An interdiffusion-controlled nucleation strategy for efficient sequential deposition of perovskite photovoltaics

The sequential deposition route is widely investigated in fabricating perovskite thin films for state-of-the-art perovskite photovoltaics. However, concerns such as lower morphological control, phase purity, and remnant unreacted salts such as methylammonium iodide (MAI) and PbI2 are raised, which can significantly deteriorate the optoelectronic properties and hence the operational durability of the devices. In this work, we developed a new interdiffusion-controlled nucleation (ICN) strategy by introducing sulfamic acid agents to improve the sequential deposition of perovskite crystals, achieving low defect density and high-quality perovskite films. Precisely, the ICN strategy can be used to tune the dense PbI2 films into a porous morphology, which promoted the adequate conversion of perovskite and reduced the residual PbI2. Owing to the enhanced crystallization of the perovskite films and passivated surface defects, we obtained a summit PCE exceeding 23% for perovskite solar cells and achieved responsivity values of up to 0.49 A W-1 with linear dynamic ranges of up to 136.75 dB for perovskite photodetectors. The ICN strategy provides a simple and effective way to improve the performance of perovskite-based photovoltaic devices.