Exact Solution of Kinetic Analysis for Thermally Activated Delayed Fluorescence Materials

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2021-09, Vol.125 (36), p.8074-8089
• Main Authors: Tsuchiya, Youichi, Diesing, Stefan, Bencheikh, Fatima, Wada, Yoshimasa, dos Santos, Paloma L, Kaji, Hironori, Zysman-Colman, Eli, Samuel, Ifor D. W, Adachi, Chihaya
• Format: Article
• Language: English
• Subjects: A: New Tools and Methods in Experiment and Theory
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/acs.jpca.1c04056

The photophysical analysis of thermally activated delayed fluorescence (TADF) materials has become instrumental for providing insights into their stability and performance, which is not only relevant for organic light-emitting diodes but also for other applications such as sensing, imaging, and photocatalysis. Thus, a deeper understanding of the photophysics underpinning the TADF mechanism is required to push materials design further. Previously reported analyses in the literature of the kinetics of the various processes occurring in a TADF material rely on several a priori assumptions to estimate the rate constants for forward and reverse intersystem crossing. In this report, we demonstrate a method to determine these rate constants using a three-state model together with a steady-state approximation and, importantly, no additional assumptions. Further, we derive the exact rate equations, greatly facilitating a comparison of the TADF properties of structurally diverse emitters and providing a comprehensive understanding of the photophysics of these systems.