講演情報
[7p-N205-8]High-performance bilayer selective solar absorber based on carbon nanotube membrane with a tailored optical response
〇(DC)Hengkai Wu1, Taishi Nishihara1,2, Takeshi Tanaka3, Hiromichi Kataura4, Yuhei Miyauchi1 (1.Kyoto Univ., IAE, 2.TUS, 3.AIST, CTMI, 4.AIST, NMRI)
キーワード：
Carbon nanotube、Solar、Optical properties
Selective solar absorbers which can maximize the sunlight absorption while minimizing thermal radiation energy leak are key components toward high-efficiency solar-thermal energy harvesting. An ideal SSA requires broadband high absorptance across the sunlight region (mainly 300–2500 nm), minimal emittance in the mid-infrared region, an appropriately located cutoff wavelength in near-infrared where the transition of absorption feature occurs rapidly, and low sensitivity of these properties to the angle of incidence. However, sophisticated structures such as antireflection layers, textured surface, cavity structures, or photonic crystal are usually needed for achieving these properties simultaneously, which hinders the thermal energy transfer, complicates the manufacturing process, and increases production difficulty.
Here, we propose a carbon nanotube-based high performance selective solar absorber with the simple absorber-reflector tandem structure. The key concept in our design strategy is to place a sub-quarter-wavelength thickness, ultrathin semiconducting layer on a metal reflector. With tailored absorption characteristic, this layer can simultaneously function as absorber and antireflection dielectric layer. Although conventional semiconductors can hardly achieve the desired absorption characteristics, we demonstrate feasibility to achieve it using semiconducting single-walled carbon nanotubes (SWCNTs). By mixing selected chirality, we tailor the optical response of the SWCNT membrane to achieve the desired absorption characteristics. As a proof-of-concept, we fabricated an absorber consisted of two SWCNT species and confirmed its outstanding spectral selectivity. Under unconcentrated sunlight, the SWCNT-SSA reaches much higher temperature than the blackbody-like absorber. The details of the design concept and sample demonstration will be discussed.
Here, we propose a carbon nanotube-based high performance selective solar absorber with the simple absorber-reflector tandem structure. The key concept in our design strategy is to place a sub-quarter-wavelength thickness, ultrathin semiconducting layer on a metal reflector. With tailored absorption characteristic, this layer can simultaneously function as absorber and antireflection dielectric layer. Although conventional semiconductors can hardly achieve the desired absorption characteristics, we demonstrate feasibility to achieve it using semiconducting single-walled carbon nanotubes (SWCNTs). By mixing selected chirality, we tailor the optical response of the SWCNT membrane to achieve the desired absorption characteristics. As a proof-of-concept, we fabricated an absorber consisted of two SWCNT species and confirmed its outstanding spectral selectivity. Under unconcentrated sunlight, the SWCNT-SSA reaches much higher temperature than the blackbody-like absorber. The details of the design concept and sample demonstration will be discussed.