Oligothiophene-multifullerene linkage molecules as high performance photovoltaic materials

Novel long oligothiophenes incorporated with four fullerenes (2C60-16T-2C60 and 2C60-24T-2C60) have been synthesized with the aim of developing good single-component photovoltaic materials. The tetracosithiophene derivative 2C60-24T-2C60, despite its giant structure, is rather more tractable regarding solubility than the hexadecithiophene derivative 2C60-16T-2C60. The electronic absorption and emission spectra of 2C60-24T-2C60 indicated no electronic interaction in the ground state but efficient intramolecular electron transfer in the excited state. The sandwich device of the Al/2C60-24T-2C60/Au structure showed a marked photocurrent upon illumination with monochromatic light from the Al side. The incident-photon to converted-electron ratio (IPCE) is 14%.