Guan Zhiqiang, Li Yang, Man Ping, Tan Hongji, Wei Qi, Liu Jinjie, Li Mingjie, Ly Thuc Hue, Yin Jun, Lee Chun-Sing
Department of Chemistry, City University of Hong Kong, Hong kong, Hong Kong SAR, 000000, P. R. China.
Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong kong, Hong Kong SAR, 000000, P. R. China.
Adv Mater. 2024 Sep;36(38):e2407406. doi: 10.1002/adma.202407406. Epub 2024 Jul 31.
Interfacial charge-transfer between perovskite and charge-transport layers plays a key role in determining performance of perovskite solar cells. The conventional viewpoint emphases the necessity of favorable energy-level alignment of the two components. In recent reports, efficient electron-transfer is observed from perovskite to fullerene-based electron-transport layers even when there are unfavorable energy-level alignments, but the mechanism is still unclear. Here, using an ultrafast in situ two-photon photoelectron spectroscopy, real-time observations of electron-transfer processes at CsPbI/C interface in both temporal and energetic dimensions are reported. Due to strong electronic coupling, a large amount of interfacial hybrid states is generated at the interfaces, aiding fast photoinduced electron-transfer in ≈124 fs. This process is further verified by nonadiabatic molecular dynamics simulations and transient absorption experiments. The short timescale explains why electron-transfer can overcome unfavorable energy-level alignments, providing a guideline for device design.
钙钛矿与电荷传输层之间的界面电荷转移在决定钙钛矿太阳能电池的性能方面起着关键作用。传统观点强调这两种组分具有良好能级匹配的必要性。在最近的报道中，即使存在不利的能级匹配，也观察到了从钙钛矿到富勒烯基电子传输层的高效电子转移，但其机制仍不清楚。在此，利用超快原位双光子光电子能谱，在时间和能量维度上实时观测了CsPbI/C界面处的电子转移过程。由于强电子耦合，在界面处产生了大量的界面杂化态，有助于在约124飞秒内实现快速光致电子转移。这一过程通过非绝热分子动力学模拟和瞬态吸收实验得到了进一步验证。如此短的时间尺度解释了电子转移为何能够克服不利的能级匹配，为器件设计提供了指导。
