Charge Carrier Regulation for Efficient Blue Quantum-Dot Light-Emitting Diodes Via a High-Mobility Coplanar Cyclopentane[b]thiopyran Derivative

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 (C₈-SS) to modify the hole transport layer poly-N-vinylcarbazole (PVK), in blue QLEDs. C₈-SS exhibits high hole mobility and conductivity due to the π···π and S···π interactions. Introducing C₈-SS to PVK significantly enhanced hole mobility, increasing it by 2 orders of magnitude from 2.44 × 10^-6 to 1.73 × 10^-4 cm² V^-1 s^-1. Benefiting from high mobility and conductivity, PVK:C₈-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.