Charge Carrier Regulation for Efficient Blue Quantum-Dot Light-Emitting Diodes Via a High-Mobility Coplanar Cyclopentane[<i>b</i>]thiopyran Derivative
Fensha Cai, Hao Zong, Meng Li, Chenguang Li, Guangguang Huang, Jorge Pascual, Chao Liang, Zhenhuang Su, Zhe Li, Xingyu Gao, Bo Hou, Shujie Wang, Gang Zhou, Zuliang Du
Abstract
The performance of blue quantum dot light-emitting diodes (QLEDs) is limited by unbalanced charge injection, resulting from insufficient holes caused by low mobility or significant energy barriers. Here, we introduce an angular-shaped heteroarene based on cyclopentane[ b ]thiopyran (C 8 –SS) to modify the hole transport layer poly- N -vinylcarbazole (PVK), in blue QLEDs. C 8 –SS exhibits high hole mobility and conductivity due to the π···π and S···π interactions. Introducing C 8 –SS to PVK significantly enhanced hole mobility, increasing it by 2 orders of magnitude from 2.44 × 10 –6 to 1.73 × 10 –4 cm 2 V –1 s –1 . Benefiting from high mobility and conductivity, PVK:C 8 –SS-based QLEDs exhibit a low turn-on voltage ( V on ) of 3.2 V. More importantly, the optimized QLEDs achieve a high peak power efficiency (PE) of 7.13 lm/W, which is 2.65 times that of the control QLEDs. The as-proposed interface engineering provides a novel and effective strategy for achieving high-performance blue QLEDs in low-energy consumption lighting applications.