通过促进多种激发态混合来实现低效率滚降的溶液加工 OLED 的高效不对称 TADF 树枝状聚合物,ACS Materials Letters

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通过促进多种激发态混合来实现低效率滚降的溶液加工 OLED 的高效不对称 TADF 树枝状聚合物
ACS Materials Letters ( IF 9.6 ) Pub Date : 2024-03-15 , DOI: 10.1021/acsmaterialslett.4c00273
Kun Shi ₁ , Yanchao Xie ₁ , Lei Hua ₂ , Shengyu Li ₁ , Zhi Yang ₁ , Yuwei Yin ₁ , Zhi Wang ₁ , Shian Ying ₁ , Yuchao Liu ₁ , Zhongjie Ren ₂ , Shouke Yan _{1,

2}

Affiliation

热激活延迟荧光 (TADF) 树枝状聚合物正在成为溶液加工有机发光二极管 (OLED) 的有希望的候选者，但生产具有低效率滚降的基于 TADF 树枝状聚合物的高效 OLED 仍然具有挑战性。在此，我们提出了三种不对称 TADF 树枝状聚合物，揭示了辐射衰变和激子上转换途径容易受到这些不对称 TADF 树枝状聚合物的外围树枝状分子的调节。尤其是第二代树枝状大分子DMAC-BP- t Bu3Cz，光致发光量子产率可达94%，反向系间窜越速率常数为1.3 × 10 ⁶ s ^–1。此外，它还表现出优异的电致发光性能，最大外量子效率（EQE）为28.0%，并在1000 cd m ^–2下保持24.9%的值，这是基于TADF树枝状聚合物的OLED在如此高的发光效率下的最高效率。同时，采用DMAC-BP -t Bu3Cz作为TADF敏化掺杂剂的超荧光三元OLED在1000 cd m ^–2下表现出18.4%的提升EQE值和仅4.9%的效率滚降，其中EQE为17.5%，同时半峰全宽为 39 nm 的纯绿光发射。

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High-Efficiency Asymmetric TADF Dendrimers via Promoting Mixing of Multiple Excited States toward Solution-Processed OLEDs with Low Efficiency Rolloff

Thermally activated delayed fluorescence (TADF) dendrimers are emerging as promising candidates for solution-processed organic light-emitting diodes (OLEDs), but it is still challenging to produce high-efficiency TADF dendrimer-based OLEDs with low efficiency roll-off. Herein, we propose three asymmetric TADF dendrimers, unveiling that the radiative decay and exciton upconversion avenues are susceptible to the regulation of peripheral dendrons for these asymmetric TADF dendrimers. Especially for the second-generation dendrimer of DMAC-BP-tBu3Cz, photoluminescence quantum yields can reach 94%, together with rate constant of reverse intersystem crossing of 1.3 × 10⁶ s^–1. Additionally, it exhibits an excellent electroluminescence properties with maximum external quantum efficiency (EQE) of 28.0%, and maintaining a value of 24.9% at 1000 cd m^–2, which is the highest efficiency of TADF dendrimer-based OLED at such a high luminescence. Meanwhile, the hyper-fluorescence ternary OLEDs employing DMAC-BP-tBu3Cz as a TADF sensitizing dopant exhibit a boosted EQE value of 18.4% and greatly alleviative efficiency rolloff of only 4.9% with 17.5% EQE at 1000 cd m^–2, accompanied by pure green emission with a full-width-at-half-maximum of 39 nm.

更新日期：2024-03-15

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