In this work, a composition dependent model based on the Cr-W alloy structure has been studied to make it possible be put into practical application. In terms of the optical properties of the Cr-W alloy with defined composition, a simpler 4-layered structure with single Cr-W alloy absorption layer has been designed to show the merit of high photon-to-heat conversion efficiency in the broad spectral region of 300-1000 nm.