Lee Ja Min, Lee Sae Won, Kim Young Sik
Department of Information Display, Hongik University, Seoul 04066, Korea.
J Nanosci Nanotechnol. 2020 Nov 1;20(11):7196-7200. doi: 10.1166/jnn.2020.18858.
We designed a novel thermally activated delayed fluorescence (TADF) host molecules for blue elec-trophosphorescence by combining the electron acceptor benzimidazole (BI) unit and the electron donor acridine derivatives into a single molecular unit based on density functional theory (DFT). We obtained the energies of the first singlet () and the first triplet () excited states of the TADF materials by performing DFT and time-dependent DFT (TD-DFT) calculations on the ground state using dependence on charge transfer amounts for the optimal Hartree-Fock percentage in the exchange-correlation of TD-DFT. The DFT and TD-DFT calculations showed that the large separation between the highest occupied molecular orbital and the lowest unoccupied molecular orbital caused a small difference in energy (Δ) between the and states. The host molecules retained a high triplet energy and demonstrated a great potential for use in blue phosphorescent organic light-emitting diodes. The results showed that these molecules are promising host materials for TADF OLEDs because they have a low barrier to hole and electron injection, a balanced charge transport for both holes and electrons, and a small Δ.
我们基于密度泛函理论（DFT），通过将电子受体苯并咪唑（BI）单元和电子供体吖啶衍生物组合成单个分子单元，设计了一种用于蓝色电磷光的新型热激活延迟荧光（TADF）主体分子。我们通过对基态进行DFT和含时密度泛函理论（TD-DFT）计算，并利用TD-DFT交换关联中最佳Hartree-Fock百分比对电荷转移量的依赖性，获得了TADF材料的第一单线态（）和第一三线态（）激发态的能量。DFT和TD-DFT计算表明，最高占据分子轨道和最低未占据分子轨道之间的大间距导致单线态和三线态之间的能量差（Δ）较小。主体分子保留了较高的三线态能量，并在蓝色磷光有机发光二极管中显示出巨大的应用潜力。结果表明，这些分子是TADF OLEDs很有前景的主体材料，因为它们具有较低的空穴和电子注入势垒、空穴和电子的平衡电荷传输以及较小的Δ。
