Neutral Ligand Triggered Low-Dimensional Reconstruction for Improving the Efficiency and Stability of Perovskite Solar Cells

Perovskite solar cells (PSCs) offer a potentially large-scale method for producing low-cost renewable energy. However, stability challenges currently limit their practical application. Consequently, alternative methods for increasing the PSC stability are urgently needed. Compared with three-dimensional (3D) perovskites, low-dimensional (LD) perovskites have been shown to have higher stability. In this study, a LD/3D hybrid perovskite strategy is used that involves post-treating the Cs-0.05(FA(0.98)MA(0.02))(0.95)Pb(I0.98Br0.02)(3) perovskite with a neutral allyl 1H-imidazole-1-carboxylate (AImC) ligand. We show that this neutral organic spacer molecule has two key roles. AImC acts as a solvent and triggers localized reconstruction to produce a LD capping layer in one postprocessing step. AImC prolongs the carrier lifetime and reduces trap-assisted recombination. As a result, the PSCs containing AImC achieve a maximum power conversion efficiency (PCE) of 21.42% compared to 20.27% for the control device and show significantly decreased hysteresis. AImC also greatly increased the stability of the films and devices to air, moisture, and heat. The results of this study imply that neutral amine liquids that have the correct solvating and ligating properties have good potential to improve the PCE and stability of the PSCs.