Surface Reconstruction-Induced Efficient CsPbI₂Br Perovskite Solar Cell using Phenylethylammonium Iodide

The presence of defects on the surface of perovskite films is one of the main factors leading to inferior power conversion efficiency and stability of CsPbI2Br perovskite solar cells. In this paper, we seek to address this limitation by coating phenylethylammonium iodide (PEAI) solution onto the surface of a CsPbI2Br perovskite film and annealing, which can effectively reduce the defect density on the surface of the CsPbI2Br film and increase the efficiency of the device accordingly. In situ characterization by X-ray diffraction and photoluminescence spectroscopy reveals that the PEAI treatment can induce surface crystal reconstruction of CsPbI2Br and decrease the trap density as a result. Finally, the CsPbI2Br perovskite solar cell with a carbon electrode obtains a high power conversion efficiency of 13.38%.