High absorption coefficients of the CuSb(Se,Te)2 and CuBi(S,Se)2 alloys enable high-efficient 100 nm thin-film photovoltaicsRongzhen Chen and Clas PerssonEPJ Photovolt., 8 (2017) 85504DOI: https://doi.org/10.1051/epjpv/2017005