Dimerization effects on the electronic properties of candidate OLED materials for optimized performance: a quantum DFT study†

Abstract

In recent years, there has been growing interest in organic light-emitting diode (OLED) materials, highlighting the importance of a thorough understanding of the key factors that influence their electronic and non-linear optical (NLO) properties. To achieve this objective, we considered five candidate OLED compounds: dibenzothio-phen-sulfone-3-yl-9-phenyl-9H-carbazole (DBTS-CzP), 9H-thioxanthene-9-one-dibenzothiophene-sulfone (TXO-CzP), spiro[fluorene-9,9-thioxanthene]-10,10-dioxide (SpDBTS-CzP), 9-[4-(diphenylphosphoryl)-2,2-dimethyl-4-biphenylyl]-9H-carbazole (mCBPPO), and N,N-bis[2-(pyridin-2-yl)phenyl]-N,N-di(n-butyl)phenylamine (DPA-2Py). We employed density functional theory (DFT) and time-dependent DFT (TD-DFT) methods to investigate how dimerization can affect their electronic and NLO characteristics. The results of electronic structure analysis, including HOMO–LUMO gaps and NLO characteristics, reveal that dimerization enhances dipole moments and polarizabilities, facilitating improved charge transfer and electronic transitions. Among the studied compounds, TXO-CzP demonstrates stable electronic properties and exhibits enhanced NLO characteristics post-dimerization—such as efficient charge mobility and superior color purity—positioning it as a promising candidate for advanced OLED applications. These findings underscore dimerized structures’ potential to enhance optoelectronic device performance.