A new double stacked a-Si:H solar cell having the structure pin/TCO/nip

The light-induced degradation (Staebler-Wronski effect) in amorphous silicon pin solar cells can be reduced by using thin i-layers. The conventionally used pin/pin stacked solar cells behave more stable than single junction devices at the same efficiency level. The electrical series connection of these stacked cells exhibits disadvantages owing to the i-layer thicknesses and changes in the solar spectrum. A parallel connected stacked solar cell overcomes these shortcomings. The new stacked solar cell presented here has the structure pin/thin conducting oxide (TCO)/nip and incorporates the electrical parallel connection of the two subcells. In this device structure, the photocurrents generated in the two subcells simply add up. The use of the same material for depositing both junctions promises the equality of photovoltages at the maximum power point. With a suitable patterning by laser scribing, an integrated solar module can be made. Changes in the solar spectrum and in the i-layer thicknesses are tolerable in the new device, thus making the production process simpler