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

[Image: see text] 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(0.2)FA(0.8)PbI(2.8)Cl(0.2)-based PeSCs was 18.9%. To further improve the photovoltaic characteristics of PeSCs, Cs(0.2)FA(0.8)PbI(2.8)Cl(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(0.2)FA(0.8)PbI(2.8)Cl(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%.