Ma Zetong, Yang Zhiqiang, Mu Lan, Deng Lisong, Chen Liangjian, Wang Bohan, Qiao Xianfeng, Hu Dehua, Yang Bing, Ma Dongge, Peng Junbiao, Ma Yuguang
Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology Guangzhou 510640 China
State Key Laboratory of Supramolecular Structure and Materials, Jilin University Changchun 130012 China.
Chem Sci. 2021 Oct 19;12(44):14808-14814. doi: 10.1039/d1sc04118e. eCollection 2021 Nov 17.
Manipulating the molecular orbital properties of excited states and the subsequent relaxation processes can greatly alter the emission behaviors of luminophores. Herein we report a vivid example of this, with luminescence conversion from thermally activated delayed fluorescence (TADF) to ultralong room-temperature phosphorescence (URTP) a facile substituent effect on a rigid benzothiazino phenothiazine tetraoxide (BTPO) core. Pristine BTPO with multiple heteroatoms shows obvious intramolecular charge transfer (ICT) excited states with small exchange energy, featuring TADF. delicately functionalizing the BTPO core with peripheral moieties, the excited states of the BTPO derivatives become a hybridized local and charge transfer (HLCT) state in the S state and a local excitation (LE) dominated HLCT state in the T state, with enlarged energy bandgaps. Upon dispersion in a polymer matrix, the BTPO derivatives exhibit a persistent bright green afterglow with long lifetimes of up to 822 ms and decent quantum yields of up to 11.6%.
调控激发态的分子轨道性质以及随后的弛豫过程能够极大地改变发光体的发射行为。在此，我们报告一个生动的例子，即通过对刚性苯并噻嗪并吩噻嗪四氧化物（BTPO）核进行简便的取代基效应，实现了从热激活延迟荧光（TADF）到超长室温磷光（URTP）的发光转换。具有多个杂原子的原始BTPO显示出明显的分子内电荷转移（ICT）激发态，其交换能较小，具有TADF特性。通过用外围基团对BTPO核进行精细功能化，BTPO衍生物的激发态在单重态成为混合局域和电荷转移（HLCT）态，在三重态成为以局域激发（LE）为主的HLCT态，且能带隙增大。在分散于聚合物基质中时，BTPO衍生物表现出持续的亮绿色余辉，寿命长达822毫秒，量子产率高达11.6%。
