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Breaking Kasha's Rule as a Mechanism for Solution-Phase Room-Temperature Phosphorescence from High-Lying Triplet Excited State.
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2020-09-11 , DOI: 10.1021/acs.jpclett.0c02180
Changfu Feng 1 , Shuai Li 1 , Liyuan Fu 2 , Xiaoxiao Xiao 2 , Zhenzhen Xu 2 , Qing Liao 2 , Yishi Wu 2 , Jiannian Yao 1, 3 , Hongbing Fu 1, 2
Affiliation  

Organic room-temperature phosphorescence (ORTP) has been demonstrated successfully in solids. In contrast, solution-phase ORTP is rarely achieved, because the T1 → S0 phosphorescence is too slow to compete against nonradiative decay and the oxygen-quenching effect. Here, we reported that suppression of Kasha’s rule is a strategy to achieve solution-phase ORTP from the high-lying T2 state by spatially separating T2 and T1 on different parts of the molecule (CzCbDBT) composed of carbonyl (Cb), dibenzothiophene (DBT), and carbazole moiety (Cz). On one hand, intersystem crossing (ISC) is much faster from S1 to T2 than that to T1, owing to the small energy-gap ΔES1–T2 and large spin–orbital coupling ξS1–T2. On the other hand, T2 → T1 internal conversion is inhibited owing to spatial separation, i.e., T2 on CbDBT and T1 on Cz, respectively. Also, combination of very fast radiative decay from T2 to S0 owing to large ξT2–S0, the efficient solution-phase ORTP emission from the T2 state was finally achieved.

中文翻译:

打破Kasha规则作为解决高相态三重态激发态的溶液相室温磷光的机制。

有机室温磷光(ORTP)已在固体中成功证明。相比之下,由于T 1 →S 0磷光太慢而无法与非辐射衰变和氧猝灭作用竞争,因此很少实现固溶相ORTP 。在这里,我们报道了抑制Kasha规则是一种通过从空间上分离由羰基(Cb)组成的分子(CzCbDBT)上不同位置的T 2和T 1来从高T 2状态获得固溶相ORTP的策略,二苯并噻吩(DBT)和咔唑部分(Cz)。一方面,从S 1到T 2的系统间穿越(ISC)比到T 1的系统间穿越要快得多,由于小的能量间隙Δ ë小号1 -T 2和大的自旋轨道耦合ξ š 1 -T 2。在另一方面,T 2 →T的1内部转换被抑制由于空间分离的,即,T 2上CbDBT和T 1分别对CZ,。此外,非常快速的辐射衰变的组合在T 2至S 0由于大ξ Ť 2 -S 0,从T高效溶液相ORTP发射2状态终于实现。
更新日期:2020-10-02
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