Flexible silicon heterojunction solar cells on 40 μm thin substrates

Silicon heterojunction solar cells were manufactured on 40 mu m thin substrates using standard industrial manufacturing processes. As the thickness of the substrates goes down, bulk Shockley-Read-Hall recombination is less dominant and surface recombination becomes the main loss mechanism at the maximum power point. In this paper we report our latest accomplishments on 40 mu m thin silicon heterojunction solar cells. We have achieved implied open-circuit voltages >760 mV and surface saturation current densities < 2 fA/cm(2). The best cell has an efficiency of 20.69%, with an open-circuit voltage of 736 mV, a short-circuit current density of 37.17 mA/cm(2) and a fill factor of 75.6%. Replacing the thick ITO front layer with an SiO2/ITO bilayer led to a gain of 1.2 +/- 0.2 mA/cm(2) in current density.