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 (NO
2
, CN, CH
3
, OCH
3
, CN, NO
2
, Cl, N(CH
3
)
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 NO
2
, CN, Cl, H, OCH
3
, CH
3
, N(CH
3
)
2
to N(Ph)
2
. Photovoltaic performances of these porphyrins in DSSCs show that introducing of electron donating groups in porphyrins and Zn
²⁺
ion favors the energy conversion of sunlight to electricity.