Fabrication and characterization of all-inorganic halide perovskite CsPbBr3 films via the two–step sol–gel process: Impact of annealing temperature

Organic–inorganic hybrid perovskite solar cells (PSCs) have realized a 23.2% power conversion efficiency (PCE), thereby making the PSC application promising. However, the compositional instability of perovskites and PSCs in high-temperature and/or –humidity ambient air condition has restricted the PSC application. All–inorganic CsPbBr 3 -based PSCs can deal with the problem due to the high stability in heat and humidity of CsPbBr 3 . Perovskite CsPbBr 3 is highly crystallized with micronscale crystallites by Pb 2+ strongly coordinating with organic molecules in the one–step sol–gel process. By contrast, CsPbBr 3 crystalizes in nanoscale crystallites in the two-step sol-gel process using nonpolar or weakly coordinating organic solvent . The related study is rarely reported so far. Herein, we reported the fabrication of all–inorganic perovskite CsPbBr 3 films via the two–step sol–gel process using weakly coordinating methanol solvent. The impact of annealing temperature (T anneal ) was in particular studied on the film's microstructure and optical properties . The Increased T anneal restricts the production of byproduct Cs 4 PbBr 6 and greatly improves the film crystallization, thereby increasing the film's photoluminescence intensity and lifetime. A transition from the compressive stress to tensile stress in the films is observed at 250 °C T anneal . The red shift in optical absorption edge with increased T anneal is mainly due to the increased compressive stress and reduced tensile stress in the films.