The role of interfaces in the end-of-life performance of a-Si:H solar cells

We address the question of interfacial contribution to the end-of-life performance of a-Si:H solar cells by focusing on the p/i interface with a comprehensive set of experimental and modeling tools. To separate interfacial from bulk defects we light-soaked a thickness series of cells with i-layers from 0.2 /spl mu/m to 1.0 /spl mu/m. The degradation of the thickness series shows that there is no extra interfacial contribution to efficiency loss. We also soaked cells with 1.0 /spl mu/m i-layers on specular substrates with blue and red light. The change in their quantum efficiency spectra also shows that the p/i interface does not degrade more than the bulk. Using the numerical model AMPS we show that light-soaking can be modeled without invoking extra interface losses.