We recently demonstrated a new process for the formation of partially spherical structures as an omnidirectional antireflection coating ͑omni-AR͒. In this paper, we report the simulation results of the angular and spectral dependences of the total reflectivity on various microstructured surfaces based on the rigorous coupled-wave analysis. Close to zero reflection can be achieved in these microstructured surfaces over an extended spectral region for large ranges of light incident angles. The impact of feature size, density, shape, and refractive index has all been investigated. The experimental results agree reasonably well with the theoretical work. Such an omni-AR structure offers an attractive solution to current crystalline silicon solar cells, as well as future thin film, quantum dot, and organic solar cells.
Copolymerization of ε-caprolactone and methyl methacrylate
with (1-tert-butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)phophoranylidenamino]-2Λ5,Λ5-catenadi(phosphazene)
(t-BuP4) as the catalyst has been studied.
Nuclear magnetic resonance (NMR) and differential scanning calorimetry
(DSC) measurements indicate that the cyclic ester and vinyl monomer
form a random copolymer. Thermogravimetric analysis (TGA) measurements
demonstrate that such a random copolymer exhibits a decomposition
temperature higher than those of the corresponding homopolymers. The
present study reveals a “hybrid copolymerization” i.e.,
a combination of vinyl polymerization and ring-opening polymerization,
which makes the incorporation of cyclic and vinyl monomers into the
same polymer chain possible. Hybrid copolymerization is expected to
produce a number of new interesting polymers.
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