Self-formed PbI2-DMSO adduct for highly efficient and stable perovskite solar cells

Currently, chemical vapor deposition (CVD) has attracted widespread attention for preparing high efficiency and large-scale perovskite solar cells (PSCs). The surface morphology and crystallinity of precursor lead iodide (PbI2) films play a critical role in the subsequent CVD process. Here, we use a self-formed PbI2-dimethyl sulfoxide adduct in precursor PbI2 for fabricating a high quality perovskite film. The results show that a larger grain size and excessive PbI2 in the perovskite film effectively suppress carrier recombination, which is helpful to improve the device stability and efficiency. It is noted that the device maintained an excellent stability with almost the same efficiency after 1000 h (in a dry N2 glovebox, 25 °C). Finally, the PSC by using the CVD method exhibits a high power conversion efficiency of 17.9% with a bandgap of 1.60 eV, an open voltage (VOC) of 1140 mV, a short-circuit current density (JSC) of 20.1 mA/cm2, and a fill factor of 78%. This method provides guidance for preparing large-area solar cells or applications in tandem solar cells.