The low-temperature deposition of textured multilayer back reflectors with enhanced light-scattering properties on polymeric substrates

In this article, we report on the low-temperature deposition of textured back reflectors using sputtered ZnO:Al/Ag/Al:Si layers in flexible nanocrystalline silicon (nc-Si:H) thin-film solar cells. The surface morphology of this multilayer system depends on that of the Al:Si bottom layers, whereas its optical properties are determined by the Ag and ZnO:Al films deposited on top of the Al:Si layers. The nc-Si:H thin-film solar cells fabricated on textured ZnO:Al/Ag/Al:Si multilayer back reflectors showed an enhanced spectral response for wavelengths between 650nm and 1100nm when compared with cells with flat multilayer back reflectors. A high conversion efficiency of 7.25% was successfully achieved for a solar cell with a moderately textured ZnO:Al/Ag/Al:Si multilayer back reflector with a root-mean-square roughness (σrms) of 30.2nm deposited at low substrate temperature of 75°C in which an additional current gain of 2mA/cm2 was obtained by effective light scattering from the textured surface without any reduction in the open circuit voltage and the fill factor compared with a solar cell with the flat multilayer back reflector with σrms=9.13nm. This result confirms that textured ZnO:Al/Ag/Al:Si multilayer back reflectors prepared at a low substrate temperature of 75°C can be used in flexible silicon thin-film solar cells using polymeric substrates with low heat resistance. [Display omitted] •We report on the low-temperature deposition of moderately textured multilayers.•The substrate temperature does not exceed 75°C.•Enhanced performance was achieved in flexible nc-Si:H solar cell.