3. 2 Amorphous and Microcrystalline Silicon Solar Cells
a-Si/µ-Si, Flexible Substrate, Module
Summary / Abstract:
The Helianthos roll-to-roll technology makes use of a temporary Al substrate to deposit high quality SnO2:F and a-Si:H and μc-Si:H layers. The unique characteristics of the roll-to–roll process allow making a series of solar cell modules with continuous variable Si-layer thickness in the roll. When this is done for the i-layer – while keeping the adjacent doped layers at normal thickness – the solar cells performance as function of thickness can be studied in great detail. In that way the thickness influence of μc-Si:H bottom cell in a tandem device is elucidated. As is expected the p/i interface plays an important role. By understanding the limiting factors and optimizing the device by striving for a constant material quality over the thickness of the device an 8.9% aperture area stabilized completely roll-to-roll produced module of 840 cm2 corresponding with a 9.4% active area stabilized efficiency was achieved.