Key Laboratory of Automobile Materials MOE, School of Materials Science & Engineering, and Jilin Provincial International Cooperation Key Laboratory of High-Efficiency Clean Energy Materials, Jilin University, Changchun 130012, People's Republic of China.
State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, People's Republic of China.
ACS Nano. 2023 May 23;17(10):9290-9301. doi: 10.1021/acsnano.3c00789. Epub 2023 May 1.
Orthorhombic γ-CsPbI possesses the highest structural stability among the optically active (light-emissive) CsPbI perovskites. Here, we make use of a seed-assisted heteroepitaxial growth to fabricate seed/core/shell CaI/γ-CsPbI/CaI nanocrystals. Ultrasmall CaI nanoparticles serve as seeds to template the Pb-centered octahedral arrangement which enables the formation of the γ-CsPbI phase and at the same time inhibit lattice strain by blocking the force transfer that otherwise leads to an octahedral twist and so improve the structural stability of the resulting nanocrystals. An outer shell composed from the same material, CaI, isolates the formed γ-CsPbI nanocrystals from the environment, which also significantly improves their stability under ambient conditions. Optical and electrical studies indicate that the seed/core/shell CaI/γ-CsPbI/CaI structure possesses a shallower set of trap states as compared to cubic α-CsPbI nanocrystals. Light-emitting diodes utilizing these γ-CsPbI nanocrystals show a record high external quantum efficiency of 25.3%, high brightness of over 13600 cd/m, and an operational lifetime of ∼14 h before reaching 50% of their initial luminance. These devices can repeatedly be illuminated over 650 times at ∼500 cd/m with no decline of brightness, which indicates their great commercial potential.
正交γ-CsPbI 在光学活性（发光）CsPbI 钙钛矿中具有最高的结构稳定性。在这里，我们利用种子辅助的异质外延生长来制备种子/核/壳 CaI/γ-CsPbI/CaI 纳米晶。超小的 CaI 纳米颗粒作为种子来模板化 Pb 中心的八面体排列，从而形成 γ-CsPbI 相，同时通过阻止力传递来抑制晶格应变，否则会导致八面体扭曲，从而提高所得纳米晶的结构稳定性。由相同材料 CaI 组成的外壳将形成的 γ-CsPbI 纳米晶与环境隔离，这也显著提高了它们在环境条件下的稳定性。光学和电学研究表明，与立方α-CsPbI 纳米晶相比，种子/核/壳 CaI/γ-CsPbI/CaI 结构具有更浅的一组陷阱态。利用这些 γ-CsPbI 纳米晶的发光二极管显示出 25.3%的创纪录高外量子效率、超过 13600 cd/m 的高亮度和在达到初始亮度的 50%之前约 14 小时的工作寿命。这些器件可以在约 500 cd/m 的亮度下重复照明超过 650 次，亮度没有下降，这表明它们具有巨大的商业潜力。
