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Impacts of surface sulfurization on Cu(In 1−x ,Ga x )Se 2 thin‐film solar cells

2014; Wiley; Volume: 23; Issue: 10 Linguagem: Inglês

10.1002/pip.2554

1099-159X

Taizo Kobayashi, Hiroshi Yamaguchi, Zacharie Jehl Li‐Kao, H. Sugimoto, Takuya Kato, H. Hakuma, Tokio Nakada,

Copper-based nanomaterials and applications

Abstract In this work, the impacts of surface sulfurization of high‐quality Cu(In 1−x ,Ga x )Se 2 (CIGS) thin films deposited by three‐stage process on the film properties and the cell performance were investigated. The CIGS thin films were sulfurized at 550 °C for 30 min using H 2 S gas. The X‐ray photoelectron spectroscopy analysis revealed that sulfur atoms diffused into the CIGS surface layer and that the valence band minimum was lowered by the film sulfurization. The open circuit voltage ( V oc ) drastically increased from 0.590 to 0.674 V as a result of the sulfurization process. Temperature‐dependent current–voltage and capacitance–frequency measurements also revealed that interface recombination was drastically decreased by the lowering of the defect's activation energy level at the vicinity of the buffer/CIGS interface after the sulfurization. Copyright © 2014 John Wiley & Sons, Ltd.