Advanced silicon wafer preparation

In the area of silicon wafer production, the NextBase objective is to produce high quality n-type cz-silicon wafers as absorber bulk and develop optimized texturing and nano-texturing to enhance light-trapping in IBC-SHJ solar cells. High quality cz-wafers are being produced exceeding 2 ms/Ω.cm, thus warranting a low bulk recombination losses. Moreover, thermal treatment on high quality wafers doubles the bulk lifetime. Using rear side textured wafers, optical analysis revealed that reflectance losses decrease by more than 0.5 mA/cm2 compared to a flat rear side. Furthermore, total reflectance losses are reduced up to 1.5 mA/cm2 using front side nano-texturing. Additionally, samples featuring front nano-texturing still achieve effective lifetime beyond 2 ms. With such light-trapping improvements in high quality c-Si bulk, IBC solar cells with short circuit current density beyond 42 mA/cm2 are feasible.