Ultra-thin MoOx as cathode buffer layer for the improvement of all-inorganic CsPbIBr2 perovskite solar cells

Abstract

Controlling the crystallization dynamics is one key in optimizing the performance of perovskite solar cells (PSCs). The present study provides a simple approach using a low temperature stable-transition-film (STF) to prepare highly-dense and pinhole-free CsPbIBr2 thin film with high crystalline quality, as well as a new structural design (FTO/NiOx/CsPbIBr2/MoOx/Au) of all-inorganic perovskite solar cells toward long-term thermal stability. For the first time, we demonstrate that MoOx can independently serve as an outstanding cathode buffer layer on an inorganic perovskite layer. The lower work-function MoOx with ultra-thin thickness (4nm) leads to decreases of the Schottky barrier, the contact resistance and the interface trap-state density. This increases the power conversion efficiency (PCE) of all-inorganic planar PSCs from 1.3% to 5.52%. Inspiringly, the FTO/NiOx/CsPbIBr2/MoOx/Au all-inorganic PSCs were demonstrated to possess excellent long-term thermal stability at high temperatures up to 160°C.