Flexible silicon heterojunction solar cells on 40 µm thin substrates

Silicon heterojunction solar cells were manufactured on 40 µm 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 µm thin silicon heterojunction solar cells. We have achieved implied open-circuit voltages >760 mV and surface saturation current densities < 2 fA/cm2. 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/cm2 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/cm2 in current density.