An improved silicon-oxide-based intermediate-reflector for micromorph solar cells

In this paper, we report on the development of an n-type silicon oxide intermediate reflector (SOIR) for a-Si:H/mu c-Si:H tandem solar cells produced in an industrial-type AKT1600 PECVD reactor. A comparison to a tunnel recombination junction with mu c-SiOx in the p-layer is made. Lower fill factors, resulting from the implementation of the SOIR, could be avoided by the deposition of a thin n-doped microcrystalline silicon (mu c-Si) recombination layer after the SOIR. A cell efficiency of 9.5 % after 168 h of light soaking at 50 degrees C and 1 sun was reached on commercially available SnO2:F front TCO, which is a 2 % relative increase over a similar cell without the SOIR. Possible explanations for the role of this recombination layer are discussed. (C) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim