Yue Yaochang, Zhou Jiyu, Cheng Qian, Zhang Xuning, Wang Boxin, Li Yanxun, Li Shilin, Cao Ruiqi, Wang Kaiyuan, Wang Hui, Zhou Huiqiong, Zhang Yuan
Heeger Research and Development Center, School of Chemistry, Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing 100191, P. R. China.
CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China.
J Phys Chem Lett. 2021 Nov 18;12(45):11228-11237. doi: 10.1021/acs.jpclett.1c03021. Epub 2021 Nov 11.
Bromine-containing metal halide all-inorganic perovskite CsPbIBr exhibits excellent photoelectric performance and supreme thermal and structural stabilities; it is thus attractive for use as photoabsorbing layers in perovskite solar cells (PSCs). However, when steric hindrance molecules are introduced, the complicated phase transition mechanism and the difficult-to-control crystallization process in CsPbIBr are not well understood. Here, we introduce a class of sterically hindered cesium naphthenate small molecules to control the crystallization process of CsPbIBr films. Of interest, a new intermediate monoclinic phase has been discovered which leads to formation of dense and nonporous polycrystalline perovskite films. This phenomenon was also explained by density functional theory. The residues of steric hindrance molecules inside the CsPbIBr film also improve its stability. We further show that as the ring number of cycloalkanes increases, the hindrance for the crystallization becomes more significant. Thus, by choosing the suitable steric hindrance, the optimal photovoltaic efficiency is 15.45%.
含溴金属卤化物全无机钙钛矿CsPbIBr表现出优异的光电性能以及极高的热稳定性和结构稳定性；因此，它作为钙钛矿太阳能电池（PSC）中的光吸收层具有吸引力。然而，当引入空间位阻分子时，CsPbIBr中复杂的相变机制和难以控制的结晶过程尚未得到很好的理解。在此，我们引入一类空间位阻的环烷酸铯小分子来控制CsPbIBr薄膜的结晶过程。有趣的是，发现了一种新的中间单斜相，它导致形成致密且无孔的多晶钙钛矿薄膜。这一现象也通过密度泛函理论得到了解释。CsPbIBr薄膜内部空间位阻分子的残留也提高了其稳定性。我们进一步表明，随着环烷烃环数的增加，对结晶的阻碍变得更加显著。因此，通过选择合适的空间位阻，最佳光伏效率为15.45%。
