Mechanism of Shunting of Nanocrystalline Silicon Solar Cells Deposited on Rough Ag/ZnO Substrates

摘要

Using a textured substrate is a basic requirement for light trapping in a thin film solar cell. In this contribution, the structure of μc-Si:H n-i-p solar cells developed on a rough Ag/ZnO coated glass substrate is carefully studied, in order to understand the substrate surface morphology dependence of solar cell properties, especially of the yield of working cells. From cross-sectional transmission electron microscopy (TEM) images it is clear that cells developed on substrates with tilted large Ag crystal grains contain pinholes that result in short-circuiting of the entire device. The formation of these pinholes is due to the inability of conformal coverage of the sub-micron sized cavities that are created by these Ag grains. Controlling the Ag deposition temperature is found to be essential to have a well performing μc-Si:H n-i-p cell.