Excimer-laser-irradiation-induced effects in C60 films for photovoltaic applications

Thin films of fullerene C-60 deposited by the molecular-beam epitaxy method have been subjected to a 248 nm excimer laser for various timings. Reduction in the electrical resistance of the films and the spectral evolution of the D and G bands in the Raman spectra, due to the sharp tendency towards graphitization accompanied by an increasing level of structural disorder, are observed during laser irradiation. Based on the above results, an attempt has been carried out on these irradiated C-60 films to make a device sandwiched with n-type Si, and the photovoltaic parameters are reported as a function of the laser exposure times. (C) 2002 American Institute of Physics.