Dispositivos fotovoltaicos orgânicos : estudo de camadas ativas e eletrodos

Orientadora: Profa. Dra. Lucimara Stoltz RomanTese (doutorado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduaçao em Engenharia - PIPE. Defesa: Curitiba, 05/03/2010Bibliografia: fls. 102-103Área de concentraçao: Engenharia e ciencia dos materiaisResumo: Neste trabalho, apresentamos os estudos de eletrodos e camadas ativas no desenvolvimento de células solares orgânicas. O óxido de estanho (SnO ) apresenta características interessantes para a aplicação como eletrodo transparente: quando depositado em um substrato de vidro formando filme fino, apresenta-se semi-transparente ao espectro da luz visível e é capaz de conduzir eletricidade. A otimização das características elétricas é feita pela dopagem do óxido com flúor. Apresentamos resultados experimentais e teóricos na caracterização dos óxidos sem dopagem, com dopagem moderada e alta dopagem de flúor. Os dispositivos fotovoltaicos orgânicos foram caracterizados tendo como base dois polímeros conjugados: o politiofeno (PT) e um novo derivado de tiofeno, Poli(9,9'-dioctil-2,7-fluorenodiilvinileno-co-5,5’-(benzo[1,2,5]tiadiazol- 4,7diil)ditiofeno)(PFTBT). A deposição da camada ativa do primeiro polímero é feita por eletroquímica e os dispositivos foram feitos em estutura monocamda, apresentando bons resultados para eficiência quântica externa. A fabricação de dispositivos fotodectores permitiu a aplicação tecnológica dos dispositivos em matrizes de detecção posicional. As camadas ativas geradas pelo segundo polímero foram obtidas pelo processo de deposição por centrifugação de solução. Os resultados fotovoltaicos são apresentados em três estruturas diferentes: monocamada, bicamada e heterojunção de volume. Os dispositivos bicamada revelam-se mais eficiêntes que os de heterojunção. Uma das verificações desta diferença está na estimativa para a taxa de éxcitons gerados na camada ativa:este valor é maior para o caso de heterojunção, no entanto, a probabilidade destas cargas se dissociarem é menor quando comparada a dispositivos bicamada. Alguns nanocompósitos também foram estudados para a aplicação em fotovoltaicos: misturas de polímero conjugado com nanotubos de carbono e misturas de polímero conjugado com nanopartículas de ouro. No primeiro caso, dois polímeros foram estudados, o comerical Poli(3-hexil tiofeno) (P3HT) e o não-comercial Poli(9,9-dihexilfluorenodiil- vinileno-alt-1,4-fenilenovinileno) (PDHFPPV). A interação entre os diferentes polímeros e os nanotubos de carbono são apresentadas em termos da caracterização óptica e elétrica. A inserção de nanopartículas de ouro na matriz do polímero P3HT revela a diminuição de eficiência de foto-conversão quando estes materiais são estudados como camadas ativas em dispositivos fotovoltaicos. Este fato pode estar associado à dificuldade na transferência de cargas das nanopartículas para o polímero, devido a este apresentar camada passivadora de dodecanotióis.Abstract: In this work, we present studies of electrodes and active layers in the development of organic solar cells. The tin oxide (SnO2) presents interesting features for application as transparent electrode: when deposited on a glass substrate to form thin film, presents semi-transparent to visible light spectrum and is capable of conducting electricity. The optimization of electrical characteristics is made by doping the oxide with fluorine. We present experimental results and theoretical characterization of the oxides without doping, moderate doping and high doping of fluorine. The organic photovoltaics have been characterized based on two conjugated polymers: the polythiophene (PT) and a new derivative of thiophene, the poly (9,9 '- dioctyl-2 ,7-fluorenedyilvinylene-co-5, 5'-(benzo [ 1,2,5] thiadiazole-4, 7dyil) dithiophene) (PFTBT). The deposition of the active layer of the first polymer is made by electrochemistry and the devices were made in monolayer structure, showing good results for external quantum efficiency. The fabrication of fotodetectors devices allowed the application of technological devices in arrays of positional detection. The active layers generated by the second polymer were obtained by chemical deposition. Photovoltaic results are presented in three different structures: monolayer, bilayer and bulk heterojunction. Bilayer devices appear more efficient than the bulk heterojunction. One of the findings of this difference is the estimate for the rate of excitons generated in the active layer: this value is larger for the heterojunction case, however, the probability to exciton dissociation in free charges is lower when compared to bilayer devices. Nanocomposites were also studied for application in photovoltaics: mixtures of conjugated polymer with carbon nanotubes and mixtures of conjugated polymer with gold nanoparticles. Two polymers were studied in the first case, the commercial Poly (3- hexyl thiophene) (P3HT) and non-commercial poly (9,9-di-hexilfluorenodiil-vinylenealt- 1 ,4-phenylenevinylene) (PDHFPPV). The interaction between different polymers and carbon nanotubes are presented in terms of optical and electrical characterization. The insertion of gold nanoparticles in a polymer matrix P3HT show the decrease in efficiency of photo-conversion when these materials are studied as active layers in photovoltaic devices. This may be associated with difficulty in transferring charges from nanoparticles to the polymer, due to the passivating layer capping the nanoparticles

Influencia de nanotubos de carbono em camadas ativas de dispositivos fotodetectores orgânicos

Orientadora: Lucimara Stolz RomanInclui apendiceDissertaçao (mestrado) - Universidade Federal do Paraná, Setor de Ciencias Exatas, Programa de Pós-Graduaçao em Física. Defesa: Curitiba, 2004Inclui bibliografi

Influencia de nanotubos de carbono em camadas ativas de dispositivos fotodetectores orgânicos

Orientadora: Lucimara Stolz RomanInclui apendiceDissertaçao (mestrado) - Universidade Federal do Paraná, Setor de Ciencias Exatas, Programa de Pós-Graduaçao em Física. Defesa: Curitiba, 2004Inclui bibliografi

Dispositivos fotovoltaicos orgânicos : estudo de camadas ativas e eletrodos

Orientadora: Profa. Dra. Lucimara Stoltz RomanTese (doutorado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduaçao em Engenharia - PIPE. Defesa: Curitiba, 05/03/2010Bibliografia: fls. 102-103Área de concentraçao: Engenharia e ciencia dos materiaisResumo: Neste trabalho, apresentamos os estudos de eletrodos e camadas ativas no desenvolvimento de células solares orgânicas. O óxido de estanho (SnO ) apresenta características interessantes para a aplicação como eletrodo transparente: quando depositado em um substrato de vidro formando filme fino, apresenta-se semi-transparente ao espectro da luz visível e é capaz de conduzir eletricidade. A otimização das características elétricas é feita pela dopagem do óxido com flúor. Apresentamos resultados experimentais e teóricos na caracterização dos óxidos sem dopagem, com dopagem moderada e alta dopagem de flúor. Os dispositivos fotovoltaicos orgânicos foram caracterizados tendo como base dois polímeros conjugados: o politiofeno (PT) e um novo derivado de tiofeno, Poli(9,9'-dioctil-2,7-fluorenodiilvinileno-co-5,5’-(benzo[1,2,5]tiadiazol- 4,7diil)ditiofeno)(PFTBT). A deposição da camada ativa do primeiro polímero é feita por eletroquímica e os dispositivos foram feitos em estutura monocamda, apresentando bons resultados para eficiência quântica externa. A fabricação de dispositivos fotodectores permitiu a aplicação tecnológica dos dispositivos em matrizes de detecção posicional. As camadas ativas geradas pelo segundo polímero foram obtidas pelo processo de deposição por centrifugação de solução. Os resultados fotovoltaicos são apresentados em três estruturas diferentes: monocamada, bicamada e heterojunção de volume. Os dispositivos bicamada revelam-se mais eficiêntes que os de heterojunção. Uma das verificações desta diferença está na estimativa para a taxa de éxcitons gerados na camada ativa:este valor é maior para o caso de heterojunção, no entanto, a probabilidade destas cargas se dissociarem é menor quando comparada a dispositivos bicamada. Alguns nanocompósitos também foram estudados para a aplicação em fotovoltaicos: misturas de polímero conjugado com nanotubos de carbono e misturas de polímero conjugado com nanopartículas de ouro. No primeiro caso, dois polímeros foram estudados, o comerical Poli(3-hexil tiofeno) (P3HT) e o não-comercial Poli(9,9-dihexilfluorenodiil- vinileno-alt-1,4-fenilenovinileno) (PDHFPPV). A interação entre os diferentes polímeros e os nanotubos de carbono são apresentadas em termos da caracterização óptica e elétrica. A inserção de nanopartículas de ouro na matriz do polímero P3HT revela a diminuição de eficiência de foto-conversão quando estes materiais são estudados como camadas ativas em dispositivos fotovoltaicos. Este fato pode estar associado à dificuldade na transferência de cargas das nanopartículas para o polímero, devido a este apresentar camada passivadora de dodecanotióis.Abstract: In this work, we present studies of electrodes and active layers in the development of organic solar cells. The tin oxide (SnO2) presents interesting features for application as transparent electrode: when deposited on a glass substrate to form thin film, presents semi-transparent to visible light spectrum and is capable of conducting electricity. The optimization of electrical characteristics is made by doping the oxide with fluorine. We present experimental results and theoretical characterization of the oxides without doping, moderate doping and high doping of fluorine. The organic photovoltaics have been characterized based on two conjugated polymers: the polythiophene (PT) and a new derivative of thiophene, the poly (9,9 '- dioctyl-2 ,7-fluorenedyilvinylene-co-5, 5'-(benzo [ 1,2,5] thiadiazole-4, 7dyil) dithiophene) (PFTBT). The deposition of the active layer of the first polymer is made by electrochemistry and the devices were made in monolayer structure, showing good results for external quantum efficiency. The fabrication of fotodetectors devices allowed the application of technological devices in arrays of positional detection. The active layers generated by the second polymer were obtained by chemical deposition. Photovoltaic results are presented in three different structures: monolayer, bilayer and bulk heterojunction. Bilayer devices appear more efficient than the bulk heterojunction. One of the findings of this difference is the estimate for the rate of excitons generated in the active layer: this value is larger for the heterojunction case, however, the probability to exciton dissociation in free charges is lower when compared to bilayer devices. Nanocomposites were also studied for application in photovoltaics: mixtures of conjugated polymer with carbon nanotubes and mixtures of conjugated polymer with gold nanoparticles. Two polymers were studied in the first case, the commercial Poly (3- hexyl thiophene) (P3HT) and non-commercial poly (9,9-di-hexilfluorenodiil-vinylenealt- 1 ,4-phenylenevinylene) (PDHFPPV). The interaction between different polymers and carbon nanotubes are presented in terms of optical and electrical characterization. The insertion of gold nanoparticles in a polymer matrix P3HT show the decrease in efficiency of photo-conversion when these materials are studied as active layers in photovoltaic devices. This may be associated with difficulty in transferring charges from nanoparticles to the polymer, due to the passivating layer capping the nanoparticles

Silsesquioxane as a New Building Block Material for Modified Electrodes Fabrication and Application as Neurotransmitters Sensors

Nanostructured films comprising a 3-n-propylpyridiniunn silsesquioxane polymer (designated as SiPy(+)Cl(-)) and copper (II) tetrasulfophthalocyanine (CuTsPc) were produced using the Layer-by-Layer technique (LbL). To our knowledge this is the first report on the use of silsesquioxane derivative polymers as building blocks for nanostructured thin films fabrication. Deposition of the multilayers were monitored by UV-Vis spectroscopy revealing the linear increment in the absorbance of the Q-band from CuTsPc at 617 nm with the number of SiPy(+)Cl(-)/CuTsPc or CuTsPc/SiPy(+)Cl(-) bilayers. FTIR analyses showed that specific interactions between SiPy+Cl- and CuTsPc occurred between SO(3)(-) groups of tetrasulfophthalocyanine and the pyridinium groups of the polycation. Morphological studies were carried out using the AFM technique, which showed that the roughness and thickness of the films increase with the number of bilayers. The films displayed electroactivity and were employed to detection of dopamine (DA) and ascorbic acid (AA) using cyclic voltammetry, at concentrations ranging from 1.96 x 10(-4) to 1.31 x 10(-3) molL(-1). The number and the sequence of bilayers deposition influenced the electrochemical response in presence of DA and AA. Using differential pulse technique, films comprising SiPy(+)/CuTsPc were able to distinguish between DA and ascorbic acid (AA), with a potential difference of approximately with 500 mV, in the concentration range of 9.0 x 10(-5) to 2.0 x 10(-4) molL(-1), in pH 3.0.TWASThe World Academy of Sciences (TWAS) for the advancement of science in developing countrie

Silsesquioxane as a New Building Block Material for Modified Electrodes Fabrication and Application as Neurotransmitters Sensors

Nanostructured films comprising a 3-n-propylpyridiniunn silsesquioxane polymer (designated as SiPy(+)Cl(-)) and copper (II) tetrasulfophthalocyanine (CuTsPc) were produced using the Layer-by-Layer technique (LbL). To our knowledge this is the first report on the use of silsesquioxane derivative polymers as building blocks for nanostructured thin films fabrication. Deposition of the multilayers were monitored by UV-Vis spectroscopy revealing the linear increment in the absorbance of the Q-band from CuTsPc at 617 nm with the number of SiPy(+)Cl(-)/CuTsPc or CuTsPc/SiPy(+)Cl(-) bilayers. FTIR analyses showed that specific interactions between SiPy+Cl- and CuTsPc occurred between SO(3)(-) groups of tetrasulfophthalocyanine and the pyridinium groups of the polycation. Morphological studies were carried out using the AFM technique, which showed that the roughness and thickness of the films increase with the number of bilayers. The films displayed electroactivity and were employed to detection of dopamine (DA) and ascorbic acid (AA) using cyclic voltammetry, at concentrations ranging from 1.96 x 10(-4) to 1.31 x 10(-3) molL(-1). The number and the sequence of bilayers deposition influenced the electrochemical response in presence of DA and AA. Using differential pulse technique, films comprising SiPy(+)/CuTsPc were able to distinguish between DA and ascorbic acid (AA), with a potential difference of approximately with 500 mV, in the concentration range of 9.0 x 10(-5) to 2.0 x 10(-4) molL(-1), in pH 3.0.11434993508Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Applied Surface Science

RESTRITOTin oxide (SnO2) is an important oxide for efficient dielectrics, catalysis, sensor devices, electrodes and transparent conducting coating oxide technologies. SnO2 thin film is widely used in glass applications due to its low infra-red heat emissivity. In this work, the SnO2 electronic band-edge structure and optical properties are studied employing a first-principle and fully relativistic full-potential linearized augmented plane wave (FPLAPW) method within the local density approximation (LDA). The optical band-edge absorption α(ω) of intrinsic SnO2 is investigated experimentally by transmission spectroscopy measurements and their roughness in the light of the atomic force microscopy (AFM) measurements. The sample films were prepared by spray pyrolysis deposition method onto glass substrate considering different thickness layers. We found for SnO2 qualitatively good agreement of the calculated optical band-gap energy as well as the optical absorption with the experimental results. PACS 71.15m; 72.80Jc; 73.61Le; 78.40Fy; 7866L

Applied Surface Science

Acesso restrito: Texto completo. p. 1874-1879The optical, electrical and structural properties of thin film tin oxide (TO), F-doped tin oxide (FTO; nF 6 1020 cm 3) and highly F-doped tin oxide (hFTO; nF 10 1020 cm 3), grown by spray pyrolysis technique, are studied by atomic force microscopy, Hall effect, X-ray fluorescence and transmission/ reflection measurements. The resistivity (r = 32 10 4 V cm for intrinsic tin oxide) shows intriguing characteristics when F concentration nF is increased (r = 6 10 4 V cm for FTO but 25 10 4 V cm for hFTO) whereas the carrier concentration is almost constant at high F concentration (nc 6 1020 cm 3 for FTO and hFTO). Thus, F seems to act both as a donor and a compensating acceptor in hFTO. The high carrier concentration has a strong effect on the optical band-edge absorption. Whereas intrinsic TO has room-temperature band-gap energy of Eg 3.2 eV with an onset to absorption at about 3.8 eV, the highly doped FTO and hFTO samples show relatively strong absorption at 2–3 eV. Theoretical analysis based on density functional calculations of FTO reveals that this is not a defect state within the band-gap region, but instead a consequence of a hybridization of the F donor states with the host conduction band in combination with a band filling of the lowest conduction band by the free carriers. This allows photonassisted inter-conduction band transitions of the free electrons to energetically higher and empty conduction bands, producing the below-gap absorption pea

Applied Surface Science

RESTRITOTin oxide (SnO2) is an important oxide for efficient dielectrics, catalysis, sensor devices, electrodes and transparent conducting coating oxide technologies. SnO2 thin film is widely used in glass applications due to its low infra-red heat emissivity. In this work, the SnO2 electronic band-edge structure and optical properties are studied employing a first-principle and fully relativistic full-potential linearized augmented plane wave (FPLAPW) method within the local density approximation (LDA). The optical band-edge absorption α(ω) of intrinsic SnO2 is investigated experimentally by transmission spectroscopy measurements and their roughness in the light of the atomic force microscopy (AFM) measurements. The sample films were prepared by spray pyrolysis deposition method onto glass substrate considering different thickness layers. We found for SnO2 qualitatively good agreement of the calculated optical band-gap energy as well as the optical absorption with the experimental results. PACS 71.15m; 72.80Jc; 73.61Le; 78.40Fy; 7866L