Contributions of bulk, interface and built-in potential to the open circuit voltage of a-Si:H solar cells

Studies have been carried out on identifying the contributions of the bulk, the p/i interface regions, and the built-in potentials, V_bi, to the open circuit voltages, V_OC, of p(a-SiC:H)/i(a-Si:H)/n(μc-Si:H) solar cells. The p-i-n solar cells studied have different i-layers and a variety of hydrogen treated p/i interface regions. Measurements are carried out on V_OC with illumination intensities from 10 to 50 AM1.5 and over the temperature range from 300 to 100°K. Although it has not yet been possible to directly identify the contributions of the i-layers, the large contributions of different p/i interface regions have been identified and characterized. Built-in potentials were measured in a variety of cells and it was found that the V_OCs at AM1.5 are not limited by the V_bi. The significance of the results and possible directions for quantifying the mechanisms limiting V_OC in these as well as other cells are discussed