Amorphous Se100-XInX thin films were prepared by flash evaporation of the pre-melt quenched bulk samples. The samples were characterised and the suitability of each composition assessed towards applications as a buffer layers in CuInSe2 photovoltaic cells. XRD studies confirmed that all the samples were amorphous. There was a descending dependence of complex dielectric constant and refractive index on wavelength which levelled in the infra-red (IR) region. A red shift in the optical energy gap Egopt from 1.76 eV for In = 5 at% to 1.46 eV for In = 20 at% was observed. The Egopt values were in the range that is compatible with solar energy conversion.