Investigation analysis of optoelectronic and structural properties of cis‐ and trans‐structures of azo dyes: density functional theory study

Abstract

AbstractAs 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 λmax at 542 and 528 nm, respectively with π–π* 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.