Low-Temperature Crystallization of CsPbIBr₂ Perovskite for High Performance Solar Cells

Inorganic cesium lead halide perovskite solar cells (PSCs) have been widely explored due to their outstanding thermal stability and photovoltaic performance. However, the application and development of CsPbIBr₂-based PSCs is still hindered by major challenges such as high fabrication temperature and large voltage loss. To address these difficulties, additive engineering is conducted using n-butylammonium iodide (BAI). It is found that it not only improves the crystallization and morphology of perovskite layers but also substantially decreases the annealing temperature. In addition, the BAI incorporation decreases trap state density and restrains nonradiative recombination. As such, a high power conversion efficiency (PCE) of 10.78% is achieved, 21% higher compared with that of the control sample (8.88%). It should be noted that this is particularly high for the CsPbIBr₂ PSCs fabricated at low temperatures ('200 °C) that are required for flexible devices based on polymeric substrates.