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Interface structure and band alignment of CZTS/CdS heterojunction: An experimental and first-principles DFT investigation

Rondiya, Sachin, Jadhav, Yogesh, Nasane, Mamta, Jadkar, Sandesh and Dzade, Nelson Y. 2019. Interface structure and band alignment of CZTS/CdS heterojunction: An experimental and first-principles DFT investigation. Materials 12 (24) , 4040. 10.3390/ma12244040

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Abstract

We report a phase-pure kesterite Cu2ZnSnS4 (CZTS) thin films, synthesized using radio frequency (RF) sputtering followed by low-temperature H2S annealing and confirmed by XRD, Raman spectroscopy and XPS measurements. Subsequently, the band offsets at the interface of the CZTS/CdS heterojunction were systematically investigated by combining experiments and first-principles density functional theory (DFT) calculations, which provide atomic-level insights into the nature of atomic ordering and stability of the CZTS/CdS interface. A staggered type II band alignment between the valence and conduction bands at the CZTS/CdS interface was determined from Cyclic Voltammetry (CV) measurements and the DFT calculations. The conduction and valence band offsets were estimated at 0.10 and 1.21 eV, respectively, from CV measurements and 0.28 and 1.15 from DFT prediction. Based on the small conduction band offset and the predicted higher positions of the VBmax and CBmin for CZTS than CdS, it is suggested photogenerated charge carriers will be efficient separated across the interface, where electrons will flow from CZTS to the CdS and and vice versa for photo-generated valence holes. Our results help to explain the separation of photo-excited charge carriers across the CZTS/CdS interface and it should open new avenues for developing more efficient CZTS-based solar cells.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Chemistry
Publisher: MDPI
ISSN: 1996-1944
Funders: EPSRC
Date of First Compliant Deposit: 3 January 2020
Date of Acceptance: 28 November 2019
Last Modified: 04 Aug 2020 01:44
URI: http://orca.cf.ac.uk/id/eprint/128179

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