DEVELOPMENT OF HIGH-EFFICIENCY Culn_xGa_(1-x)Se_2 THIN-FILM SOLAR CELLS BY SELENIZATION WITH ELEMENTAL Se VAPOR IN VACUUM

摘要

On the basis of the establishment of the two-stage method developed in this study which is directly linked to the control of the Se beam-flux intensity during the precursor preparation stage, achievements in the development of CIGS thin-film absorbers are reported with remarkably high efficiency of 14.9 % in the band gap of about 1.3 eV. Furthermore, it is, for the first time, demonstrated that the two-stage method developed in this study is applicable to the formation of a graded band-gap structure by adjusting the Se beam-flux intensity during the precursor preparation stage to over 1.5 × 10~(-5) Torr, which leads to rather high efficiency of 10.1 %. These results demonstrate 1) a significantly high capability of the two-stage method developed in this study to prepare device-quality CIGS thin-film absorbers and 2) the control of Se is the most important factor to fabricate a sufficiently high-quality CIGS thin-film absorber in this method.