From aggregation-caused quenching to aggregation-induced delayed fluorescence: the impact of the effect of substituents

Abstract

The electroluminescent mechanism of four imidazole-based luminogens are explored. Results show that introducing different substituents can change the molecules from aggregation-caused quenching to aggregation-induced delayed fluorescence.

An effective method in modulating thermally activated delayed fluorescence (TADF) emitters from green to blue emission: the role of the phenyl ring

“…The decay rate constants from the S 1 to S 0 states and the interconversion rate constants between the S 1 and T 1 states are key parameters in determining the electroluminescence mechanism of the SOXO-based TADF molecules. The radiative decay rate k r is calculated by the Einstein spontaneous emission equation as follows: 42–44 where f is the oscillator strength and Δ E fi is the vertical emission energy with the unit of wavenumber (cm −1 ).…”

“…Φ f and Φ i are the wavefunctions of the final state and the initial states, respectively. ρ ic fi is the thermal vibration correlation function (TVCF), 42–44 which is Here, Z i represents the partition function.…”

“…The intersystem crossing rate constant between the singlet and triplet states can be evaluated based on the following equation: 42,43 The detailed derivation of these equations can be found in Peng and Shuai's work. 45–47…”