Enhancement of electro-optical and non-linear optical parameters of halogenated hexahexyloxytriphenylene (HAT6) molecule: A computational approach

An investigation of electro-optical and nonlinear optical properties of pure and halogenated (-Cl, -Br) hexahexyloxytriphenylene (HAT6) molecule is presented employing a density functional theory (DFT) approach. The effect of halogenation on HAT6 molecule is studied by introducing single and double halogens (Cl, Br) in its molecular geometry. The geometries are optimized progressively to achieve stability using B3LYP method with 6-311 basis sets. The physical properties encompassing electro-optical, thermodynamic, and electronic properties of single molecule of HAT6 are computed using DFT method. The introduction of halogens to discotic HAT6 molecule to an augmentation in molecular polarizability, rendering halogenated HAT6 a suitable candidate for nonlinear optical devices due to its pi-pi conjugation and improved optical parameters. The UV-Vis spectra indicate the predominant absorptions and changes in absorption depend on the halogenations of the HAT6 molecule. Also, the halogenation effect leads to a significant reduction in the energy bandgap directly associated with electron-electron correlation, facilitating straightforward tuning. In this theoretical study, halogenated (Br/Cl) yet thermodynamically stable HAT6 molecule is observed to possess enhanced electro-optical properties so that fine-tuning of non-linear optical properties may lead to harmonic generation (SHG) and applicability in molecular electronics, photovoltaics, and biological systems.image