Authors: Mengjia Li, Jike Ding, Zuolin Zhang, Quanxing Ma, Chao Li, Menghan Lu, Hong Zhang, Thierry Pauporté, Wenlong Mo, Jian‐Xin Tang, Jiangzhao Chen, Cong Chen
Published: 2025-05-07
Source: Full article
AbstractThe instability of perovskite precursor solution induced by deprotonation of organic cations and oxidation of iodide ions substantially deteriorates the reproducibility and reliability of the photovoltaic performance of perovskite solar cells (PSCs). The above decomposition reactions can be conquered via the synergistic engineering of organic functional groups. However, how spatial conformation and type of weak acid functional groups impact the stability of perovskite precursor solution remains to be investigated. Herein, it is uncovered that the position of functional groups on the benzene and the type of weak acid functional groups remarkably influence the acid dissociation constant (pKa) and thus the stability of perovskite inks. The pKa plays a decisive role in suppressing the deprotonation of organic cations and following the amine‐cation addition‐elimination reaction. The 4‐hydrazinobenzenesulfonic acid (4‐HBSA) with the lowest pKa is optimal in stabilizing perovskite inks and mitigating nonradiative recombination through defect passivation. This breakthrough enables the inverted PSCs to deliver a power conversion efficiency (PCE) of 26.79% (certified 26.36%, the highest PCE value for PSCs prepared in ambient conditions) using vacuum flash evaporation technology. The modulated PSC could maintain 92% of its initial efficiency after 2000 h of continuous maximum power point tracking.