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