Support for this work was provided by DOE STTR grant DE-SC0003664 on Parallel Tandem Organic Solar Cells with Carbon Nanotube Sheet Interlayers and Welch Foundation grant AT-1617. The authors thank J. Bykova for providing CNT forests and A. R. Howard, K. Meilczarek, and J. Velten for technical assistance and useful discussions.

1. Índio Tin Oxide (ITO) Padronização e Limpeza NOTA: Use 15Ω / □ ITO vidro, e compra ou cortar o vidro ITO em tamanhos adequados para o revestimento de rotação e fotolitografia. É mais eficiente para realizar os passos 1,1-1,7 em um pedaço de vidro tão grande quanto possível, e, em seguida, cortá-la em dispositivos menores. Observe também que os passos 1,1-1,7 exigir o vidro ITO a ser orientado com o ITO-side up. Isto pode ser verificado facilmente com ajuste de resistência de um multímetro. <ol><li> Revestimento de spin 1 ml de S1813 fotorresistente positiva onto-ITO o lado do vidro ITO a uma velocidade de 3.000 rpm durante 1 min. Use mais resistir por grandes pedaços de vidro, certifique-se todo o vidro é revestido, e retire as bolhas antes de iniciar o coater rodada. </li><li> Recozer a resistir vidro revestido, numa placa quente, a 115 ° C durante 1 min. </li><li> Coloque a amostra ea fotomáscaras para o alinhador contato. </li><li> Expor o vidro ITO fotossensíveis revestidos por uma aprovez disso. O tempo de exposição é de cerca de 10 segundos, mas este tempo pode variar com base na intensidade da lâmpada de UV, tipo foto-resistente, e espessura. </li><li> Desenvolver os substratos expostos aos raios UV em desenvolvedor MF311. Processo automatizado de um processador de rotação produz os melhores e mais reproduzíveis resultados, mas o desenvolvimento pode ser feito manualmente, como se seguiu. <ol><li> Submerge os substratos expostos aos raios UV, durante 1 min no revelador, seguido de enxaguamento em água desionizada (DI) de água e secagem com uma pistola de azoto. Porque o desenvolvedor perde força rapidamente, substitua o desenvolvedor entre as amostras, ou, alternativamente, aumentar o tempo de desenvolvimento ao reutilizar desenvolvedor. </li></ol></li><li> Etch os substratos de ITO em ácido clorídrico concentrado (HCl). Isto leva entre 5-10 min, dependendo da concentração do HCl. Enxágüe em água DI, seco, e testar a resistividade das porções gravadas com um multímetro. Se qualquer condutividade permanece, etch para um tempo mais longo. </li><li> Uma vez que o ataque é concluída, remova o photoresist com acetona. Note-se que a remoção imediata do photoresist impede HCl residual do excesso de gravura do ITO padronizada. </li><li> Se necessário, corte as gravadas substratos de vidro ITO em tamanhos de dispositivos. </li><li> Limpar os substratos de ITO em um banho de ultrasonicator numa sequência de solventes - água DI, acetona, tolueno, metanol e, finalmente, o álcool isopropílico. </li></ol> 2. OPV fabricação de células Sub <ol><li> Prepare P3HT: PC 61 solução BM. NOTA: Para obter os resultados mais consistentes, preparar as soluções em um ambiente de nitrogênio. É possível seguir este procedimento em condições ambientais. <ol><li> Encontre e anote a massa de dois limpo, ~ 4 ml frasco de vidro e suas tampas, e marcá-los com um marcador permanente para distingui-los dos outros. </li><li> Numa caixa de luvas de azoto ou árgon, transferir aproximadamente 10 mg de poli (3-hexiltiofeno-2,5-di-il) (P3HT) para um frasco e cerca de 10 mg de fenil-C 61 éster metílico de ácido butírico (PC 61 BM) para o outro. </li><li> Pesar os frascos de novo para encontrar a massa do P3HT e PC 61 BM. </li><li> Transfira os frascos com P3HT e PC 61 BM em uma caixa de luvas para o resto do processo de tomada de solução. </li><li> Adicionar uma barra de agitação magnética em cada frasco e, em seguida, adicionar a cada clorobenzeno suficiente para criar soluções de 45 mg / ml. </li><li> Colocar as soluções em uma placa de agitação magnética quente a 55 ° C durante aproximadamente 2 horas ou até que os solutos se ter dissolvido completamente. </li><li> Misturar volumes iguais de P3HT e PC 61 BM soluções em conjunto, e deixar a celeuma solução mista por mais uma hora antes de usar. </li></ol></li><li> Prepare PTB7: PC 71 solução BM. <ol><li> Repita os passos 2.1.1 a 2.1.4 com poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl}) (PTB7) e fenil-7,1-butírico éster metílico do ácido (BM PC 71) em vez de PC e P3HT61 BM. </li><li> Fazer uma mistura de 3%, em volume, 1,8-diiodooctane (DIO) em clorobenzeno. Esta mistura é chamado o DIO-CB. </li><li> Adicionar uma barra de agitação magnética em cada frasco e, em seguida, adicionar o suficiente DIO-CB para o frasco PTB7 ter uma solução de 12 mg / ml e suficiente DIO-CB para o PC 71 BM frasco ter um / ml de solução a 40 mg. </li><li> Deixar estas soluções agitar numa placa quente a 70 ° C durante dois dias. </li><li> Misturar as soluções em uma proporção em peso de PTB7 ao PC 71 BM de 1 a 1,5. </li><li> Deixe a solução mista de agitação durante outra hora a 70 ° C antes de usar. </li></ol></li><li> Filtro de poli (3,4-etilenodioxitiofeno): poli (estirenossulfonato) (PEDOT: PSS) através de um filtro de 0,45 um de tamanho de poro de nylon. Note que este procedimento usa P VP AI4083. </li><li> Brasão rotação camadas ativas. <ol><li> Coloque substratos de ITO limpas, ITO voltado para cima, em um limpador de UV-Ozônio por 5 min. </li><li> Spin-coat 120 ul do PEDOT: PSS filtrada para UV-ozônio tratada, modelado ITO- substrato de vidros a 3000 rpm durante 1 min. Isto deve produzir uma camada de 30 nm de espessura. </li><li> Recozer o PEDOT: PSS substratos de ITO revestidas durante 5 min a 180 ° C. </li><li> Spin-coat 70 ul da P3HT mista: PC 61 BM solução para PEDOT: PSS revestido ITO substratos em cerca de 1.000 rpm por 1 min. Varie o ritmo que precisava depositar uma camada ativa nm de espessura 200. </li><li> Recozer o P3HT: substratos revestidos BM PC 61 a 170 ° C durante 5 min. Os resultados podem variar na temperatura de recozimento óptima. </li><li> Spin-coat 70 ul da PTB7 mista: PC 71 BM solução para PEDOT: PSS revestido ITO substratos em aproximadamente 700 rpm por 1 min. Varie o ritmo que precisava depositar uma camada ativa de espessura nm 100. </li><li> Carregar o PTB7: PC 71 BM substratos revestidos em alto vácuo (&lt;2 x 10 -6 Torr) para remover a câmara de DIO residual. Tipicamente, deixar as amostras na câmara de O / N. </li></ol></li></ol> 3. Fabricar o Dispositivo Tandem &lt;ol&gt; <li> Eletrodos laminado CNT. <ol><li> Corte os substratos PTB7 e P3HT ao meio para fazer um dispositivo tandem. Um padrão de ITO especializada não seria necessário este passo. O padrão de ITO deve ter pelo menos dois eletrodos ITO paralelo que se estende a partir de uma borda para um milímetro de distância da outra. </li><li> Em primeiro lugar preparar a PTB7 e substratos P3HT revestidos por polímero e enxugando PEDOT a partir das bordas do vidro, e expor a tira de ITO que irá ser utilizado como eléctrodo comum como visto no primeiro painel da Figura 1. </li><li> Laminado o eléctrodo comum CNT no topo dos eléctrodos e PTB7 P3HT. Aplicar um filme SWCNT colocando lado a CNT do papel de filtro sobre o dispositivo, pressionando suavemente, e, em seguida, descascar o papel de filtro afastado. Isto é mostrado no segundo painel da Figura 1. </li><li> Densificar o CNT eléctrodo para a superfície por aplicação de metoxi-nonafluorobutane (C 4 F 9 OCH3) (HFE) e revestindo o CNT com uma pequena amount do líquido e, em seguida, deixá-lo secar. </li><li> Enxugar o polímero e CNT no topo do vidro ITO e que terá o eléctrodo de porta, como mostrado no terceiro painel da Figura 1. Remover todo o polímero a partir do vidro para evitar a perda de porta com uma lâmina de barbear. </li><li> Laminar o eléctrodo de porta CNT para a área limpa dos substratos PTB7 e P3HT revestidos. Laminar o MWCNT puxando a partir da borda da floresta MWCNT com uma lâmina de barbear e deixe a folha ficar livremente entre alguns tubos capilares. Passe o dispositivo através da folha autoportante para laminar o CNT para o dispositivo. O eléctrodo de porta deve ter 2-3 vezes o número de camadas como definido sobre o eléctrodo comum. </li><li> Densificar o eletrodo de porta com HFE. </li></ol></li><li> Colocar uma pequena gota (≈10 ul) do líquido iónico, N, N-dietil-N-metil-N - (2-metoxietil) tetrafluoroborato de amónio, DEME-BF 4, na parte superior de ambos os eléctrodos de um CNTdos substratos. </li><li> Coloque cuidadosamente o substrato sem líquido iónico em cima do substrato com um líquido iónico com os eléctrodos de porta e comuns em cima uns dos outros,. Isto é mostrado no último painel da Figura 1. </li><li> Coloque uma fotomáscara com um tamanho de abertura mais pequeno do que o tamanho do eléctrodo sobre a área activa. Use pequenos grampos para segurar a foto-mascara no local, bem como para manter o dispositivo em conjunto durante o teste. </li></ol> 4. Meça o Dispositivo <ol><li> Transferir o dispositivo para dentro do porta-luvas de medição. </li><li> Faça as conexões elétricas. <ol><li> Ligue a fonte de alimentação portão entre o eletrodo comum eo eletrodo de porta com o comum como chão. </li><li> Ligar os dois ânodos de ITO a fios que estão ligados a um comutador, o qual permite a selecção de um ou outro ou ambos os ânodos ânodo. </li><li> Conecte a saída do interruptor para a entrada da unidade de medida de origem. </li><li> Conecte-se ao chão dos meas fonteunidade ure ao eletrodo comum. </li></ol></li><li> Meça as características do dispositivo IV, repetindo os seguintes passos para ascender V Gate. <ol><li> Definir V Portão para o próximo valor, a partir de V Portão = 0 V para V = Portão 2 V em incrementos de 0,25 V. </li><li> Esperar 5 min ou até que a corrente de porta é estabilizado. Idealmente, a corrente de porta deve se estabilizar em torno de 10s de nanoamperes. </li><li> Ajuste a chave para ambos os sub-células. </li><li> Abra o obturador da lâmpada. </li><li> Execute uma varredura de tensão na unidade de medida fonte de volts -1 a 1 volt em cerca de 100 incrementos ou mais. </li><li> Execute uma varredura de tensão de 1 volt para -1 volt. </li><li> Feche o obturador da lâmpada. </li><li> Execute as varreduras de tensão novamente. </li><li> Ajuste a chave para o sub-celular da frente. </li><li> Repita os passos 4.3.4 a 4.3.8. </li><li> Ajuste a chave para o sub-celular de volta. </li><li> Repita os passos 4.3.4 a 4.3.8. </li></ol></li><li> Calcular os parâmetros do dispositivo. &lt;ol&gt; <li> Encontrar a corrente de curto-circuito (J SC) de cada sub-celular em cada V porta, encontrando a corrente produzida pelo dispositivo quando a tensão através do sub-celular é 0 V. </li><li> Encontrar a tensão de circuito aberto (V OC) de cada sub-celular em cada porta, encontrando V a voltagem produzida pelo dispositivo quando a corrente através do sub-celular é 0 A. </li><li> Encontrar a potência máxima de saída a partir da célula solar, multiplicando cada valor de tensão com cada valor actual e seleccionando o valor máximo (mais negativo). Isso pressupõe que mede gerada por foto atual atual como negativo. </li><li> Encontre a eficiência de conversão de energia (η), dividindo a potência máxima pelo poder da luz de entrada. </li><li> Encontrar o factor de enchimento (FF) é calculada dividindo a força máxima por o produto de J SC e V OC. </li></ol></li></ol>

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The authors have nothing to disclose.

Os resultados destacam algumas considerações ao projetar células solares em série paralelo. Notavelmente, se uma das sub-células é um mau desempenho, o desempenho do conjunto de afetados negativamente. Os resultados mostram que existem dois efeitos principais. Se uma sub-célula é curto, por exemplo, mostra um comportamento ôhmico, a FF T haverá maior do que o FF da sub-célula ruim. J T SC e V T OC serão igualmente afetados. Este é o caso quando...

Semicondutores poliméricos são os principais fotovoltaicos orgânicos (OPV) de materiais, devido à alta absortividade, boas propriedades de transporte, flexibilidade e compatibilidade com substratos sensíveis à temperatura. Dispositivos OPV eficiência de conversão de energia, η, saltaram significativamente nos últimos anos, com a eficiência de células únicas tão elevadas como 9,1% 1, tornando-se uma tecnologia de energia cada vez mais viável. Apesar das melhorias em η, as finas ideais espessuras camada ativa dos dispositivos de limitar a absorção de luz e impedem a fabricação de confiança. Além disso, a largura espectral de absorção de luz de cada polímero é limitada em comparação com materiais inorgânicos. Polímeros de emparelhamento de diferentes sensibilidade espectral ignora estas dificuldades, fazendo com que as arquiteturas em tandem 2 a inovação necessária. Dispositivos em tandem Series são a arquitetura conjunto mais comum. Neste projeto, um materi transporte de elétronsai, uma camada metálica opcional a recombinação, e uma camada de transporte furo ligar duas camadas independentes fotoactivos chamados sub-células. Ligando sub-células numa configuração em série aumenta a tensão do circuito aberto do dispositivo de combinação. Alguns grupos tiveram sucesso com camadas de transporte degenerately dopados 3-5, mas mais grupos usaram partículas de ouro ou prata para ajudar a recombinação de buracos e elétrons na camada intermediária 6,7. Em contraste, tandens paralelas requerem um eléctrodo de alta condutividade, qualquer um ânodo ou cátodo, juntando-se as duas camadas activas. O intercalar deve ser altamente transparente, o que limita intercalares em tandem série contendo partículas metálicas, e mais ainda para as intercalares em tandem paralelas compostas de finos, eletrodos metálicos contínuos. Os nanotubos de carbono (CNT) folhas apresentam maior transparência do que camadas de metal. Assim, o Instituto NanoTech, em colaboração com a Universidade de Shimane, tem introduced o conceito de usar como camada intermédia do eléctrodo em dispositivos monolíticos, em tandem paralelas 8. Esforços anteriores, caracterizado, dispositivos de conjunto OPV paralelas monolíticos de folhas CNT que funcionam como ânodos entre camadas 8,9. Estes métodos exigem um cuidado especial para evitar curto-circuito de uma ou ambas as células ou camadas anteriores prejudiciais ao depositar camadas posteriores. O novo método descrito no presente documento facilita a fabricação, colocando o eléctrodo CNT no topo das camadas poliméricas activas de duas células individuais, em seguida, laminando os dois dispositivos separados em conjunto, como mostrado na Figura 1. Este método é notável quanto o dispositivo, incluindo um aparelho de ar -stable cátodo CNT, pode ser fabricado totalmente em condições ambientais empregando apenas de processamento a seco e solução. Folhas CNT não são intrinsecamente boas catodos, como eles exigem n-type doping para diminuir a função de trabalho, a fim de coletar os elétrons da região fotoativode uma célula solar 10. Carregamento eléctrico de dupla camada dentro de um electrólito, tal como um líquido iónico, pode ser usado para deslocar a função de trabalho dos eléctrodos CNT 11-14. Conforme descrito num artigo anterior 15 e representada na Figura 2, quando a tensão da porta (gate V) é aumenta, a função de trabalho do eléctrodo comum CNT é diminuída, criando eléctrodo de assimetria. Isso evita coleção buraco do doador da OPV em favor da coleta de elétrons do receptor da OPV, e os dispositivos de ligar, mudando de photoresistor ineficiente em fotodiodo 15 comportamento. Deve também ser notado que a energia utilizada para carregar o dispositivo e o poder perdido devido a correntes de fuga portão é menor em comparação com a energia gerada pela célula solar 15. Gating Ionic de eletrodos CNT tem um grande efeito sobre a função de trabalho, devido à baixa densidade de estados ea altarazão entre superfície e volume, em eléctrodos CNT. Métodos semelhantes têm sido utilizados para melhorar uma barreira Schottky na interface do CNT com n-Si 16.

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			<td height="21" style="height:21px;">Poly(3,4-ethylenedioxythiophene):poly-(styrenesulfonate)</td>
			<td style="width:191px;">Heraeus</td>
			<td colspan="2">Clevios PVP AI 4083</td>
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			<td height="21" style="height:21px;width:312px;">poly(3- hexylthiophene-2,5-diyl)&#160;</td>
			<td style="width:191px;">Rieke Metals&#160; Inc.</td>
			<td style="width:119px;">P3HT:&#160; P200</td>
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			<td height="25" style="height:25px;">phenyl-C61 -butyric&#160; acid methyl&#160; ester</td>
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		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b&#8242;]dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl})&#160;</td>
			<td style="width:191px;">1- Material</td>
			<td style="width:119px;">PTB7</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">phenyl-C61 -butyric acid methyl&#160; ester</td>
			<td style="width:191px;">Solenne</td>
			<td style="width:119px;">PC71BM</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1,8-Diiodooctane</td>
			<td style="width:191px;">Sigma Aldrich</td>
			<td align="right" style="width:119px;">250295</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Chlorobenzene</td>
			<td style="width:191px;">Sigma Aldrich</td>
			<td align="right" style="width:119px;">284513</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Indium Tin Oxide Coated Glass 15 Ohm/SQ</td>
			<td style="width:191px;">Lumtec</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">S1813</td>
			<td style="width:191px;">UTD Cleanroom</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MF311</td>
			<td style="width:191px;">UTD Cleanroom</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">HCl</td>
			<td style="width:191px;">UTD Cleanroom</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Acetone</td>
			<td style="width:191px;">Fisher Scientific</td>
			<td style="width:119px;">A18-20</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Toluene</td>
			<td style="width:191px;">Fisher Scientific</td>
			<td style="width:119px;">T323-20</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Methanol</td>
			<td style="width:191px;">BDH</td>
			<td style="width:119px;">BDH1135-19L</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Isopropanol</td>
			<td style="width:191px;">Fisher Scientific</td>
			<td style="width:119px;">A416-20</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">CEE Spincoater</td>
			<td style="width:191px;">Brewer Scientific</td>
			<td style="width:119px;"></td>
			<td>http://www.utdallas.edu/research/cleanroom/tools/CEESpinCoater.htm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Contact Printer</td>
			<td style="width:191px;">Quintel</td>
			<td style="width:119px;">Q4000-6</td>
			<td>http://www.utdallas.edu/research/cleanroom/QuintelPrinter.htm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">CPK Spin Processor</td>
			<td style="width:191px;"></td>
			<td style="width:119px;"></td>
			<td>http://www.utdallas.edu/research/cleanroom/tools/CPKsolvent.htm</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:312px;">Spin Coater</td>
			<td style="width:191px;">Laurell</td>
			<td style="width:119px;">WS-400-6NPP/LITE</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Glove Box</td>
			<td style="width:191px;">M-Braun</td>
			<td style="width:119px;">Lab Master 130</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Solar Simulator</td>
			<td style="width:191px;">Thermo Oriel/Newport</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Keithley 2400 SMU</td>
			<td style="width:191px;">Keithley/Techtronix</td>
			<td align="right" style="width:119px;">2400</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Keithley 7002 Multiplexer</td>
			<td style="width:191px;">Keithley/Techtronix</td>
			<td align="right" style="width:119px;">7002</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Ultrasonic Cleaner</td>
			<td style="width:191px;">Kendal</td>
			<td style="width:119px;">HB-S-49HDT</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Micropipette</td>
			<td style="width:191px;">Eppendorf</td>
			<td style="width:119px;">200uL</td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

Um dispositivo conjunto formado a partir de polímeros, particularmente polímeros de lacunas banda significativamente diferenciados, diferindo é de interesse prático como esses dispositivos podem absorver a maior faixa espectral da luz. Nesta estrutura do dispositivo, o sub-celular PTB7 é a célula de volta e P3HT-se do sub-celular da frente. Este destina-se a absorver a maior quantidade de luz como o sub-celular P3HT é em grande parte transparente para a luz de comprimento de onda mais absorvida pelo sub-celular P...

Watch this Scientific Journal Video about Ambient Method for the Production of an Ionically Gated Carbon Nanotube Common Cathode in Tandem Organic Solar Cells at JoVE.com

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

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 ...

ambient-method-for-production-an-ionically-gated-carbon-nanotube

Research

JoVE Journal

Engineering

9.3K visualizações.  The University of Texas at Dallas. 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.

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

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

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

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

Controlando o tamanho, forma e estabilidade de Polímeros Supramoleculares na Água

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

Engenharia

Fabrication, Densification, and Replica Molding of 3D Carbon Nanotube Microstructures

The introduction of new materials and processes to microfabrication has, in large part, enabled many important advances in microsystems, lab-on-a-chip devices, and their applications. In particular, capabilities for cost-effective fabrication of polymer microstructures were transformed by the advent of soft lithography and other micromolding techniques 1, 2, and this led a revolution in applications of microfabrication to biomedical engineering and biology. Nevertheless, it remains challenging to fabricate microstructures with well-defined nanoscale surface textures, and to fabricate arbitrary 3D shapes at the micro-scale. Robustness of master molds and maintenance of shape integrity is especially important to achieve high fidelity replication of complex structures and preserving their nanoscale surface texture. The combination of hierarchical textures, and heterogeneous shapes, is a profound challenge to existing microfabrication methods that largely rely upon top-down etching using fixed mask templates. On the other hand, the bottom-up synthesis of nanostructures such as nanotubes and nanowires can offer new capabilities to microfabrication, in particular by taking advantage of the collective self-organization of nanostructures, and local control of their growth behavior with respect to microfabricated patterns. 
Our goal is to introduce vertically aligned carbon nanotubes (CNTs), which we refer to as CNT "forests", as a new microfabrication material. We present details of a suite of related methods recently developed by our group: fabrication of CNT forest microstructures by thermal CVD from lithographically patterned catalyst thin films; self-directed elastocapillary densification of CNT microstructures; and replica molding of polymer microstructures using CNT composite master molds. In particular, our work shows that self-directed capillary densification ("capillary forming"), which is performed by condensation of a solvent onto the substrate with CNT microstructures, significantly increases the packing density of CNTs. This process enables directed transformation of vertical CNT microstructures into straight, inclined, and twisted shapes, which have robust mechanical properties exceeding those of typical microfabrication polymers. This in turn enables formation of nanocomposite CNT master molds by capillary-driven infiltration of polymers. The replica structures exhibit the anisotropic nanoscale texture of the aligned CNTs, and can have walls with sub-micron thickness and aspect ratios exceeding 50:1. Integration of CNT microstructures in fabrication offers further opportunity to exploit the electrical and thermal properties of CNTs, and diverse capabilities for chemical and biochemical functionalization 3.

We present methods for fabrication of patterned microstructures of vertically aligned carbon nanotubes (CNTs), and their use as master molds for production of polymer microstructures with organized nanoscale surface texture. The CNT forests are densified by condensation of solvent onto the substrate, which significantly increases their packing density and enables self-directed formation of 3D shapes.

Fabricação, Densificação e Replica Moldagem de Microestruturas de Nanotubos de Carbono 3D

The introduction of new materials and processes to microfabrication has, in large part, enabled many important advances in microsystems, lab-on-a-chip ...

Dry Oxidation and Vacuum Annealing Treatments for Tuning the Wetting Properties of Carbon Nanotube Arrays

In this article, we describe a simple method to reversibly tune the wetting properties of vertically aligned carbon nanotube (CNT) arrays. Here, CNT arrays are defined as densely packed multi-walled carbon nanotubes oriented perpendicular to the growth substrate as a result of a growth process by the standard thermal chemical vapor deposition (CVD) technique.1,2 These CNT arrays are then exposed to vacuum annealing treatment to make them more hydrophobic or to dry oxidation treatment to render them more hydrophilic. The hydrophobic CNT arrays can be turned hydrophilic by exposing them to dry oxidation treatment, while the hydrophilic CNT arrays can be turned hydrophobic by exposing them to vacuum annealing treatment. Using a combination of both treatments, CNT arrays can be repeatedly switched between hydrophilic and hydrophobic.2 Therefore, such combination show a very high potential in many industrial and consumer applications, including drug delivery system and high power density supercapacitors.3-5
The key to vary the wettability of CNT arrays is to control the surface concentration of oxygen adsorbates. Basically oxygen adsorbates can be introduced by exposing the CNT arrays to any oxidation treatment. Here we use dry oxidation treatments, such as oxygen plasma and UV/ozone, to functionalize the surface of CNT with oxygenated functional groups. These oxygenated functional groups allow hydrogen bond between the surface of CNT and water molecules to form, rendering the CNT hydrophilic. To turn them hydrophobic, adsorbed oxygen must be removed from the surface of CNT. Here we employ vacuum annealing treatment to induce oxygen desorption process. CNT arrays with extremely low surface concentration of oxygen adsorbates exhibit a superhydrophobic behavior.

This article describes a simple method to fabricate vertically aligned carbon nanotube arrays by CVD and to subsequently tune their wetting properties by exposing them to vacuum annealing or dry oxidation treatment.

Oxidação seca e vácuo Annealing Tratamentos para Ajustando as propriedades de umectação Matrizes Nanotubos de Carbono

In this article, we describe a simple method to reversibly  tune the wetting properties of vertically aligned carbon nanotube (CNT) arrays.  Here, CNT ...

Synthesis and Functionalization of Nitrogen-doped Carbon Nanotube Cups with Gold Nanoparticles as Cork Stoppers

Nitrogen-doped carbon nanotubes consist of many cup-shaped graphitic compartments termed as nitrogen-doped carbon nanotube cups (NCNCs). These as-synthesized graphitic nanocups from chemical vapor deposition (CVD) method were stacked in a head-to-tail fashion held only through noncovalent interactions. Individual NCNCs can be isolated out of their stacking structure through a series of chemical and physical separation processes. First, as-synthesized NCNCs were oxidized in a mixture of strong acids to introduce oxygen-containing defects on the graphitic walls. The oxidized NCNCs were then processed using high-intensity probe-tip sonication which effectively separated the stacked NCNCs into individual graphitic nanocups. Owing to their abundant oxygen and nitrogen surface functionalities, the resulted individual NCNCs are highly hydrophilic and can be effectively functionalized with gold nanoparticles (GNPs), which preferentially fit in the opening of the cups as cork stoppers. These graphitic nanocups corked with GNPs may find promising applications as nanoscale containers and drug carriers.

We discussed the synthesis of individual graphitic nanocups using a series of techniques including chemical vapor deposition, acid oxidation and probe-tip sonication. By citrate reduction of HAuCl4, the graphitic nanocups were effectively corked with gold nanoparticles due to the chemically reactive edges of the cups.

Síntese e funcionalização de nitrogênio dopado Copas de Nanotubos de Carbono com nanopartículas de ouro como Rolhas

Nitrogen-doped carbon  nanotubes consist of many cup-shaped graphitic compartments termed as  nitrogen-doped carbon nanotube cups (NCNCs).  These ...

Using Neutron Spin Echo Resolved Grazing Incidence Scattering to Investigate Organic Solar Cell Materials

The spin echo resolved grazing incidence scattering (SERGIS) technique has been used to probe the length-scales associated with irregularly shaped crystallites. Neutrons are passed through two well defined regions of magnetic field; one before and one after the sample. The two magnetic field regions have opposite polarity and are tuned such that neutrons travelling through both regions, without being perturbed, will undergo the same number of precessions in opposing directions. In this case the neutron precession in the second arm is said to &#34;echo&#34; the first, and the original polarization of the beam is preserved. If the neutron interacts with a sample and scatters elastically the path through the second arm is not the same as the first and the original polarization is not recovered. Depolarization of the neutron beam is a highly sensitive probe at very small angles (&#60;50&#160;&#956;rad) but still allows a high intensity, divergent beam to be used. The decrease in polarization of the beam reflected from the sample as compared to that from the reference sample can be directly related to structure within the sample.
In comparison to scattering observed in neutron reflection measurements the SERGIS signals are often weak and are unlikely to be observed if the in-plane structures within the sample under investigation are dilute, disordered, small in size and polydisperse or the neutron scattering contrast is low. Therefore, good results will most likely be obtained using the SERGIS technique if the sample being measured consist of thin films on a flat substrate and contain scattering features that contains a high density of moderately sized features (30 nm to 5 &#181;m) which scatter neutrons strongly or the features are arranged on a lattice. An advantage of the SERGIS technique is that it can probe structures in the plane of the sample.

Progress has been made in utilizing spin echo resolved grazing incidence scattering (SERGIS) as a neutron scattering technique to probe the length-scales in irregular samples. Crystallites of [6,6]-phenyl-C61-butyric acid methyl ester have been probed using the SERGIS technique and the results confirmed by optical and atomic force microscopy.

Usando neutron spin echo resolvi a dispersão da incidência de pastagem para investigar materiais orgânicos de células solares

The spin echo resolved grazing incidence scattering (SERGIS) technique has been used to probe the length-scales associated with irregularly shaped ...

Fabrication of Low Temperature Carbon Nanotube Vertical Interconnects Compatible with Semiconductor Technology

We demonstrate a method for the low temperature growth (350 &#176;C) of vertically-aligned carbon nanotubes (CNT) bundles on electrically conductive thin-films. Due to the low growth temperature, the process allows integration with modern low-&#954; dielectrics and some flexible substrates. The process is compatible with standard semiconductor fabrication, and a method for the fabrication of electrical 4-point probe test structures for vertical interconnect test structures is presented. Using scanning electron microscopy the morphology of the CNT bundles is investigated, which demonstrates vertical alignment of the CNT and can be used to tune the CNT growth time. With Raman spectroscopy the crystallinity of the CNT is investigated. It was found that the CNT have many defects, due to the low growth temperature. The electrical current-voltage measurements of the test vertical interconnects displays a linear response, indicating good ohmic contact was achieved between the CNT bundle and the top and bottom metal electrodes. The obtained resistivities of the CNT bundle are among the average values in the literature, while a record-low CNT growth temperature was used.

A method for the growth of low temperature vertically-aligned carbon nanotubes, and the subsequent fabrication of vertical interconnect electrical test structures using semiconductor fabrication is presented.

Fabricação de Baixa Temperatura de Nanotubos de Carbono Vertical Interconexões Compatível com Semiconductor Tecnologia

We demonstrate a method for the low temperature growth (350 &#176;C) of vertically-aligned carbon nanotubes (CNT) bundles on electrically conductive ...

Quantification of Hydrogen Concentrations in Surface and Interface Layers and Bulk Materials through Depth Profiling with Nuclear Reaction Analysis

Nuclear reaction analysis (NRA) via the resonant 1H(15N,&#945;&#947;)12C reaction is a highly effective method of depth profiling that quantitatively and non-destructively reveals the hydrogen density distribution at surfaces, at interfaces, and in the volume of solid materials with high depth resolution. The technique applies a 15N ion beam of 6.385 MeV provided by an electrostatic accelerator and specifically detects the 1H isotope in depths up to about 2 &#956;m from the target surface. Surface H coverages are measured with a sensitivity in the order of ~1013 cm-2 (~1% of a typical atomic monolayer density) and H volume concentrations with a detection limit of ~1018 cm-3 (~100 at. ppm). The near-surface depth resolution is 2-5 nm for surface-normal 15N ion incidence onto the target and can be enhanced to values below 1 nm for very flat targets by adopting a surface-grazing incidence geometry. The method is versatile and readily applied to any high vacuum compatible homogeneous material with a smooth surface (no pores). Electrically conductive targets usually tolerate the ion beam irradiation with negligible degradation. Hydrogen quantitation and correct depth analysis require knowledge of the elementary composition (besides hydrogen) and mass density of the target material. Especially in combination with ultra-high vacuum methods for in-situ target preparation and characterization, 1H(15N,&#945;&#947;)12C NRA is ideally suited for hydrogen analysis at atomically controlled surfaces and nanostructured interfaces. We exemplarily demonstrate here the application of 15N NRA at the MALT Tandem accelerator facility of the University of Tokyo to (1) quantitatively measure the surface coverage and the bulk concentration of hydrogen in the near-surface region of a H2 exposed Pd(110) single crystal, and (2) to determine the depth location and layer density of hydrogen near the interfaces of thin SiO2 films on Si(100).

We illustrate the application of 1H(15N,&#945;&#947;)12C resonant nuclear reaction analysis (NRA) to quantitatively evaluate the density of hydrogen atoms on the surface, in the volume, and at an interfacial layer of solid materials. The near-surface hydrogen depth profiling of a Pd(110) single crystal and of SiO2/Si(100) stacks is described.

Quantificação de concentrações de hidrogénio nas camadas superficiais e interface e materiais a granel através de perfis de profundidade com Análise reação nuclear

Nuclear reaction analysis (NRA) via the resonant 1H(15N,&#945;&#947;)12C reaction is a highly effective method of depth profiling that quantitatively and ...

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.

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 ...

Morphology Control for Fully Printable Organic&#8211;Inorganic Bulk-heterojunction Solar Cells Based on a Ti-alkoxide and Semiconducting Polymer

The photoactive layer of a typical organic thin-film bulk-heterojunction (BHJ) solar cell commonly uses fullerene derivatives as the electron-accepting material. However, fullerene derivatives are air-sensitive; therefore, air-stable material is needed as an alternative. In the present study, we propose and describe the properties of Ti-alkoxide as an alternative electron-accepting material to fullerene derivatives to create highly air-stable BHJ solar cells. It is well-known that controlling the morphology in the photoactive layer, which is constructed with fullerene derivatives as the electron acceptor, is important for obtaining a high overall efficiency through the solvent method. The conventional solvent method is useful for high-solubility materials, such as fullerene derivatives. However, for Ti-alkoxides, the conventional solvent method is insufficient, because they only dissolve in specific solvents. Here, we demonstrate a new approach to morphology control that uses the molecular bulkiness of Ti-alkoxides without the conventional solvent method. That is, this method is one approach to obtain highly efficient, air-stable, organic-inorganic bulk-heterojunction solar cells.

Morphology Control for Fully Printable Organic&amp;#8211;Inorganic Bulk-heterojunction Solar Cells Based on a Ti-alkoxide and Semiconducting Polymer

A method for fully printable, fullerene-free, highly air-stable, bulk-heterojunction solar cells based on Ti alkoxides as the electron acceptor and the electron-donating polymer fabrication is described here. Moreover, a method for controlling the morphology of the photoactive layer through the molecular bulkiness of the Ti-alkoxide units is reported.

Controle de morfologia para células solares Bulk-heterojunção orgânico-inorgânico totalmente Printable Baseado em um Ti-alcóxido e semicondutores Polymer

The photoactive layer of a typical organic thin-film bulk-heterojunction (BHJ) solar cell commonly uses fullerene derivatives as the electron-accepting ...

Precision Milling of Carbon Nanotube Forests Using Low Pressure Scanning Electron Microscopy

A nanoscale fabrication technique appropriate for milling carbon nanotube (CNT) forests is described. The technique utilizes an environmental scanning electron microscope (ESEM) operating with a low pressure water vapor ambient. In this technique, a portion of the electron beam interacts with the water vapor in the vicinity of the CNT sample, dissociating the water molecules into hydroxyl radicals and other species by radiolysis. The remainder of the electron beam interacts with the CNT forest sample, making it susceptible to oxidation from the chemical products of radiolysis. This technique may be used to trim a selected region of an individual CNT, or it may be used to remove hundreds of cubic microns of material by adjusting ESEM parameters. The machining resolution is similar to the imaging resolution of the ESEM itself. The technique produces only small quantities of carbon residue along the boundaries of the cutting zone, with minimal effect on the native structural morphology of the CNT forest.

Low pressure scanning electron microscopy in a water vapor ambient is used to machine nanoscale to microscale features in carbon nanotube forests.

Precision Fresagem de Nanotubos de Carbono Florestas Usando Baixa Pressão Scanning Electron Microscopy

A nanoscale fabrication technique appropriate for milling carbon nanotube (CNT) forests is described. The technique utilizes an environmental scanning ...