Interdigitated rear contact solar cells with amorphous silicon heterojunction emitter

Thin layers of intrinsic and doped amorphous silicon have been used as the emitter in a processing scheme to form heterojunction interdigitated back contact (HJ-IBC) solar cells. Such processing involved depositing the emitter across the wafer, and subsequent patterning to define the base and emitter regions. Average cell efficiencies of 14.6% have been achieved (with a best cell efficiency of 15.2%), with average short circuit current densities as high as 37.8 mA/cm² (maximum 39.1 mA/cm²), demonstrating the potential of such a solar cell structure. However, the open circuit voltage and fill factor values are lower than could be expected. The reasons behind this are discussed, as are proposed solutions to further enhance the cell performance.