Sulphonic acid functionalized porphyrin grafted ZnO nanorods: Synthesis, characterization and applications in the solid state dye sensitized solar cells

• Porphyrin adheres very strongly to ZnO nanorods via sulphonic groups.
• Free base porphyrin behaves as metallated porphyrin under the grafted state.
• Soret band undergoes a very strong bathochromic shift and Q-bands are reduced to two.
• Pre and post grafting emission spectra are completely different from each other.
• ZnO nanorods sensitized with porphyrin give better efficiency in solar cells.

This work presents the chemical modification of ZnO nanorods with a sulphonic acid functionalized porphyrin derivative. The interaction between semiconducting nanorods and the porphyrin through sulphonic groups proved enough effective that the free base porphyrin behaved as metallated porphyrin under the grafted conditions which is a better donor than its free base counterpart. The soret band of grafted dye was red-shifted by 08 nm with respect to the reference. Additionally, two out of the four Q-bands of reference dye were found missing in the post grafting UV–Visible Spectrum. Fluorescence spectra of the dye before and after grafting were found completely different from each other supporting the UV–visible data. These modified ZnO nanorods in combination with P3HT were employed in the hybrid solar cells. The cells gave better efficiencies at low concentrations of the dye than the corresponding reference device consisting of ZnO nanorods and P3HT. At high concentration of the dye the efficiency of the device was decreased.

Electron flow unidirectionally from the LUMO level of Poly(3-hexylthiophene) to the LUMO of porphyrin and finally reach the conduction band of ZnO nanorods following a cascade route.Figure optionsDownload as PowerPoint slide