Novel oxo‑titanium(IV) phthalocyanine based sensitizers for high-performance DSSCs: enhanced photovoltaic properties via combined-sensitization with YD2

High conversion and sunlight radiation absorption range are required for a suitable and efficient dye-sensitized solar cell (DSSC). These requirements are met by including a “dye cocktail” that is made up of new oxo‑titanium(IV) phthalocyanines and a porphyrin. The use of Ti(IV) as the phthalocyanine central metal allows to introduce robustly attached axial oxo ligand that prevent aggregation of the macrocycles. Novel two unsymmetrical push-pull oxo‑titanium phthalocyanines (TiOPc1 and TiOPc2) bearing bulky tert-butylphenyloxy moieties as electron donor and two different carboxylic acids as anchoring group have been designed and synthesized. The UV–Vis range is widened by preparing a cocktail with two oxo‑titanium(IV) phthalocyanine dyes and a porphyrin known as YD2. The characterization steps involving the phthalocyanines and the porphyrin consist of UV–Vis, FTIR, ¹H NMR, MALDI-TOF, electrochemistry (CV, SWV, EIS, IPCE), and TD-DFT. We have prepared different YD2:TiOPc1–2 dye mixtures at various molar ratios. The most successful DSSC devices were made up of YD2 + TiOPc1 (3:1) with 11.18 % and YD2 + TiOPc2 (3:1) with 12.28 % performances. They are greater than the single N719 dye with 8.87 % and YD2 alone with 7.96 %, which is attributed to the panchromatic effect. The detailed optical and electrochemical properties were investigated and complimented with theoretical studies (DFT). As we obtained high efficiency values, the new cocktail dyes let us expect good alternatives to the already used ruthenium-based complexes in DSSCs and potential alternative dyes are produced thereof.