Performance improvements in all-solution processed inverted QLEDs realized by inserting an electron blocking layer

Weiye Zheng; Dandan Song; Suling Zhao; Bo Qiao; Zheng Xu; Junfei Chen; Guoxu Liu; Chongyu Shen

doi:10.1088/1361-6528/abfe8e

Performance improvements in all-solution processed inverted QLEDs realized by inserting an electron blocking layer

Nanotechnology. 2021 May 25;32(33). doi: 10.1088/1361-6528/abfe8e.

Authors

Weiye Zheng^{1

2}, Dandan Song^{1

2}, Suling Zhao^{1

2}, Bo Qiao^{1

2}, Zheng Xu^{1

2}, Junfei Chen^{1

2}, Guoxu Liu³, Chongyu Shen³

Affiliations

¹ Key Laboratory of Luminescence and Optical Information, Beijing Jiaotong University, Ministry of Education, Beijing 100044, People's Republic of China.
² Institute of Optoelectronics Technology, Beijing Jiaotong University, Beijing 100044, People's Republic of China.
³ ShineOn (Beijing) Technology Co., Ltd, People's Republic of China.

PMID: 33957607
DOI: 10.1088/1361-6528/abfe8e

Abstract

Highly efficient, all-solution processed inverted quantum dot light-emitting diodes (QLEDs) are demonstrated by employing 1,3,5-tri(m-pyrid-3-yl-phenyl)benzene (TmPyPB) layer as electron blocking layer. Electron injection from ZnO electron transport layer to quantum dots (QDs) emission layer (EML) can be adjusted by thickness of TmPyPB layer, enabling the balanced charge carriers in QDs EML. With optimal thickness of this TmPyPB adjuster, 59.7% increment in the device current efficiency (from 8.2 to 13.1 cd A^-1) and 46.2% improvement in the maximum luminance (from 31916 to 46674 cd m^-2) are achieved, compared with those of the control QLED which has double hole transport layer structure. On the other hand, we find luminescence quenching process, which often happens at the interface of ZnO nanoparticles and QDs, is not obvious in our QLEDs, in which the ZnO layer is fabricated in precursor method, and this conclusion is verified through Time Resolution Photoluminescence test. In a word, this strategy provides a direction for optimizing charge carrier balance in all-solution processed inverted QLED.

Keywords: all-solution process; charge carrier balance; electron blocking layer; exciton quenching; inverted structure; quantum dot light-emitting diode.