Planar rear emitter back contact amorphous/crystalline silicon heterojunction solar cells (RECASH / PRECASH)

Point / stripe contacted, planar rear emitter back contact amorphous/crystalline Silicon, a-Si:H/c-Si, heterojunction solar cells are presented (RECASH / PRECASH solar cells), combining the high efficiency concepts of silicon heterojunctions (high VOC potential) and back contacts (high ISC potential). Electrically insulated point or stripe contacts to the solar cell absorber are embedded within a low temperature deposited rear side planar amorphous silicon emitter layer. The new contacting schemes for back contacted a-Si:H/c-Si heterojunction solar cells require less structuring and enable the use of low cost patterning technologies which result in a large structure size (i.e. inkjet printing, screen printing). The efficiency potential of back contacted a-Si:H/c-Si heterojunction solar cells (> 24 %) is discussed by means of numerical computer simulation. First RECASH and PRECASH solar cells have been realized and are compared to a conventional front contacted a-Si:H/c-Si heterojunction solar cell (SHJ). The predicted higher short circuit current potential of back contacted a-Si:H/c-Si heterojunction solar cells could be proofed.