Plasmonic Effects Of Metallic Nanostructures In Organic Solar Cells

In the past few years, organic solar cells have achieved a great progress due totheir low cost, flexibility, light weight. They are competitive compared with siliconsolar cells, and have the potential to play a critical role in future photovoltaic industry.However, the further application of organic solar cells is limited due to some technicaldifficulties. First, the exciton diffusion length in organic semiconductors is much shorterthan the thickness of active layer in organic solar cells, and the carrier mobility inorganic semiconductors is much smaller than silicon semiconductors; the intrinsicdisadvantage of organic solar cells requires thinner active layers for a higher powerconversion efficiency, but the optical absorption is reduced as active layers get thinner.Second, tin indium oxide is commonly used as transparent electrodes in organic solarcells, but this material is expensive and inappropriate for flexible photovoltaic devices.Based on these two limitations, we investigate the application of plasmonicmetallic nanostructures in organic solar cells. On the one hand, by considering theplasmonic enhancement effects, we use finite-difference time-domain electromagneticmethod to design and optimize the organic photovoltaic device with metallicnanoparticles. The methods of electron-beam evaporation and solution mixing are usedto fabricate the hybrid polymer bulk heterojunction solar cells with metallicnanoparticles to ensure sufficient optical absorption in thinner active layers. We analyzethe near-field enhancement and electronic effects of metallic nanoparticles in organicsolar cells by a theoretical and experimental research systematically. On the other hand,we expand the application of polystyrene nanosphere lithography and use it to fabricatethe metallic nanostructure film with plamsonic effects. We investigate the opticaltransmission of fabricated nanohole metal thin films. The optical properties of nanoholemetal thin films can be manipulated by tuning the geometric size in a convenienttechnical process. We successfully fabricate a metallic nanomesh as the transparentelectrode, and it is integrated with a polymer bulk heterojucntion solar cell. The cellgains a power conversion efficiency of3.12%, which is close to the efficiency of aphotovoltaic device using tin indium oxide as the electrode. There are several innovations in this thesis. First, we have studied the plasmonicenhancement and electronic effects of metallic nanostructures in organic solar cells.Second, we have designed, optimized and fabricated the plasmonic organic solar cellswith enhanced absorption. Third, we have performed the electromagnetic simulation ofmetallic nanomesh and fabricated the polymer solar cell with a metallic nanomesh bycontrolling the technical process. The achievements of our research provide theimportant guidance and reference for the development and application of plasmonicorganic solar cells and metallic nanostructrued transparent electrodes.