Synergistic Effect of 4-Hydroxypyridine for the Vertical Orientation of Quasi-2D Perovskite Solar Cells with Enhanced Efficiency

Quasi-2D perovskites capture significant attention dueto theirsuperior stability. However, the power conversion efficiency (PCE)of BA-based quasi-2D perovskite solar cells (PSCs) is always poorfor insufficient interlayer charge transport, mainly due to inappropriatecrystal alignment. Here, we doped a 4-hydroxypyridine (4-HP) additiveinto a perovskite precursor solution for its strong interaction withthe 2D perovskite to regulate the crystallization process. A stabilizedphotovoltaic PCE of 14.82% with an improved short-circuit currentdensity (J (SC)) is obtained, benefitingfrom the formation of large-n-value phases, verticallyorientated and highly crystalline quasi-2D perovskite films, and balancedelectron/hole transportation. Moreover, the BA-based quasi-2D perovskitefilms exhibit excellent phase stability with unaltered X-ray diffractionpatterns after 720 h storage in open air, and the corresponding devicesmaintained good PCE when directly stored at light/humidity/thermalenvironment for over 460 h. Our study provides a practical approachto synthesize high-quality quasi-2D perovskite films toward powerfuland remarkably stable PSCs for commercialization.