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

ABSTRACT

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 sp²-C/sp³-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 sp²-C/sp³-C ratio. An increase in Ti-target current induces a gradual decrease in the content of sp³-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 sp²-C/sp³-C and (ii) TiC grains also absorb transmitted light or scatter reflected light, inducing enhanced absorption in Ti-DLC layer.

KEYWORDS:

• Selective absorber film
• diamond-like carbon film
• C–C bond structure
• transmittance
• absorptivity

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by National Natural Science Foundation of China (grant number 51571183); and the Fundamental Research Funds for the Central Universities of China.