One-step solution deposition of CsPbBr3 based on precursor engineering for efficient all-inorganic perovskite solar cells

Abstract

All-inorganic CsPbBr₃ perovskite solar cells (PSCs) are attracting tremendous interest owing to their outstanding stability, especially under high temperature and humidity atmospheres. Limited by the low solubility of CsBr in most common solvents, it is still a great challenge to prepare high-quality CsPbBr₃ films with sufficient thickness for PSC applications by the convenient one-step solution method. Herein, a novel precursor engineering strategy with the use of cesium acetate (CsAc) and ionic liquid methylammonium acetate (MAAc) is developed to increase the concentration of the CsPbBr₃ precursor solution to 1.0 M and form uniform and high coverage CsPbBr₃ films with large sized crystalline grains. The formation mechanism for this high-quality CsPbBr₃ films is mainly due to tailoring the crystallization kinetics by MAAc. Correspondingly, high light-harvesting capacity and suppressed trap state related charge recombination are realized in the resultant PSCs. The champion CsPbBr₃ PSCs achieve an efficiency of 7.37% (J_SC = 7.40 mA cm⁻², V_OC = 1.22 V, and FF = 0.841). This device has also displayed good stability with negligible decay over a period of 1500 h under an ambient atmosphere with 30–35% relative humidity.