Preparation of microcrystalline single junction and amorphous–microcrystalline tandem silicon solar cells entirely by hot-wire CVD

The hot-wire chemical vapour deposition (HWCVD) has been used to prepare highly conducting p- and n-doped microcrystalline silicon thin layers as well as highly photoconducting, low defect density intrinsic microcrystalline silicon films. These films were incorporated in all-HWCVD, all-microcrystalline nip and pin solar cells, achieving conversion efficiencies of η=5.4% and 4.5%, respectively. At present, only the nip-structures are found to be stable against light-induced degradation. Furthermore, microcrystalline nip and pin structures have been successfully incorporated as bottom cells in all-hot-wire amorphous–microcrystalline nipnip- and pinpin-tandem solar cells for the first time. So far, the highest conversion efficiencies of the “micromorph” tandem structures are η=5.7% for pinpin-solar cells and 7.0% for nipnip solar cells.