Kim Jongseob, Lee Sung-Hoon, Im Sang Hyuk, Hong Ki-Ha
Samsung Advanced Institute of Technology, 130, Samsung-ro, Yeongtong-gu, Suwon 16678, Korea.
Department of Applied Physics and Institute of Natural Sciences, Kyung Hee University, Yongin 17104, Korea.
J Phys Chem Lett. 2020 May 21;11(10):4232-4238. doi: 10.1021/acs.jpclett.0c00499. Epub 2020 May 12.
The cesium lead triiodide (CsPbI) perovskite is a promising candidate for stable light absorbers and red-light-emitting sources due to its outstanding stability. Phase engineering is the most important approach for the commercialization of CsPbI because the optically inactive nonperovskite structure is more stable than three-dimensional (3-D) perovskite lattices at ambient temperature. This study presents an in-depth evaluation to find the optimum surface ligand and to reveal the mechanism of phase stabilization by surface ligands. Thermodynamic evaluations combined with density functional theory calculations indicate the criteria for forming stable 3-D CsPbI perovskites under surface and volume free energy competition between perovskite and nonperovskite phases. Comparative calculations for ammonium, alcohol, and thiol groups show that ammonium groups enhance the phase stability of 3-D perovskites the most. In addition, ammonium-passivated CsPbI is relatively robust against defect formation and HO adsorption.
由于其出色的稳定性，三碘化铯铅（CsPbI）钙钛矿是稳定光吸收剂和红光发射源的一个有前途的候选材料。相工程是CsPbI商业化的最重要方法，因为在环境温度下，光学惰性的非钙钛矿结构比三维（3-D）钙钛矿晶格更稳定。本研究进行了深入评估，以找到最佳表面配体并揭示表面配体的相稳定机制。热力学评估与密度泛函理论计算相结合，表明了在钙钛矿相和非钙钛矿相之间的表面和体积自由能竞争下形成稳定的3-D CsPbI钙钛矿的标准。对铵基、醇基和硫醇基的比较计算表明，铵基对3-D钙钛矿相稳定性的增强作用最大。此外，铵钝化的CsPbI对缺陷形成和HO吸附相对稳健。
