Efficient Perovskite Solar Cells via Phenethylamine Iodide Cation-Modified Hole Transport Layer/Perovskite Interface

Perovskite solar cells (PeSCs) were fabricated by using Cs _x FA_1-x PbI_3-x Cl _x as the photoactive layer, and the effects of different proportions of cesium chloride (CsCl)/formamidinium iodide on perovskites were investigated. Cesium (Cs) can stabilize the α phase of the perovskite, while chlorine (Cl) can increase the size and crystallinity of perovskite crystals and reduce non-radiative cladding, thereby improving the performance of the overall device. The maximum power conversion efficiency (PCE) measured for Cs_0.2FA_0.8PbI_2.8Cl_0.2-based PeSCs was 18.9%. To further improve the photovoltaic characteristics of PeSCs, Cs_0.2FA_0.8PbI_2.8Cl_0.2-based PeSCs were introduced into different concentrations of phenethylammonium iodide (PEAI) to modify the interface between the NiO _x hole transport layer (HTL) and the perovskite photoactive layer, which can simultaneously promote excellent crystallinity of the perovskite layer and passivated interfacial defects, reducing recombination near the perovskite/HTL interface in PeSCs, thereby increasing the efficiency of the device. Compared with the control Cs_0.2FA_0.8PbI_2.8Cl_0.2-based PeSC, the PCE of PeSC with the PEAI (10 mg/mL)-modified NiO _x /perovskite interface increased significantly from 18.9 to 20.2%.