Xu Liang-Jin, Worku Michael, Lin Haoran, Xu Zhengtao, He Qingquan, Zhou Chenkun, Zhang Heng, Xin Yan, Lteif Sandrine, Xue Jiangeng, Ma Biwu
Department of Chemistry and Biochemistry , Florida State University , Tallahassee , Florida 32306 , United States.
Materials Science and Engineering Program , Florida State University , Tallahassee , Florida 32306 , United States.
J Phys Chem Lett. 2019 Oct 3;10(19):5923-5928. doi: 10.1021/acs.jpclett.9b02387. Epub 2019 Sep 20.
Organometal halide perovskite materials, in particular colloidal perovskite nanocrystals (NCs), have been investigated extensively as next-generation light-emitting materials. However, producing highly efficient and stable perovskite thin films from colloidal NCs is not trivial, as dissociation of surfactants often occurs during the thin-film formation. Here, we demonstrate a facile solution-processing approach to prepare perovskite nanocomposite thin films by using phosphonium as the capping ligand for methylammonium lead bromide (MAPbBr) NCs. The photoluminescence and stability of thin films containing formed perovskite NCs were greatly enhanced after phosphonium passivation, with the photoluminescence quantum efficiency reaching 78% and only 5% decrease of the intensity after one month's exposure in ambient conditions. Electrically driven light-emitting diodes (LEDs) based on pristine perovskite neat thin films and organic-perovskite nanocomposite thin films were fabricated, and we observed a 10-fold improvement in the external quantum efficiency of these LEDs (from 0.6% to 6.3%) resulting from the formation of perovskite NCs with phosphonium passivation.
有机金属卤化物钙钛矿材料，特别是胶体钙钛矿纳米晶体（NCs），作为下一代发光材料已被广泛研究。然而，由胶体纳米晶制备高效且稳定的钙钛矿薄膜并非易事，因为在薄膜形成过程中表面活性剂常常会发生解离。在此，我们展示了一种简便的溶液处理方法，通过使用鏻作为甲基溴化铅（MAPbBr）纳米晶的封端配体来制备钙钛矿纳米复合薄膜。在鏻钝化后，含有所形成的钙钛矿纳米晶的薄膜的光致发光和稳定性得到了极大提高，光致发光量子效率达到78%，并且在环境条件下暴露一个月后强度仅降低5%。基于原始钙钛矿纯薄膜和有机 - 钙钛矿纳米复合薄膜制备了电驱动发光二极管（LED），并且我们观察到由于鏻钝化形成钙钛矿纳米晶，这些LED的外量子效率提高了10倍（从0.6%提高到6.3%）。
