Investigation and optimization of hybrid organic/inorganic heterojunction solar cells

Hybrid heterojunction solar cells are of large scientific interest, because substantially different materials with different exciton dynamics and charge carrier transport are involved. In this work, hybrid solar cells based on different combinations of organic and inorganic semiconductors have been investigated to study the physics of the organic/inorganic heterojunction and its impact on the solar cell performance. The results of photo-electric calculations and simulations have been confirmed by comparing them with the photovoltaic characteristics of processed hybrid solar cells and the theoretical potential of the hybrid solar cells has been estimated to analyze the dominant loss. Hybrid pentacene/gallium nitride solar cells have been studied to investigate the photocurrent generation in hybrid solar cells. Hybrid P3HT/silicon solar cells and PEDOT:PSS/silicon solar cells have been studied to investigate the electron blocking characteristics of the hybrid heterojunction. The polymer Spiro-MeOTAD has been investigated as an organic antireflection coating for silicon in a hybrid PEDOT:PSS/silicon solar cell. Furthermore, the layout and the manufacturing process of the silicon-based hybrid solar cells have been successively optimized to improve the solar cell performance. The semitransparent top contact was optimized to reduce the absorption losses in the top contact. An anisotropic etching of the silicon was applied to structure the silicon surface and, as a result, to minimize the reflection losses at the hybrid interface of the solar cell. Different backside contact interlayers have been investigated to improve the electron extraction at the backside contact. An excellent power conversion efficiency of 14.3% has been achieved for the best performing hybrid solar cell.