2,2,2-Trifluoroethanol-Assisted Construction of 2D/3D Perovskite Heterostructures for Efficient and Stable Perovskite Solar Cells Made in Ambient Air

To achieve future commercialization of perovskite solar cells (PSCs), balancing the efficiency, stability, and manufacturing cost is required. In this study, we develop an air processing strategy for efficient and stable PSCs based on 2D/3D heterostructures. The organic halide salt phenethylammonium iodide is adopted to in situ construct a 2D/3D perovskite heterostructure, in which 2,2,2-trifluoroethanol as a precursor solvent is introduced to recrystallize 3D perovskite and form an intermixed 2D/3D perovskite phase. This strategy simultaneously passivates defects, reduces nonradiative recombination, prevents carrier quenching, and improves carrier transport. As a result, a champion power conversion efficiency of 20.86% is obtained for air-processed PSCs based on 2D/3D heterostructures. Moreover, the optimized devices exhibit superior stability, remaining more than 91 and 88% of their initial efficiencies after 1800 h of storage under dark condition and 24 h of continuous heating at 100 °C, respectively. Our study provides a convenient method to fabricate all-air-processed PSCs with high efficiency and stability.