Efficient tandem organic light-emitting diodes with non-doped structures

Yue Qin; Chen-Yang Liu; Rui-Qing Li; Jiong Wang; Ya-Nan Lu; Yue-Hua Chen; Yu-Zhu Wang; Ya-Nan Xu; Xin-Wen Zhang; Wei Huang

doi:10.1364/OL.409613

Efficient tandem organic light-emitting diodes with non-doped structures

Opt Lett. 2020 Dec 1;45(23):6450-6453. doi: 10.1364/OL.409613.

Authors

Yue Qin, Chen-Yang Liu, Rui-Qing Li, Jiong Wang, Ya-Nan Lu, Yue-Hua Chen, Yu-Zhu Wang, Ya-Nan Xu, Xin-Wen Zhang, Wei Huang

PMID: 33258834
DOI: 10.1364/OL.409613

Abstract

Highly efficient tandem organic light-emitting diodes (TOLEDs) were achieved based on a non-doped charge generation unit (CGU) consisting of LiF/Al/C60/4,4',4"-tris(N-3-methylphenyl-N-phenyl-amino) triphenylamine (m-MTDATA) and ultrathin emitting layers. The current-voltage characteristics of the CGU devices and electron-only devices and the capacitance-voltage characteristics of the CGU-based capacitance devices were characterized to explore the charge generation and injection mechanisms. The charge generation process occurs at the interface of C60/m-MTDATA through electron transferring from the highest occupied molecular orbital of m-MTDATA to the lowest unoccupied molecular orbital of C60. It is found that the thinner C60 layer contributes to efficient electron injection. Under the optimal structure, the blue TOLEDs exhibit a maximum current efficiency (CE_max) of 43.3 cd/A. The CE_max and maximum external quantum efficiency (EQE_max) of the white TOLEDs reach 84.6 cd/A and 26.7%, respectively.