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Fischer, Timo. "Parapockenvirus (PPV) als neuartige Vektorvakzine Entwicklung Pseudorabiesvirus-(PRV)-spezifischer PPV-Rekombinanten und Untersuchung deren Immunogenität im Mausmodell /." [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=965634124.
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Gamael, Amin. "Ergebnisse nach kombinierter Operation PPV und Linsenchirurgie /." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972337334.
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Silva, Ricardo Manuel Pinho. "Células solares orgânicas baseadas em MEH-PPV." Master's thesis, Universidade de Aveiro, 2009. http://hdl.handle.net/10773/2626.
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Mestrado em Engenharia FísicaNo presente trabalho procedeu-se ao estudo e fabrico de células solares orgânicas do tipo bulk heterojunction, baseadas no polímero poly(2-methoxy-5- (2-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV) dopada com a nanoestrutura [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) em filmes finos . A caracterização opto-electrónica revelou uma forte absorção na zona espectral azul-verde, confirmando a aplicabilidade destes materiais para este tipo de dispositivos. Foram obtidos valores relevantes em parâmetros como factor de forma e eficiência. É apresentada uma tentativa de explicação dos resultados com base nas propriedades micro-eléctricas e morfológicas. Produziram-se, de igual forma, células flexíveis baseadas na mesma estrutura, tendo em vista a sua aplicabilidade em larga escala. ABSTRACT: In this work some thin film bulk-heterojunction organic solar cells based on polymer poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) (MEHPPV) doped with nanostructures [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) was made and studied. The opto-electrical characterization showed a strong absorption in the blue-green spectrum region, confirming the applicability of these materials for this kind of devices. Relevant data was obtained for fill-factors and efficiency. An attempt to explain the macroscopic behavior based on micro-electrical and morphological properties was done. Flexible devices based on same structure were also made in order to test the possible application in large scale.
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Cossiello, Rafael Di Falco 1980. "Fotofisica de polimeros emissores de luz : MEH-PPV." [s.n.], 2003. http://repositorio.unicamp.br/jspui/handle/REPOSIP/249455.
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Orientador: Teresa Dib Zambon AtvarsDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica
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Lear, Jeremy M. "The Synthesis of Benzyloxy Substituted DP-PPV and Examination of the Horner-Wadsworth-Emmons Reaction in the Synthesis of DP-PPV." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1401459783.
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Janakiraman, Umamaheswari. "Analysis of electrogenerated chemiluminescence of PPV type conducting polymers." Doctoral thesis, [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=968755305.
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Weir, Bruce Alexander. "Structure and morphology of PPV-derived polymers and oligomers." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621077.
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Grimes, Amy Frances. "Toward optimization of photomodulation of azobenzene-modified PPV derivatives." College Park, Md. : University of Maryland, 2007. http://hdl.handle.net/1903/7607.
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Thesis (Ph. D.)--University of Maryland, College Park, 2007.Thesis research directed by: Dept. of Chemistry and Biochemistry. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Saar, Brooklynd Dawn. "Fluorescence Quenching of PPV-SO and Bodipy-Naphthalene Systems." W&M ScholarWorks, 2012. https://scholarworks.wm.edu/etd/1539626932.
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Thamyongkit, Patchanita. "Synthesis and characterization of pyrazine and phthalocyaninatonickel(II) substituted PPV analogous oligomers Synthese und Charakterisierung von Pyrazin- und Phthalocyaninatonickel(II)-substituierten PPV-anologen Oligomeren /." [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963899929.
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Wetzel, Thierry. "Obtention d'outils moléculaires pour la détection et la différenciation du virus de la sharka (PPV) : clonage de l'ARN génomique d'une nouvelle souche de PPV." Bordeaux 2, 1991. http://www.theses.fr/1991BOR22016.
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Le plum pox potyvirus (ppv) est l'agent responsable de la sharka, la maladie virale actuellement la plus grave pour les arbres fruitiers a noyau. A cause de la faible concentration et de la repartition irreguliere du virus dans les arbres infectes, des techniques de detection du virus extremement sensibles sont necessaires. Un test de detection du ppv par hybridation moleculaire utilisant des sondes arnc marquees au #3#2p correspondant a des genes codant pour des proteines virales non structurales de ppv-d ont permis une augmentation de la polyvalence du test par rapport a une sonde correspondant au gene de la proteine de capside. Ces sondes ont detecte avec une sensibilite maximale un grand nombre d'isolats de ppv a l'exception d'un isolat egyptien: ppv-e1 amar. L'arn genomique de ppv-e1 amar a ete clone et sa moitie 3 a ete sequencee. Des niveaux de divergence de 20% ont ete observes au niveau des acides nucleiques, 10% au niveau des acides amines, par rapport aux sequences correpondantes de 3 autres souches de ppv, homologues a 98% entre elles. Ppv-e1 amar se presente donc comme une souche atypique de ppv. Un protocole de detection du ppv par pcr, dans un seul tube s'est avere polyvalent et a demontre une plus grande sensibilite par rapport a l'hybridation moleculaire utilisant des sondes arnc radiomarquees. Un protocole modifie de pcr par l'introduction d'une etape prealable d'immunocapture du virus (ic/pcr), a permis d'augmenter la sensibilite de 100 fois, 250 fois et 2000 fois par rapport a la pcr, l'hybridation moleculaire et le test elisa respectivement
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Greenham, Neil Clement. "Electroluminescence in conjugated polymers." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296643.
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Fogle, Jeffrey D. "Synthesis of Fluorinated Indenofluorenediones and Bis(2-fluorophenyl) Substituted PPV." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1309441933.
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Alves, Marcelo Caetano Oliveira. "Estudo de soluções de MEH-PPV em dosimetria de radiação gama." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/59/59135/tde-03092008-091923/.
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O presente trabalho teve por objetivo o estudo da viabilidade de utilização de soluções de poli[2-metóxi,5-(2-etil-hexiloxi)-p-fenileno vinileno] (MEH-PPV), em diversos solventes tais como CHCl3 (Clorofórmio), diclorometano (CH2Cl2), bromofórmio (CHBr3), dibromometano (CH2Br2), uma mistura de diclorometano (CH2Cl2) e diiodometano (CH2I2) e tolueno (C6H5CH3), como dosímetros de radiações ionizantes. A novidade está no fato de que estes dosímetros têm como principal característica a variação da cor, proporcionando uma medida visual e direta da radiação recebida. Além disso, a sensibilidade dos dosímetros pode ser ajustada por meio da variação da concentração das soluções do polímero. Neste trabalho, foi utilizada a radiação gama, 60Co, para os estudos de viabilidade deste dosímetro. Quando submetidos a certas doses de radiação gama, o polímero estudado sofre alterações em suas propriedades óticas e em sua estrutura molecular. Para avaliar as alterações óticas, foram utilizadas medidas de espectroscopia de absorção UV-Visível (UV-Vis) e fotoluminescência. Também foram avaliadas as alterações na estrutura molecular, como conseqüência da exposição à radiação gama por meio de técnicas como ressonância magnética nuclear (RMN) e cromatrografia de permeação de gel (GPC). Os Resultados obtidos mostraram que a radiação gama, 60Co, promove, de forma indireta, a diminuição do comprimento efetivo da conjugação do polímero, mais provavelmente em decorrência da quebra da cadeia principal do polímero devido às reações com as espécies reativas, possivelmente nos grupamento vinil. Estas quebras resultam em um deslocamento dos picos máximos dos espectros de absorção para regiões de maior energia (blueshift). Estes deslocamentos dependem não somente da dose de irradiação, mas também do solvente utilizado em da concentração da solução.The present work aims the study of the viability of using solutions of poly[2-methoxy-5-(2\'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV), in several solvents such as chloroform (CHCl3), dichloromethane (CH2Cl2), bromoform (CHBr3), dibromomethane (CH2Br2), a mix of dichloromethane (CH2Cl2) and diiodomethane (CH2I2), and toluene (C6H5CH3) as ionizing radiation dosimeters, gamma, in this case. The novelty is in the fact of the dosimeter main characteristic is color change, allowing a visual and direct received radiation measurement. Besides, the sensibility of the dosimeter can be adjusted by the polymer solution concentration variation. In this work, it was used the gamma radiation, 60Co, for the dosimeter viability studies. When exposed to certain doses of this kind of radiation, the studied polymer suffers changes in its optic properties and in its molecular structure. In order to evaluate the optical changes, UV-VIS absorption and photoluminescence spectroscopy measures were performed. Besides, the molecular structure changes, as a consequence of the exposure to gamma radiation, were evaluated by nuclear magnetic resonance (NMR) and Gel Permeation Chromatography (GPC). The results show that the gamma radiation, 60Co, promotes, indirectly, the decrease of the polymer conjugation length probably due the backbone scission caused by reactions with reactive species, probably in the vinyl side groups. These scissions resulted in a blueshift of the absorption spectra maximum peaks. Theses blueshifts depend on the irradiation dose, the used solvent and the solution concentration.
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Postacchini, Bruna Bueno. "Fotofísica em heteroestruturas contendo o polímero emissor PPV e espécies supressoras." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-30012009-114630/.
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A compreensão dos caminhos de desativação não radiativa em polímeros conjugados é fundamental para o uso desses materiais em dispositivos luminescentes, células fotovoltaicas e sensores. Nesta tese, os processos não radiativos em filmes automontados de polímero luminescente foram investigados via análise da supressão de intensidade de fotoluminescência, utilizando a técnica de fluorescência estacionária, e através da medida do tempo de vida do estado excitado com fluorescência resolvida no tempo em arranjo de contagem de fótons. A camada emissiva constituída por poli(p-fenileno vinileno) (PPV) obtido da conversão térmica do precursor poli(cloreto de xilideno tetraidrotiofeno) (PTHT) apresentou tempos de vida entre 150 e 250 ps, e fraca dependência com o comprimento de onda de detecção da emissão. Na presença de uma monocamada contendo azocorante Vermelho do Congo (CR) ou ftalocianina tetrassulfonada de níquel (NiTsPc) atuando como receptor de energia foi observada supressão da fluorescência e encurtamento do tempo de vida (50-100ps). À medida que se aumenta a distância entre as camadas de doador e receptor via interposição de bicamadas de espaçador, a dinâmica do sistema tende à dinâmica de decaimento do estado excitado do PPV na ausência de receptor. A dependência da eficiência com a distância 1/r2 ou 1/r3 apontam para transferência de energia ressonante (RET) típica da interação plano-plano ou plano-camada. Os processos não radiativos foram também estudados em função da diluição de segmentos PPV dispersos em matriz de polieletrólito poli(cloreto de dodecildimetilamônio) PDAC. A diluição dos segmentos conjugados aumenta a eficiência quântica de emissão, torna o mecanismo de desativação mais lento (500 ps) e diminui a dependência do tempo de vida com o comprimento de onda de detecção, devido à menor eficiência dos mecanismos de desativação não radiativa. Na presença de uma camada receptora, a eficiência de transferência de energia é maior para amostras com segmentos mais diluídos indicando que esse mecanismo compete com os processos internos à própria camada emissiva. O tempo de vida aumenta em filmes com mais baixo grau de conjugação e a dependência com o comprimento de onda de emissão é mais forte. Em resumo, a técnica de automontagem se mostrou adequada para obter filmes com propriedades fotofísicas controláveis no nível molecular, que puderam ser estudadas com espectroscopias de fluorescência.Understanding the pathway of excitation in conjugated polymers is important for using these materials as active layer in devices, photovoltaic cells and sensors. In this thesis, non-radiative processes in layer-by-layer (LbL) films were investigated with measurements of fluorescence quenching in steady-state fluorescence spectroscopy and of the singlet excited state lifetime using time-resolved fluorescence spectroscopy in a single photon counting (SPC) apparatus. The emissive layer of poly(p-phenylene vinylene) (PPV) obtained via thermal conversion of the soluble precursor poly(xylylidene tetrahydrothiophenium) chloride (PTHT) showed lifetime 150-250 ps and weak dependence on the emission wavelength. In the presence of an acceptor layer of either Congo Red (CR) or nickel tetrasulfonated phthalocyanine (NiTsPc) the PL intensity was quenched and the lifetime was shorter (50 -100 ps). Upon increasing the distance between the energy donor (PPV) and acceptor layers by interposing bilayers of inert polyelectrolytes the dynamics tended to the PPV dynamics. The distance-dependence of the energy transfer efficiency (1/r2 or 1/r3) points to a resonant process (RET) with a plane-to-plane or plane-to-slab interaction. The non-radiative processes were also studied for varying dilutions of the PPV segments in a matrix of the polyelectrolyte poly(dodecyl methylamonium chloride) (PDAC). This dilution increased the quantum efficiency and led to longer lifetimes (500 ps) owing to a less effective non-radiative energy transfer. When an energy acceptor layer is present, energy transfer is more efficient for the most diluted systems, indicating that such transfer competes with internal processes in the emissive layer. The lifetime increased in films with low degree of conjugation, for which there was a stronger dependence on the emission wavelength. It is concluded that the LbL methodology was suitable to obtain photophysical film properties that could be controlled at the molecular level, and investigated with varied fluorescence spectroscopies.
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Masuda, Koji. "Design and Fabrication of Nanostructures by Layer-by-Layer Assembly for Organic Photovoltaic Devices." 京都大学 (Kyoto University), 2010. http://hdl.handle.net/2433/123342.
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Sorce, Steven R. "The military housing problem Public Private Venture (PPV) and complete privatization alternatives /." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2000. http://handle.dtic.mil/100.2/ADA379322.
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Thesis (M.S. in Management) Naval Postgraduate School, June 2000.Thesis advisor(s): Simon, Cary A.; . Eaton, Donald R. "June 2000." Includes bibliographical references (p. 73-74). Also available in print.
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Kuch, Serena [Verfasser], Matthias [Akademischer Betreuer] Rehahn, and Stefan [Akademischer Betreuer] Immel. "Neue PPV-Derivate auf ungewöhnlichen Wegen / Serena Kuch ; Matthias Rehahn, Stefan Immel." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2019. http://d-nb.info/1176702017/34.
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Faleiros, Marcelo Meira. "Espectroscopia ultrarrápida do polímero semicondutor luminescente MEH-PPV com excitação no ultravioleta." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-06122012-084909/.
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A indústria optoeletrônica passa por um período de transformação em que os materiais inorgânicos estão sendo substituídos pelos orgânicos, oligômeros e polímeros, na fabricação de alguns tipos de dispositivos. No entanto, fatores como baixa eficiência e tempo de vida impedem que os aparelhos com base nos polímeros entrem definitivamente no mercado. Para resolver estas questões, é necessário um conhecimento profundo da estrutura eletrônica desses materiais. Apesar do avanço científico, ainda existem pontos a esclarecer. Por exemplo, não existe um consenso sobre a natureza das excitações óticas primárias e dos processos não radiativos nos polímeros conjugados, principalmente com excitação no ultravioleta. Tais processos limitam a eficiência e podem influenciar nos processos fotoquímicos, determinando o tempo de vida de um dispositivo. Esses fenômenos ocorrem em alguns picossegundos e, portanto, a espectroscopia ultrarrápida é a técnica mais adequada para o seu estudo. Neste trabalho, foi implementado o aparato para espectroscopia de bombeio e prova em filmes finos de polímeros conjugados, no qual podem ser usados dois métodos de aquisição de dados, sensível à fase e pulso-a-pulso. O primeiro é o método padrão citado na literatura, no qual o feixe de excitação é modulado por um chopper e os sinais são medidos por amplificadores lock-in. No segundo, o condicionamento de sinais é feito por circuitos amplificadores e o processamento dos sinais é feito pulso-a-pulso. É um método que a princípio fornece melhor estatística, pois as flutuações do laser são normalizadas pulso-a-pulso, e não na média. Além disso, apresenta menor custo e torna o experimento de bombeio e prova mais simples, pois os únicos procedimentos críticos passam a ser a sobreposição dos feixes na amostra e a determinação do atraso zero entre bombeio e prova. Foi projetado e construído o circuito eletrônico de condicionamento de sinais e o software de aquisição foi desenvolvido em linguagem LabVIEW. Entretanto, o método pulso-a-pulso forneceu uma sensibilidade inadequada para o estudo de filmes poliméricos, (ΔT⁄T ~ 0,7%, limitada pelo ruído elétrico na amplificação dos pulsos detectados), em contraste com ΔT/T ~ 0,1% que foi alcançada pelo método sensível à fase. Desta maneira, foi usado o último método para o estudo da evolução do espectro e da dinâmica de emissão estimulada de um filme de MEH-PPV, com excitação no visível e no ultravioleta, permitindo o estudo da dinâmica de relaxação dos estados de mais alta energia. Os resultados no visível são compatíveis com os da literatura, o que demonstra a confiabilidade do aparato quanto à sensibilidade e resolução temporal e espectral. Os resultados com excitação no UV indicam que a transferência de energia de bandas mais energéticas para a banda π - π∗ (conversão interna) ocorre em aproximadamente 300 fs, confirmando as suposições da literatura quanto à relaxação energética ultrarrápida (regra de Kasha), além de sugerir a existência de bandas ainda mais energéticas do que as já conhecidas. Pretende-se futuramente determinar a eficiência de tal transferência energética, pois ela pode ser um fator limitante na eficiência de fotoluminescência em polímeros conjugados com excitação no ultravioleta.The optoelectronics industry is currently undergoing a transition period in which inorganic materials are being replaced by organic materials, oligomers and polymers, in the fabrication of some types of devices. However, factors such as low efficiency and low lifetime prevent polymer based devices on entering the market definitely. The solution of these issues requires a thorough knowledge of the electronic structure of these materials, but despite of scientific advances, there are still points to be clarified. For example, there is no consensus on the nature of the primary optical excitations and non-radiative processes in conjugated polymers, specially with ultraviolet excitation. Such processes limit the efficiency and can influence the photochemical processes, determining the device lifetime. These phenomena occur on a femtosecond timescale and therefore, ultrafast spectroscopy is the most appropriate technique for their study. In this work, we implemented the apparatus for pump-probe ultrafast spectroscopy on thin films of conjugated polymers, which can be used with two methods of data acquisition, phase-sensitive and shot-by-shot. The first is the standard method reported in the literature in which the excitation beam is modulated by a chopper and the signals measured by lock-in amplifiers. In the second, the detector signal conditioning is done by conventional amplifier circuits, followed shot-to-shot signal processing. This method provides the best statistics, in principle, because the laser fluctuations are normalized for each pulse, instead of using the average. In addition, the apparatus has a lower cost and the experiment is simpler, having as critical procedures the alignment of the beams on the sample and the determination of zero delay, with all other procedures done via software. The electronic circuitry for signal conditioning was designed and built and data acquisition software that enables measurements with both methods was developed in the LabVIEW programming language. However, the shot-by-shot method provided an inadequate sensitivity for the study of polymeric films (ΔT⁄T ~0.7%, limited by electronic noise in the amplification of detector signals), compared with ΔT⁄T ~ 0.1%, which was achieved by the phase sensitive method, and was the goal at the beginning of the project. Thus, the latter method was used to study the evolution of the spectrum and dynamics of stimulated emission of a film of MEH-PPV, with excitation in the visible and UV, allowing the study of the dynamics of higher lying electronic states. The results in the visible are consistent with those reported in the literature, which demonstrates the performance of the apparatus with respect to sensitivity and time/spectral resolution. The results with UV excitation indicate that the energy transfer among the more energetic bands to the π - π* band (internal conversion) occurs in about 300 fs, confirming the assumptions of the literature on the ultrafast energy relaxation processes (Kashas rule), besides suggesting the existence of even more energetic bands than those currently known. As future work, we plan to measure the efficiency of this energy transfer process, since it may be the limiting step in determining the overall photoluminescence efficiency of conjugated polymers with ultraviolet excitation.
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Thamyongkit, Patchanita. "Synthesis and Characterization of Pyrazine and Phthalocyaninatonickel (II) Substituted PPV Analogous Oligomers." [S.l. : s.n.], 2002. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB9909232.
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Timpanaro, Salvatore. "Conductive properties and morphology of conjugated molecular materials studied by local probe techniques." Phd thesis, [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=974115991.
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Batagin, Neto Augusto [UNESP]. "Estrutura eletrônica do polímero orgânico conjugado MEH-PPV em solução sob radiação ionizante." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/88506.
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bataginneto_a_me_bauru.pdf: 728792 bytes, checksum: 1630464fa8b5bc3088ecee698a2e6b9e (MD5)Os polímeros orgânicos conjugados têm sido amplamente utilizados em diversos campos tecnológicos devido às suas características semicondutoras e ópticas. Recentemente foi relatada a possibilidade de sua utilização na área de dosimetria. O polímero MEH-PPV, quando diluído em solventes que contenham halogênios, tem apresentado características bastante promissoras nesta área, contudo não há ainda uma completa compreensão dos mecanismos envolvidos. No presente trabalho realizou-se o estudo conformacional e da estrutura eletrônica do polímero MEH-PPV em clorofórmio e as possíveis alterações provenientes da irradiação desta solução com radiações ionizantes. Métodos de modelagem de materiais foram utilizados a fim de simular o sistema. Resultados experimentais sugerem que os efeitos observados são oriundos da interação do solvente com a cadeia polimérica. A fim de investigar tal possibilidade, uma análise dos prováveis sítios de maior reatividade sobre o polímero foi realizada, apontando um mecanismo de incorporação de radicais sobre a cadeia principal.
Organic conducting polymers have been employed in several technological fields due to its semiconducting and optical properties. Recently, several reports points to applications in radiation dosimetry. When diluted in halogen-containing solvents, the polymer MEH-PPV shows interesting properties after gamma irradiation. Despite the promising application, still is lacking a complete understanding of the underlying phenomena. In the present work, we studied the geometry conformation and electronic structure of MEH-PPV in the presence of chloroform employing molecular modeling techniques to simulate the system. Several possibilities for polymer modification under gamma radiation were investigated, following suggestion from experimental results. Finally, a model for the color modifications of the solution is present.
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Batagin, Neto Augusto. "Estrutura eletrônica do polímero orgânico conjugado MEH-PPV em solução sob radiação ionizante /." Bauru : [s.n.], 2009. http://hdl.handle.net/11449/88506.
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Orientador: Francisco Carlos LavardaBanca: Carlos Frederico de Oliveira Graeff
Banca: Paulo Monteiro Vieira Braga Barone
O Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi da Unesp
Resumo: Os polímeros orgânicos conjugados têm sido amplamente utilizados em diversos campos tecnológicos devido às suas características semicondutoras e ópticas. Recentemente foi relatada a possibilidade de sua utilização na área de dosimetria. O polímero MEH-PPV, quando diluído em solventes que contenham halogênios, tem apresentado características bastante promissoras nesta área, contudo não há ainda uma completa compreensão dos mecanismos envolvidos. No presente trabalho realizou-se o estudo conformacional e da estrutura eletrônica do polímero MEH-PPV em clorofórmio e as possíveis alterações provenientes da irradiação desta solução com radiações ionizantes. Métodos de modelagem de materiais foram utilizados a fim de simular o sistema. Resultados experimentais sugerem que os efeitos observados são oriundos da interação do solvente com a cadeia polimérica. A fim de investigar tal possibilidade, uma análise dos prováveis sítios de maior reatividade sobre o polímero foi realizada, apontando um mecanismo de incorporação de radicais sobre a cadeia principal.
Abstract: Organic conducting polymers have been employed in several technological fields due to its semiconducting and optical properties. Recently, several reports points to applications in radiation dosimetry. When diluted in halogen-containing solvents, the polymer MEH-PPV shows interesting properties after gamma irradiation. Despite the promising application, still is lacking a complete understanding of the underlying phenomena. In the present work, we studied the geometry conformation and electronic structure of MEH-PPV in the presence of chloroform employing molecular modeling techniques to simulate the system. Several possibilities for polymer modification under gamma radiation were investigated, following suggestion from experimental results. Finally, a model for the color modifications of the solution is present.
Mestre
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FERRI, BODIN MANUELLE. "Etudes in vitro et in vivo des interactions prunus - plum pox virus (ppv)." Montpellier, ENSA, 2000. http://www.theses.fr/2000ENSA0025.
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Le plum pox virus (ppv) est un organisme de quarantaine responsable de la sharka, maladie majeure des arbres fruitiers du genre prunus. Peu de sources de resistance sont disponibles actuellement. L'evaluation des ressources genetiques vis-a-vis du ppv doit prendre en compte la perennite de ces especes et etre realisee en conditions confinees. Une demarche experimentale a ete developpee in vitro pour l'etude des interactions prunus - ppv. La variabilite des prunus et de l'agent pathogene a ete prise en compte a travers 6 genotypes et 9 isolats viraux. Une methodologie d'etablissement, de maintien et de multiplication d'une collection de souches virales in vitro a ete developpee sur le genotype sensible, le clone gf 8-1 de prunier mariana. Differents facteurs intervenant dans l'inoculation par greffage in vitro ont ete etudies. Le suivi de la propagation systemique du virus a ete mene in vitro et in vivo, a l'aide de la demarche amap de modelisation de l'architecture des arbres. L'optimisation de la methode d'inoculation in vitro a ete realisee sur le prunier mariana gf 8-1 et le clone resistant p1908 de prunus davidiana. Un gradient de contamination decroissant vers l'apex a ete mis en evidence in vitro et in vivo chez le genotype sensible. Aucun genotype immum n'a ete detecte, mais des resistances partielles probablement liees au mouvement systemique ont ete mises en evidence in vitro comme in vivo. L'inoculation par greffage in vitro de prunus constitue maintenant un outil fiable permettant d'apprehender les relations plante - virus, d'evaluer le comportement de genotypes issus de l'amelioration conventionnelle ou obtenus par transgenese et d'etudier le determinisme genetique de la resistance.
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Fernandes, Ricardo Vignoto. "Estudo dos efeitos de irradiação laser em filmes de PPV sintetizados com corantes." Universidade Estadual de Londrina. Centro de Ciências Exatas. Programa de Pós-Graduação em Física, 2014. http://www.bibliotecadigital.uel.br/document/?code=vtls000190200.
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Polímeros semicondutores encontram atualmente diversas aplicações em dispositivos eletrônicos e optoeletrônicos, como transistores, diodos emissores de luz e células solares fotovoltaicas. Desses materiais, um dos mais estudados é o poli (p-fenileno vinileno) (PPV), cujas propriedades de absorção e emissão de luz são muito interessantes para os dispositivos supracitados. Uma das maneiras de processar esse polímero na forma de filme fino é através da deposição e subsequente conversão do polímero precursor solúvel através de um tratamento térmico. Com a introdução, na solução do precursor, de compostos contendo o grupo sulfonato RSO3- em sua estrutura molecular, a conversão do PPV pode ser feita em temperaturas e intervalos de tempo sensivelmente menores, o que é muito interessante para a utilização deste material como camada ativa nos dispositivos. Além disso, o emprego de compostos contendo tanto o grupo sulfonato RSO3- quanto agrupamentos azo (mais especificamente, os azocorantes) na produção do PPV levou à observação de um efeito surpreendente nas propriedades de emissão do filme: a fotoluminescência (PL) apresentou uma forte intensificação (mais de dez vezes, em alguns casos) quando o filme foi irradiado com a luz linearmente polarizada fornecida por um lazer. Este trabalho foi desenvolvido com o intuito de investigar esse efeito, e desvendar as suas causas. Pelos resultados obtidos, através da análise de espectros de absorbância polarizada e de PL em função do tempo de foto-irradiação, pode-se concluir que a intensificação da emissão dos filmes de PPV está relacionada principalmente com o processo de isomerização do grupo azo na molécula do corante. Esse processo, ativado pela incidência de luz linearmente polarizada, leva a uma orientação dos momentos de dipolo da molécula do azocorante, a qual diminui a quantidade de luz absorvida pela mesma. Como essas moléculas estão embebidas na matriz polimérica de PPV, esse efeito conduz ao aumento da emissão do polímero.Semiconducting polymers are used in several applications in electronic and optoelectronic devices currently, such as transistors, light emitting diodes and photovoltaic solar cells. Of these materials, one of the most studied is poly (p-phenylene vinylene) (PPV) which properties of absorption and emission of light are very interesting for these devices. One method to handle this polymer in the form of thin film is through deposition and subsequent conversion of the soluble precursor polymer by a thermal treatment. With the introduction of SO3- group terminated compounds into the solution of the precursor, conversion to PPV can be done at considerably smaller temperatures and time intervals, which is very interesting to use this material as active layer in devices. Furthermore, the use of compounds containing both SO3- radical groups as azo (more specifically azo dyes) for the production of PPV resulted in a dramatic effect on the emission properties of the film: the photoluminescence (PL) showed a strong enhancement (more than ten times in some cases) when the film was irradiated with linearly polarized light provided by a laser. This work was developed in order to investigate this effect and to determine its causes. By analyzing the polarized absorbance and PL spectra as a function of the photo-irradiation time, it can be concluded that the increased emission of PPV films is mainly related to the process of isomerization of the azo group in the molecule of the dye. This process, which is enabled by the incidence of linearly polarized light, leads to an orientation of the dipole moments of the azo dye molecule which decreases the amount of light absorbed by it. Because these molecules are embedded in PPV polymeric matrix, this effect leads to increased emission of the polymer.
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Olivati, Clarissa de Almeida. "Estudo das propriedades elétricas e ópticas de dispositivos eletroluminescentes poliméricos." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-08122010-094137/.
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Dispositivos eletroluminescentes poliméricos apresentam alto potencial tecnológico, principalmente devido ao fato de ser possível a obtenção de dispositivos flexíveis e de grande área. Apesar disto, ainda existem alguns fatores que limitam a sua aplicação tecnológica, como por exemplo o tempo de vida e a eficiência na emissão dos dispositivos. Alguns métodos têm sido propostos para o aumento destes fatores, entre os quais estão a inserção de camadas transportadoras de elétrons e buracos. Esta tese teve como objetivo principal a busca por métodos que possibilitassem a melhora das propriedades elétricas e/ou ópticas dos dispositivos eletroluminescentes poliméricos (PLEDs). Neste contexto, filmes Langmuir-Blodgett (LB) da camada emissiva e da camada transportadora de elétrons foram aplicados nos PLEDs, devido a reprodutibilidade e ao grau de organização destes filmes, o que possibilita uma emissão polarizada. Além disso, observou-se aumento na injeção eletrônica nos dispositivos com o uso de ionômeros como camada transportadora de elétrons. Por outro lado, a combinação da POMA e ITO como eletrodo transparente no dispositivo com PPV+DBS como camada ativa (ITO/POMA/PPV+DBS/Al) mostrou a diminuição da tensão de operação quando comparado a um dispositivo convencional (lTO/PPV/Al). Os dispositivos foram caracterizados através de medidas elétricas e opto-elétricas.Polymer electroluminescent devices are promising for a number of applications, in particular due to the possibility of obtaining large area, flexible displays. There are, however, major stumbling blocks associated with the short lifetimes and limited efficiency and brightness of light-emitting diodes (LEDs) fabricated with organic molecules in comparison with the inorganic ones. Severa1 methods have been proposed to increase brightness and eficiency, which include the use of electron and/or hole transporting layers adjacent to the electrodes. ln this thesis, we report the study of severa1 methods to improve the efficiency of the polymer light emitting diodes (PLEDs). In this context, Langmuir-Blodgett (LB) films were used in PLEDs, as emitting and electron transport layer, due to the high degree of thickness control, low number of defects, and some degree of organization at the molecular scale. Besides, improvements in electron injection into the emissive layer using ionic polymers (ionomers) as electron-transporting layers were observed. Othenvise, the combination of POMA and ITO as transparent electrode and PPV+DBS as active layer (ITO/POMA/PPV+DBS/A1) leads to a decrease in the operating voltage compared with the conventional PLED, ITO/PPV/Al. The devices were characterized by electrical and opto-electrical measurements.
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McCumiskey, Edward. "Mechanical Characterization of Nanocomposite CdSe Quantum Dot – MEH-PPV Polymer Thin Films via Nanoindentation." VCU Scholars Compass, 2009. http://scholarscompass.vcu.edu/etd/1731.
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Progress in the burgeoning field of organic electronics is enabling the development of novel technologies such as low-cost, printable solar cells and flexible, high-resolution displays. One exciting avenue of research in this field is nanostructured hybrid organics such as quantum dot (QD)-polymer devices. The incorporation of QDs can greatly improve a device’s efficiency and gives one the ability to tune its electrical and optical characteristics. In order for such technologies to be commercially viable, it is important to classify their mechanical integrity and reliability. Surprisingly little is known about the mechanical properties of QD-polymer thin films (<100 nm). This is in part due to challenges of: (1) isolating the mechanical response of a thin film from the underlying substrate, (2) obtaining a homogeneous dispersion of QDs in the film, and (3) the sensitivity of mechanical properties to the inherent rate dependence of polymer deformation (i.e., viscoelasticity). All of these challenges can introduce significant errors in the measurement of mechanical properties. Furthermore, the deformation mechanisms in nanocomposites are not well understood, so it is difficult to predict the effect of adding QDs on the mechanical behavior of films. In this thesis, these challenges are addressed for characterizing the mechanical properties of thin films of CdSe QD-poly[2-methoxy-5-2(2΄-ethylhexyloxy-p-phenylenevinylene)] (MEH-PPV) nanocomposites using quasi-static nanoindentation testing. Elastic modulus, hardness, and creep are measured as a function of QD concentration and loading and unloading rates. The QDs' ligands are removed by pyridine treatment prior to mixing with MEH-PPV to improve dispersion. The films are prepared via spin-coating onto glass substrates and subsequent annealing in air. Efforts are taken in the mechanical testing to minimize errors due to viscoelastic creep and interference from the substrate. Transmission electron microscopy reveals that the QDs are relatively well-dispersed in the polymer matrix. It is observed that adding QDs increases the elastic modulus (E) and hardness (H) of the films, while reducing the viscoelastic creep. Both E and H increase linearly with the volume percent of QDs. E ranges from 14.5 GPa to 52.7 GPa for pure MEH-PPV (0% QDs) and 100% QD films, respectively, while H ranges from 220 MPa to 1430 MPa for the same films, respectively. The films behave viscoelastically at lower QD loading, but assume a more granular character as the loading approaches 100%.
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Moore, Corell H. "Modeling the peak absorption of MEH-PPV in various solvents using Density Functional Theory." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/6041.
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Density Functional Theory (DFT) and time-dependent Density Functional Theory (TD-DFT) are powerful tools for modeling orbital energy in conjugated molecules and have been useful tools for research in organic photovoltaics. In this work, DFT is first used to explain the red shift in the absorption spectrum and increased absorption observed in MEH-PPV. Initially, the modeling of the red-shift in the absorption peak of MEH-PPV is studied using Gaussian 03 software with the global hybrid functional B3LYP for exchange-correlation and the 6-31G basis set. DFT and TD-DFT are used to separately study the effects of polymer chain length, carbon-carbon double-bond stretching, and the polymer in solution vs. in gas space on red shift in absorption spectrum.
Next, Gaussian 09 software and the same B3LYP functional and 6-31G basis set are used to study interchain and intrachain interactions of MEH-PPV in solution. The red shift in the absorption peaks for three MEH-PPV configurations (single-chain pentamer, two stacked pentamers, and decamer) are compared with experimental results for five different solvents (chloroform, toluene, xylene, dichloromethane, and chlorobenzene). This investigation indicates that inter-chain interactions dominate in “good” aromatic solvents as compared to “poor” non-aromatic solvents. The results suggest that inter-chain charge transfer interactions play a critical role in real solutions and inter-chain aggregation takes precedence over intra-chain aggregation in aromatic solvents.
In the final section of the study, accurate values for the range-separation parameter (w) for three lengths of MEH-PPV polymer (trimer, tetramer, and pentamer) in five different solvents (chloroform, chlorobenzene, xylene, Tetrahydrofuran, and dichloromethane) are reported using the range-separated functionals wB97XD and CAM-B3LYP. Using these data, range separation parameters are predicted and used for longer polymer chains in chloroform solution. The differences in the range separation parameters for the different solvents is statistically significant and gives further insight into the polymer/solvent interaction.
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Cossiello, Rafael Di Falco 1980. "Eletroluminescencia e morfologia de blendas polimericas : copolimeros ionicos de SAA e blendas com MEH-PPV." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/249467.
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Orientador: Teresa Dib Zambon AtvarsTese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica
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Resumo: O copolímero SAA (poli(estireno-co-ácido acrílico-co-1-metacrilato de pirenilmetila)) foi sintetizado por via radicalar em agua e caracterizado por analises termicas (DSC, TGA), espectroscopicas (NMR C e H, UV-VIS, FTIR, fluorescência estacionária e resolvida no tempo) e elétricas (eletroluminescência). As blendas com poli[2-metóxi-5-(2¿-etilóxi)-p-fenilenovinileno] MEH-PPV foram estudadas desde 0,01; 0,05; 0,10; 0,50; 1,0; 10,0; 25; 50; 75 e 90 (% em massa) de MEH-PPV em SAA para ánalise da evolucao da morfologia por microscopia óptica, de fluorescência e eletrônica de varredura em espessuras de 70 mm (fratura criogênica) e 70 nm (espessura do dispositivo). Em baixas concentracões os domínios de MEH-PPV se apresentam em forma de núcleos dispersos e empacotados e conforme se aumenta a concentracao de MEH-PPV, observa-se que há a coalescência destes núcleos até a formação de uma fase interconectada de uma rede tridimensional. As medidas de difração à altos angulos mostram que há uma preferência de orientação do MEH-PPV ao longo do substrato e nao influencia a isotropia do SAA devido a baixa miscibilidade entre estes polímeros. As unidades de 1-pirenil metila foram utilizadas para avaliar a polaridade do microambiente e o mecanismo de transferencia de energia entre o doador (SAA) e o receptor (MEH-PPV). A dependência do tempo de fluorescência das unidades 1-pirenilmetila com a concentracao do MEH-PPV fornece subsídios para concluir que ocorre interpenetração de cadeias e, portanto uma baixíssima solubilidade entre os dois polímeros. O melhor desempenho de eletroluminescência foi do dispositivo preparado a partir da mistura 50:50 de MEH-PPV:SAA, cuja corrente elétrica foi aumentada em 2,5 vezes e a luminância em 4 vezes se comparado com o dispositivo de MEH-PPV puro. A morfologia de fase interconectada se mostrou importante para um melhor processo de transporte de cargas. O copolímero de SAA permitiu uma melhor injeção de cargas devido aos grupos carboxila presentes das unidades de ácido acrílico
Abstract: The copolymer SAA poly(styrene-co- acrylic acid -co-1-pyrenylmethyl methacrylate) was synthesized by radical emulsion in water and characterized by thermal analyses (DSC, TGA), spectroscopic (NMR 13C and 1:00, UV-VIS, FTIR, stationary and time-resolved fluorescence) and electric (electroluminescence). The blends with poly[2-methoxy-5(2'ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV) were studied from 0. 01; 0. 05; 0.10; 0.50; 1.0; 10.0; 25; 50; 75 and 90 (% in mass) of MEH-PPV in SAA to analyze the morphology evolution by optical, epifluorescence and electronic microscopy. The films were prepared in two thicknesses: one around 70 mm to be analyzed by cryogenic fractures and 70 nm, to be comparable with the device thickness. In low concentrations the domains of MEH-PPV appears dispersed nuclei and accrete when the concentration of MEH-PPV is increased forming an interconnected phase. The diffraction measures (WAXD) show a preference orientation of MEH-PPV along the substrate plane and it do not influences the SAA due the low miscibility between each other. The increase of the MEH-PPV concentration showed a redshift on electroluminescence spectrum due the inner filter and auto-absorption and re-emission effects. The units of 1-pyrenylmethyl were used to evaluate the polarity of the microenvironment and the mechanism of energy transfer of among the donor (SAA) and the acceptor (MEH-PPV). The timedependence of fluorescence with the increase of MEH-PPV concentration show that occurs an chain interpenetration following the fluorescence non-radiative energy transfer model. The best electroluminescent device was prepared using the mixture 50:50 of MEH-PPV:SAA. The interconnected phases are important for a better process of charge transport. The copolymer SAA allowed for a dilution effect avoiding the aggregation process and facilitating the charge injection processes. This technology of polymeric blends gave good results the increase of the luminance intensity and reduction of the voltage operation
Doutorado
Físico-Química
Doutor em Ciências
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Marconi, Flávia Maria. "Síntese e caracterização de polímeros com propriedades eletroluminescentes." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-14112014-102419/.
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Durante este trabalho foram sintetizados e caracterizados três derivados dialcoxilados do poli(p-fenileno-vinileno) que diferem entre si pelo tamanho de uma das cadeias laterais: o poli(2-metoxi-5-hexiloxi-p-fenileno-vinileno), MH-PPV, o poli(2-metoxi-5-dodecoxi-p-fenileno-vinileno), MD-PPV e o poli(2-metoxi-5-hexadecoxi- p-fenileno-vinileno), MHd-PPV. Esses polímeros apresentam propriedades eletroluminescentes e podem ser utilizados em dispositivos emissores de luz. A síntese consiste de três etapas: síntese do éter aromático; bisclorometilação do éter aromático, gerando o monômero; e polimerização. A maior diferença no processo de síntese foi observada na obtenção do monômero, sendo necessário um maior excesso de reagente e maiores tempos de reação para a obtenção do monômero do MD-PPV e do MHd-PPV do que para o MH-PPV. Todos os produtos foram caracterizados principalmente por espectroscopia na região do infravermelho, FTIR, e por Ressonância Magnética Nuclear de próton e carbono 13. A estrutura química dos polímeros foi confirmada por FTIR e as massas moleculares foram determinadas por Cromatografia de Exclusão por Tamanho, revelando uma alta polidispersividade e valores de massa molecular ponderal média (Mw) da ordem de 105. A análise térmica revelou valores de temperatura de transição vítrea, Tg e amolecimento, Ts, acima de 100oC, e ainda temperaturas de decomposição acima de 400oC para os três polímeros. O MHd-PPV, apresentou, além da Tg, uma transição em tomo de 50oC que pode estar relacionada à fusão das cadeias laterais. Filmes dos três polímeros preparados a partir de diferentes solventes apresentaram diferentes morfologias, observadas por Microscopia de Força Atômica, posições de máxima absorção (500-520 nm) e emissão (585-600 nrn) com pequenas variações e processos de fotodegradação com diferentes características, em função do solvente utilizado. Assim, as diferentes cadeias laterais apresentaram efeitos principalmente sobre características como temperatura de transição vítrea e morfologia dos filmes poliméricos, e, em consequência desta última, sobre o formato dos espectros de emissão e sobre o processo de degradaçãoIn this work, three dialkoxy derivatives of poly(p-phenylenevinylene),which differs from each other by the size of the side chain, were synthesized and characterized: the poly(2-methoxy-5-hexyloxy-p-phenylenevinylene), MH-PPV, the poly(2-methoxy-5-dodecoxy-p-phenylene-vinylene), MD-PPV and the poly(2-methoxy- 5-hexadecoxi-p-phenylene-vinyleno), MHd-PPV. These polymers have electroluminescent properties and can be used in light emitting devices. The synthesis consists in three steps: synthesis of aromatic ether, bischloromethylation of the ether yielding the monomer, and polymerization. The major difference regarding the synthesis processes lies on the monomer synthesis. A larger excess of reagents and longer reaction times were necessary to obtain the MD-PPV and MHd-PPV than that used to obtain the MH-PPV. All the products of the two first steps were characterized mainly by FTIR and NMR (proton and carbon 13). The chemical structures of the polymers were confirmed by FTIR and the molar masses determined by characterized by Size Exclusion Chromatography, revealing a high polydispersity and values of mean mass molecular weight (Mw) around 105. The thermal analysis presented values of glass transition temperatures, Tg, and softening, Ts, above 100 oC, and decomposition temperatures above 400oC for the three polymers. The MHd-PPV, presented, besides the Tg, a transition in 50oC, which may be related to the melting of the side chain. Films of the three polymers prepared from different solvents presented different morphologies, as observed by Atomic Force Microsocopy, slightly different absorptions (500-520 nm) and emission (585-600 nm) maxima and different photo-degradation processes depending on the solvent used to prepare the films. Therefore, the different size of the side chain presented effects mainly on characteristics as thermal transitions and film morphologies, and, in consequence of the late, on the shape of the emission and on the degradation properties
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Sarnecki, Greg. "Studies in soluble conjugated polymers." Thesis, University of Cambridge, 1994. https://www.repository.cam.ac.uk/handle/1810/272769.
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Halliday, David Alan. "The synthesis and characterisation of poly(p-phenylenevinylene)s." Thesis, University of Cambridge, 1992. https://www.repository.cam.ac.uk/handle/1810/272381.
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Pontes, Ricardo Scudeler. "Adsorção e fluorescência em filmes automontados de polianilina (PAN) e poli(p-fenileno vinileno)(PPV)." Universidade de São Paulo, 1999. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-07112013-171013/.
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A técnica de automontagem [Self-Assembly (SA)] tem sido largamente empregada na fabricação de estruturas supramoleculares de polímeros condutores que requerem controle molecular. O paradigma implícito no método de automontagem é a adsorção espontânea de camadas carregadas com cargas opostas, conduzindo assim a um filme de multicamadas formado pela alternância de policátions e poliânions. Nesta dissertação, são empregados dois tipos de polímeros conjugados e seus derivados que são identificados por suas famílias, que são a da polianilina (PAn) e a do poli(pfenileno vinileno) (PPV). São enfatizados os processos de adsorção para as polianilinas e precursores do PPV, propondo-se um mecanismo de adsorção não autolimitada sustentado por condições de não equilíbrio. O processo não autolimitado comprova que a adsorção pode ser controlada por outras interações que não a eletrostática, como as pontes de hidrogênio que são comuns nas polianilinas, e/ou por interações típicas de dispersões coloidais, visto que os polímeros se agregam em solução. Este novo método pode ter grande impacto na fabricação de estruturas supramoleculares porque podem ser obtidos filmes espessos de uma única camada com controle em nível molecular. A desvantagem deste método está na obtenção de filmes não uniformes, propriedade que ainda não é adequadamente controlada. A investigação da formação de filmes de múltiplas camadas e dos processos de fluorescência para filmes de bicamadas e não autolimitados é apresentada e discutida em função dos trabalhos da literatura. Finalmente, são correlacionados os processos de adsorção e a fluorescênciaThe self-assembly (SA) technique has been widely used for producing supramolecular structures fi-om conducting polymers, in which molecular control may be achieved. The paradigm implicit in the SA method is the spontaneous adsorption of oppositely charged layers, thus leading to a multilayer film containing polycations alternated with polyanions. In this dissertation, two types of polymer are employed in the fabrication of SA films, namely polyanilines and poly(p-phenylene vinylenes) (PPVs). For the polyanilines, emphasis was placed in the adsorption processes, where it is proposed that a non-self-limiting process may be achieved if adsorption is carried out under non-equilibrium conditions. A non-self-limiting process is proof that adsorption is not entirely controlled by electrostatic interactions, but may also depend on H-bonding which is very efficient in polyanilines and on interactions typical of colloid dispersions as the polymers aggregate while in solution. This nove1 method may have a large impact in the fabrication of supramolecular structures because much thicker films may be obtained in a single layer. The disadvantage of this method, however, lies in the fabrication of non-uniform films which cannot be controlled adequately. The investigation of the fabrication of multilayers and of fluorescence processes in films built with bilayers and via non-self-limiting adsorption is presented and discussed in terms of work published in the literature. Finally, the processes of adsorption and fluorescence are correlated
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Rabelo, Adriano César. "Filmes finos de compostos semicondutores: preparação de CdS e da junção Cu2-XSe/MEH-PPV." Universidade Federal de Uberlândia, 2008. https://repositorio.ufu.br/handle/123456789/17297.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorIn this work thin films of semiconductor compounds were prepared. Focus was on a recipe for preparation of cadmium sulphide onto copper selenide substrate. Copper selenide thin films dissolve when in contact with the chemical bath for deposition cadmium sulphide. This drawback triggered an investigation for using milder chelating agents. A new bath composition was determined from chemical equilibrium analysis of about ten species supposedly present in the bath, mass balance and charge balance. From the results, a thin film of. cadmium sulphide has been prepared on glass substrate by chemical bath deposition using sodium acetate, sodium hydroxide and thiourea. Absorption spectra of the film in the visible range was registered and compared with the spectra from others authors. The band gap of the film was estimated from the spectra. The junction copper selenide and poly-2-methoxy-5- (2 -ethylhexyloxy)-phenylenevinilene was prepared and characterized. Copper selenide was prepared on copper by chemical bath deposition using sodium selenosulphate. The polymeric film was prepared by casting technique, in which the polymer is dissolved in tetrahidrofurane, dropped onto the substrate and let to dry. Ohmic contact was prepared using graphite conductive glue. This glue was developed for this purpose and is made up from graphite powder, epoxy and polimercaptan dissolved in tetrahidrofurano. The electrical properties of the junction were determined from current-potential curves. By using the Fowler-Nordheim model, the energy barrier height was calculated. The results were compared with the literature results obtained with a similar devices, namely ITO/MEH-PPV. The energy barrier height of copper selenide/MEH-PPV is about thirty times smaller than the energy barrier height of ITO/MEH-PPV. The conclusion is that copper selenide is a promising material for use in photoluminescent diodes.
No presente trabalho prepararam-se compostos semicondutores na forma de filmes finos. Ênfase foi dada ao sulfeto de cádmio visando seu uso sobre seleneto de cobre. Filmes finos de seleneto de cobre se dissolvem quando mergulhados na solução de preparação de filmes finos de sulfeto de cádmio. Este inconveniente foi contornado mediante o uso de agentes complexantes mais suaves. Foi possível preparar sulfeto de cádmio em meio de acetato de sódio, tiouréia e hidróxido de sódio. A composição foi determinada numericamente a partir das constantes de equilíbrio das espécies presentes no meio reacional (cerca de dez espécies), pelo balanço de massa e pelo balanço de carga. Foi preparado um filme de sulfeto de cádmio nas condições experimentais encontrada sobre vidro. O espectro de absorção do filme foi medido na região do visível e comparado com o espectro obtido por outros autores. O band gap do filme foi estimado a partir dos espectros de absorção. Preparou-se e caracterizou-se a junção entre seleneto de cobre e poli- 2-metóxi-5-(2 -etilhexiloxi)-fenilenovinileno como semicondutor. O seleneto de cobre foi preparado sobre cobre por reação com selenossulfato de sódio. O filme do material polimérico foi preparado sobre o seleneto de cobre por evaporação de uma solução do polímero em tetrahidrofurano. Os contato elétrico foi estabelecido no substrato de cobre e no filme polimérico com cola de grafite. A cola de grafite foi desenvolvida para esta finalidade e constitui-se na dissolução de resina comercial epóxi e polimercaptana em tetrahidrofurano misturados com grafite em pó. As características elétricas da junção entre os dois semicondutores foram determinadas a partir de curvas corrente potencial. Com uso do modelo de Fowler- Nordheim , calculou-se o valor da barreira de energia entre banda de valência do seleneto de cobre e a banda de condução do polímero. O valor obtido foi comparado com o obtido por outros autores em dispositivos similares (ITO/MEHPPV) e foi cerca de trinta vezes menor. Concluiu-se que o seleneto de cobre é um material com características.
Mestre em Química
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Hon, Sherman Siu-Man. "Calcium vapour deposition on semiconducting polymers studied by adsorption calorimetry and visible light absorption." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/863.
Full textAbstract:
A novel UHV microcalorimeter has been used to study the interaction between
calcium and three polymers: MEH-PPV, MEH-PPP and P3HT. All three polymers
behave differently in their reaction kinetics with calcium. On MEH-PPV we measure
45 μJ/cm² of heat generated in excess of the heat of bulk metal growth, 120 μJ/cm²
for MEH-PPP, and 100 μJ/cm² for P3HT. Comparison of the MEH-PPV and MEHPPP
data indicate that the initial reaction of calcium with MEH-PPV occurs at the
vinylene group. We propose, based on hypothetical models, that calcium reacts with
the vinylene groups of MEH-PPV with a reaction heat of 360 kJ/mol and at a
projected surface density of 1.7 sites/nm², while it reacts with the phenylene groups
of MEH-PPP in a two-step process with reaction heats of 200 and 360 kJ/mol
respectively, at a projected surface density of 3.5 sites/nm².
Optical absorption experiments, using either a 1.85 eV diode laser or a xenon lamp
coupled to a scanning monochromator, have also been performed using the same
calorimeter sensor. In the case of MEH-PPV, using the laser we find an optical
absorption cross-section of 3E-¹⁷ cm² per incident calcium atom at low coverages.
The change in absorptance at higher coverages correlates perfectly with the
population of reacted Ca atoms determined calorimetrically. The size of the
absorbance cross-section, and its position just within the band gap of the polymer, are
consistent with the reaction being one of polaron formation. Calcium does not appear
to dope P3HT, while the photon energy range of 1.5 to 3.75 eV used in these
experiments is likely too small for probing polaronic energy states in MEH-PPP.
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Chen, Chiung-Yun, and 陳瓊筠. "Dilute Solutions Properties of MEH-PPV/THF and MEH-PPV/Toluene." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/97196687059510559788.
Full textAbstract:
碩士元智大學
化學工程與材料科學學系
94
We investigated the molecular conformation of poly[1-methoxy-4- (2’-ethyl- hexyloxy)-2,5-phenylene vinylene] (MEH-PPV) in tetrahydrofuran (THF) and toluene solutions using dynamic light scattering (DLS) and static light scattering (SLS). Moreover the solutions were freeze dried and the molecular conformations of MEH-PPV were observed by Transmission Electron Microscopy (TEM). From the results of light scattering, the second virial coefficient (A2) in THF is slightly negative and in toluene is positive. It revealed that toluene is a better solvent for MEH-PPV than THF. The radius of gyration (Rg) and the weight average molecular weight (Mw) is larger in THF than in toluene, indicating the molecules aggregate in THF.
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Qi, Dong Feng. "Photoluminescence from MEH-PPV and DP-PPV in bulk and encapsulated in porous alumina." Thesis, 2001. http://hdl.handle.net/2429/11797.
Full textAbstract:
Two PPV derivatives, MEH-PPV and DP-PPV, are encapsulated in the nanopores of
anodized alumina with different pore sizes (50/200 nm) and depth (10/60 urn). Time-integrated
and time resolved optical emission properties of these structures have been studied and
compared with those of thin films of the polymers. Significant blue shifts of the PL spectra
(0.034 eV-0.183 eV) are found in the porous materials as compared to the bulk. The relative
intensity of the one-phonon assisted transition increases in comparison with the intensity of the
no-phonon transition in the nanostructured samples.
The time constants of the optical emission from the bulk MEH-PPV film are very
similar in their energy dependence to results obtained previously on bulk PPV films when
considered with respect to the excess energy above the peak of the emission spectrum. The
decay times are, however, two to three times shorter in the parent. The energy dependence of
the time constants measured in DP-PPV films and DP-PPV encapsulated in nanopores (pore
diameter 200 nm, pore depth 60 um) are also very similar to each other, and to the results
obtained on the MEH-PPV. These results suggest that the intrachain diffusion of electron-hole
excitations in all of these polymers, either in bulk or encapsulated form, is very similar.
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Huang, Po-chang, and 黃柏昌. "TP-PPV和MEH-PPV共聚物之製備和光電性質." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/14479557741834733434.
Full textAbstract:
碩士國立臺灣大學
材料科學與工程學研究所
88
In this research, we employed the CPR (Chlorine Precursor Route) and Wittig methods to prepare the TP-PPV/MEH-PPV copolymers and discussed their luminescent properties. Random copolymers were obtained from CPR method and an alternative copolymer obtained from Wittig method. From initial study efforts, it was found that TP-PPV has higher PL efficiency with an emission peak at 509nm, and more stable emission than PPV but barely soluble in organic solvents. So we introduced the MEH-PPV to synthesize the TP-PPV/MEH-PPV copolymers in different ratio in order to improve their solubility and luminescent properties. Copolymers obtained by CPR method have broad absorption peaks in both their UV-VIS spectra and PL spectra. Besides, when TP-PPV content in the TP-PPV/MEH-PPV copolymer is increased to 4:1, we observed a pale blue-white color in its EL emission of the LED device. But due to the poor process condition, we couldn’t obtain the EL spectra. Further research is ongoing. However, the alternative copolymer prepared from the Wittig method has a simpler PL spectrum with an emission peak appeared at 535nm. It is a red-shifted as compared to PPV.
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Kuch, Serena. "Neue PPV-Derivate auf ungewöhnlichen Wegen." Phd thesis, 2019. http://tuprints.ulb.tu-darmstadt.de/8412/1/Dissertation_Kuch%2C%20Serena.pdf.
Full textAbstract:
Im Fokus dieser Dissertation stand die Synthese von PPVs über die GILCH-Polymerisation. Zum einen wurde der Mechanismus der photoinitiierten GILCH-Reaktion von α,α´-Dibrom-p-xylolderivaten untersucht. Es konnten detaillierte Einsichten in den Mechanismus der Photo-GILCH-Reaktion gewonnen werden. Zudem konnte diese Reaktionsführung teils optimiert werden. Zum anderen wurden diverse α,α´-Dibrom-o-xylolderivate erstmals als Monomere für die GILCH-Polymerisation eingesetzt. Hierbei konnten schließlich ortho-verknüpfte PPVs gewonnen werden, deren Emissionswellenlänge in Richtung bläulich-grün verschoben war.
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Wang, Li-Chi, and 王禮祈. "光電高分子PPV衍生物TP-PPV的合成及性質." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/53285647424698808593.
Full textAbstract:
碩士國立臺灣大學
材料科學與工程學研究所
87
In this research, Aldol Condensation Reaction was employed to prepare the 2,5-diethylacetate-3,4-diphenylcyclopentadienone from diethyl-1,3-acetonedicarboxylate and benzil. Then, it was reacted with phenylacetylene through the Dields-Alder Reaction to prepare the diethyl 2,3,5-triphenylterephthalate. After a series of reduction, chloridization, and polymerization process to prepare poly(2,3,5-triphenyl-p-chloromethylbenzene), this precursor was heated in vacuum for 10 hours at 250℃ to obtain poly(2,3,5-triphenyl-p-phenylene vinylene) (TP-PPV). In addition, Wittig Reaction was employed to prepare the copolymer of PPV and TP-PPV (1:1). Its properties was compared with pure PPV to find the effects of phenyl substitution. The advantages of TP-PPV over PPV in optoelectronic properties can be listed as follows: (1) blue shift in the PL spectrum of TP-PPV; (2) the PL efficiency of TP-PPV is higher; (3) TP-PPV is more stable when employed as a LEDs material; (4) TP-PPV is a suitable material for LEDs to emit the green-blue light.
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Li, Wen Yi, and 李文毅. "The study of photoluminescence in PPV(phenylenevinylene)." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/68640123780991255216.
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Kopecký, Adam. "Změny na předním segmentu PO 25G+ PPV." Doctoral thesis, 2019. http://www.nusl.cz/ntk/nusl-403328.
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Univerzita Karlova 1. lékařská fakulta Studijní program: Zobrazovací metody v lékařství (P5150) Studijní obor: Zobrazovací metody v lékařství (5103V000) MUDr. Adam Kopecký Změny na předním segmentu po 25G+ PPV Changes in the Anterior Segment after 25G+ PPV Abstract Vedoucí závěrečné práce/Školitel: doc. MUDr. Jiří Pašta, CSc., FEBO Praha, 2019 Abstract: Pars plana vitrectomy is a dominant surgical method in posterior segment surgery of the eye. The principle of this method is the surgical approach via the pars plana anatomical region. With this approach, surgeon performs the posterior segment surgery without directly affecting the anterior segment of the eye. Short-term effect of pars plana vitrectomy on the anterior segment of the eye has been repeatedly proven. That might be an important factor both in assessing the complications of this method and planning the surgery in complicated patients. Generally, it is presumed that we do not observe long-term effects on anterior segment after pars plana vitrectomy. The aim of our work is to evaluate the long-term changes in the anterior segment after the uncomplicated 25G + PPV with gas tamponde. The group of 20 patients was selected according to strict indication criteria. Using a series of examinations, we examined specific parameters such as: intraocular...
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Chou, Hsuan-Liang, and 周宣良. "Emission properties of MEH-PPV and its Derivatives." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/26777500610682753525.
Full textAbstract:
博士國立臺灣大學
材料科學與工程學研究所
93
The objectives of this dissertation were to modify the poly[2-(2’-ethyl-hexyl)-oxy)-5-meth-oxy-p-phenylenevinylene] (MEH- PPV) through the heat treatment, copolymerization, blending and cross-reactions with poly(2,3-diphenyl-5-octyl-p-phenylene vinylene) (DPO-PPV) to adjust the emitting color, enhance the quantum efficiency and increase the lifetime for their prepared polymer light emitting diode (PLED). Followings are the results being carried out in this dissertation: 1. The effects of heat treatments on the chemical structure, PL properties and EL performance of MEH-PPV were investigated. The maximum PL quantum yield after heat treatment was 6.5 times that of the untreated MEH-PPV, which was attributed to the reduction of chain aggregations and the interruption of conjugation length. The maximum EL quantum yield of their prepared ITO/PANI/MEH-PPV/Ca/AL light emitting diodes (PLED) was 46 (at 3 V) times that of the untreated sample. 2. The copolymerization of MEH-PV with DPO-PV via the Gilch route tended to form an alternative copolymer. As a result, the emission color of electroluminescence (EL) of MEH-PPV could be adjusted from orange-red to blue-green by copolymerization. However, the turn-on voltage of the prepared light emitting diode device was increased and the EL efficiency was decreased with the content of DPO-PV in copolymer. 3. The effects of bending with DPO-PPV on the optoelectronic properties of MEH-PPV were investigated. MEH-PPV and DPO-PPV are basically immiscible. The lower turn-on voltage for their prepared PLED compared to the pristine MEH-PPV was attributed to the “type II” heterojuction between the hole transport MEH-PPV segments and the electron-transport DPO-PPV segments. All the polyblends had the higher EL quantum yields than both pristine MEH-PPV and DPO-PPV. Although the EL spectrum of polyblend was blue-shifted with increasing the content of DPO-PPV, the majority of EL emission was from the MEH-PPV segments. DPO-PPV chains only played a supporting role to enhance the emission of MEH-PPV. 4. MEH-PPV/DPO-PPV immiscible blends turned to form a blend copolymer after thermal treatment that drew these two polymer segments closer in a vertically segregated structure. Because the charges were easily captured in the heterojuction zones, both the EL quantum efficiencies and stability of polyblends were greatly improved by thermal treatments. 5. The effects of manufacture parameters of PLED, such as the thicknesses of cathode Ca and conductive PEDOT layer, on the electroluminescent properties were investigated. The turn-on voltage of the prepared PLED was decreased and the EL intensity was increased by applying the PEDOT layer.
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Chang, Win-Pin, and 張文彬. "Light Emitting Chararcteristics of PPV-dased POlymeric Materials." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/44270384576479862570.
Full textAbstract:
博士國立交通大學
材料科學與工程研究所
84
POLY(p-phenylene vinylene) (PPV)經由其前驅體方法成功的製傋 oPPV膜本身極緻密 透明且具深黃色O從紫外-可見光譜中得知,PPV的起 始(onset)吸收大約530nm,能隙(energy gap)相當於2.34eV O Poly(p-phenylene vinylene) (PPV) has been prepared successfully fromp-xylylenebis(tetrahydrothiophenium chloride)dy its precursor route.The resultant PPV was dense,deep yellow in color and transparent.Theonset of
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Pan, Yi-Hsiu, and 潘苡秀. "The photoluminescence of MEH-PPV in mesoporous zeolites." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/13107567822370541527.
Full textAbstract:
碩士國立中央大學
化學研究所
91
The present work describes the preparation and characterization of electroluminescence polymer MEH-PPV inside the mesoporous channels of MCM-41 and SBA-15 silicate molecular sieves. There is no distinguished feature was observed between zeolites and MEH-PPV loaded zeolites in both SEM and TEM micrographs. Nitrogen adsorption/desorption isotherms show that MEH-PPV loaded MCM-41 and free MCM-41 has the similar pore size, but the surface area of MEH-PPV loaded MCM-41 is smaller than that of free MCM-41. Diffusion reflectance UV/Vis spectra and Fluorescence spectra of the MEH-PPV loaded zeolite powder showed a blue shift with respect to the free MEH-PPV powder, consistent with the quantum size effect of the dispersed MEH-PPV. The luminescence efficiency of the polymer dispersed in uncalcined MCM-41 is higher than that dispersed in calcined MCM-41. For example 3wt.% MEH-PPV in uncalcined MCM-41 has the highest luminescence efficiency. This may imply that some MEH-PPV has encapsulated in the pores of calcined MCM-41 and MEH-PPV inside the pores of zeolites may have lower quantum efficiency. MEH-PPV in zeolite has better thermal stability compared to free MEH-PPV. Interestingly, when the MEH-PPV loaded MCM-41 was heated at 900℃ in air, the polymer did not combust totally to H2O and CO2, instead, it forms a carbide-like material with large surface area and high thermal stability.
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Chen, Yuh-Tzong, and 陳育宗. "Continuous Wave Photo-induced Absorption Spectrum of PPV." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/69310225690376255866.
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Chen, Yu-Zong, and 陳育宗. "Continuous Wave Photo-induced Absorption Spectrum of PPV." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/42236306939816900056.
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Fischer, Timo [Verfasser]. "Parapockenvirus (PPV) als neuartige Vektorvakzine : Entwicklung Pseudorabiesvirus-(PRV)-spezifischer PPV-Rekombinanten und Untersuchung deren Immunogenität im Mausmodell / vorgelegt von Timo Fischer." 2002. http://d-nb.info/965634124/34.
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Ingle, Shauna Elizabeth. "Investigating self-assembly of linked oligomeric PPV-based materials." Thesis, 2014. http://hdl.handle.net/2152/28095.
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Single molecule wide-field polarization fluorescence imaging is an experimental method to determine the self-assembly of molecules dispersed in a thin film. Through a combination of wide-field imaging and confocal spectroscopy, the effect of synthetic structure of the oligomeric PPV-based materials was investigated to understand the effect of conjugation length, role of hydrogen bonding side chains, and influence of regioregularity on controlling chromophore folding. By studying alkoxy-linked and alkyl-linked bis(2-ethylhexyl)-p-phenylene vinylene (BEH-PPV) units of varying lengths (three, five, or seven), it was determined that conjugation length controlled the extent of molecular ordering and emission properties. Comparison of the experimental results to molecular dynamics simulations performed by collaborators confirmed that the materials became increasingly ordered as conjugation length increased. Further regulation of the assembly can be obtained through inclusion of hydrogen bonding side chains as seen in the altered amine and carboxylic acid alkoxy-linked trimer BEH-PPV in contrast to the bulky side chain tert-butyl trimer. The study of regio-regular (RR) and regio-random (RRa) alkoxy-linked pentamer poly(2-methoxy-5-(2’-ethylhexyloxy)-p-phenylenevinylene) (MEH-PPV) illustrates the limited effect of regioregularity of the side chains on self-assembly. Through synthetic structure, it is possible to design highly ordered materials through control of conjugation length and selection of side chains.text
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Tsai, Chao-Yi, and 蔡朝儀. "The measurement of photocurrent in conjugated polymer MEH-PPV." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/16162061994974025693.
Full textAbstract:
碩士國立臺灣大學
物理學研究所
88
There are two main purposes in this research. One is to establish the system of measurement in photocurrent. The other one is to measure the photocurrent’s spectra of conjugated polymer MEH-PPV in forward, reversed bias and short-circuit with different temperatures, in order to realize the mechanism which influences photocurrent. Is it exactly tended to the general theory of semiconductor’s band model or exciton model? According to our measurements, we find that it has much accordance in forward-circuit photocurrent’s spectrum with its absorption spectrum at room temperature. We also find that the first state the peak around 500nm has a red shift inits reversed bias-circuit photocurrent’s spectrum. In addition,in low temperature, we observe that no matter in forward or reversed bias circuit that all the first state’s photocurrent has evidently the same situation to be quenched. As a result, we conjecture that the result of mechanism is from the carriers’ different processes by light, but is not caused by the different proceeding transportation. Besides, when decreasing the temperature, the reduce of the photocurrent’s spectrum in the first state and the second state (the peak around 340nm) is inconsistent. And from experiment of changing temperatures, we find that the first state has the tendency of red-shift, except in reversed bias. However, on the contrary, the second state has a slightly blue shift. As a result, we infer that two states are from different carriers’ mechanism. Besides, in an analysis of photocurrent with the temperature, in 500nm, above 200K, no matter 0V, 1.0V or —2.0V we can discover that the relationship with photocurrent and the temperature has reciprocal linear relation. But when below 200K, the photocurrent doesn’t have strong relation with temperature. Also in 340nm,the relationship with photocurrent and temperature is neither reciprocal form nor exponential form when with bias. But in the short-circuit, it has the relation of exponential form.