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

摘要

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 CsPbBr3-based PSCs can deal with the problem due to the high stability in heat and humidity of CsPbBr3. Perovskite CsPbBr3 is highly crystallized with micronscale crystallites by Pb2+ strongly coordinating with organic molecules in the one-step sol-gel process. By contrast, CsPbBr3 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 CsPbBr3 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 Cs4PbBr6 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 degrees 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. (C) 2019 Elsevier B.V. All rights reserved.