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.