Front Side Recombination Losses Analysis in Rear Emitter Silicon Heterojunction Solar Cells

Rear emitter silicon heterojunction solar cells are attractive because of the lateral conductivity of electrons through the wafer yielding a higher fill factor than conventional front emitter structures. However, minority carriers being collected at the rear of the cell, they are more sensitive to recombination at the front interface. In this paper we present a detailed analysis of recombination losses impacting the short-circuit current; the roles of the (i)a-Si:H buffer layer and of the (n)a-Si:H layers are identified thanks to variation of their thicknesses. We point out the critical role played by both bulk a-Si:H absorption and recombination, as well as the field effect induced by the (n)a-Si:H layer.