezzi di vetro in modo che un contatto elettrico può essere realizzato con il vetro conduttivo. Questo dovrebbe avere un pre-foro al centro per consentire il riempimento elettrolita in seguito. </li><li> Calore su una piastra calda ad una temperatura di 110 C e applicare una leggera pressione con una pinzetta sull&#39;area del distanziatore di tenuta. Dopo 30 secondi gli elettrodi devono essere sigillati insieme. </li><li> Colmare il divario tra i due elettrodi con un / elettro tri-ioduro iodurolyte in acetonitrile ad una concentrazione di 50 mM, iniettando attraverso il pre-foro nel vetro rivestito di platino con una siringa. </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=Influence+of+TiO2+Film+Thickness+on+the+Electrochemical+Behaviour+of+Dye-Sensitized+Solar+Cells.">Influence of TiO2 Film Thickness on the Electrochemical Behaviour of Dye-Sensitized Solar Cells.</a> Int. J. Electrochem. Sci. 6, 3375-3384 (2011).</li><li>Ito, 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=High-Efficiency+Organic-Dye-+Sensitized+Solar+Cells+Controlled+by+Nanocrystalline-TiO2+Electrode+Thickness.">High-Efficiency Organic-Dye- Sensitized Solar Cells Controlled by Nanocrystalline-TiO2 Electrode Thickness.</a> Adv. Mater. 18, 1202-1205 (2006).</li><li>Ito, S., Kalyanasundaram, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Dye sensitized solar cells. , 251-266 (2010).</li><li>Tsai, J., Hsu, W., Wu, T., Meen, T., Chong, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+compressed+TiO2+nanoparticle+thin+film+thickness+on+the+performance+of+dye-sensitized+solar+cells.">Effect of compressed TiO2 nanoparticle thin film thickness on the performance of dye-sensitized solar cells.</a> Nanoscale Res Lett. 8, 1-6 (2013).</li><li>Shin, I., 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=Analysis+of+TiO2+thickness+effect+on+characteristic+of+a+dye-sensitized+solar+cell+by+using+electrochemical+impedance+spectroscopy.">Analysis of TiO2 thickness effect on characteristic of a dye-sensitized solar cell by using electrochemical impedance spectroscopy.</a> Curr. Appl. Phys. 10, 422-424 (2010).</li><li>Brus, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electronic+wave+functions+in+semiconductor+clusters:+experiment+and+theory.">Electronic wave functions in semiconductor clusters: experiment and theory.</a> J. Phys. Chem. 90, 2555-2560 (1986).</li><li>Jung, 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=All-Inkjet-Printed,+All-Air-Processed+Solar+Cells.">All-Inkjet-Printed, All-Air-Processed Solar Cells.</a> Adv Energy Mater. 4, 1-9 (2014).</li><li>Cherrington, R., Hughes, D. J., Senthilarasu, S., Goodship, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inkjet-Printed+TiO2+Nanoparticles+from+Aqueous+Solutions+for+Dye-Sensitized+Solar+Cells+(DSSCs).">Inkjet-Printed TiO2 Nanoparticles from Aqueous Solutions for Dye-Sensitized Solar Cells (DSSCs).</a> Energy Technology. 3, (2015).</li></ol>

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A particular challenge when formulating inks is the natural tendency for nanoparticles to cluster together. These are known as either aggregates or agglomerates, depending on the nature and strength of the bonds between the particles. The energy of simply stirring particles into water or binder is not great enough to overcome the particle attractive forces preventing the breakup of agglomerates. Ball milling, high shear mixing or ultrasonication are commonly used to break up agglomerated nanoparticles. Various anionic, nonionic, and cationic surfactants and polymers can also be used to provide long-term stabilization. By minimizing the number of these agglomerates, a good quality suspension can be achieved. The fluids should be filtered through the correct size filter just before loading into the cartridge to remove large particle aggregates which can clog the nozzles.
The particle size within the TiO2 layer also has been shown to influence the overall efficiency of DSSCs. The photocatalytic activity of titanium dioxide increases as particle sizes decrease due to an increase in the specific surface area40. A study comparing the efficiency of DSSCs incorporating TiO2 nanoparticles with 5 different sizes ranging from 400 nm to 14 nm and found that those with smaller particle sizes resulted in better electrical conversion efficiencies33.
Inkjet printing is a non-contact deposition technique capable of multi-pass printing. This presents the unique opportunity to rapidly fabricate multilayer devices in one operation on a wide range of substrates with minimal material waste. It also potentially provides a way to integrate other components (such as batteries) into the system through the printing of functional materials41. Although the representative results shown for the inkjet printed devices do not perform as well as the doctor-bladed devices, it demonstrates the potential for the deposition technique. With further ink optimization, it could perform on a comparable level to currently used methods and may provide further scope for cost-effective, environmentally friendly integration of photovoltaic cells onto a wide range of substrates. We hope to improve the efficiency of the inkjet printed devices by increasing the thickness of the printed layer closer to that of the doctor-bladed TiO2 and will continue to look at the printing of other materials and layers within DSSCs.

Conventional silicon solar cells are made from highly pure materials that require expensive and high-energy consuming specialist equipment. These conventional silicon cells incorporate a p-n junction that requires highly pure materials at the interface to generate electron-hole pairs. Dye-sensitized solar cells (DSSCs) have a fundamentally different working principle, where charge generation takes place at the materials interface. This means that processing under vacuum, ultrahigh temperatures or the use of clean room facilities are not required1. Therefore they are seen as a potentially low cost alternative; however up-scaling from small laboratory test cells into large prototypes for industrial manufacturing involves overcoming several issues including the rapid patterning of substrates.
Electronics manufacturing generally requires a degree of patterning, which is either achieved by masking or selective removal of the material after deposition. These steps can be removed through the use of "additive" digital printing techniques such as inkjet printing or spray coating. Digital printing is a promising method for direct deposition of functional materials for electronic devices. The technique can be described as printing from a digital-based pattern directly to a variety of substrates2. They are non-contact methods, which will not damage or contaminate the substrate surface and deposit material only where it is required, resulting in little or no wastage3. These techniques have been highlighted as being ideally suited to being scaled up to high-volume production3. Since digital printing methods use liquid forms of materials dispersed in a solvent, it is critical to understand the deposition of ink to determine the applications of the technique. 
DSSCs have three main components: a porous layer of wide bandgap metal oxide material, a dye that covers the particles, and a "charge transporter" that infiltrates the pores within the porous layer of semiconductor. These are sandwiched in between a transparent conductive electrode and a counter electrode4. The counter electrode is coated with a catalytic material for electron transfer, which in most cases is platinum. Under illumination, the dye molecules will absorb energy in the form of photons. The dye molecules then become excited and charge separation occurs at the interface of the titanium dioxide and the dye. Electrons are ejected into the adjacent metal oxide particles and 'holes' are left behind on the dye molecule. The injected electrons travel through the metal oxide particles and reach the transparent conductive electrode. When a load is connected, the electrons move to the counter electrode through the external circuit and are finally reunited with their counter charges through the redox couple present in the electrolyte1. The nano-structured metal oxide layer within DSSCs plays a critical role in the overall performance of the cell, with material choice, processing methods and nature of the structure all having influencing factors5-10. One of the most important requirements for the photoanode is that it needs to have an extremely large surface area. This is achieved through the deposition of nanoparticle materials, commonly TiO21,11. This has been fabricated by countless different processes, however wet coating techniques such as screen-printing and doctor-blading, are still the most popular approach9,12,13. 
Inkjet technology is a potential manufacturing route for dye-sensitized solar cells. It uses the movement of a piezoelectric crystal to expel a fixed quantity of liquid through a nozzle onto the desired substrate. This deposition method allows material to be jetted very accurately but also at high frequency with a potentially high print speed or deposition rate. Inkjet technology is sensitive to the viscosity of the ink used and this was previously a barrier to the development of functional inks. Recent work in the development of solvents suitable for ink formulation has helped to alleviate this problem, and printing of electronic components using 2D layered materials such as graphene has been demonstrated14. The viscosity of nanoparticle suspensions such as these has been found to depend on the nanoparticle size and concentration15. High concentrations of nanoparticles result in higher viscosities, therefore particle loadings are usually around 10 wt% to avoid nozzle blockages16, however higher concentrations have been achieved17.
The key advantages of inkjet technology include it being non-contact, additive patterning and maskless18. The latter two attributes are due to the ability to position many nozzles together on one or more printheads, with each nozzle separately addressable by the control software. This allows highly complex, multi-layered patterns to be created very rapidly as the printheads move across the substrate. No masking between materials or layers is required as the position of each ink drop is accurately controlled, in some systems to an accuracy of ~1.5 &#181;m19. One of the key benefits is that inkjet technology is mature, with significant development carried out in the latter half of the twentieth century. The result is that the inkjet is a very scalable technology, with roll-to-roll systems capable of printing accurately onto flexible substrates at rates of many meters per second. Traditionally this was used for high volume production, e.g., newspapers. However, developments in technology have allowed the inkjet to be used in roll-to-roll production of electronic circuits using nanoparticulate silver inks20. The inkjet is therefore an attractive process for the potential production of dye-sensitized solar cells by digital printing.

<table>
	<tbody>
		<tr>
			<td>Titanium dioxide</td>
			<td>Sigma Aldrich</td>
			<td>718467</td>
			<td></td>
		</tr>
		<tr>
			<td>Deionized water&#160;</td>
			<td></td>
			<td></td>
			<td>Supplied from a filter in the laboratory</td>
		</tr>
		<tr>
			<td>Hydrochloric acid, 2M(2N)&#160;</td>
			<td>Fisher Scientific</td>
			<td>J/4250/17</td>
			<td></td>
		</tr>
		<tr>
			<td>Dimethylformamide (DMF)</td>
			<td>Fisher Scientific</td>
			<td>D/3840/08</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>VWR Chemicals</td>
			<td>20721.33</td>
			<td></td>
		</tr>
		<tr>
			<td>Dispersing additive&#160;</td>
			<td>Air Products</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Defoaming agent</td>
			<td>Air Products</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ethylene glycol</td>
			<td>Fluka</td>
			<td>107-21-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Polyvinylidene fluoride (PVDF) syringe filter</td>
			<td>VWR International</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Cleaning detergent&#160;</td>
			<td>Fisher Scientific</td>
			<td>10335650</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorine doped tin oxide (FTO) glass, 8 &#937;/sq</td>
			<td>Pilkington</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ruthenizer dye</td>
			<td>Solaronix</td>
			<td>21613</td>
			<td></td>
		</tr>
		<tr>
			<td>Pre-cut 60 &#181;m thick thermoplastic sealing film&#160;</td>
			<td>Solaronix</td>
			<td>74301</td>
			<td></td>
		</tr>
		<tr>
			<td>50 mM iodide/tri-iodide electrolyte&#160; in acetonitrile</td>
			<td>Solaronix</td>
			<td>31111</td>
			<td></td>
		</tr>
		<tr>
			<td>Platinum coated FTO glass&#160;</td>
			<td>Solaronix</td>
			<td>74201</td>
			<td></td>
		</tr>
		<tr>
			<td>Vac&#39;n&#39;Fill Syringe</td>
			<td>Solaronix</td>
			<td>65209</td>
			<td></td>
		</tr>
		<tr>
			<td>Polyimide tape (6.35 mm)</td>
			<td>Onecall Farnell</td>
			<td>1676087</td>
			<td></td>
		</tr>
	</tbody>
</table>

digital printing of titanium dioxide for dye sensitized solar cells

Silicon solar cell manufacturing is an expensive and high energy consuming process. In contrast, dye sensitized solar cell production is less environmentally damaging with lower processing temperatures presenting a viable and low cost alternative to conventional production. This paper further enhances these environmental credentials by evaluating the digital printing and therefore additive production route for these cells. This is achieved here by investigating the formation and performance of a metal oxide photoelectrode using nanoparticle sized titanium dioxide. An ink-jettable material was formulated, characterized and printed with a piezoelectric inkjet head to produce a 2.6 &#181;m thick layer. The resultant printed layer was fabricated into a functioning cell with an active area of 0.25 cm2 and a power conversion efficiency of 3.5%. The binder-free formulation resulted in a reduced processing temperature of 250 &#176;C, compatible with flexible polyamide substrates which are stable up to temperatures of 350 &#730;C. The authors are continuing to develop this process route by investigating inkjet printing of other layers within dye sensitized solar cells.

Un inchiostro TiO 2 è stato formulato secondo la procedura descritta. La dimensione delle particelle sospese all&#39;interno l&#39;inchiostro è stata misurata usando dispersione dinamica della luce (DLS) e una granulometria media di 80 nanometri (nm) è stata osservata. La viscosità dell&#39;inchiostro in questo lavoro è risultata 3 cP, misurata usando un viscosimetro rotazionale con un adattatore del campione e un diametro albero 18 mm. La tensione superficiale è stata misurata utilizzando un tensiometro ed è stato calcolato per essere una media di 26 mN / m. L&#39;energia superficiale del vetro FTO è stata calcolata secondo la norma europea EN 828 per determinare la bagnabilità di una superficie solida misurando l&#39;angolo di contatto e superficie di energia libera. Dieci gocce di tre differenti liquidi (acqua, glicole etilenico e diiodometano) sono stati dispensati su una superficie di prova piece aereo. Per ogni goccia, l&#39;angolo di contatto a destra ea sinistra erano measured. Da gli angoli di contatto medi di ogni liquido combinata con la sua tensione superficiale, l&#39;energia libera di superficie della provetta viene calcolato. Il metodo Fowkes calcola l&#39;energia di superficie totale (γ) dalla somma dei contributi di interazioni dispersive (γd) e le interazioni γnon dispersivo (γp). Questo metodo ha comportato una energia libera superficiale di 26,45 mN / m per il vetro rivestito FTO. La stampa è stata effettuata secondo la procedura di cui sopra per produrre 5 mm quadrati. Lo spessore dello strato stampato sul vetro è stata misurata usando un profiler superficie. Lo spessore massimo al centro dello strato stampato è stata misurata a 2,6 micron. La trasmittanza del vetro rivestito è stato misurato usando uno spettrometro UV-VIS. Ad una lunghezza d&#39;onda di 700 nm, una trasmittanza del 60% è stata misurata per il film stampato TiO 2 rispetto al 78% per il vetro FTO. <p class="jove_content" fo:keep-together.within-page = &quot;1&quot;&gt; dispositivi fotovoltaici sono stati prodotti secondo lo schema procedimento sopra e caratterizzati direttamente dopo la fabbricazione per minimizzare l&#39;effetto di degradazione causata da acqua e ossigeno nell&#39;aria. Ci sono cinque parametri elettrici prestazioni utilizzati per caratterizzare e confrontare celle solari 28. I valori della corrente di corto circuito (I sc) e tensione a circuito aperto (V oc) possono essere derivate dalla corrente-tensione (IV) della curva. Questi possono poi essere utilizzati per determinare il fattore di riempimento (FF) e l&#39;efficienza di conversione di potenza (η). Il FF dà un rapporto delle cellule effettiva potenza massima al prodotto della tensione a circuito aperto e corto circuito corrente 29. Questo è un parametro fondamentale per valutare le prestazioni delle celle solari. Un alto FF significa basse perdite elettrochimici, mentre una bassa FF indica che c&#39;è spazio per il miglioramento. Diversi fattori sono noti per influenzare la FF compresa la qualità e l&#39;interfaccia degli strati all&#39;interno della cellula. DSSC incorpora una coppia redox ioduro / triiodide con il record di efficienza del rapporto di 11,9% di riempimento fattori di 0,71 30. Tutti questi parametri devono essere determinati in condizioni di prova standard in cui la temperatura del dispositivo è di 25 ° C, la distribuzione irraggiamento spettrale della luce ha una massa d&#39;aria di 1,5, irradianza totale misurata (E m) presso la cella solare è di 100 mW / cm 2. Massimo teorico per l&#39;efficienza di conversione per una singola cella giunzione pn è stato ampiamente segnalato come 37,7% 31, tuttavia per DSSCs è stato segnalato che l&#39;efficienza massima è più vicino al 15,1% con un inizio assorbimento a 920 nm 32. La corrente di uscita e tensioni sono stati misurati utilizzando un misuratore di sorgente mentre le cellule sono state illuminate con un / cm sorgente luminosa 100 mW 2 con filtro per abbinare la distribuzione irradianza spettrale con una massa d&#39;aria di 1,5. I risultati sono stati confrontati con una cellaprodotta utilizzando un livello medico-pale TiO 2 con una pasta disponibile in commercio, che è una miscela di particelle di anatasio 20 nm e 450 nm. Lo strato stampato ha una superficie di 0,25 cm 2 e uno spessore medio di 18 micron che è stata misurata utilizzando un profiler superficie. Un confronto tra l&#39;efficienza fotoelettrico tra i due dispositivi è illustrata in Figura 1 e Tabella 1. Diversi studi hanno indagato il rapporto tra lo spessore dello strato di TiO 2 e l&#39;efficienza di conversione entro DSSCs. I risultati variano notevolmente, con spessore di pellicola ottimale segnalato da qualsiasi punto tra 9,5 micron e 20 micron 33-39. Tabella 1 delinea gli spessori degli strati TiO 2 incisioni e le efficienze. Lo spessore del getto di inchiostro stampato TiO 2 è significativamente inferiore al medico pale TiO 2, risultantein una minore efficienza. Il lavoro futuro esaminerà l&#39;uso di leganti organici nella formulazione dell&#39;inchiostro per aumentare lo spessore dello strato di inchiostro stampato. <img alt="Figura 1" src="/files/ftp_upload/53963/53963fig1.jpg" /> Figura 1. Curve caratteristiche di DSSCs con getto d&#39;inchiostro stampato e dottore a lame TiO 2 strati. Curve attuale densità / tensione per DSSCs incorporano un getto di inchiostro stampato TiO 2 strati e uno strato medico-lama TiO 2. La densità di corrente di corto circuito nel dispositivo con il getto di inchiostro stampato TiO2 strato è significativamente inferiore rispetto al dispositivo con il medico lama strato di TiO2 con una conseguente minore efficienza generale di conversione. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/53963/53963fig1large.jpg" target="_blank">Si prega di cliccare qui per vedere una versione più grande di questa figura.</a> <table><tbody><tr><tdrowspan = &quot;3&quot;&gt; </td><td> Corrente di corto circuito </td><td> tensione a circuito aperto </td><td rowspan="3"> Fattore di riempimento </td><td> Efficienza </td><td> Spessore </td></tr><tr><td> (mA / cm 2) </td><td> (MV) </td><td></td><td></td></tr><tr><td></td><td></td><td> (%) </td><td> (Micron) </td></tr><tr><td> a getto d&#39;inchiostro stampato </td><td> 9.42 </td><td> 760 </td><td> 0.49 </td><td> 3.5 </td><td> 2.6 </td></tr><tr><td> medico lame </td><td> 11 </td><td> 756 </td><td> 0.58 </td><td> 4.8 </td><td> 18 </td></tr></tbody></table> Tabella 1. Key Performance caratteristiche delle cellule in Figura 1. Questa tabella mette a confronto i parametri chiave della cella solare, tra cui la tensione a circuito aperto (V oc), corrente di corto circuito (I SC) che determinano l&#39;efficienza (η) sotto la luce specificato condizioni sono presentati. I parametri ocella fa prodotta utilizzando un livello medico-lama TiO2 sono stati inclusi anche per il confronto. I fattori di riempimento (FF) di entrambi i dispositivi sono molto bassi che viene generalmente attribuito ad una elevata resistenza interna della cella.

Watch this Scientific Journal Video about Digital Printing of Titanium Dioxide for Dye Sensitized Solar Cells at JoVE.com

Digital Printing of Titanium Dioxide for Dye Sensitized Solar Cells

This paper investigates the suitability of inkjet printing for the manufacturing of dye-sensitized solar cells. A binder-free TiO2 nanoparticle ink was formulated and printed onto a FTO glass substrate. The printed layer was fabricated into a cell with an active area of 0.25 cm2 and an efficiency of 3.5%.

La stampa digitale di biossido di titanio per le celle solari dye sensibilizzato

Silicon solar cell manufacturing is an expensive and high energy consuming process. In contrast, dye sensitized solar cell production is less ...

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12.7K Views.  University of Warwick. This paper investigates the suitability of inkjet printing for the manufacturing of dye-sensitized solar cells. A binder-free TiO2 nanoparticle ink was formulated and printed onto a FTO glass substrate. The printed layer was fabricated into a cell with an active area of 0.25 cm2 and an efficiency of 3.5%.

Video: Digital Printing of Titanium Dioxide for Dye Sensitized Solar Cells

Micro 3D Printing Using a Digital Projector and its Application in the Study of Soft Materials Mechanics

Buckling is a classical topic in mechanics. While buckling has long been studied as one of the major structural failure modes1, it has recently drawn new attention as a unique mechanism for pattern transformation. Nature is full of such examples where a wealth of exotic patterns are formed through mechanical instability2-5. Inspired by this elegant mechanism, many studies have demonstrated creation and transformation of patterns using soft materials such as elastomers and hydrogels6-11. Swelling gels are of particular interest because they can spontaneously trigger mechanical instability to create various patterns without the need of external force6-10. Recently, we have reported demonstration of full control over buckling pattern of micro-scaled tubular gels using projection micro-stereolithography (P&mu;SL), a three-dimensional (3D) manufacturing technology capable of rapidly converting computer generated 3D models into physical objects at high resolution12,13. Here we present a simple method to build up a simplified P&mu;SL system using a commercially available digital data projector to study swelling-induced buckling instability for controlled pattern transformation.
A simple desktop 3D printer is built using an off-the-shelf digital data projector and simple optical components such as a convex lens and a mirror14. Cross-sectional images extracted from a 3D solid model is projected on the photosensitive resin surface in sequence, polymerizing liquid resin into a desired 3D solid structure in a layer-by-layer fashion. Even with this simple configuration and easy process, arbitrary 3D objects can be readily fabricated with sub-100 &mu;m resolution.
This desktop 3D printer holds potential in the study of soft material mechanics by offering a great opportunity to explore various 3D geometries. We use this system to fabricate tubular shaped hydrogel structure with different dimensions. Fixed on the bottom to the substrate, the tubular gel develops inhomogeneous stress during swelling, which gives rise to buckling instability. Various wavy patterns appear along the circumference of the tube when the gel structures undergo buckling. Experiment shows that circumferential buckling of desired mode can be created in a controlled manner. Pattern transformation of three-dimensionally structured tubular gels has significant implication not only in mechanics and material science, but also in many other emerging fields such as tunable matamaterials.

We demonstrate controlled pattern transformation of swelling gel tubes by elastic instability. A simple projection micro stereo-lithography setup is built using an off-the-shelf digital data projector to fabricate three-dimensional polymeric structures in a layer-by-layer fashion. Swelling hydrogel tubes under mechanical constraint display various circumferential buckling modes depending on dimension.

Micro 3D Stampa con un proiettore digitale e la sua applicazione nello studio della meccanica dei materiali morbidi

Buckling is a classical topic in mechanics. While buckling has long been studied as one of the major structural failure modes1, it has recently drawn new ...

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Integrating a Triplet-triplet Annihilation Up-conversion System to Enhance Dye-sensitized Solar Cell Response to Sub-bandgap Light

The poor response of dye-sensitized solar cells (DSCs) to red and infrared light is a significant impediment to the realization of higher photocurrents and hence higher efficiencies. Photon up-conversion by way of triplet-triplet annihilation (TTA-UC) is an attractive technique for using these otherwise wasted low energy photons to produce photocurrent, while not interfering with the photoanodic performance in a deleterious manner. Further to this, TTA-UC has a number of features, distinct from other reported photon up-conversion technologies, which renders it particularly suitable for coupling with DSC technology. In this work, a proven high performance TTA-UC system, comprising a palladium porphyrin sensitizer and rubrene emitter, is combined with a high performance DSC (utilizing the organic dye D149) in an integrated device. The device shows an enhanced response to sub-bandgap light over the absorption range of the TTA-UC sub-unit resulting in the highest figure of merit for up-conversion assisted DSC performance to date.

An integrated device, incorporating a dye-sensitized solar cell and triplet-triplet annihilation up-conversion unit was produced, affording enhanced light harvesting, from a wider section of the solar spectrum. Under modest irradiation levels a significantly enhanced response to low energy photons was demonstrated, yielding a record figure of merit for dye-sensitized solar cells.

L&#39;integrazione di un Triplet-tripletta Annihilation sistema Up-conversione per migliorare Dye-sensibilizzati Risposta Solar Cell a Sub-bandgap Luce

The poor response of dye-sensitized solar cells (DSCs) to red and infrared light is a significant impediment to the realization of higher photocurrents ...

Ambient Method for the Production of an Ionically Gated Carbon Nanotube Common Cathode in Tandem Organic Solar Cells

A method of fabricating organic photovoltaic (OPV) tandems that requires no vacuum processing is presented. These devices are comprised of two solution-processed polymeric cells connected in parallel by a transparent carbon nanotubes (CNT) interlayer. This structure includes improvements in fabrication techniques for tandem OPV devices. First the need for ambient-processed cathodes is considered. The CNT anode in the tandem device is tuned via ionic gating to become a common cathode. Ionic gating employs electric double layer charging to lower the work function of the CNT electrode. Secondly, the difficulty of sequentially stacking tandem layers by solution-processing is addressed. The devices are fabricated via solution and dry-lamination in ambient conditions with parallel processing steps. The method of fabricating the individual polymeric cells, the steps needed to laminate them together with a common CNT cathode, and then provide some representative results are described. These results demonstrate ionic gating of the CNT electrode to create a common cathode and addition of current and efficiency as a result of the lamination procedure.

A method of fabricating, in ambient conditions, organic photovoltaic tandem devices in a parallel configuration is presented. These devices feature an air-processed, semi-transparent, carbon nanotube common cathode.

Metodo ambiente per la produzione di un ionicamente Gated Nanotubi di carbonio catodo comune in celle solari tandem Organic

A method of fabricating organic photovoltaic (OPV) tandems that requires no vacuum processing is presented. These devices are comprised of two ...

Integration of Light Trapping Silver Nanostructures in Hydrogenated Microcrystalline Silicon Solar Cells by Transfer Printing

One of the potential applications of metal nanostructures is light trapping in solar cells, where unique optical properties of nanosized metals, commonly known as plasmonic effects, play an important role. Research in this field has, however, been impeded owing to the difficulty of fabricating devices containing the desired functional metal nanostructures. In order to provide a viable strategy to this issue, we herein show a transfer printing-based approach that allows the quick and low-cost integration of designed metal nanostructures with a variety of device architectures, including solar cells. Nanopillar poly(dimethylsiloxane) (PDMS) stamps were fabricated from a commercially available nanohole plastic film as a master mold. On this nanopatterned PDMS stamps, Ag films were deposited, which were then transfer-printed onto block copolymer (binding layer)-coated hydrogenated microcrystalline Si (&#181;c-Si:H) surface to afford ordered Ag nanodisk structures. It was confirmed that the resulting Ag nanodisk-incorporated &#181;c-Si:H solar cells show higher performances compared to a cell without the transfer-printed Ag nanodisks, thanks to plasmonic light trapping effect derived from the Ag nanodisks. Because of the simplicity and versatility, further device application would also be feasible thorough this approach.

A viable transfer printing-based methodology to introduce plasmonic metal nanostructures in solar cells is described. Using nanopillar poly(dimethylsiloxane) stamps, an Ag-based ordered nanodisk array was integrated with standard hydrogenated microcrystalline Si solar cells, which led to improved device performances due to plasmonic light trapping.

Integrazione di luce Trapping Argento Nanostrutture in silicio microcristallino idrogenato celle solari tramite bonifico stampa

One of the potential applications of metal nanostructures is light trapping in solar cells, where unique optical properties of nanosized metals, commonly ...

Printing Fabrication of Bulk Heterojunction Solar Cells and In Situ Morphology Characterization

Polymer-based materials hold promise as low-cost, flexible efficient photovoltaic devices. Most laboratory efforts to achieve high performance devices have used devices prepared by spin coating, a process that is not amenable to large-scale fabrication. This mismatch in device fabrication makes it difficult to translate quantitative results obtained in the laboratory to the commercial level, making optimization difficult. Using a mini-slot die coater, this mismatch can be resolved by translating the commercial process to the laboratory and characterizing the structure formation in the active layer of the device in real time and in situ as films are coated onto a substrate. The evolution of the morphology was characterized under different conditions, allowing us to propose a mechanism by which the structures form and grow. This mini-slot die coater offers a simple, convenient, material efficient route by which the morphology in the active layer can be optimized under industrially relevant conditions. The goal of this protocol is to show experimental details of how a solar cell device is fabricated using a mini-slot die coater and technical details of running in situ structure characterization using the mini-slot die coater.

Printing Fabrication of Bulk Heterojunction Solar Cells and In Situ Morphology Characterization

Here, we present a protocol to fabricate organic thin film solar cells using a mini-slot die coater and related in-line structure characterizations using synchrotron scattering techniques.

La stampa Fabbricazione di massa eterogiunzione celle solari e<em&gt; In Situ</em&gt; Morfologia Caratterizzazione

Polymer-based materials hold promise as low-cost, flexible efficient photovoltaic devices. Most laboratory efforts to achieve high performance devices ...

Monovalent Cation Doping of CH3NH3PbI3 for Efficient Perovskite Solar Cells

Here, we demonstrate the incorporation of monovalent cation additives into CH3NH3PbI3 perovskite in order to adjust the optical, excitonic, and electrical properties. The possibility of doping was investigated by adding monovalent cation halides with similar ionic radii to Pb2+, including Cu+, Na+, and Ag+. A shift in the Fermi level and a remarkable decrease of sub-bandgap optical absorption, along with a lower energetic disorder in the perovskite, was achieved. An order-of-magnitude enhancement in the bulk hole mobility and a significant reduction of transport activation energy within an additive-based perovskite device was attained. The confluence of the aforementioned improved properties in the presence of these cations led to an enhancement in the photovoltaic parameters of the perovskite solar cell. An increase of 70 mV in open circuit voltage for AgI and a 2 mA/cm2 improvement in photocurrent density for NaI- and CuBr-based solar cells were achieved compared to the pristine device. Our work paves the way for further improvements in the optoelectronic quality of CH3NH3PbI3 perovskite and subsequent devices. It highlights a new avenue for investigations on the role of dopant impurities in crystallization and controls the electronic defect density in perovskite structures.

Monovalent Cation Doping of CH3NH3PbI3 for Efficient Perovskite Solar Cells

Here, we present a protocol to adjust the properties of solution-processed CH3NH3PbI3 through the incorporation of monovalent cation additives in order to achieve highly efficient perovskite solar cells.

Cationi monovalenti doping di CH<sub&gt; 3</sub&gt; NH<sub&gt; 3</sub&gt; PBI<sub&gt; 3</sub&gt; Per efficienti celle solari Perovskite

Here, we demonstrate the incorporation of monovalent cation additives into CH3NH3PbI3 perovskite in order to adjust the optical, excitonic, and electrical ...

Electrospinning of Photocatalytic Electrodes for Dye-sensitized Solar Cells

This work demonstrates a protocol to fabricate a fiber-based photoanode for dye-sensitized solar cells, consisting of a light-scattering layer made of electrospun titanium dioxide nanofibers (TiO2-NFs) on top of a blocking layer made of commercially available titanium dioxide nanoparticles (TiO2-NPs). This is achieved by first electrospinning a solution of titanium (IV) butoxide, polyvinylpyrrolidone (PVP), and glacial acetic acid in ethanol to obtain composite PVP/TiO2 nanofibers. These are then calcined at 500 &#176;C to remove the PVP and to obtain pure anatase-phase titania nanofibers. This material is characterized using scanning electron microscopy (SEM) and powder X-ray diffraction (XRD). The photoanode is prepared by first creating a blocking layer through the deposition of a TiO2-NPs/terpineol slurry on a fluorine-doped tin oxide (FTO) glass slide using doctor blading techniques. A subsequent thermal treatment is performed at 500 &#176;C. Then, the light-scattering layer is formed by depositing a TiO2-NFs/terpineol slurry on the same slide, using the same technique, and calcinating again at 500 &#176;C. The performance of the photoanode is tested by fabricating a dye-sensitized solar cell and measuring its efficiency through J-V curves under a range of incident light densities, from 0.25-1 Sun.

The overall goal of this project was to use electrospinning to fabricate a photoanode with improved performance for dye-sensitized solar cells.

Elettrospinning degli elettrodi fotocatalitici per le celle solari sensibilizzate a tinte

This work demonstrates a protocol to fabricate a fiber-based photoanode for dye-sensitized solar cells, consisting of a light-scattering layer made of ...

In Situ Monitoring of the Accelerated Performance Degradation of Solar Cells and Modules: A Case Study for Cu(In,Ga)Se2 Solar Cells

The levelized cost of electricity (LCOE) of photovoltaic (PV) systems is determined by, among other factors, the PV module reliability. Better prediction of degradation mechanisms and prevention of module field failure can consequently decrease investment risks as well as increase the electricity yield. An improved knowledge level can for these reasons significantly decrease the total costs of PV electricity. 
In order to better understand and minimize the degradation of PV modules, the occurring degradation mechanisms and conditions should be identified. This should preferably happen under combined stresses, since modules in the field are also simultaneously exposed to multiple stress factors. Therefore, two 'Combined Stress test with in situ measurement' setups have been designed and constructed. These setups allow the simultaneous use of humidity, temperature, illumination, and electrical biases as independently controlled stress factors on solar cells and minimodules. The setups also allow real-time monitoring of the electrical properties of these samples. This protocol presents these setups and describes the experimental possibilities. Moreover, results obtained with these setups are also presented: various examples about the influence of both deposition and degradation conditions on the stability of thin film Cu(In,Ga)Se2 (CIGS) as well as Cu2ZnSnSe4 (CZTS) solar cells are described. Results on the temperature dependency of CIGS solar cells are also presented.

In Situ Monitoring of the Accelerated Performance Degradation of Solar Cells and Modules: A Case Study for CuIn,GaSe2 Solar Cells

Two &#39;Combined Stress test with in situ measurement&#39; setups, which allow real-time monitoring of accelerated degradation of solar cells and modules, were designed and constructed. These setups allow the simultaneous use of humidity, temperature, electrical biases, and illumination as independently controlled stress factors. The setups and various experiments executed are presented.

In Situ Monitoraggio del degrado prestazioni accelerate di celle e moduli solari: un caso di studio per le celle solari di Cu (In, Ga) Se2

The levelized cost of electricity (LCOE) of photovoltaic (PV) systems is determined by, among other factors, the PV module reliability. Better prediction ...

Indoor Experimental Assessment of the Efficiency and Irradiance Spot of the Achromatic Doublet on Glass (ADG) Fresnel Lens for Concentrating Photovoltaics

We present a method to characterize achromatic Fresnel lenses for photovoltaic applications. The achromatic doublet on glass (ADG) Fresnel lens is composed of two materials, a plastic and an elastomer, whose dispersion characteristics (refractive index variation with wavelength) are different. We first designed the lens geometry and then used ray-tracing simulation, based on the Monte Carlo method, to analyze its performance from the point of view of both optical efficiency and the maximum attainable concentration. Afterwards, ADG Fresnel lens prototypes were manufactured using a simple and reliable method. It consists of a prior injection of plastic parts and a consecutive lamination, together with the elastomer and a glass substrate to fabricate the parquet of ADG Fresnel lenses. The accuracy of the manufactured lens profile is examined using an optical microscope while its optical performance is evaluated using a solar simulator for concentrator photovoltaic systems. The simulator is composed of a xenon flash lamp whose emitted light is reflected by a parabolic mirror. The collimated light has a spectral distribution and an angular aperture similar to the real Sun. We were able to assess the optical performance of the ADG Fresnel lenses by taking photographs of the irradiance spot cast by the lens using a charge-coupled device (CCD) camera and measuring the photocurrent generated by several types of multi junction (MJ) solar cells, which have been previously characterized at a solar simulator for concentrator solar cells. These measurements have demonstrated the achromatic behavior of ADG Fresnel lenses and, as a consequence, the suitability of the modelling and manufacturing methods.

Indoor Experimental Assessment of the Efficiency and Irradiance Spot of the Achromatic Doublet on Glass ADG Fresnel Lens for Concentrating Photovoltaics

The achromatic doublet on glass (ADG) Fresnel lens makes use of two materials with differing dispersion to reduce chromatic aberration and increase attainable concentration. In this paper, a protocol for the complete characterization of the ADG Fresnel lens is presented.

Valutazione interna sperimentale dell'efficienza e dell'irraggiamento Spot del doppietto acromatico su vetro (ADG) lente di Fresnel per fotovoltaico a concentrazione

We present a method to characterize achromatic Fresnel lenses for photovoltaic applications. The achromatic doublet on glass (ADG) Fresnel lens is ...

Developing High Performance GaP/Si Heterojunction Solar Cells

To improve the efficiency of Si-based solar cells beyond their Shockley-Queisser limit, the optimal path is to integrate them with III-V-based solar cells. In this work, we present high performance GaP/Si heterojunction solar cells with a high Si minority-carrier lifetime and high crystal quality of epitaxial GaP layers. It is shown that by applying phosphorus (P)-diffusion layers into the Si substrate and a SiNx layer, the Si minority-carrier lifetime can be well-maintained during the GaP growth in the molecular beam epitaxy (MBE). By controlling the growth conditions, the high crystal quality of GaP was grown on the P-rich Si surface. The film quality is characterized by atomic force microscopy and high-resolution x-ray diffraction. In addition, MoOx was implemented as a hole-selective contact that led to a significant increase in the short-circuit current density. The achieved high device performance of the GaP/Si heterojunction solar cells establishes a path for further enhancement of the performance of Si-based photovoltaic devices.

Here, we present a protocol to develop high-performance GaP/Si heterojunction solar cells with a high Si minority-carrier lifetime.

Lo sviluppo di celle solari ad alte prestazioni GaP/Si Heterojunction

To improve the efficiency of Si-based solar cells beyond their Shockley-Queisser limit, the optimal path is to integrate them with III-V-based solar ...