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High-power-efficiency thermally activated delayed fluorescence white organic light-emitting diodes based on asymmetrical host engineering
Nano Energy ( IF 17.6 ) Pub Date : 2021-01-10 , DOI: 10.1016/j.nanoen.2021.105746
Jing Zhang , Ying Wei , Hui Xu

Developing thermally activated delayed fluorescence (TADF) white organic light emitting diodes (WOLED) featuring high power efficiencies faces a challenge in balancing carrier transport, energy transfer and quenching suppression. Here, we demonstrate that host matrix is crucial for the modification of optoelectronic process in emissive layers (EML) and the achievement of high power efficiency. Through asymmetrically introducing two or three diphenylphosphine oxide (DPPO) groups, three phosphine oxide (PO) hosts 24DBFDPO, 26DBFDPO and 248DBFTPO were constructed, in which dibenzofuran (DBF) chromophore is embedded by rationally spatial distribution of DPPO groups in 26DBFDPO and 248DBFTPO. Direct steric effect of DPPOs suppresses the host-dopant and dopant-dopant interaction induced quenching and mitigates excessive dopant-dopant energy transfer. Dually-doped white TADF films of 248DBFTPO reveal the improved white color purity with a high quantum yield of ~ 90%. Simultaneously, remote steric and electron-withdrawing effects of DPPOs remedy carrier transport in 248DBFTPO films. Based on a simple trilayer single-EML device structure, 248DBFTPO endowed its full-TADF WOLEDs with the state-of-the-art performance, especially the top-rank power efficiency beyond 70 lm W−1. This work indicates host engineering can provide a feasible approach to realize the practical application of TADF daily lighting.



中文翻译:

基于不对称主体工程的高效率热激活延迟荧光白色有机发光二极管

开发具有高功率效率的热激活延迟荧光(TADF)白色有机发光二极管(WOLED)面临着平衡载流子传输,能量转移和抑制猝灭的挑战。在这里,我们证明了主机矩阵对于修改发光层(EML)中的光电工艺和实现高功率效率至关重要。通过不对称引入两个或三个二苯基膦氧化物(DPPO)基团,构建了三个膦氧化物(PO)主体24DBFDPO26DBFDPO248DBFTPO,其中二苯并呋喃(DBF)发色团通过合理分布26DBFDPO248DBFTPO中的DPPO基团而嵌入。DPPO的直接空间效应抑制了主体-掺杂剂和掺杂剂-掺杂剂相互作用引起的猝灭,并减轻了过量的掺杂剂-掺杂剂能量转移。的双重掺杂的白色TADF膜248DBFTPO显示改进的白色色纯度为〜90%的高量子产率。同时,DPPO的空间位阻和电子吸收效应可以弥补248DBFTPO薄膜中的载流子传输。基于简单的三层单EML器件结构,248DBFTPO赋予其全TADF WOLED先进的性能,尤其是超过70 lm W -1的顶级功率效率。这项工作表明主机工程可以提供一种可行的方法来实现TADF日常照明的实际应用。

更新日期:2021-01-22
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