(Invited) Perovskite Single Crystals with Free-Hole Trapping Centers for Photodetector and Solar Cell Applications

Abstract

The methylammonium lead iodide (MAPbI3) single crystals show extremely low trap-state density, high charge carrier diffusion length, long radiative carrier lifetime and high charge carrier mobility, making them outstanding candidates for a variety of potential applications including solar cells and photodetectors. However, these single crystals whatever the structure compositions still severely suffer from the presence of impurity traces such as triiodide that formed during their growth at high temperature. These traces can act as electron and hole quenching centers on the surface and at the device interface, hindering the further development of the performance of the solar cells and photodetectors based on these crystals. They also suffer from ions migrauion, vacancies, interstitials, and surface resturcturing and degradation especially under environmental conditions. Here, we will first show tremendous impact of the presence of excess triiodide on the charge carrier lifetime, carrier mobility and the performance of their solar cell and photodetector devices. We will also show the significant impact of the structure of organic cations on halogen migration, vacancies, and interstitials, carrier lifetimes as well as surface degradation of these single crystal perovskites using a combination of experimental and theoretical investigations. Finally, the unprecedented photo-response and photo-conversion efficiency after the chemical treatment of these single crystals will be presented and discussed.