Abstract

The solar absorptance of a single ideal film on an idealized metallic substrate has been calculated as a function of its optical constants to determine the optimum parameters for selective absorber applications. High normal solar absorptances (>0.9) are possible for single uniform interference films if n < 1.5 and 0.2 < k < 0.8, values that are achievable using cermet materials. Grading the refractive index of single interference films improves the absorptance, with optimum results given by a uniformly increasing dielectric constant through the layer. With such a linear grading to air, normal solar absorptances of greater than 0.9 can be achieved for n < 1.5 and 0.1 < k < 5. Grading an absorbing material with a dielectric also improves the performance of the absorbing material. For bulk films, the optimum profile with minimum material is one where the dielectric constant increases slowly at the surface of the film.

© 1977 Optical Society of America

Spectral selectivity of high-temperature solar absorbers

D. M. Trotter and A. J. Sievers
Appl. Opt. 19(5) 711-728 (1980)

Silicon films as selective absorbers for solar energy conversion

D. E. Ackley and J. Tauc
Appl. Opt. 16(11) 2806-2809 (1977)

Infrared spectral emittance profiles of spectrally selective solar absorbing layers at elevated temperatures

D. E. Soule and D. W. Smith
Appl. Opt. 16(11) 2818-2821 (1977)

Antireflective property of thin film a-Si solar cell structures with graded refractive index structure

Sung Jun Jang, Young Min Song, Chan Il Yeo, Chang Young Park, Jae Su Yu, and Yong Tak Lee
Opt. Express 19(S2) A108-A117 (2011)

Graded-index thin-film stack for cladding and coupling

Kim Peng Lim, Doris Keh Ting Ng, Jing Pu, Yeow Teck Toh, Tjiptoharsono Febiana, Krishnamurthy Vivek, and Qian Wang
Appl. Opt. 55(24) 6752-6756 (2016)