P -layer Optimization in High Performance a-Si:H Solar Cells

We report our progress toward high-performance hydrogenated amorphous silicon (a-Si:H) solar cells fabricated in NREL’s newly installed multi-chamber film Si deposition system. The a-Si:H layers are made by standard radio frequency plasma-enhanced chemical vapor deposition. This system produces a-Si:H p-i-n single-junction devices on Asahi U-type transparent conducting oxide glass with >10% initial efficiency. The importance of the p-layer to the cell is identified: it plays a critical role in further improving cell performance. Our optimization process involves changing p -layer parameters such as dopant levels, bandgap, and thickness in cells as well as applying a double p -layer. With the optimized p -layer, we are able to increase the fill factor of our cells to as high as 72% while maintaining high open-circuit voltage.