Germanium-doped Czochralski silicon for photovoltaic applications

Germanium (Ge)-doped Czochralski (GCZ) silicon has been grown for photovoltaic (PV) applications. It is found that Ge doping improves the mechanical strength of CZ silicon, resulting in the reduction of breakage during wafer cutting, cell fabrication and module assembly. Boron–oxygen (B–O) defects that lead to the light-induced degradation (LID) of carrier lifetime are effectively suppressed by Ge doping. The decrease in the maximum concentration of B–O defects increases with an increase of Ge concentration. The efficiency of GCZ silicon solar cells and the power output of corresponding PV modules both exhibit smaller loss under sunlight illumination. The current work suggests that GCZ silicon should be potentially a novel substrate for thin solar cells with low LID effect.

Graphical abstractThis figure shows the average efficiencies of the as-fabricated and illuminated CZ and GCZ solar cells. An average degradation of 2.0% in efficiency can be observed for the conventional CZ silicon solar cells, while a less efficiency degradation of 1.68% for the GCZ ones.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► GCZ silicon has higher fracture strength, reducing breakage during cell and module fabrications. ► Ge doping can effectively suppress the formation of B–O defects in CZ silicon. ► Initial efficiency of the GCZ silicon solar cells is similar to that of conventional CZ ones. ► Ge doping can reduce the light-induced degradation in CZ silicon solar cells and modules.