Design and theoretical investigation of diphenylsulfone-based blue-emitting TADF materials for advanced OLED...

This theoretical study addresses the challenge of creating efficient and stable blue-emitting materials for organic light-emitting diodes (OLEDs) by investigating a new series of diphenylsulfone (DPS) derivatives. The research focuses on designing compounds with favorable properties for thermally activated delayed fluorescence (TADF), a mechanism that allows for highly efficient light emission by utilizing both singlet and triplet excitons. The designed compounds demonstrate optimized singlet-triplet energy gaps ( $\Delta E_{\mathrm{ST}}$ ) ranging from 0.11 to 0.29 eV, which facilitates efficient reverse intersystem crossing (RISC). Simulations of their UV-Vis spectra show blue to bluish-green emission, with high photoluminescence quantum yields and peak wavelengths between 367 and 433 nm. Further analyses using electrostatic potential maps, a localized-orbital locator (LOL), and a reduced density gradient (RDG) confirm the electronic localization and non-covalent interactions essential for efficient TADF emission. The findings underscore the effectiveness of molecular design in tuning properties for advanced optoelectronic applications.

Density functional theory (DFT) and time-dependent DFT (TD-DFT) were used to explore the structural, electronic, and photophysical properties of the compounds. Ground-state geometries were optimized using the B3LYP/6-311G(d,p) level of theory in the gas phase. For accurate simulation of intermolecular charge transfer, excited-state calculations were performed with the CAM-B3LYP/6-311G(d,p) level. Computational analyses, including electrostatic potential, localized-orbital locator, and reduced density gradient, were conducted using the Gaussian 09 and Multiwfn 3.8 program suites. Molecular structures and properties were visualized with GaussView 5.0.8, while spectroscopic data were analyzed with Origin(Pro) 2024b.