High reflectance materials for photovoltaics applications: analysis and modelling

The paper involves reflectance structures fabricated with application of sol–gel method. High reflectance was obtained through the fabrication of one-dimensional photonic crystals on glass substrate. The paper presents both the results of theoretical analysis as well as the results of experimental studies. Using the 2 × 2 transfer matrix method, we determined reflectance and transmittance characteristics of the analyzed structures as well as power distributions in the photonic crystals. The one-dimensional photonic crystals were fabricated by the successive deposition of quarter-wave layers of silica and titania on glass substrate using the dip-coating method. For the fabricated reflectance structures with four bilayers (TiO₂/SiO₂), for the wavelength ~500 nm we have obtained the reflectance value equal to 0.933, and for the structures with five bi-layers the reflectance was equal to about 0.967. The uniformity of the fabricated structures and the repeatability of the technological process are discussed. We discuss also some slight divergence between theoretical predictions and experimental results.