Experimental and DFT insights into molecular structure and optical properties of new chalcones as promising photosensitizers towards solar cell applications

Abstract

A new series of (hydroxyl-arylazo)-chalcone derivatives (5a → e) has been prepared by condensation of 4-(4-acetylphenyl)-azo dyes 3 with 4-anisaldehyde in basic medium. The chemical structures were confirmed by elemental analysis, FT-IR, 1H NMR and Mass Spectra. The thin films of chalcone derivatives have been prepared using thermal evaporation technique under vacuum pressure of 10−5 mbar. The structural formation of these pristine films has been investigated using the field emission scanning electron microscopy (FESEM) and showed nanorod-structured chalcone thin films. The optical features of films are studied using spectrophotometric technique in the spectral wavelength range 200–2500 nm, from which the optical constants and the dispersion parameters are calculated. To identify these obtained experimental results, DFT calculations have been carried out at the B3LYP/6-311G (d,p) level of theory. The value of transport energy (Et) computed from DFT can exceed the value of optical energy gap (Egopt) determined from UV-vis spectroscopy by 0.45–1.15 eV due to the exciton binding energy (EB).Unraveling the correlated structural and optical properties of chalcones 5a → e with photosensitizer-type structure open up the avenue towards fabrication organic/inorganic hybrid (chalcone 5e/silicon) heterojunction solar cell. The optoelectronic properties and photovoltaic parameters of the cell have been studied.