Improving the optoelectronic efficiency of novel meta-azo dye-sensitized TiO2 semiconductor for DSSCs

A series of novel azo dyes possessing varying conjugation lengths and different donor moieties, based on 5-amino isophthalic acid were designed and synthesized. Azobenzene unites were utilized as the pi-spacer part to extend the conjugation range and connect the donor to acceptor unit. When the dialkylamino substituent was changed from dimethyl to diethanol, a red shift in the absorption spectra and konset was observed. The photophysical and electrochemical properties of the straightforward-synthesized dyes were investigated in solution and on photoanode surface which promised the suitability of the dyes as photosensitizers for dye sensitized solar cells (DSSCs). Increased dye adsorption strength on the TiO2 surface as well as light harvesting capability was expected due to bearing two anchoring-electron accepting groups which could lead to enhanced electron transfer (ET). The ATR absorption spectra clearly showed that these dyes were adsorbed on the TiO2 surface. It was realized that increasing pi-conjugation length as well as hydroxyl containing donor group gave rise to improved photovoltaic performance of DSSCs. Reduced band gap along with suppressed electron recombination and amended dye regeneration were recognized to play an important role in enhancing performance parameters. DSSCs based on these dyes exhibited higher solar conversion efficiency in comparison with efficiency of other meta azo dyes that were previously synthesized. Theoretical calculations (DFT/TDDFT) expressed that among the dyes, members 3a and 3b possessed localized and non-continuous electron distribution in their frontier orbitals as well as maximum amount of oscillator strength. (C) 2020 Published by Elsevier B.V.

Automated summary

A series of novel azo dyes with varying conjugation lengths and different donor moieties were designed and synthesized based on 5-amino isophthalic acid, showing potential as photosensitizers for dye sensitized solar cells. Adjusting the alkylamino substituent resulted in a red shift in absorption spectra and enhanced dye adsorption on the TiO2 surface. Increasing pi-conjugation length and using a hydroxyl-containing donor group were found to improve the photovoltaic performance of DSSCs.