Distinguishing the Quantum Yield and Lifetime of Carbazole‐Based Room‐Temperature Phosphorescence Materials: QM/MM Study
Distinguishing the Quantum Yield and Lifetime of Carbazole‐Based Room‐Temperature Phosphorescence Materials: QM/MM Study
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DOI：
10.1002/andp.202200342
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发表时间：
2022-10
影响因子：
2.4
通讯作者：
Yonggang Yang;Tiantian Guan;Yang Liu;Qi Zhang;Zhinan Jiang;Kai Jiang;Yufang Liu
中科院分区：
文献类型：
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作者：
Yonggang Yang;Tiantian Guan;Yang Liu;Qi Zhang;Zhinan Jiang;Kai Jiang;Yufang Liu
商业咔唑衍生物作为典型的电子给体广泛应用于室温磷光材料中。用量子力学和分子力学方法研究了咔唑基（9 H-咔唑-9-基）异烟腈（P-34 N）晶体的高磷光量子产率（Φp）和短寿命（τp）。P-34 N的高Φp有两个诱因：i）大的自旋轨道耦合（0.63 cm−1）诱导最低单重激发态（S1）到最低三重激发态（T1）的快速系间穿越（ISC），ii）分子间π-π相互作用稳定三重激子。同时，P-34 N的3（n，π*）→1（π，π*）有利于T1的非辐射衰变到基态（S 0），从而导致短τp。与P-34 N相比，6-（9 H-咔唑-9-基）烟腈（P-24 N）晶体的低Φp是由于S1态和更高三重态（T2）之间的小ΔEST（0.3 eV）诱导的有效的逆ISC过程，而长τp是由于T1（π，π*）→ S 0（π，π*）跃迁的不利轨道反转和T2 → T1的内转换过程。这项工作提出了一个合理的解释的Φp和τp的两个咔唑基晶体。
Commercial carbazole derivatives are widely used as typical electron donors in room‐temperature phosphorescence materials. The high phosphorescence quantum yield (Φp) and short lifetime (τp) of the carbazole‐based (9H‐carbazol‐9‐yl)isonicotinonitrile (P‐34N) crystal are distinguished by quantum mechanics and molecular mechanics method. Two inducements are accounted for the high Φp of P‐34N: i) large spin–orbit coupling (0.63 cm−1) induces fast intersystem crossing (ISC) of the lowest singlet excited state (S1) to the lowest triplet excited state (T1), ii) the intermolecular π–π interactions stabilize triplet excitons. Meanwhile, the 3(n, π*) →1(π, π*) of P‐34N favors the nonradiative decay of T1to the ground state (S0), and thus, causes short τp. In contrast to P‐34N, the low Φp of 6‐(9H‐carbazol‐9‐yl)nicotinonitrile (P‐24N) crystal results from the effective reverse ISC process induced by small ΔEST (0.3 eV) between S1 state and the higher triplet state (T2), and the long τp is due to the unfavorable orbital reversals of T1 (π, π*)→S0 (π, π*) transition and the internal conversion process of T2 → T1. This work presents a reasonable interpretation of the Φp and τp of two carbazole‐based crystals.