Electronic structure and optical properties of wurtzite-kesterite Cu2ZnSnS4

As promising light-absorber material for solar cells, Cu2ZnSnS4 was found to have another crystal structure (wurtzite-kesterite) in addition to the conventional zinc blende-kesterite structure. Structural flexibility of Cu2ZnSnS4 opens up an avenue to develop light-absorber material with novel exciting properties and applications. However, its electronic and optical properties have not been comprehensively studied yet. For this purpose, the method of density functional theory within hybrid functional of PBE0 was adopted to study the structural, electronic, and optical properties of wurtzite-kesterite Cu2ZnSnS4 in this Letter. The calculated results suggested that the energy of its band gap is about 1.372 eV and it has obvious optical anisotropy. Furthermore, its crystal structure leads local internal fields that are especially beneficial to suppress the recombination of photoexcited electron–hole pairs.

► Electronic and optical properties of wurtzite-kesterite Cu2ZnSnS4 have been studied.
► The calculated band gap of wurtzite-kesterite Cu2ZnSnS4 is about 1.372 eV.
► Wurtzite-kesterite Cu2ZnSnS4 has obvious optical anisotropy.
► Its crystal structure is beneficial to suppress the recombination of carriers.