中国科学技术大学姚宏斌团队报道了采用尺寸超过玻尔激子直径的钙钛矿纳米晶的高色纯度高效绿色发光二极管。相关研究成果发表在2021年11月12日出版的《美国化学会杂志》。

卤化铅钙钛矿型纳米晶（PNC）是一种很有前途的发光材料，在高色纯度和高效发光二极管方面具有广阔的应用前景。然而，大多数报道的卤化铅钙钛矿型纳米晶发光二极管（PNCLED）遇到了由量子限制效应引起的发射线宽展宽和工作电压升高的问题。

该文中，研究人员报告了一种使用尺寸远超过玻尔激子直径CsPbBr3 PNCs的新型PNCLED，实现了超窄发射线宽度和在开关电压附近的亮度快速上升。研究人员采用氧化三丁基膦钙杂化配体钝化法制备了高度分散的大尺寸胶体CsPbBr3 PNCs，具有弱的尺寸限制效应和较高的光致发光量子产率（～85%）。研究表明，利用这些大尺寸PNCs作为发射体，在器件中可以避免量子限制效应造成的有害影响，从而实现绿色PNCLEDs的最高色纯度，最大半宽度为16.4nm，校正后的最大外部量子效率为17.85%。此外，大尺寸PNCLEDs的工作半衰期是小尺寸PNCs的5倍。

研究工作为改进基于非常规大尺寸效应的PNCLEDs的性能提供了新的途径。

附：英文原文

Title: High Color Purity and Efficient Green Light-Emitting Diode Using Perovskite Nanocrystals with the Size Overly Exceeding Bohr Exciton Diameter

Author: Jun-Nan Yang, Tian Chen, Jing Ge, Jing-Jing Wang, Yi-Chen Yin, Yi-Feng Lan, Xue-Chen Ru, Zhen-Yu Ma, Qun Zhang, Hong-Bin Yao

Issue&Volume: November 12, 2021

Abstract: Lead halide perovskite nanocrystals (PNCs) are emerging as promising light emitters to be actively explored for high color purity and efficient light-emitting diodes. However, the most reported lead halide perovskite nanocrystal light-emitting diodes (PNCLEDs) encountered issues of emission line width broadening and operation voltage elevating caused by the quantum confinement effect. Here, we report a new type of PNCLED using large-size CsPbBr3 PNCs overly exceeding the Bohr exciton diameter, achieving ultranarrow emission line width and rapid brightness rise around the turn-on voltage. We adopt calcium-tributylphosphine oxide hybrid ligand passivation to produce highly dispersed large-size colloidal CsPbBr3 PNCs with a weak size confinement effect and also high photoluminescence quantum yield (～85%). Utilizing these large-size PNCs as emitters, we manifest that the detrimental effects caused by the quantum confinement effect can be avoided in the device, thereby realizing the highest color purity in green PNCLED, with a narrow full width at half-maximum of 16.4 nm and a high corrected maximum external quantum efficiency of 17.85%. Moreover, the operation half-life time of the large-size PNCLED is 5-fold of that based on smaller-size PNCs. Our work provides a new avenue for improving the performance of PNCLEDs based on unconventional large-size effects.

DOI: 10.1021/jacs.1c09948

Source: https://pubs.acs.org/doi/10.1021/jacs.1c09948