Influence of parameters on Al/Ti-DLC/DLC selective absorber film

摘要

This work explores the effects of target current and argon gas flow on structural and optical properties of Al/Ti-DLC/DLC selective absorber films used in solar-thermal conversion processes. The transmittance of DLC (diamond-like carbon) anti-reflection layer is affected by the sp(2)-C/sp(3)-C ratio in it. An increase in C-target current and argon gas flow is seen to induce an initial increase followed by a subsequent decrease in film transmittance. The absorptivity of Ti-DLC (titanium-containing) layer is affected by the sp(2)-C/sp(3)-C ratio. An increase in Ti-target current induces a gradual decrease in the content of sp(3)-C bonds in absorbing layer. A further increase in Ti-target current results in decreased absorption. It is concluded that in the Ti-DLC layer, (i) TiC grains can change absorbing layer temperature and C-C bond structure, thereby gradually increasing the ratio of sp(2)-C/sp(3)-C and (ii) TiC grains also absorb transmitted light or scatter reflected light, inducing enhanced absorption in Ti-DLC layer.