Nano Research

, Volume 9, Issue 8, pp 2354–2363 | Cite as

Ultrathin planar broadband absorber through effective medium design

  • Dong Liu
  • Haitong Yu
  • Zhen Yang
  • Yuanyuan DuanEmail author
Research Article


Ultrathin planar absorbers hold promise in solar energy systems because they can reduce the material, fabrication, and system cost. Here, we present a general strategy of effective medium design to realize ultrathin planar broadband absorbers. The absorber consists of two ultrathin absorbing dielectrics to design an effective absorbing medium, a transparent layer, and metallic substrate. Compared with previous studies, this strategy provides another dimension of freedom to enhance optical absorption; therefore, destructive interference can be realized over a broad spectrum. To demonstrate the power and simplicity of this strategy, we both experimentally and theoretically characterized an absorber with 5-nm-thick Ge, 10-nm-thick Ti, and 50-nm-thick SiO2 films coated on an Ag substrate fabricated using simple deposition methods. Absorptivity higher than 80% was achieved in 15-nm-thick (1/50 of the center wavelength) Ge and Ti films from 400 nm to near 1 μm. As an application example, we experimentally demonstrated that the absorber exhibited a normal solar absorptivity of 0.8 with a normal emittance of 0.1 at 500 °C, thus demonstrating its potential in solar thermal systems. The effective medium design strategy is general and allows material versatility, suggesting possible applications in real-time optical manipulation using dynamic materials.


ultrathin planar film broadband absorber effective medium design solar energy 


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Copyright information

© Tsinghua University Press and Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  • Dong Liu
    • 1
    • 2
  • Haitong Yu
    • 2
  • Zhen Yang
    • 2
  • Yuanyuan Duan
    • 2
    Email author
  1. 1.School of Energy and Power EngineeringNanjing University of Science & TechnologyNanjingChina
  2. 2.Key Laboratory of Thermal Science and Power Engineering of Ministry of Education, Key Laboratory for CO2 Utilization and Reduction TechnologyTsinghua UniversityBeijingChina

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