Origin of the difference in the open circuit voltage between p-i-n type and n-i-p type hydrogenated amorphous silicon solar cells

The origin of the difference in the open circuit voltage Voc between a p-i-n and n-i-p type hydrogenated amorphous silicon solar cells is discussed theoretically, considering the interaction of photogenerated free electrons and holes, i.e., the effect of a self-field. It has been clarified that the self-field aids the carrier collection in an n-i-p cell whereas it impedes the carrier collection in a p-i-n cell. This difference in the effect of the self-field on the photovoltaic process causes the difference in Voc between these two type cells.