Optoelectronic and spectroscopic characterization of vapour-transport grown Cu2ZnSnS4 single crystals

Tat Ming Ng, Mark T. Weller, Gabriela P. Kissling, Laurence M. Peter, Phillip Dale, Finn Babbe, Jessica De Wild, Bernard Wenger, Henry J. Snaith, David Lane

Research output: Contribution to journalArticle

  • 4 Citations

Abstract

Single crystals of Cu2ZnSnS4 (CZTS) have been grown by iodine vapor transport with and without addition of NaI. Crystals with tin-rich copper-poor and with zinc-rich copper-poor stoichiometries were obtained. The crystals were characterized by single crystal X-ray diffraction, energy-dispersive X-ray spectroscopy, photocurrent spectroscopy and electroreflectance spectroscopy using electrolyte contacts as well as by spectroscopic ellipsometry, Raman spectroscopy and photoluminescence spectroscopy (PL)/decay. Near-resonance Raman spectra indicate that the CZTS crystals adopt the kesterite structure with near-equilibrium residual disorder. The corrected external quantum efficiency of the p-type crystals measured by photocurrent spectroscopy approaches 100% close to the bandgap energy, indicating efficient carrier collection. The bandgap of the CZTS crystals estimated from the external quantum efficiency spectrum measured using an electrolyte contact was found to be 1.64-1.68 eV. An additional sub-bandgap photocurrent response (Urbach tail) was attributed to sub bandgap defect states. The room temperature PL of the crystals was attributed to radiative recombination via tail states, with lifetimes in the nanosecond range. At high excitation intensities, the PL spectrum also showed evidence of direct band to band transitions at ∼1.6 eV with a shorter decay time. Electrolyte electroreflectance spectra and spectra of the third derivative of the optical dielectric constant in the bandgap region were fitted to two optical transitions at 1.71 and 1.81 eV suggesting a larger valence band splitting than predicted theoretically. The high values of the EER broadening parameters (192 meV) indicate residual disorder consistent with the existence of tail states.

LanguageEnglish
Pages1192-1200
Number of pages9
JournalJournal of Materials Chemistry A
Volume5
Issue number3
DOIs
StatusPublished - 21 Jan 2017

Fingerprint

Optoelectronic devices
Vapors
Single crystals
Energy gap
Crystals
Photoluminescence spectroscopy
Photocurrents
Electrolytes
Spectroscopy
Quantum efficiency
Copper
Optical transitions
Spectroscopic ellipsometry
Tin
Valence bands
Iodine
Stoichiometry
Raman spectroscopy
Raman scattering
Zinc

Cite this

Optoelectronic and spectroscopic characterization of vapour-transport grown Cu2ZnSnS4 single crystals. / Ng, Tat Ming; Weller, Mark T.; Kissling, Gabriela P.; Peter, Laurence M.; Dale, Phillip; Babbe, Finn; De Wild, Jessica; Wenger, Bernard; Snaith, Henry J.; Lane, David.

In: Journal of Materials Chemistry A, Vol. 5, No. 3, 21.01.2017, p. 1192-1200.

Research output: Contribution to journalArticle

Ng, TM, Weller, MT, Kissling, GP, Peter, LM, Dale, P, Babbe, F, De Wild, J, Wenger, B, Snaith, HJ & Lane, D 2017, 'Optoelectronic and spectroscopic characterization of vapour-transport grown Cu2ZnSnS4 single crystals' Journal of Materials Chemistry A, vol. 5, no. 3, pp. 1192-1200. DOI: 10.1039/c6ta09817g
Ng, Tat Ming ; Weller, Mark T. ; Kissling, Gabriela P. ; Peter, Laurence M. ; Dale, Phillip ; Babbe, Finn ; De Wild, Jessica ; Wenger, Bernard ; Snaith, Henry J. ; Lane, David. / Optoelectronic and spectroscopic characterization of vapour-transport grown Cu2ZnSnS4 single crystals. In: Journal of Materials Chemistry A. 2017 ; Vol. 5, No. 3. pp. 1192-1200
@article{643ed8fc42c54659a3be81a968a044ac,
title = "Optoelectronic and spectroscopic characterization of vapour-transport grown Cu2ZnSnS4 single crystals",
abstract = "Single crystals of Cu2ZnSnS4 (CZTS) have been grown by iodine vapor transport with and without addition of NaI. Crystals with tin-rich copper-poor and with zinc-rich copper-poor stoichiometries were obtained. The crystals were characterized by single crystal X-ray diffraction, energy-dispersive X-ray spectroscopy, photocurrent spectroscopy and electroreflectance spectroscopy using electrolyte contacts as well as by spectroscopic ellipsometry, Raman spectroscopy and photoluminescence spectroscopy (PL)/decay. Near-resonance Raman spectra indicate that the CZTS crystals adopt the kesterite structure with near-equilibrium residual disorder. The corrected external quantum efficiency of the p-type crystals measured by photocurrent spectroscopy approaches 100{\%} close to the bandgap energy, indicating efficient carrier collection. The bandgap of the CZTS crystals estimated from the external quantum efficiency spectrum measured using an electrolyte contact was found to be 1.64-1.68 eV. An additional sub-bandgap photocurrent response (Urbach tail) was attributed to sub bandgap defect states. The room temperature PL of the crystals was attributed to radiative recombination via tail states, with lifetimes in the nanosecond range. At high excitation intensities, the PL spectrum also showed evidence of direct band to band transitions at ∼1.6 eV with a shorter decay time. Electrolyte electroreflectance spectra and spectra of the third derivative of the optical dielectric constant in the bandgap region were fitted to two optical transitions at 1.71 and 1.81 eV suggesting a larger valence band splitting than predicted theoretically. The high values of the EER broadening parameters (192 meV) indicate residual disorder consistent with the existence of tail states.",
author = "Ng, {Tat Ming} and Weller, {Mark T.} and Kissling, {Gabriela P.} and Peter, {Laurence M.} and Phillip Dale and Finn Babbe and {De Wild}, Jessica and Bernard Wenger and Snaith, {Henry J.} and David Lane",
year = "2017",
month = "1",
day = "21",
doi = "10.1039/c6ta09817g",
language = "English",
volume = "5",
pages = "1192--1200",
journal = "Journal of Materials Chemistry A",
issn = "2050-7488",
publisher = "Royal Society of Chemistry",
number = "3",

}

TY - JOUR

T1 - Optoelectronic and spectroscopic characterization of vapour-transport grown Cu2ZnSnS4 single crystals

AU - Ng,Tat Ming

AU - Weller,Mark T.

AU - Kissling,Gabriela P.

AU - Peter,Laurence M.

AU - Dale,Phillip

AU - Babbe,Finn

AU - De Wild,Jessica

AU - Wenger,Bernard

AU - Snaith,Henry J.

AU - Lane,David

PY - 2017/1/21

Y1 - 2017/1/21

N2 - Single crystals of Cu2ZnSnS4 (CZTS) have been grown by iodine vapor transport with and without addition of NaI. Crystals with tin-rich copper-poor and with zinc-rich copper-poor stoichiometries were obtained. The crystals were characterized by single crystal X-ray diffraction, energy-dispersive X-ray spectroscopy, photocurrent spectroscopy and electroreflectance spectroscopy using electrolyte contacts as well as by spectroscopic ellipsometry, Raman spectroscopy and photoluminescence spectroscopy (PL)/decay. Near-resonance Raman spectra indicate that the CZTS crystals adopt the kesterite structure with near-equilibrium residual disorder. The corrected external quantum efficiency of the p-type crystals measured by photocurrent spectroscopy approaches 100% close to the bandgap energy, indicating efficient carrier collection. The bandgap of the CZTS crystals estimated from the external quantum efficiency spectrum measured using an electrolyte contact was found to be 1.64-1.68 eV. An additional sub-bandgap photocurrent response (Urbach tail) was attributed to sub bandgap defect states. The room temperature PL of the crystals was attributed to radiative recombination via tail states, with lifetimes in the nanosecond range. At high excitation intensities, the PL spectrum also showed evidence of direct band to band transitions at ∼1.6 eV with a shorter decay time. Electrolyte electroreflectance spectra and spectra of the third derivative of the optical dielectric constant in the bandgap region were fitted to two optical transitions at 1.71 and 1.81 eV suggesting a larger valence band splitting than predicted theoretically. The high values of the EER broadening parameters (192 meV) indicate residual disorder consistent with the existence of tail states.

AB - Single crystals of Cu2ZnSnS4 (CZTS) have been grown by iodine vapor transport with and without addition of NaI. Crystals with tin-rich copper-poor and with zinc-rich copper-poor stoichiometries were obtained. The crystals were characterized by single crystal X-ray diffraction, energy-dispersive X-ray spectroscopy, photocurrent spectroscopy and electroreflectance spectroscopy using electrolyte contacts as well as by spectroscopic ellipsometry, Raman spectroscopy and photoluminescence spectroscopy (PL)/decay. Near-resonance Raman spectra indicate that the CZTS crystals adopt the kesterite structure with near-equilibrium residual disorder. The corrected external quantum efficiency of the p-type crystals measured by photocurrent spectroscopy approaches 100% close to the bandgap energy, indicating efficient carrier collection. The bandgap of the CZTS crystals estimated from the external quantum efficiency spectrum measured using an electrolyte contact was found to be 1.64-1.68 eV. An additional sub-bandgap photocurrent response (Urbach tail) was attributed to sub bandgap defect states. The room temperature PL of the crystals was attributed to radiative recombination via tail states, with lifetimes in the nanosecond range. At high excitation intensities, the PL spectrum also showed evidence of direct band to band transitions at ∼1.6 eV with a shorter decay time. Electrolyte electroreflectance spectra and spectra of the third derivative of the optical dielectric constant in the bandgap region were fitted to two optical transitions at 1.71 and 1.81 eV suggesting a larger valence band splitting than predicted theoretically. The high values of the EER broadening parameters (192 meV) indicate residual disorder consistent with the existence of tail states.

UR - http://www.scopus.com/inward/record.url?scp=85010303360&partnerID=8YFLogxK

UR - http://dx.doi.org/10.1039/c6ta09817g

U2 - 10.1039/c6ta09817g

DO - 10.1039/c6ta09817g

M3 - Article

VL - 5

SP - 1192

EP - 1200

JO - Journal of Materials Chemistry A

T2 - Journal of Materials Chemistry A

JF - Journal of Materials Chemistry A

SN - 2050-7488

IS - 3

ER -