Secondary crystalline phases identification in Cu2ZnSnSe4 thin films: contributions from Raman scattering and photoluminescence

In this work, we present the Raman peak positions of the quaternary pure selenide compound Cu2ZnSnSe4 (CZTSe) and related secondary phases that were grown and studied under the same conditions. A vast discussion about the position of the X-ray diffraction (XRD) reflections of these compounds is presented. It is known that by using XRD only, CZTSe can be identified but nothing can be said about the presence of some secondary phases. Thin films of CZTSe, Cu2SnSe3, ZnSe, SnSe, SnSe2, MoSe2 and a-Se were grown, which allowed their investigation by Raman spectroscopy (RS). Here we present all the Raman spectra of these phases and discuss the similarities with the spectra of CZTSe. The effective analysis depth for the common back-scattering geometry commonly used in RS measurements, as well as the laser penetration depth for photoluminescence (PL) were estimated for different wavelength values. The observed asymmetric PL band on a CZTSe film is compatible with the presence of CZTSe single-phase and is discussed in the scope of the fluctuating potentials’ model. The estimated bandgap energy is close to the values obtained from absorption measurements. In general, the phase identification of CZTSe benefits from the contributions of RS and PL along with the XRD discussion.info:eu-repo/semantics/publishedVersio

High-speed electrodeposition of copper–tin–zinc stacks from liquid metal salts for Cu2ZnSnSe4 solar cells

Cu2ZnSnSe4-based solar cells with 5.5% power conversion efficiency were fabricated from Cu/Sn/Zn stacks electrodeposited from liquid metal salts. These electrolytes allow metal deposition rates one order of magnitude higher than those of other deposition methods.crosscheck: This document is CrossCheck deposited related_data: Supplementary Information related_data: Crystal Structure Data identifier: Luc Van Meervelt (ORCID) identifier: Phillip J. Dale (ORCID) identifier: Phillip J. Dale (ResearcherID) copyright_licence: The Royal Society of Chemistry has an exclusive publication licence for this journal history: Received 18 November 2016; Accepted 20 December 2016; Accepted Manuscript published 20 December 2016; Advance Article published 23 December 2016; Version of Record published 10 January 2017status: publishe

Discrimination and detection limits of secondary phases in Cu2ZnSnS4 using X ray diffraction and Raman spectroscopy

The formation of single phase Cu2ZnSnS4 thin films is known to be challenging, mainly due to the difficulties to detect secondary phases in the Cu2ZnSnS4 system. Here, the ability to quantitatively discriminate the most likely secondary phases ZnS and Cu2SnS3 from Cu2ZnSnS4 using common approaches but also using more complex and time consuming Rietveld refinement analysis techniques to analyse X ray diffractograms is investigated in a comparative study to the peak analysis of Raman spectra measured with standard conditions. In studying not only individual samples of the respective phases but also a phase gradient sample containing various amounts of Cu2SnS3 and ZnS alongside Cu2ZnSnS4, we found that refinement analyses can only discriminate more than 10 ZnS and 50 Cu2SnS3 from Cu2ZnSnS4, respectively. In comparison, Raman measurements performed with green wavelength excitation can discern more than 30 Cu2SnS3 from Cu2ZnSnS4 while ZnS is indiscernible. The results show that the identification of secondary phases in the Cu2ZnSnS4 system is more difficult than currently assumed in literature. Furthermore, the potential of multiple wavelength Raman spectroscopy as a tool to identify ZnS secondary phases is shown. Characterization of a Sn rich sample composition nearly Cu2ZnSn3S8 shows no sign of a Sn rich quaternary phase, questioning its existence under typical annealing condition

High-speed Electrodeposition of Copper-Tin-Zinc Stacks from Liquid Metal Salts for Cu2ZnSnSe4 Solar Cells

High speed electrochemical deposition of copper, tin, and zinc from custom designed ionic liquids for large scale solar applications.</p