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- Title
Tailoring Excited State Properties and Energy Levels Arrangement via Subtle Structural Design on D-π-A Materials.
- Authors
Liang, Xiaoming; Wang, Zhiheng; Wang, Liangxuan; Hanif, Muddasir; Hu, Dehua; Su, Shijian; Xie, Zengqi; Gao, Yu; Yang, Bing; Ma, Yuguang
- Abstract
The donor-π-conjugated-acceptor (D-π-A) structure is an important design for the luminescent materials because of its diversity in the selections of donor, π-bridge and acceptor groups. Herein, we demonstrate two examples of D-π-A structures capable to finely modulate the excited state properties and arrangement of energy levels, TPA-AN-BP and CZP-AN-BP, which possess the same acceptor and π-bridge but different donor. The investigation of their photophysical properties and DFT calculation revealed that the D-π-A structure with proper donor, π-bridge and acceptor can result in separation of frontier molecular orbitals on the corresponding donor and acceptor with an obvious overlap on the π-bridge, resulting in a hybridized local and charge-transfer ( HLCT) excited state with high photoluminescent ( PL) efficiencies. Meanwhile, their singlet and triplet states are arranged on corresponding moieties with large energy gap between T2 and T1, and a small energy gap between S1 and T2, which favor the reverse intersystem crossing ( RISC) from high-lying triplet levels to singlet levels. As a result, the sky-blue emission non-doped OLED based on the TPA-AN-BP reached maximum external quantum efficiency ( EQE) of 4.39% and a high exciton utilization efficiency ( EUE) of 77%. This study demonstrates a new strategy to construct highly efficient OLED materials.
- Subjects
ENERGY levels (Quantum mechanics); PHOTOLUMINESCENCE; SOLAR cells; LUMINOPHORES; INTRAMOLECULAR charge transfer; CHARGE transfer
- Publication
Chinese Journal of Chemistry, 2017, Vol 35, Issue 10, p1559
- ISSN
1001-604X
- Publication type
Article
- DOI
10.1002/cjoc.201700211