Ding Yunxuan, Shen Yujie, Lee Ming-Hsien, Wang Haifeng, Hu P, Huang Meilan
School of Chemistry and Chemical Engineering, The Queen's University of Belfast, Belfast BT9 5AG, U.K.
Department of Physics, Tamkang Univeristy, New Taipei, 25137, Taiwan.
JACS Au. 2025 Mar 18;5(4):1738-1745. doi: 10.1021/jacsau.4c01261. eCollection 2025 Apr 28.
Metal halide perovskite solar cells show great promise, in terms of their high-power conversion efficiency. However, the dynamic electron-hole separation process remains elusive. Using ab initio molecular dynamics, we discover that the presence of photogenerated electron trapped at a Pb ion can induce significant electron-hole separations on the CHNHPbI perovskite in the presence of HI solution. In this dynamic process, the separated electron is transferred to the Pb ion to form a Pb atom, while the separated hole is trapped in an I dimer. The reason behind this induced electron-hole separation is clearly revealed. Furthermore, the charge carrier transfer mechanism is elucidated, which not only explains the carrier migration but also the degradation of the perovskite in a humid environment. Comparing the atomic motions in CHNHPbI and CHNHPbCl quantitatively demonstrates that CHNHPbI is more active but less stable than CHNHPbCl. The proposed mechanism for the electron-hole separation mechanism and perovskite degradation in humid conditions provides insights into the design of a highly efficient perovskite with good stability.
金属卤化物钙钛矿太阳能电池因其高功率转换效率而展现出巨大的潜力。然而，动态的电子-空穴分离过程仍然难以捉摸。通过从头算分子动力学，我们发现，在HI溶液存在的情况下，被困在Pb离子上的光生电子的存在会在CHNHPbI钙钛矿上引发显著的电子-空穴分离。在这个动态过程中，分离出的电子转移到Pb离子上形成一个Pb原子，而分离出的空穴被困在一个I二聚体中。这种诱导电子-空穴分离背后的原因被清晰地揭示出来。此外，阐明了电荷载流子转移机制，这不仅解释了载流子迁移，还解释了钙钛矿在潮湿环境中的降解。定量比较CHNHPbI和CHNHPbCl中的原子运动表明，CHNHPbI比CHNHPbCl更活跃但稳定性更低。所提出的电子-空穴分离机制以及钙钛矿在潮湿条件下的降解机制为设计具有良好稳定性的高效钙钛矿提供了见解。
