Sulfur-bridged oxotitanium phthalocyanine- and porphyrin-based cocktail dyes as sensitizers for improved dye sensitized solar cell efficiency

Effective non-symmetrical push–pull oxotitanium phthalocyanine dyes substituted with tert-butylsulfanyl groups as electron donors and carboxyethynyl units as anchor groups have been designed, prepared, and used with YD2 porphyrin as sensitizer cocktail dyes in dye-sensitized solar cells (DSSCs). The innovative phthalocyanine structures and YD2 and dye cocktails are designed to harvest a broad range from sunlight. The novel phthalocyanine dyes have been characterized via ¹H NMR, FTIR, MALDI-TOF, UV–Vis absorption, CV, SWV and TD-DFT techniques. Moreover, the TiO₂ NPs has been synthesis by hydrothermal procedure and characterized via XRD, FE-SEM, Raman and DRS techniques. The photoanode has been prepared with synthesized anatase TiO₂ NPs using a spin coating procedure. TiO₂ photoanode, dye/dye cocktails, I⁻/I₃⁻ electrolyte and Pt/FTO counter electrode have been utilized in the preparation of solar cells. The characterization of the prepared solar cells has been achieved via J-V, Nyquist, Bode, IPCE, normalized J_SC and stability measurements. The highest conversion efficiency of the solar cell prepared with YD2:TiOSPPc (3:1) has been performed 10.96%, which this value was found to be higher than the solar cell efficiency of N719 standard dye (8.90%). With these innovative dye cocktails, it is expected that the dye system with not only high efficiency but also a relatively stable and higher V_OC value will be an alternative to ruthenium-based dyes.