Tuning of the open-circuit voltage by wide band-gap absorber and doped layers in thin film silicon solar cells

We present an experimental study combined with computer simulations on the effects of wide band-gap absorber and window layers on the open-circuit voltage (V-oc) in single junction thin film silicon solar cells. The quantity Delta E-p, taking as the difference between the band gap and the activation energy in < p > layer, is treated as a measure of the p-layer properties and shows a linear relation with V-oc over a range of 100 mV with a positive slope of around 430 mV/eV. Two limiting mechanisms of V-oc are identified: the built-in potential at lower Delta E-p and the band gap of the absorber layer at higher Delta E-p. The results of the experimental findings are confirmed by computer simulations. (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim