The effect of central transition metals and electron-donating substituent on the performances of dye/TiO2 interface for dye-sensitized solar cells applications

Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) approaches were applied to explore the effect of central transition metals and the dye/TiO₂ interface on dye-sensitized solar cell (DSSC) performance and supply a promising way to estimate and screen possible candidates for DSSC applications. The interaction properties, bonding characteristics, sensitized mechanisms, charge transfer, frontier molecular orbitals, energy gap, partial densities of states (PDOS), non-covalent interactions (NCI), and electronic absorption spectra were examined and analyzed to provide the photovoltaic characteristics of Sc, Cu, and Ti tetrasulfonic acid phthalocyanine sensitizer@TiO₂ interface in both gas phase and polar solvent as acetonitrile. The interfacial of TiPc-(SO₃H)₄ with TiO₂, which facilitates the driving force for the electron injection of photosensitizers (ΔG^inj), increases the charge separation, open-circuit voltage (V_oc), and high light-harvesting efficiency (LHE) values. However, minimize the charge recombination, lifetime of the excited state (τ), regeneration driving force (ΔG^reg). Our results reveal that TiPc-(SO₃H)₄@TiO₂ is superior to those of ScPc-(SO₃H)₄, CuPc-(SO₃H)₄, TiPc-(SO₃H)₄ and Pc-(SO₃H)₄/TiO₂, indicating the novel TiPc-(SO₃H)₄@TiO₂ interface could be promising candidates for DSSC photovoltaic devices performance. In addition, the static mean polarizability and first hyperpolarizability of all six dyes elucidated that the TiPc-(SO₃H)₄@TiO₂ interface can be regarded as a potential performer in non-linear optical (NLO) properties. These theoretical identifications may provide novel perspectives and instructions for future experimental researchers to promote the synthesis and application of TiPc-(SO₃H)₄@TiO₂ interfaces to improve the photo-to-current conversion efficiency.