Computational Investigation of SomeXanthene-Based Molecules for Optoelectronic Properties: DFT and TD-DFT Study

Abstract

In this study, we present the design and theoretical investigation of four xanthene-based molecules such as fluorescein (F), fluorescein hydrazide (FH), 2-((4-(dimethylamino) benzylidene) amino)-3′,6′- dihydroxyspiro[isoindoline-1,9′-xanthen] 3-one (DMAB-HIX) and 2-((anthracen-9-ylmethylene) amino)-3',6'-dihydroxyspiro[isoindoline-1,9'-xanthen]-3-one (ANT-HIX) to explore the optical and electronic properties for potential application in optoelectronic devices. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations were employed to evaluate frontier molecular orbitals, chemical reactivity descriptors, absorption and emission spectra, excitation binding energies, excited-state lifetime and light-harvesting efficiencies. The results reveal that molecular functionalization significantly influences the optoelectronic behaviour of the studied systems. In particular, DMAB-HIX shows a shorter excited-state lifetime, higher light-harvesting efficiency and a lower HOMO-LUMO energy gap, attributed to the strong electron-donating effect of the dimethylamino substituents (DMA). These finding establish clear structure-property relationships and suggest that DMAB-HIX shows potential as a high-performance OLED emissive material.

KEYWORDS

Optoelectronic properties; Xanthene; DFT; light-emitting; excitation energy.