A Green Anti‐Solvent Process for High Performance Carbon‐Based CsPbI2Br All‐Inorganic Perovskite Solar Cell

Mixed‐halide CsPbI 2 Br inorganic perovskite shows great promise in photovoltaic application due to its reasonable band gap required for tandem top‐cell, and more stable perovskite cubic phase. To date, conventional one‐step spin‐coating is still the major process for fabricating CsPbI 2 Br films, which, however, is difficult to yield homogeneous and compact CsPbI 2 Br layer due to its slow crystallization. Herein, effective anti‐solvent engineering for fabricating high‐quality inorganic perovskite absorbers is successfully developed by using a green solvent of ethyl acetate (EA). Compared with traditional spin‐coating and widely employed toxic chlorobenzene (CB) anti‐solvent processes, the green EA anti‐solvent engineered CsPbI 2 Br films exhibit improved surface morphology and larger grain size. By using highly stable and low‐cost carbon electrodes to replace unstable organic hole transporters and expensive noble metal electrodes, all‐inorganic perovskite solar cells (PSCs) based on EA engineered CsPbI 2 Br exhibit an exceptional power conversion efficiency (PCE) of 10.0%, and a remarkable long‐term device stability. This study provides an effective strategy for developing high performance and stable all‐inorganic PSCs with low‐cost and green manufacturing processes.