Towards Efficient and Stable Donor-Acceptor Luminescent Radicals

Chen Lu, Eunkyung Cho, Zhiyuan Cui, Yuhang Gao, Wenjuan Cao, Jean Luc Brédas, Veaceslav Coropceanu, Feng Li

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

In contrast to closed-shell luminescent molecules, the electronic ground state and lowest excited state in organic luminescent radicals are both spin doublet, which results in spin-allowed radiative transitions. Most reported luminescent radicals with high photoluminescent quantum efficiency (PLQE) have a donor-acceptor (D–A•) chemical structure where an electron-donating group is covalently attached to an electron-withdrawing radical core (A•). Understanding the main factors that define the efficiency and stability of D-A• type luminescent radicals remains challenging. Here, we designed and synthesized a series of tri(2,4,6-trichlorophenyl)methyl (TTM) radical derivatives with donor substituents varying by their extent of conjugation and their number of imine-type nitrogen atoms. The experimental results suggest that the luminescence efficiency and stability of the radicals are proportional to the degree of conjugation but inversely proportional to the number of imine nitrogen atoms in the substituents. These experimental trends are very well reproduced by density functional theory calculations. The theoretical results indicate that both the luminescence efficiency and radical stability are related to the energy difference between the charge transfer (CT) and local-excitation (LE) states, which decreases as either the number of imine nitrogen atoms in the substituent increases or its conjugation length decreases.

Original languageEnglish (US)
Article number2208190
JournalAdvanced Materials
Volume35
Issue number6
DOIs
StatePublished - Feb 9 2023
Externally publishedYes

Keywords

  • charge transfer state
  • local-excitation state
  • luminescent radicals
  • photoluminescent quantum efficiency
  • stability

ASJC Scopus subject areas

  • General Materials Science
  • Mechanics of Materials
  • Mechanical Engineering

Fingerprint

Dive into the research topics of 'Towards Efficient and Stable Donor-Acceptor Luminescent Radicals'. Together they form a unique fingerprint.

Cite this