Sequential deposition method fabricating carbonbased fully-inorganic perovskite solar cells

Hybrid organic-inorganic halide perovskite material has been considered as a potential candidate for various optoelectronic applications. However, their high sensitivity to the environment hampers the actual application. Hence the technology replacing the organic part of the hybrid solar cells needs to be developed. Herein, we fabricated fullyinorganic carbon-based perovskite CsPbBr₃ solar cells via a sequential deposition method with a power conversion efficiency of 2.53% and long-time stability over 20 d under ambient air conditions without any encapsulation. An evolution process from tetragonal CsPb₂Br₅ to CsPb₂Br₅-CsPbBr₃ composites to quasi-cubic CsPbBr₃ was found, which was investigated by scanning electron microscopy, X-ray diffraction spectra, UV-vis absorption spectra and Fourier transform infrared spectroscopy. Detailed evolution process was studied to learn more information about the formation process before 10 min. Our results are helpful to the development of inorganic perovskite solar cells and the CsPb₂Br₅ based optoelectronic devices.