A₃B type Zn(II) phthalocyanines and porphyrin cocktail dye sensitizers for highly efficient DSSCs

Dye-sensitized solar cell (DSSC) technology has recently seen some drastic advancement by new concepts and tailor-made new materials. Phthalocyanines and porphyrins were the most investigated solar sensitive dyes. It has been determined that push–pull phthalocyanines containing carboxylic acid groups are among the promising photosensitizers for dye sensitized solar cells (DSSCs) with their absorption spectra in the NIR region. In particular, carboxylic acid-substituted non-symmetrical metallophthalocyanines appear to be extremely important for electron injection into the TiO₂ conduction band in applications where DSSCs have significant potential to achieve greater efficiency. Zinc phthalocyanines containing these groups appear to be candidate molecules for DSSC. However, there is no apparent research in the literature regarding the syntheses and recommendations on analogues of zinc phthalocyanines containing three t-butylsulfanyl or ferrocenylphenol groups and mono aliphatic or aromatic alkynyl anchoring carboxylic acid groups as sensitizing agents for dye-sensitized solar cells. In this actual paper, zinc phthalocyanines and YD2 porphyrin macrocycles were combined as dye cocktails, to extend and complement the absorbance window of sensitizer dyes in the visible region. Thus, four novel A₃B type non-symmetrical zinc phthalocyanines have been synthesized and characterized via spectroscopic (¹H NMR, FTIR, UV–Vis, MALDI-TOF, etc.), electrochemical (CV, SWV), and molecular (TD-DFT) analysis methods. The reported novel solar sensitive dye-coated cells have been characterized in detail by electrochemical methods i.e., J-V, IPCE and measurements of stability. YD2:ZnPc3 (3:1) cocktail dye yielded the highest conversion efficiency, accomplishing 10.87 % exceeding the respective individual dye counterparts, but also the well-known Ru-based commercial N719 sensitizer's (8.90 %) solar cell efficiencies.