OPTICAL AND ELECTRICAL PROPERTIES OF SYNTHETIC MELANIN THIN FILMS FOR PHOTOVOLTAIC APPLICATIONS

摘要

Optical and electrical resistance properties of synthetic melanin thin films, spray-coated on glass, havebeen investigated as a function of thickness, d. Independent of d, films showed a broadband monotonic increase inabsorbance with decrease in wavelength in the UV-Visible range. A residual absorption tail in near Infrared region hasbeen observed.Electrical resistance measurements revealed that the synthetic melanin behaves like a semiconductor. However, afterthermal annealing at 475 K it showed a hysteretic behaviour. Thermal activation energies extrapolated by resistancecurves have been explained by using the framework of a band-model for amorphous semiconductor.