Role of a disperse carbon interlayer on the performances of tandem a-Si solar cells

We report the effect of a disperse carbon interlayer between the n-a-Si:H layer and an aluminium zinc oxide (AZO) back contact on the performance of amorphous silicon solar cells. Carbon was incorporated to the AZO film as revealed by x-ray photoelectron spectroscopy and energy-dispersive x-ray analysis. Solar cells fabricated on glass substrates using AZO in the back contact performed better when a disperse carbon interlayer was present in their structure. They exhibited an initial efficiency of 11%, open-circuit voltage V_oc = 1.6 V, short-circuit current J_SC = 11 mA cm^-2 and a filling factor of 63%, that is, a 10% increase in the J_SC and 20% increase in the efficiency compared to a standard solar cell.