Monocationic porphyrin dyads with fullerene as the electron-accepting material

Abstract

Dyad compounds in which a fullerene [Formula: see text] was covalently linked to a monocationic porphyrin at a N,N[Formula: see text]-bridge substituent, were synthesized by condensation reaction. The low solubility of a dyad containing tetraphenylporphyrin (TPP) derivative was improved by using octaethylporphyrin (OEP) derivatives and introduction of an alkyl substituent to the porphyrin derivatives. The energy levels of the frontier orbitals, estimated experimentally using potentiometric data and the optical energy band gaps obtained by the UV-vis spectra, were sufficiently low to be comparable to acceptor materials. They varied depending on the peripheral substituents on the porphyrin unit. DSC analysis of the drop-cast films of the P3HT/dyad blends showed that the film containing the OEP dyad, annealed at a higher temperature, had more amorphous fractions than the films containing the TPP dyad.