Stability Study of Silicon Heterojunction Solar Cells Fabricated with Gallium‐ and Boron‐Doped Silicon Wafers

Abstract

Herein, a comparison of industrial silicon heterojunction (SHJ) solar cells formed using p‐type (boron‐ or gallium‐doped) Czochralski‐grown silicon (Cz‐Si) wafers is provided. Standard n‐type SHJ solar cells are also fabricated as a reference. Boron‐doped SHJ solar cells are heavily susceptible to boron–oxygen light‐induced degradation (BO‐LID), with an open‐circuit voltage ( V OC ) reduction of 100 mV in some cells with starting V OC of >720 mV. While an advanced hydrogenation process (AHP) is sufficient to completely stabilize BO‐LID in some cells, resulting in stable V OC of 724 mV, the impact in reducing BO‐LID is variable. This suggests that an AHP alone may not be a reliable method of reducing BO‐LID in industrial SHJ solar cells. In contrast, SHJ solar cells formed using gallium‐doped wafers exhibit V OC > 730 mV and show no degradation during light‐soaking. Yet, the same AHP treatment for gallium‐doped SHJ cells results in a 0.4% abs increase in the conversion efficiency to 22.6% ( V OC of 734 mV). The conversion efficiency of the gallium‐doped SHJ solar cells is still lower than the n‐type reference cells, which is largely due to a reduced fill factor (FF). Further work is required to overcome this FF limitation to facilitate high‐efficiency gallium‐doped SHJ solar cells.