Kumar Sudhir, Marcato Tommaso, Krumeich Frank, Li Yen-Ting, Chiu Yu-Cheng, Shih Chih-Jen
Institute for Chemical and Bioengineering, ETH Zürich, 8093, Zürich, Switzerland.
Laboratory of Inorganic Chemistry, ETH Zürich, 8093, Zürich, Switzerland.
Nat Commun. 2022 Apr 19;13(1):2106. doi: 10.1038/s41467-022-29812-5.
Quantum dot (QD) light-emitting diodes (LEDs) are emerging as one of the most promising candidates for next-generation displays. However, their intrinsic light outcoupling efficiency remains considerably lower than the organic counterpart, because it is not yet possible to control the transition-dipole-moment (TDM) orientation in QD solids at device level. Here, using the colloidal lead halide perovskite anisotropic nanocrystals (ANCs) as a model system, we report a directed self-assembly approach to form the anisotropic nanocrystal superlattices (ANSLs). Emission polarization in individual ANCs rescales the radiation from horizontal and vertical transition dipoles, effectively resulting in preferentially horizontal TDM orientation. Based on the emissive thin films comprised of ANSLs, we demonstrate an enhanced ratio of horizontal dipole up to 0.75, enhancing the theoretical light outcoupling efficiency of greater than 30%. Our optimized single-junction QD LEDs showed peak external quantum efficiency of up to 24.96%, comparable to state-of-the-art organic LEDs.
量子点（QD）发光二极管（LED）正成为下一代显示器最有前途的候选者之一。然而，它们的固有光出射耦合效率仍远低于有机发光二极管，因为在器件层面还无法控制量子点固体中的跃迁偶极矩（TDM）取向。在此，我们以胶体卤化铅钙钛矿各向异性纳米晶体（ANC）为模型系统，报告了一种形成各向异性纳米晶体超晶格（ANSL）的定向自组装方法。单个ANC中的发射极化重新调整了水平和垂直跃迁偶极的辐射，有效地导致了优先的水平TDM取向。基于由ANSL组成的发光薄膜，我们展示了高达0.75的水平偶极增强比，将理论光出射耦合效率提高了30%以上。我们优化后的单结QD LED显示出高达24.96%的峰值外量子效率，与最先进的有机LED相当。
