Efficient Perovskite Solar Cells with Cesium Acetate-Modified TiO2 Electron Transport Layer

The photovoltaic performance of perovskite solar cells (PSCs) is still below the Shockley–Queisser limit due to the impact of defects originated from the surface and the bulk of the perovskite. Hence, it is particularly important to alleviate non-radiative losses in the solar cell by employing an interface modification strategy. We implemented TiO2/CsAC as an electron transport layer to achieve high-performance devices based on diethylammonium bromide (DABr)-doped MAPbI3. The critical role of cesium acetate (CsAC) is designed to improve perovskite crystallization and achieve a high-quality interfacial contact between TiO2 and the perovskite layer. TiO2/CsAC promotes the shift of Br ions to form the Br-rich region at the perovskite/HTL interface simultaneously, which can enhance the extraction of holes and block the diffusion of electrons. Attributing to the modification of CsAC to TiO2, the performance of DABr-doped MAPbI3 PSC is improved significantly.