Band alignments, valence bands, and core levels in the tin sulfides SnS, SnS2, and Sn2S3: Experiment and Theory

Thomas J. Whittles, Lee A. Burton, Jonathan M. Skelton, Aron Walsh, Tim D. Veal, Vin R. Dhanak

Research output: Contribution to journalArticle

  • 38 Citations

Abstract

Tin sulfide solar cells show relatively poor efficiencies despite attractive photovoltaic properties, and there is difficulty in identifying separate phases, which are also known to form during Cu2ZnSnS4 depositions. We present X-ray photoemission spectroscopy (XPS) and inverse photoemission spectroscopy measurements of single crystal SnS, SnS2, and Sn2S3, with electronic-structure calculations from density functional theory (DFT). Differences in the XPS spectra of the three phases, including a large 0.9 eV shift between the 3d5/2 peak for SnS and SnS2, make this technique useful when identifying phase-pure or mixed-phase systems. Comparison of the valence band spectra from XPS and DFT reveals extra states at the top of the valence bands of SnS and Sn2S3, arising from the hybridization of lone pair electrons in Sn(II), which are not present for Sn(IV), as found in SnS2. This results in relatively low ionization potentials for SnS (4.71 eV) and Sn2S3 (4.66 eV), giving a more comprehensive explanation as to the origin of the poor efficiencies. We also demonstrate, by means of a band alignment, the large band offsets of SnS and Sn2S3 from other photovoltaic materials and highlight the detrimental effect on cell performance of secondary tin sulfide phase formation in SnS and CZTS films.
LanguageEnglish
Pages3718–3726
Number of pages8
JournalChemistry of Materials
Volume28
Issue number11
Early online date9 May 2016
DOIs
StatusPublished - 14 Jun 2016

Fingerprint

Core levels
Photoelectron spectroscopy
Valence bands
Tin
X ray spectroscopy
Density functional theory
Experiments
Ionization potential
Electronic structure
Solar cells
Single crystals
Sulfides
tin sulfide
Electrons

Cite this

Whittles, T. J., Burton, L. A., Skelton, J. M., Walsh, A., Veal, T. D., & Dhanak, V. R. (2016). Band alignments, valence bands, and core levels in the tin sulfides SnS, SnS2, and Sn2S3: Experiment and Theory. DOI: 10.1021/acs.chemmater.6b00397

Band alignments, valence bands, and core levels in the tin sulfides SnS, SnS2, and Sn2S3 : Experiment and Theory. / Whittles, Thomas J.; Burton, Lee A.; Skelton, Jonathan M.; Walsh, Aron; Veal, Tim D.; Dhanak, Vin R.

In: Chemistry of Materials, Vol. 28, No. 11, 14.06.2016, p. 3718–3726.

Research output: Contribution to journalArticle

Whittles, TJ, Burton, LA, Skelton, JM, Walsh, A, Veal, TD & Dhanak, VR 2016, 'Band alignments, valence bands, and core levels in the tin sulfides SnS, SnS2, and Sn2S3: Experiment and Theory' Chemistry of Materials, vol. 28, no. 11, pp. 3718–3726. DOI: 10.1021/acs.chemmater.6b00397
Whittles TJ, Burton LA, Skelton JM, Walsh A, Veal TD, Dhanak VR. Band alignments, valence bands, and core levels in the tin sulfides SnS, SnS2, and Sn2S3: Experiment and Theory. Chemistry of Materials. 2016 Jun 14;28(11):3718–3726. Available from, DOI: 10.1021/acs.chemmater.6b00397
Whittles, Thomas J. ; Burton, Lee A. ; Skelton, Jonathan M. ; Walsh, Aron ; Veal, Tim D. ; Dhanak, Vin R./ Band alignments, valence bands, and core levels in the tin sulfides SnS, SnS2, and Sn2S3 : Experiment and Theory. In: Chemistry of Materials. 2016 ; Vol. 28, No. 11. pp. 3718–3726
@article{31e82f4402c14b99899d81d4bd0730bf,
title = "Band alignments, valence bands, and core levels in the tin sulfides SnS, SnS2, and Sn2S3: Experiment and Theory",
abstract = "Tin sulfide solar cells show relatively poor efficiencies despite attractive photovoltaic properties, and there is difficulty in identifying separate phases, which are also known to form during Cu2ZnSnS4 depositions. We present X-ray photoemission spectroscopy (XPS) and inverse photoemission spectroscopy measurements of single crystal SnS, SnS2, and Sn2S3, with electronic-structure calculations from density functional theory (DFT). Differences in the XPS spectra of the three phases, including a large 0.9 eV shift between the 3d5/2 peak for SnS and SnS2, make this technique useful when identifying phase-pure or mixed-phase systems. Comparison of the valence band spectra from XPS and DFT reveals extra states at the top of the valence bands of SnS and Sn2S3, arising from the hybridization of lone pair electrons in Sn(II), which are not present for Sn(IV), as found in SnS2. This results in relatively low ionization potentials for SnS (4.71 eV) and Sn2S3 (4.66 eV), giving a more comprehensive explanation as to the origin of the poor efficiencies. We also demonstrate, by means of a band alignment, the large band offsets of SnS and Sn2S3 from other photovoltaic materials and highlight the detrimental effect on cell performance of secondary tin sulfide phase formation in SnS and CZTS films.",
author = "Whittles, {Thomas J.} and Burton, {Lee A.} and Skelton, {Jonathan M.} and Aron Walsh and Veal, {Tim D.} and Dhanak, {Vin R.}",
year = "2016",
month = "6",
day = "14",
doi = "10.1021/acs.chemmater.6b00397",
language = "English",
volume = "28",
pages = "3718–3726",
journal = "Chemistry of Materials",
issn = "0897-4756",
publisher = "American Chemical Society",
number = "11",

}

TY - JOUR

T1 - Band alignments, valence bands, and core levels in the tin sulfides SnS, SnS2, and Sn2S3

T2 - Chemistry of Materials

AU - Whittles,Thomas J.

AU - Burton,Lee A.

AU - Skelton,Jonathan M.

AU - Walsh,Aron

AU - Veal,Tim D.

AU - Dhanak,Vin R.

PY - 2016/6/14

Y1 - 2016/6/14

N2 - Tin sulfide solar cells show relatively poor efficiencies despite attractive photovoltaic properties, and there is difficulty in identifying separate phases, which are also known to form during Cu2ZnSnS4 depositions. We present X-ray photoemission spectroscopy (XPS) and inverse photoemission spectroscopy measurements of single crystal SnS, SnS2, and Sn2S3, with electronic-structure calculations from density functional theory (DFT). Differences in the XPS spectra of the three phases, including a large 0.9 eV shift between the 3d5/2 peak for SnS and SnS2, make this technique useful when identifying phase-pure or mixed-phase systems. Comparison of the valence band spectra from XPS and DFT reveals extra states at the top of the valence bands of SnS and Sn2S3, arising from the hybridization of lone pair electrons in Sn(II), which are not present for Sn(IV), as found in SnS2. This results in relatively low ionization potentials for SnS (4.71 eV) and Sn2S3 (4.66 eV), giving a more comprehensive explanation as to the origin of the poor efficiencies. We also demonstrate, by means of a band alignment, the large band offsets of SnS and Sn2S3 from other photovoltaic materials and highlight the detrimental effect on cell performance of secondary tin sulfide phase formation in SnS and CZTS films.

AB - Tin sulfide solar cells show relatively poor efficiencies despite attractive photovoltaic properties, and there is difficulty in identifying separate phases, which are also known to form during Cu2ZnSnS4 depositions. We present X-ray photoemission spectroscopy (XPS) and inverse photoemission spectroscopy measurements of single crystal SnS, SnS2, and Sn2S3, with electronic-structure calculations from density functional theory (DFT). Differences in the XPS spectra of the three phases, including a large 0.9 eV shift between the 3d5/2 peak for SnS and SnS2, make this technique useful when identifying phase-pure or mixed-phase systems. Comparison of the valence band spectra from XPS and DFT reveals extra states at the top of the valence bands of SnS and Sn2S3, arising from the hybridization of lone pair electrons in Sn(II), which are not present for Sn(IV), as found in SnS2. This results in relatively low ionization potentials for SnS (4.71 eV) and Sn2S3 (4.66 eV), giving a more comprehensive explanation as to the origin of the poor efficiencies. We also demonstrate, by means of a band alignment, the large band offsets of SnS and Sn2S3 from other photovoltaic materials and highlight the detrimental effect on cell performance of secondary tin sulfide phase formation in SnS and CZTS films.

UR - http://dx.doi.org/10.1021/acs.chemmater.6b00397

U2 - 10.1021/acs.chemmater.6b00397

DO - 10.1021/acs.chemmater.6b00397

M3 - Article

VL - 28

SP - 3718

EP - 3726

JO - Chemistry of Materials

JF - Chemistry of Materials

SN - 0897-4756

IS - 11

ER -