Neutral Ligand Triggered\nLow-Dimensional Reconstruction\nfor Improving the Efficiency and Stability of Perovskite Solar Cells

Perovskite solar cells (PSCs) offer a potentially large-scale\nmethod\nfor producing low-cost renewable energy. However, stability challenges\ncurrently limit their practical application. Consequently, alternative\nmethods for increasing the PSC stability are urgently needed. Compared\nwith three-dimensional (3D) perovskites, low-dimensional (LD) perovskites\nhave been shown to have higher stability. In this study, a LD/3D hybrid\nperovskite strategy is used that involves post-treating the Cs<sub>0.05</sub>(FA<sub>0.98</sub>MA<sub>0.02</sub>)<sub>0.95</sub>Pb(I<sub>0.98</sub>Br<sub>0.02</sub>)<sub>3</sub> perovskite with a neutral\nallyl 1H-imidazole-1-carboxylate (AImC) ligand. We show that this\nneutral organic spacer molecule has two key roles. AImC acts as a\nsolvent and triggers localized reconstruction to produce a LD capping\nlayer in one postprocessing step. AImC prolongs the carrier lifetime\nand reduces trap-assisted recombination. As a result, the PSCs containing\nAImC achieve a maximum power conversion efficiency (PCE) of 21.42%\ncompared to 20.27% for the control device and show significantly decreased\nhysteresis. AImC also greatly increased the stability of the films\nand devices to air, moisture, and heat. The results of this study\nimply that neutral amine liquids that have the correct solvating and\nligating properties have good potential to improve the PCE and stability\nof the PSCs.