[17a-F310-1~11] 13.9 Compound solar cells

[17a-F310-4] Characterization of electronic structure of the interface between CdS buffer and KF-treated Cu(In,Ga)(S,Se)₂ absorber

〇Norio Terada¹, Suehiro Kawamura¹, Yuya Iwamoto¹, Kohei Tanigawa¹, Takuya Kato², Hironori Sugimoto², Hajime Shibata³, Koji Matsubara³, Shigeru Niki³ (1.Kagoshima Univ., 2.Solar Frontier K. K., 3.AIST)

Keywords:CIS-based Solar Cell, Electronic Structure, Photoemission and Inverse Photoemission Spectroscopy

Impact of the "post deposition treatment" using KF (KF-PDT) on electronic structure of Cu(In, Ga)(S, Se)₂ (CIGSSe) layers which are identically fabricated as the absorbers in the solar cells with conversion efficiency above 19% and on band alignment of CdS/CIGSSe interface has been studied by means of in-situ photoemission and inverse photoemission spectroscopy. The obtained results reveals that KG-PDT induces a rise of energetic location of band edges of the CIGSSe surface which results in an increase of built-in potential through the buffer/CIGSSe interface. KF-PDT also changes band offset at the interface, since interface induced band bending does not fully follow the increase of built-in potential. The present study indicates that the modifications in the electronic structure induce by KF-PDT are beneficial mainly to open circuit voltage of solar cells, and that there are rooms for improvement in band alignment.