24 center dot 5% efficiency silicon PERT cells on MCZ substrates and 24 center dot 7% efficiency PERL cells on FZ substrates

This paper reports the recent improvements in the energy conversion efficie ncies of solar cells on magnetically-confined Czochralski gr own (MCZ) and float zone (FZ) silicon substrates at the University of New South Wales. A PERT (passivated emitter, rear totally-diffused) cell structure has been us ed to I educe the cell series resistance from higher resistivity substrates . The total rear boron diffusion in this PERT structure appears to improve the surface passivation quality of MCZ and some FZ substrates. Hence, highe r open-circuit voltages were observed for some PERT cells. One of these cel ls on MCZ substrates demonstrated 24.5% energy conversion efficiency at San dia National Laboratories under the standard global spectrum (100 in mW/cm( 2)) at 25 degrees C. This is the highest efficiency ever reported for a MCZ silicon solar cell. The cells made on MCZ substrates also showed stable ce ll performance rather than the usually reported unstable performance for bo ron-doped CZ substrates. Also reported is a PERL (passivated emitter, rear locally-diffused) cell on a FZ substrate of 24.7% efficiency, which is the highest efficiency ever reported for any silicon solar cell. Copyright (C) 1999 John Wiley & Sons, Ltd.