2023-Sustainable Industrial Processing Summit
Echegoyen Intl. Symp / Nanomaterials for Future Energy Demands
| Editors: | F. Kongoli, M.P. Brzezinska, M.A. Alario-Franco, F. Marquis, M.S. Noufal, E.Palomares, J.M. Poblet, D.M. Guldi, A.A. Popov, A.R. Puente Santiago, B. Raveau, D. G. Rodriguez, S. Stevenson, T. Torres, A. Tressaud, M. de Campos |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2023 |
| Pages: | 166 pages |
| ISBN: | 978-1-989820-78-0 (CD) |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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X-RAY PHOTOELECTRON SPECTROSCOPIC INSIGHT INTO OXIDATION OF A RANGE OF SEMICONDUCTOR KESTERITE Cu2ZnSnS4 NANOPOWDERS AFTER 6 MONTH-EXPOSURE TO AMBIENT AIR
Jerzy F. Janik1; Katarzyna Lejda2;1AGH UNIVERSITY OF KRAKOW, Kraków, Poland; 2AGH UNIVERSITY OF KRAKOW, FACULTY OF ENERGY AND FUELS, Kraków, Poland;
Type of Paper: Regular
Id Paper: 253
Topic: 16
Abstract:
Kesterite Cu2ZnSnS4 for prospective applications in photovoltaic (PV) cells is a complex quaternary metal sulfide semiconductor that as a tetragonal polytype shows the advantageous energy band gap Eg of 1.3-1.5 eV. Yet, from a practical viewpoint, not much is know about the compound’s susceptibility to oxidation in air which can impact its synthesis and characterization as well as stability in the application/storage stages.
One of the kesterite materials forms are nanopowders that can be used to make special inks or as sputtering targets in PV cell preparations. We recently developed a few precursor systems for the preparation of kesterite nanopowders by the mechanochemically assisted synthesis method. The isolated raw nanopowder from the synthesis in all cases is a cubic polytype of kesterite (tentatively called prekesterite) that does not show semiconductor properties. Only, after annealing under a neutral gas atmosphere at 500 °C this form is converted to the tetragonal kesterite semiconductor.
In this study, both the raw prekesterite and annealed kesterite nanopowders were synthesized from three precursor systems [1,2], i.e., from the mixture of the (i) component elements (CE) {2Cu+Zn+Sn+4S}, (ii) selected metal sulfides and sulfur (MS) {Cu2S+ZnS+SnS+S}, and (iii) from in-situ made Zn/Sn copper alloys that were further reacted with sulfur (CA) {2Cu+Zn+Sn} → Zn/Sn copper alloys+4S}. The resulting black powders were investigated as freshly made and after a 6-month exposure to ambient air.
The X-ray photoelectron spectroscopy XPS confirmed in all nanopowders the characteristic binding energies of copper Cu(I), zinc Zn(II), tin Sn(IV), and sulfur S (in sulfides) as expected in both kesterite polytypes. However, for the air-exposed samples the S 2p region contained a set of two additional peaks (S 2p3/2 and S 2p1/2) above 168 eV that are typical for sulfur binding energies in the sulfate -SO4 groups. Their presence was confirmed by the analysis of the relevant oxygen O 1s peaks. The intensities of the sulfate-related peaks were higher for the prekesterites compared to the related kesterites, which pointed out to the higher oxidation reactivity of the former forms. This trend was further corroborated by the XRD patterns that confirmed substantial oxidation of all nanopowders after 6 months in air. The oxidation by-products in the amounts of up to several tens wt% included the hydrated forms of copper(II) and zinc(II) sulfates, and tin(IV) oxide SnO2.
(NCN grant No. 2020/37/B/ST5/00151)
Keywords:
Characterization; Nanomaterials; Photovoltaic; Spectroscopy; SynthesisReferences:
[1] K. Lejda, M. Drygaś, J.F. Janik, J. Szczytko, A. Twardowski, Z. Olejniczak, Materials 13 (2020) 3487.[2] K. Kapusta, M. Drygas, J.F. Janik, Z. Olejniczak, J. Mater. Res. Technol. 9 (2020), 13320.