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

Cai, Fensha; Zong, Hao; Li, Meng; Li, Chenguang; Huang, Guangguang; Pascual, Jorge; Liang, Chao; Su, Zhenhuang et al. · Nano Lett · 2024

basic_science · Level V

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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[<i>b</i>]thiopyran (C<sub>8</sub>-SS) to modify the hole transport layer poly-<i>N</i>-vinylcarbazole (PVK), in blue QLEDs. C<sub>8</sub>-SS exhibits high hole mobility and conductivity due to the π···π and S···π interactions. Introducing C<sub>8</sub>-SS to PVK significantly enhanced hole mobility, increasing it by 2 orders of magnitude from 2.44 × 10<sup>-6</sup> to 1.73 × 10<sup>-4</sup> cm<sup>2</sup> V<sup>-1</sup> s<sup>-1</sup>. Benefiting from high mobility and conductivity, PVK:C<sub>8</sub>-SS-based QLEDs exhibit a low turn-on voltage (<i>V</i><sub>on</sub>) 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.