Synchronous Perovskite Crystallization Regulation and Buried Interface Modification Improve the Stability and Efficiency of a Planar Inorganic Perovskite Solar Cell

The numerous defects in inorganic perovskites and inferior buried interfaces result in serious nonradiative recombination and energy loss, exacerbating the deterioration of the performance of inorganic perovskite solar cells. Here, we develop a facile strategy to simultaneously improve CsPbIBr2 perovskite quality by regulating perovskite crystallization and modify the buried interface by forming a 6-aminonicotinic acid (6AA) molecular interlayer through adding 6AA into a CsPbIBr2 precursor solution. It is found that adding 6AA into the CsPbIBr2 precursor effectively regulates the crystallization process of CsPbIBr2 perovskite because 6AA molecules exhibit a strong intermolecular interaction with CsPbIBr2 precursor components, resulting in forming a compact CsPbIBr2 perovskite film with improved morphology and decreased defects. Meanwhile, 6AA molecules are pushed downward during the perovskite crystallization process and accumulate at the buried interface to form the 6AA interlayer, which improves the interface contact and enhances the charge transport at the buried interface. The perovskite quality improvement and the buried interface modification effectively decrease the nonradiative recombination and interface charge loss. Consequently, the fabricated planar carbon-based CsPbIBr2 solar cell demonstrates an efficiency of 10.97% with a remarkably promoted long-term stability.