Site Effect of Electron Acceptors on Ultralong Organic Room-Temperature Phosphorescence

作者：Xingda Zhang, Yiran Liu, Lijuan Bu, Jingjuan Bai, Zewei Li, Zhimin Ma, Zhimin Ma, Mingxing Chen, Yan Guan, Zhiyong Ma, Zhiyong Ma · 发表于：ACS Applied Materials & Interfaces · 年份：2024 · DOI：10.1021/acsami.4c16078 · 被引用次数：15 · 研究领域：Luminescence and Fluorescent Materials、Organic Light-Emitting Diodes Research、Conducting polymers and applications

Herein, we successfully observe the site effect of electron acceptors on ultralong organic room-temperature phosphorescence (UORTP) in the case of 7 H -benzo[ c ]carbazole (BCz) derivatives: cyanophenyl on the nitrogen site can promote intersystem crossing (ISC) efficiency and enhance phosphorescence intensity by facilitating n –π* transitions but make a slight change to the phosphorescence wavelength; cyanophenyl on the naphthalene site can cause a remarkable red shift of phosphorescence wavelength by reducing the T 1 energy level of BCz derivatives and also enhance phosphorescence intensity by promoting ISC but weaken phosphorescence intensity by lowering the molecular symmetry. Three BCz derivatives (1-BCzPhCN, 2-BCzPhCN, and 3-BCzPhCN) with the electron acceptor cyanophenyl at different sites (nitrogen site and naphthalene site) were synthesized through a combination of the nucleophilic substitution reaction and the Suzuki coupling reaction. The phosphorescence properties of 1-BCzPhCN, 2-BCzPhCN, and 3-BCzPhCN in toluene solution, in a copolymerized MMA film, and in a PVA film were measured and analyzed. 1-BCzPhCN emits intrinsic green ultralong phosphorescence at ∼500, ∼536, and ∼580 nm, while 2-BCzPhCN and 3-BCzPhCN give out intrinsic yellow ultralong phosphorescence with a red shift of 27 and 40 nm, showing that cyanophenyl on the naphthalene site leads to a remarkable red shift of the intrinsic phosphorescence wavelength, but cyanophenyl on the nitrogen site makes a s...