Improvement of hetero-interface engineering by partial substitution of Zn in Cu2ZnSnS4-based solar cells
Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB UMR 6303 CNRS), Université de Bourgogne Franche-Comté, BP 47 870, 21078 Dijon, France
2 Laboratoire de Microscopie Electronique et Sciences des Matériaux (LMESM), Université des Sciences et de la Technologie d'Oran Mohamed Boudiaf USTO-MB, El M'naouar BP 1505, Bir El Djir, 31000 Oran, Algeria
3 Univ. Lyon, INSA Lyon, CNRS, Ecole Centrale de Lyon, Université Claude Bernard Lyon 1, CPE Lyon, INL, UMR 5270, 69621 Villeurbanne, France
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Received in final form: 4 July 2022
Accepted: 21 September 2022
Published online: 18 October 2022
This paper investigates the effects of partial substitution of zinc (Zn) in pure sulfide kesterite (Cu2ZnSnS4) by cadmium (Cd) and manganese (Mn) incorporation. Thin films of Cu2ZnSnS4 (CZTS), Cu2Zn1–xCdxSnS4 (CCZTS) and Cu2Zn1–xMnxSnS4(CMZTS) were produced chemically. A comparison of pure CZTS with CCZTS and CMZTS was performed to study the influence of Cd and Mn incorporation on the morphology, structure, optical and electronic properties of the films. The results show an improvement of the morphology and an adjustment of the band gap and valence band position by partial substitution of Zn with Cd and Mn. In addition, for the first time, the band alignment at the absorber/buffer hetero-interface is studied with partial Zn substitution. Band alignments at the absorber/buffer hetero-interface were estimated by XPS and UV/Visible measurements. The results show a cliff-like CBO for CZTS/CdS heterojunction, a spike-like CBO for CCZTS/CdS and a near flat-band CBO for CMZTS/CdS heterojunction.
Key words: Kesterite / solar cell / cation substitution / band alignment
© C. Tamin et al., Published by EDP Sciences, 2022
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