[21p-B202-1~13] 13.9 Compound solar cells

[21p-B202-4] Band Alignment at CdS/Cu₂O Interface

〇Norio Terada¹, Katsuhiro Okubo¹, Daisuke Mukai¹, Kazushige Yamamoto², Naoyuki Nakagawa², Takehiko Nagai³, Hitoshi Tampo³ (1.Kagoshima Univ., 2.TOSHIBA Co., 3.AIST)

Keywords:compound solar cell, copper oxide, photoemission spectroscpy

Cu₂O which has a band gap energy of about 2 eV is a promising material for the absorber in top cell of 4-terminal tandem solar cell. At the present time, it is useful to accumulate systematic information about electronic structure at the interface based on Cu₂O. In this study, the band alignment at interface between the high quality Cu₂O sputtered layer and CdS which is a popular n-type layer for compound solar cells is determined by means of in-situ direct and inverse photoemission spectroscopy. The experiments reveal that the conduction band connection at the CdS/Cu2O interface is a “large cliff”, unfavorable for suppressing interface loss, though an interface induced band bending is large over 0.6 eV. The results also indicate a vacuum level discontinuity.