An anti-reflection (AR) moth-eye structure made of acrylic resin and deposited on a polyethylene terephthalate (PET) substrate was optimized in the wavelength range from 400 to 1170 nm; crystalline silicon (c-Si) solar cells function efficiently in this wavelength range. The rigorous coupled wave analysis (RCWA) method was used for optical simulation, and the Taguchi method was used for efficient optimization. The simulation results showed that the reflectance of the optimized structure over the above-mentioned wavelength range was less than 0.87% and that a minimal reflectance of 0.1% was observed at 400 nm. Experimental results showed that the reflectance of a fabricated moth-eye structure was less than 1.0% in the wavelength range and that a minimal reflectance of 0.55% was observed at 700 nm. A c-Si solar cell, which was enclosed in a polyvinyl butyral (PVB) layer of uniform thickness, was coated with the fabricated moth-eye film, and it was observed that the moth-eye film increased electric generation (EG) up to 15%, depending on the incident angle. Further, a daily increase in EG of up to 8.7% was estimated on a clear summer day in Japan when the moth-eye film was used.
A novel chain transfer polymerization mediated by Cp*2 Sm(III) species and organic acids is described. The chain transfer polymerization involves the reaction of organic acids such as thiols or ketones with an active bond between samarium(III) and the enolate at a living chain end of poly(methyl methacrylate) (PMMA). This chain transfer reaction resulted in termination of the living chain end and the regeneration of the active initiator which would consist of (C5Me5)2Sm(III) and deprotonated organic acids. The chain transfer polymerization were confirmed by turnover numbers (TON). tert‐Butyl thiol exhibited the chain transfer reactivity effectively to control the molecular weight of PMMA without decreasing of the polymer yield and the stereoregularity. As a result of this chain transfer polymerization, thermal and optical properties of the PMMA obtained were improved by the control of chain end groups or by reducing a large amount of the samarium initiator.
A divalent samarium complex that bears two bulky phenoxide ligands promotes the living polymerization of methyl methacrylate in the absence of cocatalyst. The initiation involves a tail‐to‐tail coupling reaction of the samarium‐enolate radical followed by a one‐electron reduction of the monomer with the divalent samarium initiator. The polymerization takes place stereospecifically and the samarium initiator affords highly syndiotactic poly(methyl methacrylate). The stereoregularity of the polymer is variable with the ratio of the samarium initiator to aluminium compound (2,6‐di‐tert‐butyl‐4‐methylphenoxy)2AlMe. The polymer obtained when the [Al]/[Sm] ratio is 4.0 has a unique tacticity, [mm]/[mr]/[rr] = 42:11:47, and the polymer has a melting point at 161 °C, which suggests the formation of a stereocomplex between syndiotactic and isotactic poly(methyl methacrylate).
We have examined the performance of a see-through photovoltaics module that uses a low-concentration prism concentrator by undertaking ray-tracing analysis and an on-site experiment. The incident angle dependency of the prism concentrator makes it possible to concentrate direct solar radiation onto solar cells and transmit diffuse solar radiation. Fewer solar cells can then be used without sacrificing the conversion efficiency or lighting performance. The module generates approximately 1.15 more electricity than a conventional module while operating with 63% less solar cell area. We also introduce a design method for the concentrator geometry that adjusts the incident angle dependency for different latitude and tilt angles.
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