Mo/alumina cermet-based selective coatings are of great interest for concentrated solar-thermal power systems, in particular, parabolic trough collectors. We report on the sputter deposition of high-performance multilayer Mo/alumina cermet coatings on stainless steel with a solar absorptance of 94% and a thermal emittance of 8% (at 400 °C), and excellent thermal stability. The selective coatings were deposited in a 0.95 m3 sputtering chamber in order to correlate the deposition parameters, such as presence of residual gases, deposition power, and sputtering method (DC or RF), with the coating composition and the resulting optical properties. X-ray photoelectron spectroscopy, x-ray diffraction, and Raman spectroscopy have been applied to quantitatively describe the effect of residual oxygen on the distribution of oxidation states of Mo in the metallic infrared reflector layer, the high and low metallic volume fraction cermet layers, as well as the composition of the alumina top layer. The results provide strategies to obtain optimal selective coatings under conditions where residual oxygen cannot be avoided, which are essential for a successful transition from a laboratory to pre-industrial scale of vacuum deposition systems.
Mixed-halide organic–inorganic hybrid perovskites are considered
promising light-absorbing materials in the development of solar cells
related to the obtained high-power conversion efficiency. Current
efforts are focused on the study of the energy-conversion mechanisms,
where the nonradiative recombination pathway is the least explored. In
this work, a combination of optical and photoacoustic spectroscopies
is used to determine the visible spectral light-into-heat conversion
efficiency of lead-based mixed-halide organic–inorganic hybrid
perovskites in a semicomplete n-i-p mesoscopic perovskite solar cell
(PSC). A remarkable average conversion efficiency of about 87% has
been found for the nonradiative combination in the perovskite, with the
estimated composition
F
A
0.71
M
A
0.29
P
b
I
2.9
B
r
0.1
in the wavelength range of 400 to
800 nm. As a result, 13% of the incident light is transformed in
radiative recombination processes and/or photodegradation of the
material. Furthermore, the extinction coefficient and refractive index
of the material are reported, and it was found that the optical
constants and the optical absorption in the short-wavelength range are
significantly smaller than previously reported for
M
A
P
b
I
3
.
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