Jia Qiaoying, Li Cong, Tian Weiye, Johansson Malin B, Johansson Erik M J, Yang Rusen
Academy of Advanced Interdisciplinary Research, School of Advanced Materials and Nanotechnology, Xidian University, Xi'an 710126, People's Republic of China.
Department of Chemistry-Ångström, Physical Chemistry, Uppsala University, Uppsala 75120, Sweden.
ACS Appl Mater Interfaces. 2020 Sep 30;12(39):43876-43884. doi: 10.1021/acsami.0c14512. Epub 2020 Sep 16.
Bismuth halide perovskites have recently been considered a potential alternative to lead halide analogues due to their low toxicity and high stability. However, the layered flake structure and wide band gap limit their applications in perovskite solar cells (PSCs). We herein show that large-grained all-inorganic bismuth-based perovskites with a narrow band gap can be obtained from a Lewis acid-base adduct reaction under ambient conditions. Thiourea (CHNS) is utilized as a Lewis base to interact with BiI, confirmed with infrared (IR) spectra. The strong coordination between thiourea and the Bi center could slow down the perovskite crystallization and promote the preferred orientation of the perovskite crystals with a hexagonal phase. The morphology of the perovskite films varies dramatically with an increase of molar ratio of BiI and thiourea in the precursor. The perovskites derived from a BiI/thiourea ratio of 1:2 display extrathick grains, higher surface coverage, extended light absorption, higher crystallinity, and similar air stability compared to the pristine sample. The power conversion efficiency (PCE) of the thiourea-induced bismuth perovskite solar cells is significantly enhanced due to the higher surface coverage and the broader absorption of the perovskite film.
卤化铋钙钛矿由于其低毒性和高稳定性，最近被认为是卤化铅类似物的一种潜在替代品。然而，层状片状结构和宽带隙限制了它们在钙钛矿太阳能电池（PSC）中的应用。我们在此表明，在环境条件下，通过路易斯酸碱加合物反应可以获得具有窄带隙的大晶粒全无机铋基钙钛矿。硫脲（CHNS）被用作路易斯碱与BiI相互作用，这通过红外（IR）光谱得到证实。硫脲与铋中心之间的强配位作用可以减缓钙钛矿的结晶过程，并促进具有六方相的钙钛矿晶体的择优取向。随着前驱体中BiI与硫脲摩尔比的增加，钙钛矿薄膜的形态发生了显著变化。与原始样品相比，BiI/硫脲比例为1:2衍生的钙钛矿显示出超厚晶粒、更高的表面覆盖率、扩展的光吸收、更高的结晶度以及相似的空气稳定性。由于钙钛矿薄膜具有更高的表面覆盖率和更宽的吸收范围，硫脲诱导的铋钙钛矿太阳能电池的功率转换效率（PCE）得到了显著提高。
