Homogenizing the Halogen Distribution via a Multifunctional Fluorine-Containing Additive Toward High-Performance Inverted Wide-Bandgap Perovskite Solar Cells

Wide-bandgap perovskite solar cells, which are essential for tandem photovoltaics, easily suffer from open-circuit voltage (VOC) losses due to challenges in suppressing halogen heterogeneity and defect-related nonradiative recombination in the active layers. Herein, a multifunctional fluorine-containing additive of 8-pentafluorobenzyloxy quinoline (8-PFBQ) is explored to modulate the crystallization and defect properties of wide-bandgap (1.67 eV) perovskites, enhancing both efficiency and operational stability of ensuing solar cells. It is demonstrated that the quinoline group of 8-PFBQ can strongly coordinate with the lead ions and the fluorinated benzyl group effectively interacts with the organic halides through anion-pi and hydrogen bonding interactions simultaneously. These synergistic effects improve crystal quality and composition homogeneity, holistically reducing defects in the perovskite active layers. The resulting wide-bandgap solar cells achieve a champion power conversion efficiency of 22.22%, featuring a high VOC of 1.243 V and a two-fold enhancement in the operational stability. This work presents an alternative strategy for defect management in wide-bandgap perovskites, offering insights for advancements in both single-junction and tandem photovoltaics.