Orientation-controlled mesoporous PbI2 scaffold for 22.7% perovskite solar cells

Abstract

Sequential deposition is a promising tactic for perovskite film fabrication. However, the highly crystalline and compact morphology of PbI2 film will hinder the quality and reproducibility of perovskite films. Here, nicotinamide (NTM) derivatives were introduced as simple and effective multifunctional ligands into the PbI2 precursor solution. Orientation-controlled and mesoporous PbI2 scaffolds formed due to strong chemical interaction and accelerated solvent volatilization. Nanobelt PbI2 crystals were also generated at the grain boundaries of perovskite films with NTM derivatives, which can passivate the defects and enhance the carrier lifetime. As a result, the perovskite solar cells based on 6-(trifluoromethyl) nicotinamide-modulated films showed an enhanced power conversion efficiency of 22.7%, of which 98.8% was maintained even after 2000 h of aging. Our findings offer a distinctive understanding of regulating the crystallization of PbI2 films and manipulating excess PbI2 structure for efficient perovskite solar cells.