Abstract
In this work, 4-layered SiO2/Bi2Te3/SiO2/Cu film structures were designed and fabricated and the optical properties investigated in the wavelength region of 250–1200 nm for their promising applications for direct solar-thermal-electric conversion. A typical 4-layered film sample with the structure SiO2 (66.6 nm)/Bi2Te3 (7.0 nm)/SiO2 (67.0 nm)/Cu (>100.0 nm) was deposited on a Si or K9-glass substrate by magnetron sputtering. The experimental results agree well with the simulated ones showing an average optical absorption of 96.5%, except in the shorter wavelength region, 250–500 nm, which demonstrates the superior absorption property of the 4-layered film due to the randomly rough surface of the Cu layer resulting from the higher deposition power. The high reflectance of the film structure in the long wavelength region of 2–20 μm will result in a low thermal emittance, 0.064 at 600 K. The simpler 4-layered structure with the thermoelectric Bi2Te3 used as the absorption layer may provide a straightforward way to obtain solar-thermal-electric conversion more efficiently through future study.
Highlights
In this work, 4-layered SiO2/Bi2Te3/SiO2/Cu film structures were designed and fabricated and the optical properties investigated in the wavelength region of 250–1200 nm for their promising applications for direct solar-thermal-electric conversion
In solar-to-thermal conversion processes, selective solar absorbers will play a significant role of efficiently absorbing most of the solar energy in the region of radiated wavelengths while suppressing the infrared re-radiation induced by the heating of the selective absorber[3,5,9]
The thermoelectric material Bi2Te3 was used as the photon absorption layer in the 4-layered SiO2/ Bi2Te3/SiO2/Cu selective solar absorbers with a high and average absorptance (96.50%) achieved in the wavelength region of 250–1200 nm
Summary
4-layered SiO2/Bi2Te3/SiO2/Cu film structures were designed and fabricated and the optical properties investigated in the wavelength region of 250–1200 nm for their promising applications for direct solar-thermal-electric conversion. The simpler 4-layered structure with the thermoelectric Bi2Te3 used as the absorption layer may provide a straightforward way to obtain solar-thermal-electric conversion more efficiently through future study. In the photo-thermal processes, heat can be generated by the device by efficiently absorbing the incident photons from the solar radiation with applications such as solar-heating, solar-thermal-electricity generation, solar-thermoelectrics, solar-thermophotovoltaics, and so on[1,3,4,5,6]. Among them, multilayered thin-film structures consisting of alternating metal and dielectric layers show the unique advantage of excellent spectral properties in both of broad solar spectral and wide incident angle regions, low thermal emittance, and good www.nature.com/scientificreports/. In a typical dielectric/metal/dielectric/metal multilayered film structure, incident solar radiation in a wide wavelength range can be absorbed by the partially transparent metal layer due to the multiple reflections at the interface between layers in the multilayered film structure[3]
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