Formation of nanometer-sized Cu-Sn-Se particles in Cu2ZnSnSe4 thin-films and their effect on solar cell efficiency. (15th June 2017)

• Record Type: Journal Article
• Authors: Schwarz, Torsten; Cojocaru-Mirédin, Oana; Mousel, Marina; Redinger, Alex; Raabe, Dierk; Choi, Pyuck-Pa
• Is Part Of: Acta materialia. Volume 132(2017)
• Page Start: 276
• Page End: 284
• Publication Date: 2017-06-15
• Subjects: Atom probe tomography -- Microstructure -- Precipitates -- Transmission electron microscopy -- Thin films; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2017.04.056
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: Atom probe tomography and transmission electron microscopy are used to study the formation of nano-sized Cu-Sn-Se particles in Cu2 ZnSnSe4 thin-films. For a Cu-rich precursor, which was deposited at 320 °C under Cu- and Zn-rich growth conditions, Cu2-x Se grains at the surface are detected. During annealing the precursor at 500 °C in a SnSe + Se atmosphere most of the Cu2-x Se is transformed to Cu2 ZnSnSe4 via the consumption of excessive ZnSe and incorporation of Sn. However, atom probe tomography studies also reveal the formation of various nanometer-sized Cu-Sn-Se particles close to the CdS/Cu2 ZnSnSe4 interface. One of those particles has a composition close to the Cu2 SnSe3 compound. This phase has a smaller band gap than Cu2 ZnSnSe4 and is proposed to lead to a significant drop in the open-circuit voltage and could be the main cause for a detrimental p-n junction and the zero efficiency of the final device. Possible effects of the other phases on solar cell performance and formation mechanisms are discussed as well. Graphical abstract: Image 1