Chen Cheng, Xuan Tongtong, Yang Yang, Huang Fan, Zhou Tianliang, Wang Le, Xie Rong-Jun
Fujian Key Laboratory of Materials, College of Materials, Xiamen University, Xiamen 361005, China.
Shenzhen Research Institute of Xiamen University, Shenzhen 518000, China.
ACS Appl Mater Interfaces. 2022 Apr 13;14(14):16404-16412. doi: 10.1021/acsami.2c00621. Epub 2022 Mar 30.
Perovskite light-emitting diodes (PeLEDs) are promising candidates used for superthin emissive displays with high resolution, high brightness, and wide color gamut, but the CsPbI nanocrystal (NC) based ones usually have an external quantum efficiency (EQE) of less than 20%, which needs further enhancement to minimize the gap between their counterparts. Herein, we propose to improve optical properties of the CsPbI:Sr emissive layer (EML) by inserting an additional potassium iodide (KI) passivation layer between the hole transport layer and EML to increase the film quality, photoluminescence quantum yield, and thermal stability of the EML. The KI layer can also increase the carrier mobility to balance the charge injection in PeLEDs, leading to a reduction in Auger recombination and Joule heating. An interesting deep-red-emitting PeLED (λ = 687 nm) with a record EQE of 21.8% and a lifetime of 69 min is obtained by applying the additional KI passivation layer. Moreover, a flexible PeLED consisting of the KI layer is also demonstrated to have a record EQE of 12.7%. These results indicate that the use of a functional KI layer is a feasible way to develop high-performance electroluminescent devices.
钙钛矿发光二极管（PeLEDs）是用于具有高分辨率、高亮度和宽色域的超薄发光显示器的有前途的候选材料，但基于CsPbI纳米晶体（NC）的二极管通常具有小于20%的外量子效率（EQE），这需要进一步提高以缩小与同类产品之间的差距。在此，我们建议通过在空穴传输层和发射层（EML）之间插入额外的碘化钾（KI）钝化层来改善CsPbI:Sr发射层的光学性能，以提高发射层的薄膜质量、光致发光量子产率和热稳定性。KI层还可以提高载流子迁移率，以平衡PeLEDs中的电荷注入，从而减少俄歇复合和焦耳热。通过应用额外的KI钝化层，获得了一种有趣的深红色发光PeLED（λ = 687 nm），其EQE达到创纪录的21.8%，寿命为69分钟。此外，由KI层组成的柔性PeLED也被证明具有创纪录的12.7%的EQE。这些结果表明，使用功能性KI层是开发高性能电致发光器件的可行方法。
