Effect of the post-annealing temperature on the thermal-decomposed NiOx hole contact layer for perovskite solar cells

A hysteresis-less inverted perovskite solar cell (PSC) with power conversion efficiency (PCE) of 13.57% was successfully achieved based on the thermal-decomposed NiOx hole contact layer, possessing better electron blocking and hole extraction properties for its suitable work function and high-conduction band edge position. Herein, the transparent and high-crystalline NiOx film is prepared by thermal-decomposing of the solution-derived Ni(OH)2 film in our study, which is then employed as hole transport layer (HTL) of the organic–inorganic hybrid PSCs. Reasonably, the post-annealing treatment, especially for the annealing temperature, could greatly affect the Ni(OH)2 decomposition process and the quality of decomposed NiOx nanoparticles. The vital NiOx HTLs with discrepant morphology, crystallinity and transmission certainly lead to a wide range of device performance. As a result, an annealing process of 400∘C/2h significantly promotes the photovoltaic properties of the NiOx layer and the further device performance.