Dual Coordination of Ti and Pb Using Bilinkable Ligands Improves Perovskite Solar Cell Performance and Stability

Charge recombination due to interfacial defects is an important source of loss in perovskite solar cells. Here, a two-sided passivation strategy is implemented by incorporating a bilinker molecule, thiophene-based carboxylic acid (TCA), which passivates defects on both the perovskite side and the TiO(2)side of the electron-extracting heterojunction in perovskite solar cells. Density functional theory and ultrafast charge dynamics reveal a 50% reduction in charge recombination at this interface. Perovskite solar cells made using TCA-passivated heterojunctions achieve a power conversion efficiency of 21.2% compared to 19.8% for control cells. The TCA-containing cells retain 96% of initial efficiency following 50 h of UV-filtered MPP testing.