Facile modification of multi-resonance acceptors and donors in intramolecular TSCT-TADF emitters for OLEDs: a computational study

Recently, through-space charge transfer (TSCT) has attracted considerable interest in the development of thermally activated delayed fluorescence (TADF) emitters. Therefore, the TSCT-TADF molecules were designed by extending the reported carbazole donor with additional diphenylamine and dimethylacridine donors, combined with MRAs containing oxygen and heavy atoms. The molecular frameworks are based on phenyl and pyridine core, connected via a tCz linker, enabling the investigation of effects of donors and heavy-atom substitution on the photophysical and electronic properties using DFT and TD-DFT using Gaussian-09 software. The findings reveal that PDPA containing molecules with MRA exhibit low ΔE_ST, moderate SOC, and enhanced radiative and effective RISC rates. The desired properties are achieved in the PDPA with the OB molecule showing reduced structural relaxation and achieving a narrow FWHM with high PLQY. These findings highlight that donor strength, along with the MRA acceptor, plays a key role in determining the efficiency of TSCT-TADF molecules.