Effect of Extended Conjugation on the Photosensitizers for DSSC: DFT and TD-DFT Study

Dye sensitized solar cells have achieved more than 12% efficiency[1][2] since 1991 when first metal organicphotosensitizer was made by Gratzel based on ruthenium complex[3].Here we discussed the effect ofextended conjugation absorption spectra of photosensitizers[4]. The designed dye molecules are ondonor- π -acceptor model. dyes named as S1 [naphthalene-pyrrole-butanoic acid] and S2[naphthalene-pyrrole-thiophene-butanoic acid]. In both systems naphthalene is donor butanoicacid acceptor moiety. pyrrole bridging molecule in along with thiophene thebridging moiety S2. Both optimized under framework density functional theory usingB3LYP hybrid 6-31+G(d,p) basis set calculated utilizing time dependentdensity at CAM-B3LYP Gaussian 16W software. geometriesare also checked for their global minima potential energy surface through frequency calculation. Thecalculated maxima 286.66 nm S2 observed at296.89 nm. frontier molecular orbital gap HOMO-LUMO found 4.34 eV itis 3.75 eV. This shows that HLG reduces increasing bridge system whichenhances towards red shift visible spectrum. 10.23 inthe compared to S1. Thus, theabsorption length plays a key role enhancing thedesigned photosensitizer. Therefore, this study would help designing novel conjugated organic moleculesas better photosensitizers high-performance DSSCs.