Impact of a Spun-Cast MoO_<i>x</i> Layer on the Enhanced Moisture Stability and Performance-Limiting Behaviors of Perovskite Solar Cells

Abstract

Organic–inorganic perovskite solar cells (PSCs), which have good environmental durability, are of great interest for practical applications. In this work, we show that a solution-processed MoOx layer acts as a buffer layer against high moisture stress to suppress defects in the perovskite and as a hole transport layer. The inversion of the photoinduced charge migration behaviors, that is, the electron preferentially moving toward the surface when MoOx is directly deposited onto the perovskite, is found to cause a significant loss in device functionality. The deposition of MoOx onto spiro-OMeTAD results in a lower photocurrent density–voltage (J–V) hysteresis behavior, a greatly enhanced electrical conductivity, and a significantly stabilized power conversion efficiency (PCE) when compared with those of devices without the MoOx layer. More importantly, the PCEs of the MoOx-based devices are retained at over 85% of their initial value, while only 75% is retained for a reference cell. This work highlights the facial fabrication approach of the solution-based MoOx layer and provides experimental evidence of the photogenerated charge migration behaviors on the perovskite/MoOx interface. This information would be beneficial for the further design and development of PSC technology.