Pre-Fabrication Gettering and Hydrogenation Treatments for Silicon Heterojunction Solar Cells: A Possible Path to >700 mV Open-Circuit Voltages Using Low-Lifetime Commercial-Grade p-Type Czochralski Silicon

Pre-fabrication gettering and bulk hydrogenation processes are applied to low-bulk-lifetime (25 mu s) p-type Czochralski silicon wafers before silicon heterojunction (SHJ) solar cell fabrication, resulting in effective minority carrier lifetime enhancements by a factor of six. On complete SHJ solar cells, this translates to an improvement in the open-circuit voltage (V-OC) of 71 mV, resulting in V-OC values as high as 692 mV. This remarkably high V-OC suggests that efficiencies approaching 25% could be possible for low-cost p-type Czochralski silicon wafers - not the typical expensive, high-quality n-type ones with lifetimes of several milliseconds - in the near future. This method is also likely applicable to n-type SHJ solar cells to reduce the incoming wafer lifetime requirements and to other silicon solar cell structures featuring passivated contacts.