Cu₂Zn1-xCd_xSn(Se1-yS_y)₄solid solutions as absorber materials for solar cells

Cu 2 Zn 1-x Cd x Sn(Se 1-y S y ) 4 monograin powders with different x- and y-values were prepared from binary compounds in the liquid phase of flux material (KI) in evacuated quartz ampoules. All the materials had uniform composition and p-type conductivity. PL spectra (10 K) of the as grown Cu 2 Zn 1-x Cd x Sn(Se) 4 monograin powders showed one PL band with peak position around 0.85 eV which shifted linearly to the lower energy side with increasing Cd content. Cu 2 ZnSnS 4 material showed asymmetrical PL band at 1.31 eV attributed to band-to-tail recombination. RT Raman spectra of Cu 2 ZnSnSe 4 revealed two main peaks at 196 cm -1 and 173 cm -1 and a third less intensive peak with varying peak position in the region 231-253 cm -1 . Raman spectra of Cu 2 ZnSnS 4 showed an intensive peak at 338 cm -1 and additional peaks at 287 cm -1 and 368 cm -1 . Narrow sieved fractions of grown powders were used as absorber materials in monograin layer (MGL) solar cell structures: graphite/ Cu 2 Zn 1-x Cd x Sn(Se 1-y S y ) 4 /CdS/ZnO. The best so far solar cell that was based on the Cu 2 Zn 0.8 Cd 0.2 SnSe 4 had open circuit voltage 422 mV, short circuit current 12 mA/cm 2 and fill fac tor 44%.