Interface optimization and growth control for high efficiency wide bandgap perovskite solar cells

High-performance wide bandgap perovskite single-junction solar cells (PSCs) are the key elements for the fabrication of high-efficiency tandem solar cells. However, the development of wide bandgap PSCs is currently limited by pernicious interface contact and uncontrolled crystal evolution. In this work, the potassium iodide (KI) additive and solvent annealing method simultaneously are employed to control crystallization kinetics evolution of triple-cation hybrid halide wide bandgap perovskites. The interface is modified with phenethylammonium iodide (PEAI) to form 2D PEAI2PbI4 layer to further enhance the electron collection efficiency and reduce non-radiative recombination caused by the defects trap between the perovskite and electron transport layer. As a result, the photovoltaic performance parameters of the PSCs devices for open-circuit voltage, short-circuit current, and fill factor could be increased from 1.14 V, 14.98 mA cm−2, and 53% to 1.22 V, 17.65 mA cm−2, and 73%, respectively, obtaining the impressive solar cell device with 15.7% power conversion efficiency. The improvement in photovoltaic performance should be attributed to the optimization of crystal evolution and management of interface contact. Therefore, this study provides a promising strategy for fabricating the high-performance wide bandgap PSCs.