Qiu Weidong, Cai Xinyi, Li Mengke, Chen Zijian, Wang Liangying, Xie Wentao, Liu Kunkun, Liu Ming, Su Shi-Jian
State Key Laboratory of Luminescent Materials and Devices and Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Wushan Road 381, Tianhe District, Guangzhou 510640, Guangdong, P. R. China.
South China Institute of Collaborative Innovation, Dongguan 523808, China.
J Phys Chem Lett. 2021 May 20;12(19):4600-4608. doi: 10.1021/acs.jpclett.1c01095. Epub 2021 May 10.
Strategies for developing purely organic materials exhibiting both high efficiency and persistent room-temperature phosphorescence (RTP) have remained ambiguous and challenging. Herein, we propose that introducing an intermediate charge transfer (CT) state into the donor-acceptor binary molecular system holds promise for accomplishing this goal. Guest materials showing gradient ionization potentials were selected to fine-tune the intermolecularly formed CT state when doped into the same host material with a large electron affiliation potential. Such a CT intermediate state accelerates the population of the triplet exciton to benefit phosphorescent emission and decreases the phosphorescence lifetime via quenching the long-lived triplet excitons. As a result, a "trade-off" between a long phosphorescence lifetime (595 ms) and a high phosphorescent quantum yield (27.5%) can be obtained by tuning the host-guest energy gap offset. This finding highlights the key role of CT in RTP emission and provides new guidance for developing novel RTP systems.
开发兼具高效率和持久室温磷光（RTP）的纯有机材料的策略一直不明确且具有挑战性。在此，我们提出在供体-受体二元分子体系中引入中间电荷转移（CT）态有望实现这一目标。当掺杂到具有大电子亲和势的同一主体材料中时，选择具有梯度电离势的客体材料来微调分子间形成的CT态。这种CT中间态加速了三重态激子的布居以利于磷光发射，并通过猝灭长寿命三重态激子来降低磷光寿命。结果，通过调节主体-客体能隙偏移，可以在长磷光寿命（595毫秒）和高磷光量子产率（27.5%）之间实现“权衡”。这一发现突出了CT在RTP发射中的关键作用，并为开发新型RTP系统提供了新的指导。
