Performance of sol–gel SiO2 coatings onto glass/SnO2 superstrates

From commercial glass/SnO2 superstrates, by dipping in an appropriate sol–gel solution, new SiO2/glass/SnO2/SiO2 superstrates have been obtained, with improved transmittance controlled by SiO2 deposition parameters such as the alcohol/alkoxide ratio in the sol–gel solution and the sample withdrawal velocity. In this way, close to 15% visible transmittance enhancement has been achieved, without infrared optical losses. The electrical characteristics of the sol–gel-coated samples have been evaluated by applying electro-deposited coatings on them. Electrodeposition of a CuInSe2 absorber layer onto SiO2-coated conducting superstrates has been found to be heterogeneous at low cathodic potentials, but can be made homogeneous by increasing the work electrode polarisation, in order to achieve the disruptive voltage for the SiO2 electrical insulation.