2018 
Solar Energy Materials and Solar Cells 
                 Increase in conversion efficiency of above 14% in Cu (In, Ga) 3Se5 (β-CIGS) solar cells by Na2S incorporation through the surface of β–CIGS film 
                 Ji Hye Kim, Seung Tae Kim, Liudmila Larina, Byung Tae Ahn. KiHwan Kim, Jae Ho Yun