Universal Multistate Kinetic Models for the In-Silico Discovery of Thermally Activated Delayed Fluorescence Emitters

Abstract: Many thermally activated delayed fluorescence (TADF) emitters exhibit complex photophysical behaviors that cannot be fully captured by the conventional three state model (S0, S1, T1). The lack of kinetic models that incorporate vibronic coupling effects and high lying excited states has long limited the systematic understanding and rational design of these materials. To address this, we developed KinLuv, an extended multistate kinetic model that not only includes higher lying excited states (S2, T2) but also accounts for the Herzberg Teller (HT) vibronic coupling in the rate constant calculations. Applied to two representative TADF emitters, i.e., DOBNA and DiKTa, KinLuv successfully predicts photoluminescence quantum yields (PLQY) and prompt/delayed fluorescence lifetimes in good agreement with reported experimental results. These findings highlight that incorporating HT vibronic coupling effects and higher lying excited states is essential for quantitatively modeling TADF mechanisms and guiding the design of high performance emitters.