Theoretical investigation for dye-sensitized solar cells: effect of donor variation on the optoelectronic properties and charge transfer parameters

In this study, we are interested to the effect of the variation in donor groups (D) mainly carbazole, triphenylamine, diethylaniline and phenothiazine, on a series of organic compounds, using Density-Functional Theory (DFT) and Time-Dependent Becke-Half and Half-Lee-Yang-Parr's (TD-BHandHLYP). The aim is to elucidate the different geometrical and optoelectronic properties, as well as the charge transfer parameters (Ionization potential (IP), Electron affinity (EA), Reorganization energy (lambda), Light harvesting efficiency (LHE), Open circuit voltage (V-oc), Injection energy (Delta G(inject)) and Regeneration energy (Delta G(reg))), chemical reactivity parameters (Electronegativity (chi), Chemical potential (mu), and Electrophilicity index (omega)) of the studied dyes and intermolecular interactions dyes/semiconductor. Using triphenylamine and diethylaniline as donors (D), we have been able to get the lowest Egap energies, with respective values roughly equivalent to 1.77 and 1.78 eV and high maximum absorption wavelengths (607.84 and 609.70 nm) when compared to the other donor groups. Likewise, the introduction of these units increased the photon-current conversion capacity, characterized by better LHE values (0.980 and 0.975 eV, respectively) and higher V-oc (0.91 and 0.95 eV, respectively), which would improve the charge transfer performance and chemical reactivity indices.

Automated summary

In this study, the effect of different donor groups on organic compounds was investigated using Density-Functional Theory and Time-Dependent Becke-Half and Half-Lee-Yang-Parr's methods. The results revealed the impact of donor variation on geometrical and optoelectronic properties, as well as charge transfer and chemical reactivity parameters. Among the donor groups, triphenylamine and diethylaniline showed the lowest Egap energies and highest absorption wavelengths, indicating improved charge transfer performance and chemical reactivity indices.