Highly Efficient Organic Room-Temperature Phosphorescent Luminophores through Tuning Triplet States and Spin-Orbit Coupling with Incorporation of a Secondary Group

Bowen Li; Yanbin Gong; Lu Wang; Hang Lin; Qianqian Li; Fengyun Guo; Zhen Li; Qian Peng; Zhigang Shuai; Liancheng Zhao; Yong Zhang

doi:10.1021/acs.jpclett.9b02885

Highly Efficient Organic Room-Temperature Phosphorescent Luminophores through Tuning Triplet States and Spin-Orbit Coupling with Incorporation of a Secondary Group

J Phys Chem Lett. 2019 Nov 21;10(22):7141-7147. doi: 10.1021/acs.jpclett.9b02885. Epub 2019 Nov 7.

Authors

Bowen Li¹, Yanbin Gong², Lu Wang^{3

4}, Hang Lin⁵, Qianqian Li², Fengyun Guo¹, Zhen Li², Qian Peng³, Zhigang Shuai⁴, Liancheng Zhao¹, Yong Zhang^{1

6}

Affiliations

¹ School of Materials Science and Engineering , Harbin Institute of Technology , Harbin 150001 , China.
² Department of Chemistry, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials , Wuhan University , Wuhan 430072 , China.
³ Laboratory of Organic Solids and Beijing National Laboratory for Molecular Science , Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190 , China.
⁴ Department of Chemistry and MOE Key Laboratory of Organic Optoelectronics and Molecular Engineering , Tsinghua University , Beijing 100084 , China.
⁵ Key Laboratory of Design and Assembly of Functional Nanostructures , Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences , Fuzhou 350002 , China.
⁶ School of Materials Science and Engineering , Zhengzhou University , Zhengzhou 450001 , China.

PMID: 31659902
DOI: 10.1021/acs.jpclett.9b02885

Abstract

Achieving efficient ultralong purely organic phosphorescent luminophores is still a big challenge due to the slow intersystem crossing (ISC) process. Herein, we present a facile molecular design strategy that incorporates a secondary group (Br atom or methoxy group) into o-BrCz that can significantly enhance the ISC rate constant (k_ISC) and achieve high phosphorescence quantum yields (Φ_P). As a result, DBrCz and MeBrCz achieved a profound increase of k_ISC ≈ 10⁸ s^-1 and obtained excellent Φ_P values up to 24.53 and 27.81% in solid powder, respectively. Given the highly efficient Φ_P and proper τ_p, DBrCz and MeBrCz are applied to alternating current (AC) light-emitting diodes (LEDs), achieving a white LED with CIE coordinates (0.28, 0.29) and a CRI over 90. As a proof of concept, we demonstrate its compensation effect on the dark duration of AC-LED with a reduced percent flicker of 78%. This result extends a new potential application for RTP luminophores in the lighting field.