Wang Jing, Yin Wan-Jian
College of Energy, Soochow Institute for Energy and Materials InnovationS (SIEMIS), and Jiangsu Provincial Key Laboratory for Advanced Carbon Materials and Wearable Energy Technologies, Soochow University, Suzhou 215006, China.
Light Industry Institute of Electrochemical Power Sources, Soochow University, Suzhou 215006, Jiangsu, China.
J Phys Chem Lett. 2022 Jul 28;13(29):6694-6700. doi: 10.1021/acs.jpclett.2c01815. Epub 2022 Jul 17.
Current knowledge on the nature of surface iodine vacancies (V), which are important for the photovoltaic performance and stability of perovskite solar cells, is debatable. We investigated V on a stable MAI-terminated CHNHPbI (MAPbI) surface. First-principles calculations indicated the sensitivity of the atomic structure of surface V to the charge states and locations on the surface layer. V in the outermost layer are benign; however, those near the surface can be detrimental. Illumination can promote the diffusion of V from the outermost layer into the bulk, making them detrimental. There are two mechanisms for the surface passivation of V: (i) passivation in the second layer to eliminate deep-state V and (ii) passivation in the outermost layer to inhibit V diffusion upon illumination (working condition of solar cells). This work rationalizes contradictory reports on the surface properties of halide perovskites and proposes insights into their surface passivation to fabricate high-performing solar cells.
目前关于表面碘空位（V）性质的知识存在争议，而表面碘空位对钙钛矿太阳能电池的光伏性能和稳定性至关重要。我们研究了稳定的MAI端接的CHNHPbI（MAPbI）表面上的V。第一性原理计算表明，表面V的原子结构对表面层上的电荷状态和位置敏感。最外层的V是无害的；然而，靠近表面的那些V可能是有害的。光照可促进V从最外层扩散到体相中，使其变得有害。V的表面钝化有两种机制：（i）在第二层进行钝化以消除深能级V，以及（ii）在最外层进行钝化以抑制光照时（太阳能电池的工作条件）V的扩散。这项工作使关于卤化物钙钛矿表面性质的相互矛盾的报道合理化，并提出了对其表面钝化的见解，以制造高性能太阳能电池。
