Abstract
As azo dyes act as photoisomers, upon the UV-visible light fall the cis configuration azo dye transforms into trans. In this work, a series of four cis-trans isomers of aminoazobenzene based derivatives consist of dipropylamine as electron-donating and different electron-withdrawing groups (-OH, -NH2, -CN, and -NO2) have been investigated theoretically for solar cells applications. Optoelectronic and structural properties of the designed molecules are studied at PBE1PBE/6-31+G** level of theory using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The use of different electron-withdrawing groups has significantly affected the structural properties of all 1-4 trans and cis molecules. Among all investigated molecules, 4-trans and 4-cis molecules have shown smaller energy gap (Eg) of 2.91 and 2.69 eV, respectively. Absorption spectra of 4-trans and 4-cis dyes have shown a prominent redshift of lambda(max) at 542 and 528 nm, respectively with pi-pi* transitions. The reorganization energy analysis has indicated that 1-trans, 2-trans, and 4-trans molecules would act as good hole transfer materials. Hence, it is concluded that different electron-withdrawing groups influence the structural and optoelectronic properties. Thus, it is proved that these designed azo-based derivatives can act as high-performance and potential candidates for organic dye-sensitized solar cells.