Hoang Minh Tam, Pannu Amandeep Singh, Yang Yang, Madani Sepideh, Shaw Paul, Sonar Prashant, Tesfamichael Tuquabo, Wang Hongxia
Faculty of Science, School of Chemistry and Physics, Queensland University of Technology, Brisbane, QLD, 4001, Australia.
Centre for Materials Science, Queensland University of Technology, Brisbane, QLD, 4001, Australia.
Nanomicro Lett. 2022 Mar 2;14(1):69. doi: 10.1007/s40820-022-00813-9.
The remarkable evolution of metal halide perovskites in the past decade makes them promise for next-generation optoelectronic material. In particular, nanocrystals (NCs) of inorganic perovskites have demonstrated excellent performance for light-emitting and display applications. However, the presence of surface defects on the NCs negatively impacts their performance in devices. Herein, we report a compatible facial post-treatment of CsPbI nanocrystals using guanidinium iodide (GuI). It is found that the GuI treatment effectively passivated the halide vacancy defects on the surface of the NCs while offering effective surface protection and exciton confinement thanks to the beneficial contribution of iodide and guanidinium cation. As a consequence, the film of treated CsPbI nanocrystals exhibited significantly enhanced luminescence and charge transport properties, leading to high-performance light-emitting diode with maximum external quantum efficiency of 13.8% with high brightness (peak luminance of 7039 cd m and a peak current density of 10.8 cd A). The EQE is over threefold higher than performance of untreated device (EQE: 3.8%). The operational half-lifetime of the treated devices also was significantly improved with T of 20 min (at current density of 25 mA cm), outperforming the untreated devices (T ~ 6 min).
在过去十年中，金属卤化物钙钛矿的显著发展使其有望成为下一代光电子材料。特别是，无机钙钛矿纳米晶体（NCs）在发光和显示应用中表现出优异的性能。然而，NCs表面缺陷的存在对其在器件中的性能产生负面影响。在此，我们报道了一种使用碘化胍（GuI）对CsPbI纳米晶体进行的兼容且简便的后处理方法。研究发现，GuI处理有效地钝化了NCs表面的卤化物空位缺陷，同时由于碘化物和胍阳离子的有益作用，提供了有效的表面保护和激子限制。因此，经处理的CsPbI纳米晶体薄膜表现出显著增强的发光和电荷传输性能，并由此制备出高性能发光二极管，其最大外量子效率为13.8%，具有高亮度（峰值亮度为7039 cd m，峰值电流密度为10.8 cd A）。该外量子效率比未处理器件的性能（外量子效率：3.8%）高出三倍多。经处理器件的工作半衰期也得到显著改善，在20分钟（电流密度为25 mA cm）时的半衰期优于未处理器件（半衰期约为 6分钟）。
