Development of hole transport transparent conductive electrodes for n-type crystalline silicon solar cells

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2018
Akdemir, Ozan
Conventional transparent conductive electrodes (TCEs) used in crystal silicon (c-Si) solar cells are commonly made of indium tin oxide (ITO) which provides low sheet resistance and high transparency. However, due to indium scarcity, ITO layers increase the fabrication cost; thus, alternative TCEs, such as fluorine-doped tin oxide (FTO), zinc oxide (ZnO), metal nanowires and Oxide/Metal/Oxide (OMO) multilayers, are being investigated. Conventional solar cells also make use of doped layers, to create the junction and back surface field that leads to several intrinsic losses such as parasitic absorption and doping related recombination. Dopant-free carrier selective contacts, that enable one type of carrier to pass while blocking the other type, are being studied as replacements of doped layers in c-Si solar cells. In this study, OMO multilayers with molybdenum oxide (MoOx), and silver (Ag) are formed via thermal evaporation as dopant-free hole transport transparent conductive electrodes (HTTCEs) for n-type c-Si solar cells. Semi-dopant-free c-Si cells, made from wafers with different doping concentrations that utilize OMO multilayers are compared in terms of solar cell performance. Comparison of two HTTCE design, optimizations of outer MoOx layer thickness and Ag deposition rates, and comparison of pyramid textured and flat surface solar cells are performed to increase optical and electrical properties. An efficiency of 9.3 ± 0.2 % is achieved with a pyramid textured semi-dopant-free solar cell that employs HTTCE structure. Results of this study can be used in research on dopant-free solar cells and any other photonic applications that require TCE layers.

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Citation Formats
O. Akdemir, “Development of hole transport transparent conductive electrodes for n-type crystalline silicon solar cells,” M.S. - Master of Science, Middle East Technical University, 2018.