Influence of auxiliary acceptor substitution at D-A1-π-A2 structured highly efficient organic molecules for dye-sensitized solar cells using computational study

Context

This study used the PTRA-based molecule to design and investigate seven new donor-acceptor1-π-acceptor2 (D-A1-π-A2) organic dyes (PTRA1-PTRA7) for dye-sensitized solar cells (DSSCs). All dyes had an electron-A2 group made of rhodanine-3-acetic acid and a thiophene group as a spacer, while the electron-A1 unit varied from D-A1-π-A2. Optoelectronics was explored in relation to a structure and its influences. For the dyes PTRA1–PTRA7, the computational analysis of density functional theory (DFT) and its extended time-dependent DFT (TD-DFT) approaches was performed. The driving force of electron injection (\(\Delta G_{inject}\)), dye regeneration (\(\Delta G_{reg}\)), exciton binding energy (E_b), molecular orbitals (MOs) energy levels, optical ultraviolet-visible (UV-Vis) spectra, and electronic properties were all thoroughly discussed. The findings show that PTRA1–PTRA7 have smaller energy gaps (E_g) and higher absorption wavelength (λ_max) than PTRA. Out of all of them, PTRA6 has the lowest E_g (2.15 eV) and the red-shifted λ_max (559 nm). It has been determined that dyes PTRA1–PTRA7 are the most promising option for having highly efficient DSSCs, especially PTRA6. Additionally, these molecules serve as the most promising functional group in D-A1-π-A2 dyes for auxiliary electron-A. Due to its excellent electronic, optical, and photovoltaic (PV) characteristics, it could be utilized as a potential sensitizer for DSSCs.

Methods

Formalisms of the conductor-like polarizable continuum model (CPCM) have been used to study solvent effects. The results of the CPCM/TD-DFT demonstrate that precise absorption energies can only be obtained when the solvent effect is taken into account in the geometries of the excited states. The Gaussian 09w software package is used for related calculations.