Selective removal of Cu2−x(S, Se) phases from Cu2ZnSn(S, Se)4 thin films. Issue 21 (16th August 2016)

• Record Type: Journal Article
• Authors: Pinto, Alexandre H.; Shin, Seung Wook; Aydil, Eray S.; Penn, R. Lee
• Is Part Of: Green chemistry. Volume 18:Issue 21(2016)
• Page Start: 5814
• Page End: 5821
• Publication Date: 2016-08-16
• Subjects: Environmental chemistry -- Industrial applications -- Periodicals; Environmental management -- Periodicals; 660
• DOI: 10.1039/c6gc01287f
• Languages: English
• ISSNs: 1463-9262

Abstract

Abstract : A safer etchant is developed to replace toxic KCN for dissolving undesired impurities from thin films used in solar cells. Abstract : The selective removal of Cu2− x (S, Se) impurity phases from Cu2 ZnSn(S, Se)4 (CZTSSe) and Cu(In, Ga)Se2 (CIGS) thin films is a major barrier to achieving high efficiencies in solar cells based on these films. A toxic and hazardous potassium cyanide (KCN) solution is commonly used as a selective etchant to remove Cu2− x (S, Se) from CZTSSe and CIGS thin films. Herein, we report the selective removal of Cu2− x (S, Se) compounds from kesterite CZTSSe thin films using a mixture of ethylenediamine and 2-mercaptoethanol, a safer chemical mixture than KCN. We found that Cu2− x S and kesterite CZTS nanocrystals dissolve in this mixture in seconds and 6 hours, respectively, while wurtzite CZTS nanocrystals do not dissolve even after 6 hours. Etching CZTSSe thin films containing small amounts of Cu2− x (S, Se) phases for 20 minutes removes the Cu2− x (S, Se) phases completely.