Improvement and optimization of Cu2ZnSn(S1-xSex)4 structure for optoelectronic applications

The use of semiconductors based on abundant and less expensive materials in photovoltaic industry has grown since electricity consumption has increased, alloys such as Cu2ZnSn(S1-xSex)4 have recently attracted attention, due to its structural, optical and electronic properties which make it a very promising candidate as an absorber layer in photovoltaic applications. The lattice mismatch of Cu2ZnSn(S1-xSex)4 with Cu2NiGeS4 as substrate for solar cell architecture reveals that low Se content (0.1≤x≤0.4) is favorable, and thus, by reducing Se content from 40 to 10% induces a decrease in optical parameters such as refractive index from 5.475 to 3.834 for near-infrared wavelengths, and both extinction and absorption coefficients are from 0.478 to 0.211 and from 7.956×104 to 6.912×104 cm-1 , respectively, for almost along the visible spectrum. Additionally, the bandgap energy of Cu2ZnSn(S1-xSex)4 in kesterite structure increases from 1.267 to 1.442 eV at room temperature, while the compressive strain of the epitaxial layer reduces from 3.93 to 2.39% and from 4.62 to 3.17% on the growth plane and following the direction of growth, respectively.