Red-shifted optical absorption induced by donor–acceptor–donor π-extended dibenzalacetone derivatives

Abstract

Chalcones demonstrate significant absorption in the near ultraviolet-visible spectrum, making them valuable for applications such as solar cells, light-emitting diodes, and nonlinear optics. This study investigates four dibenzalacetone derivatives (DBAd), DBA, DBC, DEP, and DMA, examining the impact of electron-donating and electron-withdrawing groups and conjugation elongation on their electronic structure in solvents of varying polarities. Using the Polarizable Continuum Model (PCM) and time-dependent density functional theory (TD-DFT), we characterized the excited states of these compounds. Our results reveal a consistent red-shift in the absorption spectrum, with electron-donating groups like ethoxy inducing a more pronounced red-shift than chlorine. Extending conjugation in DMA further shifted the absorption band to lower energy. Solvatochromism influenced the absorption intensities, underscoring the importance of evaluating parameters beyond λ_max. Although our methodologies provided a satisfactory correlation between theoretical and experimental data, they also indicate the need for further theoretical models to accurately capture solute–solvent interactions and describe charge-separated states. The results indicated that dibenzalacetone derivatives have potential as alternative materials for development of organic solar cells.