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

Résultats de recherche: Contribution à un journal/une revueArticleRevue par des pairs

Résumé

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.

langue originaleAnglais
Numéro d'article1804490
Pages (de - à)e1804490
journalAdvanced materials
Volume31
Numéro de publication21
Les DOIs
Etat de la publicationPublié - 24 mai 2019
Modification externeOui

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