He Jinlu, Zhu Yonghao, Fang Weihai, Long Run
College of Chemistry, Key Laboratory of Theoretical and Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing, 100875, People's Republic of China.
J Phys Chem Lett. 2021 Feb 18;12(6):1664-1670. doi: 10.1021/acs.jpclett.0c03851. Epub 2021 Feb 8.
Metal halide perovskites are promising materials for photovoltaics and optoelectronics. However, transfer of an electron from perovskite to oxygen leads to the formation of superoxide that significantly decreases the stability and charge carrier lifetime of perovskites, which constitutes major issues for real applications. Using nonadiabatic (NA) molecule dynamics simulations, we demonstrate that the introduction of a perylene diimide (PDI) molecule into the CHNHPbI system adsorbed with an oxygen molecule creates a midgap state above the trap state generated by the oxygen molecule, and thus the PDI midgap state can rapidly capture the photogenerated electron of perovskite at about 100 ps prior to the O-related trap state, which takes about double the time. The route simultaneously avoids the formation of superoxide and enhances the stability of perovskites. The fast electron trapping originates from the strong NA coupling and small energy gap between the PDI midgap state and the CHNHPbI conduction band minimum. Our simulations suggest that a rational choice an electron-accepting molecule can improve the stability and performance of perovskite solar cells and photoelectric devices.
金属卤化物钙钛矿是用于光伏和光电子学的有前途的材料。然而，电子从钙钛矿转移到氧会导致超氧化物的形成，这会显著降低钙钛矿的稳定性和电荷载流子寿命，这是实际应用中的主要问题。通过非绝热（NA）分子动力学模拟，我们证明将苝二亚胺（PDI）分子引入吸附有氧分子的CHNHPbI系统中，会在氧分子产生的陷阱态上方产生一个中间能隙态，因此PDI中间能隙态可以在与氧相关的陷阱态之前约100皮秒快速捕获钙钛矿的光生电子，而氧相关陷阱态捕获光生电子所需时间约为其两倍。该途径同时避免了超氧化物的形成并提高了钙钛矿的稳定性。快速的电子捕获源于PDI中间能隙态与CHNHPbI导带最小值之间的强NA耦合和小能隙。我们的模拟表明，合理选择电子接受分子可以提高钙钛矿太阳能电池和光电器件的稳定性和性能。
