Theoretical design and characterization of D-A1-A based organic dyes for efficient DSSC by altering promising acceptor (A1) moiety

The electronic, optical and photovoltaic properties of dyes can be readily tuned by modifying the structure. Herein, the thieno [2,3-b]indole (Thi)-based molecules derived from dye NTU-2 (D-A(1)-A) have been designed by substituting BT by DPP(O), DPP(S), QuT and BBT units and dicyanovinylene by cyanoacetic acid. Based on density functional theory (DFT) and time-dependent DFT (TD-DFT) methods, the regulation effect of acceptor groups on designed compounds was theoretically investigated. Indeed, in this context, the effects of various acceptor groups (A(1)) in D-A(1)-A dyes before and after binding to (TiO2)(8) cluster on the electron injection have been studied. The optimized structures, electronic parameters, FMOs, NBO, PDOS analysis, the absorption spectra, and ICT parameters were evaluated to predict the suitable candidates for DSSC device. Our investigations reveal that all designed compounds have not only a significant lambda(max )in the range of 593-824 nm, with a bandgap in the order, 2.31-1.56 eV, larger adsorption energies (E-ads) and lower Lambda(total), but also large light harvesting efficiency (LHE) and significant intramolecular charge transfer (ICT) properties compared to dye R. Accordingly, these theoretical calculations can provide an efficient strategy to design new promising sensitizers for DSSCs.

Automated summary

This study theoretically investigates the properties of molecules based on thieno [2,3-b]indole, including electron injection and absorption spectra. The designed compounds show significant absorption wavelengths, bandgaps, and light harvesting efficiencies compared to reference dye R, indicating their potential as promising sensitizers for DSSCs.