Analysis of photovoltaic properties of C60-Si heterojunction solar cells

Photovoltaic and photoconductive properties of C-60/p-Si heterojunction solar cells grown by molecular beam epitaxy have been analyzed using a device simulator based on measured optical absorption coefficients of C-60 films. The spectral response of cell photocurrents in the short wavelength region of less than 700 nm is determined to be due to the optical absorption of the C-60 layer. Marked improvements in photovoltaic properties of the cells have also been observed by increasing the light intensity. Analytical results suggest that photoconductive effects on C-60 layers under light illumination increase the carrier concentration and decrease the series resistance of the C-60 layer, resulting in an increase of the open-circuit voltage and short-circuit current of the C-60/p-Si heterojunction cells. The possibility of improving the conversion efficiency of C-60-based solar cells is also discussed.