Details

Autor(en) / Beteiligte

• Bai, Xue
• Wu, Shui-xing
• Duan, Ying-chen
• Pan, Qing-qing
• Gao, Feng-wei
• Kan, Yu-he
• Su, Zhong-min

Titel

Turning conventional non-TADF units into high-lying reverse intersystem crossing TADF emitters: different symmetric D-A-D-type modified donor units

Ist Teil von

• New journal of chemistry, 2022-08, Vol.46 (31), p.15168-15174

Ort / Verlag

Cambridge: Royal Society of Chemistry

Erscheinungsjahr

2022

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• In a variety of skeletal structures of delayed fluorescence molecular materials, the donor-acceptordonor (D-A-D) type has been widely considered for improving the efficiency of the reverse intersystem crossing (RISC) process. Herein, three new D-A-D molecules (PTZ-MPS, TPA-MPS and PCz-MPS) bearing 9,9-dimethylthioxanthene-S,S-sulfur dioxide (MPS) as the electron acceptor group are designed and investigated using theoretical calculations. PTZ-MPS shows the feature of the high-lying reverse intersystem crossing process, which is conducive to improving the exciton utilization of organic light-emitting diodes (OLEDs). PTZ-MPS has a much smaller singlettriplet energy splitting ( E S 1 T 3 = 0.03 eV) than TPA-MPS (Δ E S 1 T 3 = 0.32 eV) and PCz-MPS ( E S 1 T 3 = 0.59 eV). However, it has a much larger spinorbital coupling (SOC) strength (S 1 SOC |T 3 〉 = 1.013 cm −1 ) than TPA-MPS (〈S 1 | SOC |T 3 = 0.311 cm −1 ) and PCz-MPS (〈S 1 | SOC |T 3 〉 = 0.354 cm −1 ), which makes it easy to induce a sufficient RISC from the T n state to the S 1 state. The Δ E ST and SOC are the two most important factors in determining TADF molecules. Therefore, PTZ-MPS is expected to be a potential high-lying excited state delayed fluorescence material candidate, and our work demonstrates that high-performance TADF materials can also be obtained successfully by designing rational molecules. DFT and TD-DFT calculations were performed to turn conventional non-TADF units into high-lying reverse intersystem crossing D-A-D-type TADF emitters.