Photoluminescence Quenching Probes Spin Conversion and Exciton Dynamics in Thermally Activated Delayed Fluorescence Materials

Brett Yurash, Hajime Nakanotani, Yoann Olivier, David Beljonne, Chihaya Adachi, Thuc Quyen Nguyen

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

Fluorescent materials that efficiently convert triplet excitons into singlets through reverse intersystem crossing (RISC) rival the efficiencies of phosphorescent state-of-the-art organic light-emitting diodes. This upconversion process, a phenomenon known as thermally activated delayed fluorescence (TADF), is dictated by the rate of RISC, a material-dependent property that is challenging to determine experimentally. In this work, a new analytical model is developed which unambiguously determines the magnitude of RISC, as well as several other important photophysical parameters such as exciton diffusion coefficients and lengths, all from straightforward time-resolved photoluminescence measurements. From a detailed investigation of five TADF materials, important structure–property relationships are derived and a brominated derivative of 2,4,5,6-tetrakis(carbazol-9-yl)isophthalonitrile that has an exciton diffusion length of over 40 nm and whose excitons interconvert between the singlet and triplet states ≈36 times during one lifetime is identified.

Original languageEnglish
Article number1804490
JournalAdvanced Materials
Volume31
Issue number21
DOIs
Publication statusPublished - May 24 2019

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

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