Different metal upper porphyrin based self-assembly sensitizers for application in efficient dye-sensitized solar cells

Four different metal atom dyes MP (M: Zn, Cd, Ag, Cu) as upper porphyrin molecular have been designed and synthesized. On the other side of ZnPA contains four carboxylic acids as the horizontal anchor porphyrin for binding to TiO₂. We constructed MP-ZnPA assembled approach, and applied in dye-sensitized solar cells. Photoelectrochemical studies reveal the self-assembled structure dye photocurrent (J_sc) are higher than anchor porphyrin. The enhancement of J_sc can be ascribed to the improved light-harvesting ability induced by the axially coordinated MP. However, upper different metal atom porphyrins cannot play a positive role in improving the photovoltages (V_oc) because of MP-ZnPA devices possess the dye aggregation. The effects of the MP-ZnPA assembled on the optical, theory calculations and photovoltaic properties were investigated. AgP-ZnPA and ZnP-ZnPA have the higher molar extinction coefficient and sufficient charge injection into the TiO₂ conduction band. Therefore, AgP-ZnPA and ZnP-ZnPA have superior photovoltaic behavior. We constructed a three-layer self-assembled (ZnP1-AgP-ZnPA) solar cell, which the photovoltaic efficiency of the three-layer self-assembled solar cell is significantly reduced. Consequently, double-layer self-assembly, which is one of the effective strategies for improving the performance of self-assembly supramolecular solar cells.