<br>基于含有吲哚[3,2,1-jk]咔唑的 MR-TADF 材料的高效 OLED，可降低效率滚降,Advanced Optical Materials

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基于含有吲哚[3,2,1-jk]咔唑的 MR-TADF 材料的高效 OLED，可降低效率滚降
Advanced Optical Materials ( IF 8.0 ) Pub Date : 2024-03-27 , DOI: 10.1002/adom.202400200
Shi‐Quan Song ₁ , Ching‐Fai Yip ₁ , Qi‐Ming Liu ₁ , Xiao‐Sheng Zhong ₁ , Yi Wang ₁ , You‐Xuan Zheng ₁

Affiliation

多重共振热激活延迟荧光（MR-TADF）材料由于其窄带发射，可以满足显示器高色域的要求。然而，大多数报道的基于 MR-TADF 材料的有机发光二极管 (OLED) 都存在严重的效率下降问题。在此，通过将大的吲哚并[3,2,1-jk]咔唑（ICz）单元引入到其中，获得了三种绿色MR-TADF发射器：p-ICz-BNCz、m-ICz-BNCz和dm-ICz-BNCz。经典的 DtBuCzB 骨架位于相对于硼取代苯环的对位或间位。与ICz的对位取代相比，间位取代不仅使m-ICz-BNCz和dm-ICz-BNCz的反向系间窜越速率常数增加了近3倍，而且使它们的构型更加扭曲。这两个因素共同作用，提高了发射体三线态激子的利用率，光致发光量子产率超过90%。结果，两个相应的 OLED 的最大外量子效率 (EQE _max ) 值分别为 28% 和 32.9%，并且效率滚降较低。在1000 cd m ⁻² 的高亮度下，两款器件的EQE值仍然分别维持在19.3%和25.0%。此外，还观察到国际照明委员会坐标为（0.20，0.70）和（0.30，0.67）的绿色排放。

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Efficient OLEDs with Alleviated Efficiency Roll-Off Based on MR-TADF Materials Containing Indolo[3,2,1-jk]carbazole

The multiple resonance thermally activated delayed fluorescence (MR-TADF) materials can meet the requirement of a high color gamut of displays due to their narrowband emission. However, most reported organic light-emitting diodes (OLEDs) based on MR-TADF materials suffer from severe efficiency roll-off. Herein, three green MR-TADF emitters, p-ICz-BNCz, m-ICz-BNCz, and dm-ICz-BNCz, are obtained by introducing bulky indolo[3,2,1-jk]carbazole (ICz) units into the classical DtBuCzB skeleton at the para or meta positions relative to the boron-substituted phenyl ring. Compared with the para-substitution of ICz, the meta-substitution not only increases the reverse intersystem crossing rate constants of m-ICz-BNCz and dm-ICz-BNCz by nearly three times, but also makes their configurations more twisted. The two factors work together to improve the utilization of triplet excitons of the emitters, showing photoluminescence quantum yields exceeding 90%. As a result, the two corresponding OLEDs exhibit maximum external quantum efficiency (EQE_max) values of 28% and 32.9%, respectively, with low-efficiency roll-off. At the high brightness of 1000 cd m⁻², the EQE values of the two devices still maintain at 19.3% and 25.0%, respectively. In addition, green emissions with Commission Internationale de l'Eclairage coordinates of (0.20, 0.70) and (0.30, 0.67) are also observed.

更新日期：2024-03-27

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