Suppressing Open-Circuit Voltage Loss in Perovskite Solar Cells via Ligand-Assisted Crystallization Dynamics Regulation Strategy.

Despite the dazzling progress since the emergence of perovskite solar cells (PSCs), a significant ideal-reality discrepancy with respect to the open-circuit voltage (VOC) still reminds the primarily weak parameter, inducing the limited power conversion efficiency (PCE) relative to its Shockley-Queisser theoretical limit. Eliminating the detrimental non-radiative recombination centers enriched at the surface/grain boundaries of perovskite films is generally regarded as the key approaches to bridge this gap. Herein, a perovskite crystallization dynamic regulation template is conducted to ensure the realization of both rapid nucleation and suppressed crystal growth through the synchronous incorporation of SCN- and volatility NH4 + ligands. Thereby promoting the formation of high-quality perovskite films with enlarged grain size, superior crystallinity, ordered surface texture and compensated residual strain. Notably, residual SCN- ligands detected in the buried interface of perovskite films is also inclined to serves as an interface passivators. In conjunction with the above analysis, desired perovskite films with decreased defect density and suppressed non-radiative recombination are acquired for the NH4SCN sample, leading to impressive power conversion efficiencies of 26.13% with one of the lowest VOC losses among all reported p-i-n structure PSCs, reaching 96.13% of their theoretical VOC limit.