4-Carboxyphenyl as efficient donor group in nano Zn-Porphyrin for dye sensitized solar cells

Dye-sensitized solar cells, represent the alternate technology in solar research due to their cost effective, easy fabrication processes, higher efficiencies, and design flexibility. In this research, dual donor group modified zinc porphyrin dyes, have been synthesized for DSSCs. The complexes of zinc porphyrin functioned as acceptor or attaching groups within each mesophenyl ring and carboxylic acid. These complexes exhibited diverse alkyl substituents and sizable electron-donating substituents, contributing to their varied chemical structures and potential applications. The dual Donor-π bridge -Acceptor group sensitizers, Zn[5,15-diphenylcarbazole-10,20-(4-carboxyphenyl) Porphyrin] (KSR-1) and Zn [5,15-thiadiazole-10,20-(4-carboxyphenyl) Porphyrin] (KSR-2) have been synthesized and adopted for DSSCs implementation. The molar absorption coefficients (ε) of KSR-2 and KSR-1 Soret bands were 0.56 x 10⁵ mol/L/cm and 0.47 x 10⁵ mol/L/cm, respectively. The Q bands of the KSR-1 and KSR-2 dyes were 1.10 x 10⁵ mol/L/cm and 1.0 x 10⁵ mol/L/cm, respectively and the molar absorption coefficient of the KSR-1 dye was greater when compared to the KSR-2 dye. The molar absorption coefficient of 0.71 x 105 mol/L/cm was visible in the KSR -1 Q-band. DFT calculations and the electrochemical characteristics of the KSR-1 and KSR-2 dyes have been studied and discussed. The exploration involved in investigating the photophysical properties and photovoltaic performance which were affected by varying the length and number of the donor entities. The wall-plug efficiency of the KSR-1 based solar panel was V_oc = 0.68 V, J_sc = 8.94 mA/m², FF = 56 and Efficiency (μ) = 3.44%. The wall-plug efficiency of the KSR-2 based solar panel was V_oc = 0.63 V, J_sc = 5.42 mA/m², FF = 53 and Efficiency (μ) = 1.83%.