High-efficiency amorphous and "micromorph" silicon solar cells

LP-CVD ZnO has been developed at IMT as front TCO for a-Si:H p-i-n single-junction and "micromorph" (microcrystalline/amorphous silicon) tandem solar cells. An amorphous silicon single-junction p-i-n cell (/spl sim/1 cm/sup 2/) with a stabilized efficiency of 9.47% has independently been confirmed by NREL. Applying the monolithic series connection by laser-scribing, both for amorphous single-junction and micromorph tandem cells, modules have been fabricated on LP-CVD ZnO. After light-soaking, mini-modules, with an aperture efficiency of 8.7% in the case of amorphous silicon cells (confirmed by NREL), and of 9.8% in the case of micromorph tandem cells, have been obtained. Micromorph tandem cells with an intermediate TCO reflector between the amorphous top and the microcrystalline bottom cell reveal an almost stable performance (/spl eta/=10.7%) with respect to light-soaking.