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Dissertation Defense

Solution-Processed Perovskite Active Materials for Photovoltaics and High-Energy Radiation Detection

Suneel Joglekar
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Abstract:

Solution-processed semiconductor materials can greatly reduce the cost of semiconductor devices, while also enabling facile device scalability, especially large-area or large-volume devices.  A promising solution processed semiconductor material family is that of organic-inorganic hybrid perovskites (OIHPs), which have been extensively investigated as the active material for photovoltaic applications.  While the progress in OIHPs has been rapid and extensive, device stability and performance were impacted by the interfaces between OIHP and charge carrier selective transport layers (STLs), due to the large density of surface trap states.  Furthermore, process and material compatibility issues with OIHPs constrain the material choices for STLs, ruling out many traditional materials (i.e. inorganic STLs) and methods (i.e. physical vapor deposition).  For large-volume semiconductor devices, methods for growing high-quality active material with smooth facets in a controlled manner were also underdeveloped.

This work addresses these concerns in different aspects.  The fabrication processes for thin-film, large-area scalable devices were optimized to result in improved device performance and uniformity, where the effect of these processes on the interface quality were investigated.  A solution-based surface treatment and coating method was developed for perovskite single crystals (PSCs), which resulted in improved device performance and consistency for high-energy spectroscopic photodetectors.  Computer-controlled growth processes have also been developed for growing large (> 0.5 cm3) PSCs, for which optimized contact materials were chosen, and alternative sensing algorithms have been designed to maximize the performance of PSC detectors.  The results of this work will impact solution-based semiconductor material processing in terms of optimizing active material growth, surface passivation, and in designing sensors using solution-grown semiconductors as the active material.

Chair: Professor L. Jay Guo

Remote Access: https://umich.zoom.us/j/94547160614