In our works , we used P3HT and PCBM blended in xylene as donor and acceptor materials for polymer solar cells . For the standard devices with the configuration of ITO/PEDOT/P3HT¡GPCBM/Al , the power conversion efficiency of 2.3% is achieved under AM1.5 100 mW/cm2 illumination . In order to enhance the hole transportation , we used PANi nanotube , which has high conductivity , as an anode interlayer between the PEDOT¡GPSS layer and the organic active layer . The device structure was ITO/PEDOT/PANi/P3HT:PCBM/Al , and the power conversion efficiency increased from 2.3% to 2.6% . The efficiency of polymer solar cell was also increased with different rpm by using spin-coating process . For devices , at the process parameters under 4000rpm and 100Å thickness of PANi , the power conversion efficiency was 60% higher than that of standard device . We suggested that PANi can act as a good anode interlayer material for polymer solar cells .

In this study, P3HT and PCBM were used as donor and acceptor materials for polymer solar cells. The standard device was constructed of ITO / PEDOT:PSS / P3HT:PCBM / Al and the power conversion efficiency of 2% was achieved under AM1.5G 100mW/cm2 illumination. In order to increase the hole transporting ability, we used PEDOT nanorods with high conductivity as an anode interlayer between the PEDOT:PSS and the P3HT:PCBM layer, with a configuration of ITO / PEDOT:PSS / PEDOT nanorods / P3HT:PCBM / Al. According to experimental results. PEDOT nanorods dispersed well on the PEDOT:PSS surface through the spin-coating process. As the concentration of PEDOT nanorods 1wt% casting film, the conductivity of anode buffer layer raised about two times and the power conversion efficiency of device reached 2.63%. The short-circuit current and the power conversion efficiency of the polymer solar cell containing 1wt% PEDOT nanorods were obtained about 170% and 30% increasement, respectively. In conclusion, it is quite useful to apply the PEDOT nanorods into polymer solar cells as an interlayer. The improvement in the short-circuit current which resulted in an enhancement of the power conversion efficiency originated from the increased conductivity of the buffer layer.

Recently, a variety of conducting polymer have great potentials for practical utility. Among these polymers, polyaniline (polyaniline,PANI) has the widest applications . Using electrochemical synthesis to fabricate Aniline copolymer has several kind of advantages (i) Aniline is cheap and easy to polymerize¡F (ii) High stability¡F(iii) The conductivity of the polymer can be modulated¡F(iv) The thickness of PANI film can be controlled. In conclusion, it is quite useful to apply the PANI into polymer solar cells as the hole transporting layer. We used Cyclic Voltammetry to grow the PANI thin film. Then, we investigated the performance of the device affected by morphology with different sweep rate and the difference of electric characteristic and transmission between PEDOT and PANI. P3HT was used as a donor material because of its high stability and high absorption in visible light. PCBM was used as a acceptor material because of its high stability and high electron transportation. The device was constructed of ITO (150 nm) / PANI (50 nm) / P3HT:PCBM (100 nm) / Al (200 nm). When the sweep speed is lower, the particle of PANI thin film is closer and its scale size is more similar. When the sweep rate is 0.01 V/s, PANI thin film would grow about 80 nm, and the power conversion efficiency of 1.83% was achieved under AM1.5G 100mW/cm2 illumination.

Organic solar cells have emerged as an important cheap photovoltaic technology. In this thesis work, a study of P3HT:PCBM heterojunction solar cells was presented. By incorporation of photo-active film slow growth, PEDOT:PSS (Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate)) de-water treatment and application of highly conductive PEDOT:PSS (HC-PEDOT), a maximum PCE (power conversion efficiency) of 4% was achieved. Inkjet printing technique was on the other hand introduced into fabrication process. The morphological, electrical and optical properties of printed HC-PEDOT were investigated. Fine silver girds with well-designed pattern, combining with a transparent thin film of HC-PEDOT, was inkjet-printed to form the anode of solar cells. A functional device with printed anode and printed photo-active layer was demonstrated, showing the possibility of realizing fully printed organic solar cells.

<p>Organic solar cells have emerged as an important cheap photovoltaic technology. In this thesis work, a study of P3HT:PCBM heterojunction solar cells was presented. By incorporation of photo-active film slow growth, PEDOT:PSS (Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate)) de-water treatment and application of highly conductive PEDOT:PSS (HC-PEDOT), a maximum PCE (power conversion efficiency) of 4% was achieved.</p><p>Inkjet printing technique was on the other hand introduced into fabrication process. The morphological, electrical and optical properties of printed HC-PEDOT were investigated. Fine silver girds with well-designed pattern, combining with a transparent thin film of HC-PEDOT, was inkjet-printed to form the anode of solar cells. A functional device with printed anode and printed photo-active layer was demonstrated, showing the possibility of realizing fully printed organic solar cells.</p><p> </p>

Orientador: Fernando Rogério de Paula / Resumo: Questões ambientais vêm sendo destaque nos meios de comunicação, motivando a busca por técnicas e materiais que possam amenizar os efeitos nocivos ao meio ambiente causados pelo crescimento populacional. Dentre essas técnicas, os Processos Oxidativos Avançados vêm se desenvolvendo, pois possibilitam a degradação de poluentes por meio da atividade fotocatalítica de alguns materiais semicondutores. O dióxido de titânio é um dos materiais semicondutores que se destacam nessa aplicação devido a suas propriedades físicas e químicas. No presente trabalho, o dióxido de titânio foi sintetizado por uma nova rota sintética envolvendo oxisulfato de titânio, peróxido de hidrogênio e água deionizada. Inicialmente, as amostras foram sintetizadas com diferentes concentrações de peróxido de hidrogênio e tratadas termicamente a 600 °C. A morfologia, estrutura e atividade fotocatalítica dessas amostras foram analisadas. Os resultados mostraram que concentrações a partir de 0,392 mol/L de H2O2 proporcionaram a formação de microtubos e que esta morfologia favorece a atividade fotocatalítica do dióxido de titânio. A temperatura de tratamento térmico foi outro parâmetro estudado, amostras foram sintetizadas com uma concentração fixa de 0,392 mol/L de peróxido de hidrogênio e submetidas a diferentes temperaturas. Os resultados obtidos com difratometria de raios-X mostraram a existência de fases puras anatase e rutilo, assim como fases mistas com diferentes percentuais. Dentre elas, a amostra tratad... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre

Controlling the blend morphology is one of the ways to achieve high power conversion efficiency in organic bulk heterojunction (BHJ) photovoltaic device. One sample yet effective method is ¡§ additive¡¨ approach, which involves the addition of a small concentrations of additive into the blend of donor/acceptor dissolved in solution. When adding small concentrations of additives in solution, we can change the donor/acceptor of internal micro-structure and films of morphology. In this work, we performed a systematic study of the effect of nanocrystals of phenolic additives, such as the small concentrations of 4,4'-Sulfonyldiphenol(BPDT), 4,4'-Dihydroxybiphenyl(BP) and Biphenyl-4,4¡¦-dithiol(BPS), on the nanoscals phase separation of and P3HT:PCBM blends and consequently, the power conversion efficiency(PCE) of the devices. The extent of the additive-induced phase separation and crystallize of P3HT is related to the additive acidity constant (pKa) and the degree of interaction between the additive and P3HT/PCBM, as evident from X-ray diffractmeter, UV-Vis spectrometer, Raman spectrometer and current density-voltage characteristic data. Lastly, PCE as increasing as 25% and short current increasing as 15% can be achieved in an optimally phase-separated blend due to an improvement in the charge dissociation and a dcrease in bimolecular recombination and parallel resistance.

Organic solar cells promise a cheap and easy alternative to silicon photovoltaics, but there are many problems that must be solved before they can be a stable and efficient substitute. One such problem is the degradation of solar cells under exposure to light and oxygen. In response to evidence of change in electronic properties of polymer:PCBM solar cells, the mechanical properties of pristine PCBM films are investigated for analogous development using atomic force microscopy. Although no signicant change in the elastic modulus is detected, differences in material response indicate a skin effect which is beyond measurement sensitivity. Presence of a hard skin is verified in tapping phase imaging and spectroscopy.

Two of the main technological challenges of the century are the production of clean energy, on the one hand, and the development of new materials for electronic and spintronic applications that could increase the speed and the storage capacity of regular electronic devices, on the other hand. Organic materials, including fullerenes, organic polymers and organic molecules with metal centres are promising candidates for low-cost, flexible and clean technologies that can address these challenges. A thorough description of the electronic properties of such materials is, therefore, crucial. The interaction of electromagnetic radiation with the molecule can provide the needed insight into the electronic and vibrational levels and on possible chemical interactions. In order to explain and interpret experimentally measured spectra, a good theoretical description of the particular spectroscopy is necessary. Within density functional theory (DFT), the current thesis discusses the theoretical tools used to describe the spectroscopic properties of molecules with emphasis on two classes of organic materials for photovoltaics, molecular electronics and spintronics. Specifically, the stability of the fullerene derivative PC60BM is investigated in connection with its use as an electron acceptor in organic solar cells and the valence band electronic structure of several transition metal phthalocyanines is studied for their possible application in electronics and spintronics. The spectroscopies discussed in the current work are: the photoelectron spectroscopy of the valence band, X-ray photoelectron spectroscopy of the core levels, near-edge X-ray absorption fine structure, Infrared and Raman vibrational spectroscopies

The emergence of organic semiconductors is exciting since it promises to open up for straightforward and low-cost fabrication of a wide range of efficient and novel electronic devices. However, in order for this promise to become reality it is critical that new and functional fabrication techniques are developed. This thesis demonstrates the conceptualization, development, realization and implementation of a particularly straightforward and scalable fabrication process: the photo-induced and resist-free imprint patterning technique.Initial experiments revealed that some members of a group of carbon-cage molecular semiconductors – termed fullerenes – can be photochemically modified into dimeric or polymeric structures during exposure to laser light, and, importantly, that the exposed fullerene material retains its good electron-transport property while its solubility in common organic solvents is drastically lowered. With this information at hand, it was possible to design and create well-defined patterns in a solution-deposited fullerene film by exposing selected film areas to laser light and then developing the entire film in a tuned developer solution. An electronically active fullerene pattern emerges at the locations defined by the incident laser beam, and the patterning technique was successfully utilized for the fabrication of arrays of efficient field-effect transistors.In a later stage, the capacity of the photo-induced and resist-free imprint technique was demonstrated to encompass the fabrication of ubiquitous and useful CMOS circuits. These are based on a combination of p-type and n-type transistors, and a blend between a p-type organic semiconductor and an n-type fullerene compound was designed so that the latter dominated. By solution-depositing the blend film on an array of transistor structures, exposing selected transistors to laser light, and then developing the entire transistor array in a developer solution, it was possible to establish a desired combination of (non-exposed) p-type transistors and (exposed) n-type transistors. We finally utilized this combination of transistors for the fabrication of a CMOS circuit in the form of well a-functional organic inverter stage.