Spectroscopic ellipsometry study of Cu2Zn(GexSi1-x)Se4 bulk poly-crystals

The present study addresses to the synthesis and determination of the dielectric function of Cu2Zn(GexSi1-x)Se-4 solid solutions with x = 0.4 and 0.8 over the range 1-4.5 eV by spectroscopic ellipsometry analysis, with the aim to achieve a suitable band gap tuning. The dielectric function of the samples is determined using the Adachi model. From the analysis the lowest E-0 transition and high energy E-1A and E-1B transitions are identified. It is found that the band gap varies nonlinearly on composition in the Cu2Zn(GexSi1-x)Se-4 alloys and band gap values as large as 1.87 eV are obtained. These results are essential for the design of efficient tailored photovoltaic solar cells and show the high potential of the kesterite compounds for the development of low-cost sustainable future solar cells.

Automated summary

This study focuses on the synthesis and determination of the dielectric function of Cu2Zn(GexSi1-x)Se-4 solid solutions, with x = 0.4 and 0.8, in the range of 1-4.5 eV. Spectroscopic ellipsometry analysis is used to achieve suitable band gap tuning. The results show that the band gap of Cu2Zn(GexSi1-x)Se-4 alloys varies nonlinearly with composition, with band gap values reaching up to 1.87 eV. These findings are crucial for the design of efficient tailored photovoltaic solar cells and demonstrate the potential of kesterite compounds for the development of low-cost sustainable future solar cells.