Local nearly non-strained perovskite lattice approaching a broad environmental stability window of efficient solar cells

Twist and fracture of surface lattice tend to occur under harsh condition due to the soft lattice natures of hybrid perovskite materials. Accordingly, surface defects and lattice distortion are produced, which allow the performance loss and notorious degradation in perovskite solar cells (PSCs). In our work, judiciously selected conjugated ligand was employed as the film intermediary, from which rigid and delocalization 4-phenylpyridine (4-pPy) exhibited the most significant improvement on both optoelectrical performance and stability of PSCs. By regulating the film crystallization kinetics, high-quality perovskite films can be obtained with preferable crystal orientation. Moreover, benefiting from the defects passivation and unidirectional bonding effect, coordinated 4-pPy “scaffold” on the lattice surface could mitigate vacancy formation and lattice twist/fracture under severe conditions. The resulted p-i-n planar device shows a considerable PCE of 21.12% (certified 20.2%) with negligible hysteresis, as well as an excellent storage (90% of original PCE after 1000 h at 60% RH), operating (90% of original PCE after 600 h at maximum power point) and thermal stress (89% of original PCE after 500 h at 85 °C) stability. It is hoped that our findings could open a new way to accelerate continued progress on PSCs regimes for efficieny maximization and stability prolongation.