Esta pesquisa é gratamente realizado com o apoio da Engenharia e Ciências Físicas Research Council (EPSRC), financiado através de uma bolsa de formação de doutoramento. Abrir acesso taxas de processamento artigo (APCs) foram financiados pela Research Conselhos Reino Unido (RCUK). Todos os dados são fornecidos na íntegra na seção de resultados do papel. Os resultados representativos foram previamente publicados pelos autores 42. Nós gostaríamos de agradecer ao Dr. Senthilarasu Sundaram, da Universidade de Exeter por sua ajuda na caracterização do desempenho elétrico das células.

1. fórmula da tinta Nota: formulações de tinta são frequentemente mantidos em segredo bem guardado pelos fabricantes. Sucesso formulações equilíbrio jacto, gota formação, molhamento e comportamento de secagem ao lado de desempenho funcional. Normalmente, um material funcional é disperso num solvente e pelo menos um outro componente para torná-los jettable. Esta seção detalha o desenvolvimento de um TiO2 de tinta para uso dentro de impressão jato de tinta. Um pequeno lote de tinta foi preparada pelo método seguinte. Cuidado: preparação da tinta deve ser realizada em uma área adequadamente ventilada, por exemplo, sob um exaustor, enquanto vestindo olho óculos de proteção e luvas de látex. <ol><li> Prepara-se uma solução aquosa 0,1 mM de ácido clorídrico (HCl) para produzir um pH de aproximadamente 4. </li><li> Adicionar 32 g de solução de ácido de 8 g de um solvente compatível com um ponto de ebulição mais elevado e mais baixo do que a tensão superficial da água (tal como dimetilformamida (DMF)). A adição de um co-solvent actua como um agente de secagem para induzir um fluxo de circulação no interior da gotícula de tinta tal como a evaporação da tinta, que conduz a um posicionamento uniforme das nanopartículas sobre a superfície da gotícula de 21. </li><li> Adicionar 1,5 g de dispersão de aditivo (45% de solução activa de propileno glicol e tetrametil-5-decino-4,7-diol em água). </li><li> Adiciona-se 10 g de etileno glicol, como um humectante para evitar a secagem nos bicos. </li><li> Adicionar 0,5 g de agente anti-espuma (20% de solução activa de diol acetilénico em methoxypolyethyleneglycol) para a tinta para evitar que as bolhas de ar de se desenvolver. </li><li> Realizar um teste simples agitar tomando uma alíquota da tinta em um recipiente fechado e agitar à mão durante 60 segundos. Se qualquer espuma é observada depois adicionar mais 0,5 g de agente anti-espuma para a tinta. </li><li> Misture a solução durante 8 horas usando uma barra de agitação magnética, para assegurar a homogeneidade à TA. </li><li> Adicionar 1,5 g de dióxido de titânio (TiO2) nanopartículas com um tamanho de partícula primária de 21 nm, e a área de superfície de35-65 m2 / g. </li><li> Sonicar a mistura utilizando uma sonda de ultra-sons durante 15 minutos com uma frequência de 60 Hz. </li><li> Medir os tamanhos de partículas, usando uma técnica de medição apropriado, tal como espalhamento dinâmico da luz (DLS) de acordo com o protocolo do fabricante, para assegurar que eles vão fluir facilmente através das aberturas de bocal. Adicione medições nas mesmas condições (por ex., Mesmo solvente, pH, concentração de dispersante) a serem utilizados para a tinta à medida que cada componente pode influenciar a formação de aglomerados de tinta dentro da. Para jacto bem sucedida, as partículas dentro do fluido deve ser 100 vezes mais pequeno do que a abertura de injector. </li><li> Medir a viscosidade da tinta, utilizando uma técnica de medição apropriado, tal como um viscosímetro rotacional de acordo com o protocolo do fabricante, para assegurar jacto fiável a partir da cabeça de impressão de jacto de tinta como a impressão requer tintas de baixa viscosidade de entre 2 e 20 centipoise (cP). Aumentar a viscosidade através da additino dos materiais polímeros ou de materiais à base de celulose; no entanto, estes precisam ser removidos após a deposição de liberar locais para o corante dentro do filme impresso 22. </li><li> Medir a tensão superficial da tinta, utilizando uma técnica de medição apropriado, tal como um tensiómetro de acordo com o protocolo do fabricante, para assegurar jacto fiável. As diretrizes de formulação de fluidos jettable para impressoras jato de tinta sugerem uma tensão superficial entre 28 e 33 mN / m para permitir a impressão de confiança. </li></ol> 2. Inkjet Printing <ol><li> Antes da impressão, embeber os substratos de vidro numa solução a 2% em peso de detergente de limpeza (uma mistura de agentes tensioactivos aniónicos e de superfície não iónico, agentes, alcalis, detergentes sem fosfatos e agentes sequestrantes de estabilização, numa base aquosa) em água desionizada. Lavar o vidro completamente com água desionizada, logo que eles são removidos da solução de limpeza para remover os vestígios de contaminação e de limpeza do detergente. </li&gt; <li> Medir a energia de superfície do substrato, utilizando uma técnica de medição apropriado, tal como um tensiómetro de acordo com o protocolo do fabricante. Para uma boa aderência, a energia de superfície do substrato não deverá exceder a tensão superficial do fluido em mais de 10 - 15 mN / m. Modificar a energia de superfície do substrato, utilizando métodos tais como tratamento de coroa 23, o tratamento por plasma 24 e ataque químico 25, se não é adequada. </li><li> Carregar o substrato na impressora de acordo com o protocolo do fabricante. </li><li> Lave a cabeça de impressão com a tinta através da porta localizada no lado da cabeça para deslocar qualquer ar ou solução de limpeza dentro do reservatório e bicos. </li><li> Insira o cabeçote de impressão para a impressora. Conectar-se a cabeça de impressão com a placa de cabeça personalidade. </li><li> Filtra-se a tinta através do filtro de tamanho correcto apenas antes de carregar para dentro do cartucho para remover grandes agregados de partículas que podem entupir os bocais. ocabeça de impressão utilizada neste trabalho tem bicos com um diâmetro de 40 um (por exemplo, Konica KM512.); Por conseguinte, as tintas não devem conter partículas com um diâmetro superior a 400 nm. Passar as suspensões por meio de uma 5? M, seguido por um filtro de 1,2 uM de fluoreto de polivinilideno (PVDF) para remover quaisquer partículas grandes. </li><li> Coloque a tinta dentro da seringa 150 ml localizado acima da cabeça de impressão, que fornece a tinta na cabeça de impressão. Coloque a tampa hermética no topo da seringa e ligar a bomba de vácuo. </li><li> Purgar a tinta através dos bocais, premindo o botão de &quot;purga&quot; localizada na bomba de vácuo. </li><li> Através do servidor de impressão sistema de informação geográfica (GIS), os parâmetros de forma de onda e impressão de set-up. Note-se que a impressora pode imprimir até uma velocidade de 1,5 metros por segundo, no entanto, para esta tinta uma velocidade de impressão de 0,3 metros por segundo foi encontrado para fornecer o revestimento ideal </li><li> GIS aberta usuário do software de interface e carregar o padrão desejado. </li><li> Print do cartucho carregado de acordo com o protocolo do fabricante. </li><li> Remover o substrato a partir do rolo de impressão e aquecer as películas impressas a 150 ºC durante 30 min, seguido de 250 ° C durante mais 30 min, quer por uma placa de aquecimento ou num forno. </li></ol> 3. Análise dos filmes impressos <ol><li> Usar um microscópio óptico ou um microscópio de varrimento electrónico (SEM) a olhar para a superfície das películas impressas a baixa ampliação (100X) para analisar a morfologia da superfície e na ampliação elevada (35,000X) para analisar a porosidade dos filmes impressos. Verifique se as imagens mostram uma cobertura uniforme, sem rachaduras e boa porosidade. Informações mais detalhadas sobre a operação SEM pode ser encontrada nas seguintes referências 26,27. </li><li> Medir a espessura da camada impressa, usando uma técnica de medição apropriado, tal como um gerador de perfil de superfície de acordo com o protocolo do fabricante. A espessura e porosidade da sagacidade camada de TiO 2Hin DSSCs influenciar a quantidade de corante que pode ser absorvido na superfície das nanoparticulas, que influenciam, por conseguinte, a eficiência global de conversão eléctrica da célula 18. É, portanto, um parâmetro importante para avaliar. Usar um perfilador de superfície (precisão de 1 nm) para medir a espessura das películas impressas. </li><li> Medir a transmitância do filme, utilizando uma técnica de medição apropriado, tal como um espectrofotómetro de ultravioleta-visível (UV-VIS) para determinar a quantidade de luz visível vai transmitir através da película impressa. Use o protocolo do fabricante. </li></ol> 4. Tornar o celular <ol><li> Adicione uma solução de corante por mistura de 20 ml de etanol e 2 mg de corante ruténio num copo de vidro com um agitador magnético, durante 8 h. </li><li> Submergir o vidro revestido TiO2 na solução à TA (20 a 25 ° C) durante 24 horas para permitir que o corante de absorção sobre a superfície das partículas de TiO 2. </li><li> Remover o TiO2 </sub&gt; vidro revestido a partir da solução e coloque sobre papel absorvente para absorver qualquer solução corante em excesso (com o TiO 2 virada para cima para evitar a contaminação). </li><li> Colocar o pré-corte de 60 um de espessura de vedação espaçador termoplástico no topo do vidro condutor, em torno do revestimento de TiO2. </li><li> Coloque a platina revestido contra-eltrodo no topo do pré-corte de 60 um de espessura de vedação espaçador termoplástico de modo a que os lados activos do ânodo e do cátodo estão voltadas uma para a outra. Permitir sobreposição suficiente entre as duas peças de vidro de modo a que um contacto eléctrico podem ser feitos com o vidro condutor. Este deve ter um furo pré-furado no centro a fim de permitir o enchimento do electrólito mais tarde. </li><li> Aquece-se em uma placa quente a uma temperatura de 110 C e aplica uma pressão ligeira com uma pinça sobre a área de vedação do espaçador. Após 30 seg os eletrodos devem ser seladas. </li><li> Preencher a lacuna entre os dois eléctrodos com uma electro iodeto / tri-iodetoLyte em acetonitrilo a uma concentração de 50 mM, por injecção através do furo pré-furado na platina de vidro revestido utilizando uma seringa. </li></ol>

<ol>
	<li>Docampo, P., 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=Lessons+Learned:+From+Dye-Sensitized+Solar+Cells+to+All-Solid-State+Hybrid+Devices.">Lessons Learned: From Dye-Sensitized Solar Cells to All-Solid-State Hybrid Devices.</a> Adv. Mater. 26, 4013-4030 (2014).</li><li>Hudd, A., Magdassi, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The Chemistry of Inkjet Inks. , 3-18 (2009).</li><li>Krebs, F. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabrication+and+processing+of+polymer+solar+cells:+A+review+of+printing+and+coating.">Fabrication and processing of polymer solar cells: A review of printing and coating.</a> Sol. Energ. Mat. Sol. Cells. 93, 394-412 (2009).</li><li>Reddy, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Solar Power Generation: Technology, New Concepts &amp; Policy. , (2012).</li><li>Gemeiner, P., Mikula, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Acta. Chem. Slov. 6, 29 (2013).</li><li>Xue, Z., Jiang, C., Wang, L., Liu, W., Liu, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabrication+of+Flexible+Plastic+Solid-State+Dye-Sensitized+Solar+Cells+Using+Low+Temperature+Techniques.">Fabrication of Flexible Plastic Solid-State Dye-Sensitized Solar Cells Using Low Temperature Techniques.</a> J. Phys. Chem. C. 118, 16352-16357 (2014).</li><li>Oh, Y., Yoon, H. G., Lee, S. -. N., Kim, H. -. K., Kim, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inkjet-Printing+of+TiO2+Co-Solvent+Ink:+From+Uniform+Ink-Droplet+to+TiO2+Photoelectrode+for+Dye-Sensitized+Solar+Cells.">Inkjet-Printing of TiO2 Co-Solvent Ink: From Uniform Ink-Droplet to TiO2 Photoelectrode for Dye-Sensitized Solar Cells.</a> J. Electrochem. Soc. 159, 34-38 (2011).</li><li>Lin, L. -. Y., 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=Low-temperature+flexible+Ti/TiO2+photoanode+for+dye-sensitized+solar+cells+with+binder-free+TiO2+paste.">Low-temperature flexible Ti/TiO2 photoanode for dye-sensitized solar cells with binder-free TiO2 paste.</a> Prog. Photovolt. Res. Appl. 20, 181-190 (2012).</li><li>Gong, J., Liang, J., Sumathy, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Review+on+dye-sensitized+solar+cells+(DSSCs):+Fundamental+concepts+and+novel+materials.">Review on dye-sensitized solar cells (DSSCs): Fundamental concepts and novel materials.</a> Renew. Sustainable Energy Rev. 16, 5848-5860 (2012).</li><li>Bosch-Jimenez, P., Yu, Y., Lira-Cantu, M., Domingo, C., Ayll&#242;n, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Solution+processable+titanium+dioxide+precursor+and+nanoparticulated+ink:+Application+in+Dye+Sensitized+Solar+Cells.">Solution processable titanium dioxide precursor and nanoparticulated ink: Application in Dye Sensitized Solar Cells.</a> J Colloid Interf Sci. 416, 112-118 (2014).</li><li>Jose, R., Thavasi, V., Ramakrishna, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metal+Oxides+for+Dye-Sensitized+Solar+Cells.">Metal Oxides for Dye-Sensitized Solar Cells.</a> J. Am. Ceram. Soc. 92, 289-301 (2009).</li><li>Gemeiner, P., Mikula, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficiency+of+dye+sensitized+solar+cells+with+various+compositions+of+TiO2+based+screen+printed+photoactive+electrodes.">Efficiency of dye sensitized solar cells with various compositions of TiO2 based screen printed photoactive electrodes.</a> Acta. Chem. Slov. 6, 29-34 (2013).</li><li>Lee, K. E., Charbonneau, C., Demopoulos, G. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thin+single+screen-printed+bifunctional+titania+layer+photoanodes+for+high+performing+DSSCs+via+a+novel+hybrid+paste+formulation+and+process.">Thin single screen-printed bifunctional titania layer photoanodes for high performing DSSCs via a novel hybrid paste formulation and process.</a> J. Mater. Res. 28, 480-487 (2013).</li><li>Li, J., Lemme, M. C., &#246;stling, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inkjet+Printing+of+2D+Layered+Materials.">Inkjet Printing of 2D Layered Materials.</a> ChemPhysChem. 15, 3427-3434 (2014).</li><li>Rudyak, V. Y., Krasnolutskii, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dependence+of+the+viscosity+of+nanofluids+on+nanoparticle+size+and+material.">Dependence of the viscosity of nanofluids on nanoparticle size and material.</a> Phys. Lett. A. 378, 1845-1849 (2014).</li><li>Dispoto, G., Moroney, N., Hanson, E., Meyer, J. D., Allen, R. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Color Desktop Printer Technology Optical Science and Engineering. , 111-155 (2006).</li><li>Hsien-Hsueh, L., Kan-Sen, C., Kuo-Cheng, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inkjet+printing+of+nanosized+silver+colloids.">Inkjet printing of nanosized silver colloids.</a> Nanotechnology. 16, 2436 (2005).</li><li>Singh, M., Haverinen, H. M., Dhagat, P., Jabbour, G. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inkjet+Printing:+Inkjet+Printing-Process+and+Its+Applications.">Inkjet Printing: Inkjet Printing-Process and Its Applications.</a> Adv. Mater. 22, 673-685 (2010).</li><li>St&#252;we, D., Mager, D., Biro, D., Korvink, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inkjet+Technology+for+Crystalline+Silicon+Photovoltaics.">Inkjet Technology for Crystalline Silicon Photovoltaics.</a> Adv. Mater. 27, 599-626 (2015).</li><li>Perelaer, J., 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=Roll-to-Roll+Compatible+Sintering+of+Inkjet+Printed+Features+by+Photonic+and+Microwave+Exposure:+From+Non-Conductive+Ink+to+40%+Bulk+Silver+Conductivity+in+Less+Than+15+Seconds.">Roll-to-Roll Compatible Sintering of Inkjet Printed Features by Photonic and Microwave Exposure: From Non-Conductive Ink to 40% Bulk Silver Conductivity in Less Than 15 Seconds.</a> Adv. Mater. 24, 2620-2625 (2012).</li><li>Hwang, M. -. s., Jeong, B. -. y., Moon, J., Chun, S. -. K., Kim, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inkjet-printing+of+indium+tin+oxide+(ITO)+films+for+transparent+conducting+electrodes.">Inkjet-printing of indium tin oxide (ITO) films for transparent conducting electrodes.</a> Mat. Sci. Eng. B. 176, 1128-1131 (2011).</li><li>Hara, K., Arakawa, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Handbook of Photovoltaic Science and Engineering. , 663-700 (2003).</li><li>Ryu, J., Wakida, T., Takagishi, T. <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+Corona+Discharge+on+the+Surface+of+Wool+and+Its+Application+to+Printing.">Effect of Corona Discharge on the Surface of Wool and Its Application to Printing.</a> Text. Res. J. 61, 595-601 (1991).</li><li>Yang, L., Chen, J., Guo, Y., Zhang, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface+modification+of+a+biomedical+polyethylene+terephthalate+(PET)+by+air+plasma.">Surface modification of a biomedical polyethylene terephthalate (PET) by air plasma.</a> Appl. Surf. Sci. 255, 4446-4451 (2009).</li><li>Qian, B., Shen, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabrication+of+Superhydrophobic+Surfaces+by+Dislocation-Selective+Chemical+Etching+on+Aluminum,+Copper,+and+Zinc+Substrates.">Fabrication of Superhydrophobic Surfaces by Dislocation-Selective Chemical Etching on Aluminum, Copper, and Zinc Substrates.</a> J. Am. Chem. Soc. 21, 9007-9009 (2005).</li><li>Echlin, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Handbook of Sample Preparation for Scanning Electron Microscopy and X-Ray Microanalysis. , (2011).</li><li>Flegler, S. L., Heckman, J. W., Klomparens, K. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Scanning and Transmission Electron Microscopy: An Introduction. , (1993).</li><li>O'Donnell, M. Z. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=How+To+Minimize+Measurement+Errors+In+Solar+Cell+Testing.">How To Minimize Measurement Errors In Solar Cell Testing.</a> Solar Industry Magazine. , (2011).</li><li>Gr&#228;tzel, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dye-sensitized+solar+cells.">Dye-sensitized solar cells.</a> J. Photochem. Photobiol. C: Photochem. Rev. 4, 145-153 (2003).</li><li>Green, M. A., Emery, K., Hishikawa, Y., Warta, W., Dunlop, E. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Solar+cell+efficiency+tables+(version+46).">Solar cell efficiency tables (version 46).</a> Prog. Photovolt. Res. Appl. 23, 805-812 (2015).</li><li>Shockley, W., Queisser, H. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detailed+Balance+Limit+of+Efficiency+of+p-n+Junction+Solar+Cells.">Detailed Balance Limit of Efficiency of p-n Junction Solar Cells.</a> J. Appl. Phys. 32, 510-519 (1961).</li><li>Snaith, H. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Estimating+the+Maximum+Attainable+Efficiency+in+Dye-Sensitized+Solar+Cells.">Estimating the Maximum Attainable Efficiency in Dye-Sensitized Solar Cells.</a> Adv. Funct. Mater. 20, 13-19 (2010).</li><li>Jeng, M. -. J., Wung, Y. -. L., Chang, L. -. B., Chow, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Particle+Size+Effects+of+TiO2+Layers+on+the+Solar+Efficiency+of+Dye-Sensitized+Solar+Cells.">Particle Size Effects of TiO2 Layers on the Solar Efficiency of Dye-Sensitized Solar Cells.</a> Int. J. Photoenergy. 2013, 9 (2013).</li><li>Song-Yuan, D., Kong-Jia, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimum+Nanoporous+TiO2+Film+and+Its+Application+to+Dye-sensitized+Solar+Cells.">Optimum Nanoporous TiO2 Film and Its Application to Dye-sensitized Solar Cells.</a> Chin. Phys. Lett. 20, 953-955 (2002).</li><li>Baglio, V., Girolamo, M., Antonucci, V., Aric&#242;, A. 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>

Os autores não têm nada para revelar.

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.

Uma tinta de TiO 2 foi formulada de acordo com o procedimento delineado. O tamanho de partículas em suspensão no interior da tinta foi medida usando dispersão dinâmica de luz (DLS) e um tamanho de partícula médio de 80 nanómetros (nm) foi observado. A viscosidade da tinta no presente trabalho verificou-se ser de 3 cP, medida usando um viscosímetro rotacional com um adaptador de amostra pequeno e um diâmetro de fuso de 18 mm. A tensão superficial foi medida utilizando um tensiómetro e foi calculado como sendo uma média de 26 mN / m. A energia de superfície do vidro FTO foi calculada de acordo com a Norma Europeia EN 828 para determinar a molhabilidade de uma superfície sólida através da medição do ângulo de contacto e a energia livre de superfície. Dez gotas de três diferentes líquidos (água, etilenoglicol e di-iodometano) foram distribuídos sobre uma superfície plana de teste peça. Para cada queda, o ângulo de contato esquerda e direita foram MEASUREd. A partir dos ângulos de contacto médios de cada líquido combinada com a sua tensão superficial, a energia livre de superfície da peça de ensaio é calculado. O método Fowkes calcula a energia de superfície total (γ) a partir da soma das contribuições das interações dispersivas (γd) e interações γnon dispersivo (γp). Este método resultou num energia livre de superfície de 26,45 mN / m, para o vidro revestido FTO. A impressão foi realizada de acordo com o procedimento acima para produzir 5 mm quadrados. A espessura da camada impressa sobre o vidro foi medida utilizando um perfilador de superfície. A espessura máxima no centro da camada impressa foi medido como sendo de 2,6 uM. A transmitância do vidro revestido foi medida utilizando um espectrómetro de UV-VIS. Num comprimento de onda de 700 nm, uma transmitância de 60% ​​foi medido para o filme impresso de TiO 2, em comparação com 78% para o vidro FTO. <p class="jove_content" fo:keep-together.within-páginas = &quot;1&quot;&gt; dispositivos fotovoltaicos foram produzidos de acordo com o contorno procedimento acima e caracterizadas imediatamente após a fabricação para minimizar o efeito da degradação provocada pela água e o oxigénio no ar. Há cinco parâmetros de desempenho elétricos que são usados ​​para caracterizar e comparar células solares 28. Os valores de corrente de curto circuito (I SC) e tensão de circuito aberto (V OC) pode ser derivada a partir da corrente-tensão (IV) curva. Estes podem então ser utilizados para determinar o factor de enchimento (FF) e a eficiência de conversão de energia (η). O FF dá uma proporção das células de saída de potência máxima real para o produto da tensão de circuito aberto e de corrente de curto-circuito 29. Este é um parâmetro chave na avaliação do desempenho de células solares. A alta FF significa baixas perdas eletroquímicos, enquanto um baixo FF indica que há espaço para melhorias. Vários factores são conhecidos por influenciar o FF incluindo a qualidade e a interface de camadas no interior da célula. DSSCs incorporando um par redox iodeto / triiodide com eficiências recorde de relatório de 11,9% factores de 0,71 30 preencher. Todos estes parâmetros devem ser determinados sob condições de teste padrão, onde a temperatura do dispositivo é 25 C, distribuição de irradiância espectral da luz tem uma massa de ar de 1,5, irradiância total medido (E m) na célula solar é de 100 mW / cm 2. Máximo teórico para a eficiência de conversão para uma única célula junção pn tem sido amplamente relatado como 37,7% 31, no entanto, para DSSCs tem sido relatado que a eficiência máxima está mais perto de 15,1% com um início de absorção a 920 nm de 32. A corrente de saída e as tensões foram medidas usando um medidor de fonte, enquanto as células foram iluminadas com uma fonte cm2 a 100 mW / luz equipado com um filtro para igualar a distribuição da irradiância espectral com uma massa de ar de 1,5. Os resultados foram comparados com uma célulaproduzido usando uma camada de TiO 2 médico de lâmina utilizando uma pasta comercialmente disponível que tem uma mistura de anatase partículas de 20 nm e 450 nm. A camada impressa tinha uma área de 0,25 cm2 e uma espessura média de 18 uM, que foi medida utilizando um perfilador de superfície. Uma comparação do desempenho fotoeléctrica entre os dois dispositivos é mostrada na Figura 1 e Tabela 1. Vários estudos investigaram a relação entre a espessura da camada de TiO 2 e a eficiência de conversão dentro DSSCs. Os resultados variam de forma significativa, com espessura do filme óptima relatada em qualquer lugar entre 9,5 uM e 20 uM 33-39. A Tabela 1 descreve as espessuras das camadas de TiO 2 impressos e as eficiências. A espessura do jacto de tinta impressa de TiO 2 é significativamente menor do que o médico laminado de TiO 2, resultandonuma eficiência mais baixa. Trabalho futuro será investigado o uso de ligantes orgânicos, na formulação de tinta para aumentar a espessura da camada de jacto de tinta impressos. <img alt="figura 1" src="/files/ftp_upload/53963/53963fig1.jpg" /> Figura 1. Curvas de Desempenho de DSSCs com jato de tinta impressa e Doutor Bladed TiO 2 camadas. Curvas de densidade de corrente / tensão para DSSCs incorporam um jato de tinta impressa TiO 2 camada e uma camada de TiO 2 médico de lâmina. A densidade de corrente de curto-circuito no dispositivo com o jato de tinta impressa TiO 2 camada é significativamente menor do que o dispositivo com o médico lâmina camada de TiO 2, resultando em uma menor eficiência de conversão global. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/53963/53963fig1large.jpg" target="_blank">Por favor clique aqui para ver uma versão maior desta figura.</a> <table><tbody><tr><tdrowspan = &quot;3&quot;&gt; </td><td> corrente de curto circuito </td><td> Voltagem de circuito aberto </td><td rowspan="3"> Fator de preenchimento </td><td> Eficiência </td><td> Espessura </td></tr><tr><td> (mA / cm 2) </td><td> (MV) </td><td></td><td></td></tr><tr><td></td><td></td><td> (%) </td><td> (Mm) </td></tr><tr><td> Inkjet impresso </td><td> 9,42 </td><td> 760 </td><td> 0,49 </td><td> 3,5 </td><td> 2.6 </td></tr><tr><td> Doutor laminado </td><td> 11 </td><td> 756 </td><td> 0.58 </td><td> 4.8 </td><td> 18 </td></tr></tbody></table> Tabela 1. Características chave de desempenho das células na Figura 1. Esta tabela compara os parâmetros-chave da célula solar, incluindo tensão de circuito aberto (V OC), a corrente de curto-circuito (I sc) que determinam a eficiência (η) sob a luz especificada condição são apresentados. Os parâmetros Scélula fa produzido usando uma camada de TiO 2 médico lâminas foram também incluídos para comparação. Os fatores de enchimento (FF) de ambos os dispositivos são bastante baixa, o que é geralmente atribuído a uma elevada resistência interna dentro da célula.

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%.

Impressão digital de dióxido de titânio para células solares Dye sensibilizados

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

digital-printing-of-titanium-dioxide-for-dye-sensitized-solar-cells

Nanyang Technological University

Research

JoVE Journal

Engineering

12.7K visualizações.  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%.

Vídeo: 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 impressão 3D usando um projetor digital e sua aplicação no estudo de Mecânica dos materiais macios

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 ...

Engenharia

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.

Integrando um Triplet-triplete Annihilation Sistema Up-conversion para melhorar Dye-sensibilizadas Response célula solar para a Luz Sub-bandgap

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.

Método ambiente para a produção de um Common Cathode ionicamente fechado de Nanotubos de Carbono em Células solares orgânicas Tandem

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.

Integração da luz Interceptação de prata Nanoestruturas em células solares de silício hidrogenado microcristalina por Transferência de impressão

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.

Impressão Fabricação de massa Heterojunction células solares e<em&gt; In Situ</em&gt; Morfologia Caracterização

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.

Monovalente Cation Doping de CH<sub&gt; 3</sub&gt; NH<sub&gt; 3</sub&gt; PBI<sub&gt; 3</sub&gt; For eficientes células solares Perovskita

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.

Electrospinning de eletrodos fotocatalíticos para células solares sensibilizadas por corante

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 Monitoramento da degradação desempenho acelerado de células solares e módulos: um estudo de caso de Cu (In, Ga) Se2 células solares

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.

Interior avaliação Experimental da eficiência e da irradiância Spot do dubleto acromático em vidro (ADG) lente de Fresnel para concentrar a energia fotovoltaica

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.

Desenvolvimento de células solares de alta Performance 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 ...