Effects of Bi Incorporation on Cu(In1-x,Gax)Se2 Thin Films and Solar Cells

• Published in: Jpn J Appl Phys 2012-10, Vol.51 (10), p.10NC24-10NC24-3
• Main Authors: Nakakoba, Hiroya, Yatsushiro, Yuta, Mise, Takahiro, Kobayashi, Taizo, Nakada, Tokio
• Format: Article
• Language: eng ; jpn
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.51.10NC24

The effects of bismuth (Bi) incorporation into Cu(In 1-x ,Ga x )Se 2 (CIGS) thin films and solar cells have been investigated. 10--50-nm-thick Bi thin layers were deposited onto Mo-coated soda-lime glass (SLG) and SiO x -coated SLG substrates by vacuum evaporation. CIGS thin films were then deposited by a three-stage process at substrate temperatures of 450--550 °C. The grain growth of CIGS thin films was enhanced, and the open-circuit voltage and hence the conversion efficiency was improved by the Bi incorporation when the SLG substrates were used. However, little effect was observed when the alkali barrier SiO x layer was deposited on SLG substrates. As a result, we found that the Bi incorporation is beneficial for improving the cell performance when sodium exists simultaneously in CIGS layers.