Blue light-emitting diodes based on colloidal quantum dots with reduced surface-bulk coupling

Xingtong Chen; Xiongfeng Lin; Likuan Zhou; Xiaojuan Sun; Rui Li; Mengyu Chen; Yixing Yang; Wenjun Hou; Longjia Wu; Weiran Cao; Xin Zhang; Xiaolin Yan; Song Chen

doi:10.1038/s41467-023-35954-x

Blue light-emitting diodes based on colloidal quantum dots with reduced surface-bulk coupling

Nat Commun. 2023 Jan 17;14(1):284. doi: 10.1038/s41467-023-35954-x.

Authors

Xingtong Chen^{1

2}, Xiongfeng Lin³, Likuan Zhou³, Xiaojuan Sun^{1

2}, Rui Li^{1

2}, Mengyu Chen^{1

2}, Yixing Yang³, Wenjun Hou³, Longjia Wu⁴, Weiran Cao³, Xin Zhang³, Xiaolin Yan³, Song Chen^{5

6}

Affiliations

¹ Suzhou Key Laboratory of Novel Semiconductor-optoelectronics Materials and Devices, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123, Jiangsu, China.
² Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University, Suzhou, 215123, Jiangsu, China.
³ TCL Corporate Research, Shenzhen, 518067, Guangdong, China.
⁴ TCL Corporate Research, Shenzhen, 518067, Guangdong, China. wulongjia@tcl.com.
⁵ Suzhou Key Laboratory of Novel Semiconductor-optoelectronics Materials and Devices, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123, Jiangsu, China. songchen@suda.edu.cn.
⁶ Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University, Suzhou, 215123, Jiangsu, China. songchen@suda.edu.cn.

Abstract

To industrialize printed full-color displays based on quantum-dot light-emitting diodes, one must explore the degradation mechanism and improve the operational stability of blue electroluminescence. Here, we report that although state-of-the-art blue quantum dots, with monotonically-graded core/shell/shell structures, feature near-unity photoluminescence quantum efficiency and efficient charge injection, the significant surface-bulk coupling at the quantum-dot level, revealed by the abnormal dipolar excited state, magnifies the impact of surface localized charges and limits operational lifetimes. Inspired by this, we propose blue quantum dots with a large core and an intermediate shell featuring nonmonotonically-graded energy levels. This strategy significantly reduces surface-bulk coupling and tunes emission wavelength without compromising charge injection. Using these quantum dots, we fabricate bottom-emitting devices with emission colors varying from near-Rec.2020-standard blue to sky blue. At an initial luminance of 1000 cd m^-2, these devices exhibit T₉₅ operational lifetimes ranging from 75 to 227 h, significantly surpassing the existing records.