Simplified processing for 23%-efficient silicon concentrator solar cells

The authors have developed a three-photomask process that requires only a single furnace step above 800°C to fabricate silicon concentrator cells with efficiencies approaching 23% on float-zone (FZ) Si and, for the first time, an efficiency of 20% on solar-grade Czochralski (Cz) Si. Until now, high-efficiency silicon concentrator cells that have demonstrated conversion efficiencies greater than 22% have used FZ silicon and required multiple dopant diffusions and several high-temperature furnace steps. These complexities increase processing costs and preclude the use of lower cost CZ silicon, which is easily degraded by repeated high-temperature cycling. This simplified processing schedule retains most of the benefit available from high-performance solar cell designs while holding down processing costs, and it makes the use of lower cost CZ Si a viable option. The incorporation of a better optimized antireflection coating and a lower recombination back-surface field are projected to increase this performance even further