Nano-electronics research center imec said it had achieved a record cell conversion efficiency of 22.5% for its large area (6-inch) n-type PERT (passivated emitter, rear totally diffused) Cz-Si solar cell.
Researchers at imec noted that the new record was the highest efficiency achieved for a two-side-contacted solar cell which had been processed on six inch commercially available n-type Cz-Si wafers, without the use of passivated contacts. The record efficiency was said to have been calibrated at ISE CalLab.
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The cells feature Ni/Cu/Ag front contacts, rear local contacts, a diffused front surface field (FSF) and a rear emitter. The cells achieved an independently confirmed open-circuit voltage (Voc) of 689mV, a short-circuit current (Jsc) of 40.3 mA/cm2, and 80.9 percent fill factor (FF).
Filip Duerinckx, manager of imec’s n-PERT technology platform, said “This new record is a testimony of our technology leadership in developing next-generation silicon photovoltaics solutions. We have a strong commitment to continue increasing the efficiency our n-PERT technology, and are very optimistic that these achievements will further pave the way to industrialization in the near term.”
The research centre noted that it was exploring material and architectural improvements to extend its n-PERT solar cell concept for commercial applications.
This includes n-PERT solar cells with a rear side p-type emitter using epitaxial growth or heterojunction processes that are hoped to provide conversion efficiencies approaching 22%.
Demand for N-type silicon solar cells is expected to increase in coming years as wafer costs reduce and the inherent higher quality silicon provides for higher overall conversion efficiencies than P-type multicrystalline wafers. Higher resistance to LID (light-induced degradation) and higher tolerance to common metal impurities offer improved performance and lower overall lifetime degradation.
