Impact of Dielectric Constant on the Singlet-Triplet Gap in Thermally Activated Delayed Fluorescence Materials

Haitao Sun, Zhubin Hu, Cheng Zhong, Xiankai Chen, Zhenrong Sun, Jean Luc Brédas

研究成果: ジャーナルへの寄稿学術誌査読

88 被引用数 (Scopus)

抄録

Thermally activated delayed fluorescence (TADF) relies on the presence of a very small energy gap, ΔEST, between the lowest singlet and triplet excited states. ΔEST is thus a key factor in the molecular design of more efficient materials. However, its accurate theoretical estimation remains challenging, especially in the solid state due to the influence of polarization effects. We have quantitatively studied ΔEST as a function of dielectric constant, ϵ, for four representative organic molecules using the methodology we recently proposed at the Tamm-Dancoff approximation ωB97X level of theory, where the range-separation parameter ω is optimized with the polarizable continuum model. The results are found to be in very good agreement with experimental data. Importantly, the polarization effects can lead to a marked reduction in the ΔEST value, which is favorable for TADF applications. This ΔEST decrease in the solid state is related to the hybrid characters of the lowest singlet and triplet excited states, whose dominant contribution switches to charge-transfer-like with increasing ϵ. The present work provides a theoretical understanding on the influence of polarization effect on the singlet-triplet gap and confirms our methodology to be a reliable tool for the prediction and development of novel TADF materials.

本文言語英語
ページ(範囲)2393-2398
ページ数6
ジャーナルJournal of Physical Chemistry Letters
8
11
DOI
出版ステータス出版済み - 6月 1 2017
外部発表はい

!!!All Science Journal Classification (ASJC) codes

  • 材料科学(全般)
  • 物理化学および理論化学

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