Zhang Qian, Song Yong-Hui, Hao Jing-Ming, Lan Yi-Feng, Feng Li-Zhe, Ru Xue-Chen, Wang Jing-Jing, Song Kuang-Hui, Yang Jun-Nan, Chen Tian, Yao Hong-Bin
Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China.
Department of Applied Chemistry, Hefei Science Center of Chinese Academy of Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China.
J Am Chem Soc. 2022 May 11;144(18):8162-8170. doi: 10.1021/jacs.2c01034. Epub 2022 Apr 20.
All-inorganic CsPbI perovskite is attractive for deep-red light-emitting diodes (LEDs) because of its excellent carrier mobility, high color purity, and solution processability. However, the high phase transition energy barrier of optically active CsPbI black phase hinders the fabrication of efficient and bright LEDs. Here, we report a novel α-BaF nanoparticle substrate-promoted solution-processable heteroepitaxial growth to overcome this hindrance and obtain high-quality optically active γ-CsPbI thin films, achieving efficient and bright deep-red LEDs. We unravel that the highly exposed planes on the α-BaF nanoparticle-based heteroepitaxial growth substrate have a 99.5% lattice matching degree with the (110) planes of γ-CsPbI. This ultrahigh lattice matching degree initiates solution-processed interfacial strain-free epitaxial growth of low-defect and highly oriented γ-CsPbI thin films on the substrate. The obtained γ-CsPbI thin films are uniform, smooth, and highly luminescent, based on which we fabricate efficient and bright deep-red LEDs with a high peak external quantum efficiency of 14.1% and a record luminance of 1325 cd m.
全无机CsPbI钙钛矿因其优异的载流子迁移率、高色纯度和溶液可加工性，对深红色发光二极管（LED）具有吸引力。然而，光学活性CsPbI黑色相的高相变能垒阻碍了高效明亮LED的制造。在此，我们报道了一种新型的α-BaF纳米颗粒衬底促进的溶液可加工异质外延生长，以克服这一障碍并获得高质量的光学活性γ-CsPbI薄膜，从而实现高效明亮的深红色LED。我们发现，基于α-BaF纳米颗粒的异质外延生长衬底上高度暴露的平面与γ-CsPbI的（110）平面具有99.5%的晶格匹配度。这种超高的晶格匹配度引发了低缺陷、高取向的γ-CsPbI薄膜在衬底上的溶液加工无界面应变外延生长。所获得的γ-CsPbI薄膜均匀、光滑且高发光，基于此我们制造出了高效明亮的深红色LED，其具有14.1%的高峰值外量子效率和1325 cd m的创纪录亮度。
