The structure and photovoltaic property relationship of porphyrins for high efficiency solar cells

Several 5-(4-carboxyphenyl)-10,15,20-tris(phenyl) porphyrin derivatives with different substituents (NO2, CN, CH3, OCH3, CN, NO2, Cl, N(CH3)2, N(Ph)2) in the para-positions of phenyl groups are designed and synthesized for systematic study of structural effect on their photovoltaic performance in dye-sensitized solar cells (DSSCs). Density Functional Theory (DFT) level calculation indicates the decrease of energy levels of frontier molecular orbitals (HOMO and LUMO) when substituents change from NO2, CN, Cl, H, OCH3, CH3, N(CH3)2 to N(Ph)2. Photovoltaic performances of these porphyrins in DSSCs show that introducing of electron donating groups in porphyrins and Zn²⁺ ion favors the energy conversion of sunlight to electricity.