Dual Encapsulation of Electron Transporting Materials To Simplify High-Efficiency Blue Thermally Activated Delayed Fluorescence Devices
Dual Encapsulation of Electron Transporting Materials To Simplify High-Efficiency Blue Thermally Activated Delayed Fluorescence Devices
复制标题
电子传输材料的双重封装可简化高效蓝色热激活延迟荧光器件
DOI：
10.1021/acs.chemmater.6b03518
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发表时间：
2016
影响因子：
8.6
通讯作者：
Xu Hui
中科院分区：
文献类型：
--
作者：
Kan Wenjing;Duan Chunbo;Sun Mingzhi;Han Chunmiao;Xu Hui
电荷通量平衡和界面优化是简化蓝色热激活延迟荧光（TADF）二极管时的两个核心问题，这反映了对载流子传输材料（CTM）的更严格要求，因为CTM体现了电荷传输和猝灭抑制之间的矛盾，而对分子间相互作用的要求则相反。本文以苯基苯并咪唑（PBI）为核，用两个二苯基氧化膦（DPPO）基团取代，合成了六种双包封的电荷-激子分离（CES）型电子传输材料（ETM），统称为xyPBIDPO。通过调整DPPO基团的取代位置，将其共振和空间位阻两种功能进行整合优化，在不降低电活性的前提下，提高了电荷包封率。结果表明，双台面取代结构和近似对称的构型使双台面取代PBIDPO，mmPBIDPO成功地实现了良好的电学性能和界面相互作用的平衡，具有2.8eV的良好电子亲和势和10- 6cm ~ 2 V ~（-1）s ~（-1）的高电子迁移率，并实现了有效的PBI-核封装。因此，mmPBIDPO被用于极大地简化蓝色TADF器件，其具有三层和四层结构的最先进性能，例如最大外部量子效率（EQE）超过20%和提高的效率稳定性。该工作不仅为高性能简单结构蓝色TADF器件的CES型ETM材料的制备奠定了坚实的基础，而且为今后此类材料的发展提供了方向。
The charge flux balance and interfacial optimization are two core concerns when simplifying blue thermally activated delayed fluorescence (TADF) diodes, which reflects the more stringent demand on carrier transporting materials (CTM) as the embodiment of the contradiction between charge transportation and quenching suppression with the opposite requirement on intermolecular interactions. Herein, phenylbenzimidazole (PBI) was used as the core substituted with two diphenylphosphine oxide (DPPO) groups to form six dual-encapsulated charge–exciton separation (CES)-type electron transporting materials (ETM) with the collective name ofxyPBIDPO. Through tuning the substitution positions of DPPO group, its two functions of resonance and steric effects were integrated and optimized to enhance charged moiety encapsulation without cost of reducing electroactivity. As the result, amongxyPBIDPO,mmPBIDPOsuccessfully realizes the balance of favorable electrical performance and interfacial interaction suppressions in virtue of its doubledmesa-substitution structure and roughly symmetrical configuration, rendering the good electron affinity of 2.8 eV, the high electron mobility by the level of 10–6cm2V–1s–1and effectivePBI-core encapsulation. Consequently,mmPBIDPOwas used to extremely simplify the blue TADF devices with the state-of-the-art performance from trilayer and quadruple-layer configurations, such as the maximum external quantum efficiency (EQE) beyond 20% and improved efficiency stability. This work not only established a solid example of CES-type ETM for high-performance simple structured blue TADF devices but also provided the direction of developing this kind of materials in the future.