Efficient and Stable Carbon‐Based CsPbIBr2 Perovskite Solar Cells by 4‐Aminomethyltetrahydropyran Acetate Modification

Inorganic cesium lead halide perovskite solar cells have attracted widespread attention owing to their excellent stability relative to organic–inorganic solar cells. However, all‐inorganic perovskite solar cells without hole transport layers and using carbon layers as electrodes have serious energy level mismatch problems. To overcome this problem, here, the CsPbIBr2 surface is treated with 4‐aminomethyltetrahydropyran acetate to form a gradient energy band on the CsPbIBr2 perovskite/carbon interface. As a result, the hole extraction efficiency is successfully improved, and the morphology and crystallization of the perovskite layer are also improved. Moreover, the nonradiative recombination inside the perovskite and the charge recombination at the interface are effectively inhibited. Therefore, the power conversion efficiency of CsPbIBr2 solar cell is enhanced to 10.12%, and the high photovoltage of 1.32 V is obtained under one solar illumination, which are both higher than the pristine one (7.79%, 1.23V, respectively). 4‐Aminomethyltetrahydropyran acetate is used as the surface passivation agent for CsPbIBr2 perovskite, which can passivate the surface defects and form a more beneficial energy level arrangement of CsPbIBr2 film. These benefits contribute to reduced recombination of carriers inside the corresponding device and yield faster hole extraction. Thereby, the CsPbIBr2 hole transport layer free carbon‐based perovskite solar cells with better photovoltaic performance and long‐term stability are fabricated.