Device Physics of Organic-Inorganic Hybrid Perovskite Semiconductors
This dissertation explores various aspects of metal halide perovskite semiconductors for photovoltaic and optoelectronic applications. The research focuses on addressing key challenges and advancing the understanding of perovskite field-effect transistors (FETs) for improved device performance. The study begins by investigating electrochemical reactions occurring at the interface between the perovskite and gold metal electrode in perovskite single crystal FETs. By delaminating the electrodes and employing surface analytical techniques, it is revealed that an electrochemical reaction occurs during device operation. This issue is mitigated by modifying the electrode with organic interlayers, leading to the demonstration of single crystal perovskite transistors with the highest reported mobilities of up to 15cm²/Vs at low temperatures. Subsequently, the research tackles challenges related to low mobility, high trap density, and hysteresis in low-dimensional perovskite FETs. Comparative studies involving different dielectric layers and a low-temperature bromide chemistry route are conducted to reduce charged impurities and trap densities, resulting in improved device performance. High mobilities of up to 10cm²/V s at room temperature are achieved in PEASnI₄ transistors through interface engineering. Finally, the dissertation explores the doping of metal halide perovskites as a means to control charge carrier concentration. An additive-assisted strategy is developed for n-type molecular doping of organic-inorganic hybrid perovskite (OIHP) MAPbI₃, with a specific focus on the effects of electron donor CsF. Doping at the top of the perovskite film leads to enhanced FET performance, with reliable electron mobility significantly improved up to 5cm²/V s. This approach offers a promising method for effectively doping perovskite MAPbI₃ and holds implications for other optoelectronic applications, including solar cells and LEDs. In summary, this dissertation contributes to the advancement of perovskite-based optoelectronic devices, providing valuable insights into interface engineering, materials doping, and device optimization. The findings pave the way for the development of high-performance perovskite FETs and offer promising avenues for future research and practical applications in the field of perovskite-based optoelectronics.
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