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

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-9<i>H</i>-carbazole (DBTS-CzP), 9<i>H</i>-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]-9<i>H</i>-carbazole (mCBPPO), and <i>N</i>,<i>N</i>-bis[2-(pyridin-2-yl)phenyl]-<i>N</i>,<i>N</i>-di(<i>n</i>-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.