Shuai Yuan1, Zhao-Kui Wang*,1, Ming-Peng Zhuo1, Qi-Sheng Tian1, Yan Jin1, and Liang-Sheng Liao*,1,2
1 Institute of Functional Nano & Soft Materials (FUNSOM), Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, 199 Ren-AiRoad, Suzhou, Jiangsu 215123, China.
2 Institute of Organic Optoelectronics, Jiangsu Industrial Technology Research Institute (JITRI), Wujiang, Suzhou, Jiangsu 215211, P. R. China
Full inorganic cesium lead halide perovskites (IOPs) are regarded as attractive candidates for light-emitting diodes (LEDs) by their excellent luminescent conversion. However, unsatisfactory efficiency and stability are still the main drawbacks that hinder the commercialization progress of perovskite LEDs (PeLEDs). Here, we report an extremely uniform and flat CsPbBr3 film composing of self-assembly core-shell structured quantum dots (SCQDs) based on one-step precursor coating. The QDs size in the CsPbBr3 film is around 4.5 nm (smaller than Bohr radius), which significantly confine injected carriers and lead to a ultra-high exciton binding energy (Eb) of 198 meV. In addition, unfavorable surficial defects are dramatically passivated by a thin surficial-capping layer composed of long-chain ammonium groups (phenylalanine bromide, PPABr), resulting in an ultralow non-radiative recombination rate. Consequently, CsPbBr3 SCQDs film presents a high photoluminescence quantum yield (PLQY) of 85%. It enables the resulting green PeLEDs deliver a recorded external quantum efficiency (EQE) over 15%. Furthermore, the developed CsPbBr3 SCQDs film also demonstrates promising potential in multifunctional lighting sources such as flexible and smart devices.