Yang Yi, Hou Chunju, Liang Tong-Xiang
College of Rare Earths and Faculty of Materials, Metallurgy and Chemistry, Jiangxi University of Science and Technology, Ganzhou, China.
Phys Chem Chem Phys. 2021 Mar 28;23(12):7145-7152. doi: 10.1039/d0cp04893c. Epub 2021 Mar 23.
Surface properties of all-inorganic halide perovskites play a crucial role in determining optoelectronic performance of these materials. We investigate the surface energies and electronic structures of cubic CsPbBr surfaces systematically using density functional theory (DFT) methods. We calculate the surface phase diagrams of low-index surfaces of CsPbBr, i.e., (100), (110), (111) surfaces. We found that nonpolar (100) surfaces are more stable than polar (110) and (111) surfaces. The nonpolar CsBr-terminated (100) surface shows the best stability, which is attributed to the effect of surface relaxation and high ionicity of the surface layer. The electronic structures reveal that charge transfer to compensate the polarity raises the energy of polar surfaces, which makes polar surfaces unstable. Furthermore, we found that the modulation of surface chemical composition provides an effective way to compensate polarity and thus make polar surfaces of CsPbBr stable. Our results provide physical insights into understanding and further enhancing the surface stability of all-inorganic halide perovskites. This would be helpful in promoting the advancement of all-inorganic halide perovskite-based materials and devices.
全无机卤化物钙钛矿的表面性质在决定这些材料的光电性能方面起着至关重要的作用。我们使用密度泛函理论（DFT）方法系统地研究了立方CsPbBr表面的表面能和电子结构。我们计算了CsPbBr低指数表面，即(100)、(110)、(111)表面的表面相图。我们发现非极性的(100)表面比极性的(110)和(111)表面更稳定。非极性的CsBr端接的(100)表面表现出最佳稳定性，这归因于表面弛豫效应和表面层的高离子性。电子结构表明，为补偿极性而进行的电荷转移提高了极性表面的能量，这使得极性表面不稳定。此外，我们发现表面化学成分的调制提供了一种补偿极性从而使CsPbBr极性表面稳定的有效方法。我们的结果为理解和进一步提高全无机卤化物钙钛矿的表面稳定性提供了物理见解。这将有助于推动基于全无机卤化物钙钛矿的材料和器件的发展。
