Thermal evaporation of lead-free inorganic perovskite CsGeI3 for photodetection

CsGeI3 as one of the lead-free inorganic perovskite materials has received great attention in recent years, benefiting from its excellent optoelectronic properties, good stability, and low toxicity. Previous studies on this perovskite are mainly based on its theoretical calculation and, to a lesser degree, on experimental work. In this work, we propose a facile thermal evaporation method to prepare uniform and dense CsGeI3 perovskite thin films with high crystallinity and negligible pin-holes. We have systematically studied evaporation parameters and examined their influence on the chemical composition, morphology, optical properties, stability, and charge carrier dynamics of the obtained CsGeI3 perovskite films. Moreover, we also demonstrate that photodetectors based on evaporated CsGeI3 thin films show good response in the visible region.