Cu2ZnSnS4 is a promising low-cost, nontoxic, earth-abundant absorber material for thin-film solar cell applications. In this study, combinatorial coevaporation was used to synthesize individual thin-film samples spanning a wide range of compositions at low (325 °C) and high (475 °C) temperatures. Film composition, grain morphology, crystalline-phase and photo-excitation information have been characterized by x-ray fluorescence, scanning electron microscopy, x-ray diffraction, Raman spectroscopy, and photoluminescence imaging and mapping. Highly textured columnar grain morphology is observed for film compositions along the ZnS-Cu2ZnSnS4-Cu2SnS3 tie line in the quasi-ternary Cu2S-ZnS-SnS2 phase system, and this effect is attributed to structural similarity between the Cu2ZnSnS4, Cu2SnS3, and ZnS crystalline phases. At 475 °C growth temperature, Sn-S phases cannot condense because of their high vapor pressures. As a result, regions that received excess Sn flux during growth produced compositions falling along the ZnS-Cu2ZnSnS4-Cu2SnS3 tie line. Room-temperature photoluminescence imaging reveals a strong correlation for these samples between film composition and photoluminescence intensity, where film regions with Cu/Sn ratios greater than ∼2 show strong photoluminescence intensity, in comparison with much weaker photoluminescence in regions that received excess Sn flux during growth or subsequent processing. The observed photoluminescence quenching in regions that received excess Sn flux is attributed to the effects of Sn-related native point defects in Cu2ZnSnS4 on non-radiative recombination processes. Implications for processing and performance of Cu2ZnSnS4 solar cells are discussed.

1.
I.
Repins
,
M. A.
Contreras
,
B.
Egaas
,
C.
DeHart
,
J.
Scharf
,
C. L.
Perkins
,
B.
To
, and
R.
Noufi
,
Prog. Photovoltaics
16
,
235
239
(
2008
).
2.
P.
Jackson
,
R.
Würz
,
U.
Rau
,
J.
Mattheis
,
M.
Kurth
,
T.
Schlötzer
,
G.
Bilger
, and
J. H.
Werner
,
Prog. Photovoltaics
15
,
507
519
(
2007
).
3.
P.
Jackson
,
D.
Hariskos
,
E.
Lotter
,
S.
Paetel
,
R.
Wuerz
,
R.
Menner
,
W.
Wischmann
, and
M.
Powalla
,
Prog. Photovoltaics
19
,
894
897
(
2011
).
4.
X.
Wu
,
J.
Zhou
,
A.
Duda
,
J. C.
Keane
,
T. A.
Gessert
,
Y.
Yan
, and
R.
Noufi
,
Prog. Photovoltaics
14
,
471
483
(
2006
).
6.
T. K.
Todorov
,
J.
Tang
,
S.
Bag
,
O.
Gunawan
,
T.
Gokmen
,
Y.
Zhu
, and
D. B.
Mitzi
,
Adv. Energy Mater.
3
,
34
38
(
2013
);
M. T.
Winkler
,
W.
Wang
,
O.
Gunawan
,
H. J.
Hovel
,
T. K.
Todorov
, and
D. B.
Mitzi
,
Energy Environ. Sci.
7
,
1029
(
2014
).
7.
T. K.
Todorov
,
K. B.
Reuter
, and
D. B.
Mitzi
,
Adv. Mater.
22
,
E156
E159
(
2010
).
8.
K.
Wang
,
O.
Gunawan
,
T.
Todorov
,
B.
Shin
,
S. J.
Chey
,
N. A.
Bojarczuk
,
D.
Mitzi
, and
S.
Guha
,
Appl. Phys. Lett.
97
,
143508
(
2010
).
9.
Q.
Guo
,
H. W.
Hillhouse
, and
R.
Agrawal
,
J. Am. Chem. Soc.
131
,
11672
11673
(
2009
).
10.
Q.
Guo
,
G. M.
Ford
,
W.-C.
Yang
,
B. C.
Walker
,
E. A.
Stach
,
H. W.
Hillhouse
, and
R.
Agrawal
,
J. Am. Chem. Soc.
132
,
17384
17386
(
2010
).
11.
D. A. R.
Barkhouse
,
O.
Gunawan
,
T.
Gokmen
,
T. K.
Todorov
, and
D. B.
Mitzi
,
Prog. Photovoltaics
20
,
6
11
(
2012
).
12.
B.
Shin
,
O.
Gunawan
,
Y.
Zhu
,
N. A.
Bojarczuk
,
S. J.
Chey
, and
S.
Guha
,
Prog. Photovoltaics
21
,
72
76
(
2013
).
13.
A.
Nagoya
,
R.
Asahi
,
R.
Wahl
, and
G.
Kresse
,
Phys. Rev. B
81
,
113202
(
2010
).
14.
I. D.
Olekseyuk
,
I. V.
Dudchak
, and
L. V.
Piskach
,
J. Alloys Compd.
368
,
135
143
(
2004
).
15.
S.
Chen
,
J.
Yang
,
X. G.
Gong
,
A.
Walsh
, and
S. H.
Wei
,
Phys. Rev. B
81
,
245204
(
2010
).
16.
K.
Biswas
,
S.
Lany
, and
A.
Zunger
,
Appl. Phys. Lett.
96
,
201902
(
2010
).
17.
S.
Chen
,
A.
Walsh
,
X. G.
Gong
, and
S. H.
Wei
,
Adv. Mater.
25
,
1522
1539
(
2013
).
18.
W. J.
Yin
,
Y.
Wu
,
S. H.
Wei
,
R.
Noufi
,
M. M.
Al-Jassim
, and
Y.
Yan
,
Adv. Energy Mater.
4
,
1300712
(
2014
).
19.
X.-D.
Xiang
,
Ann. Rev. Mater. Sci.
29
,
149
171
(
1999
).
20.
P. A.
Fernandes
,
P. M. P.
Salome
, and
A. F.
da Cunha
,
Thin Solid Films
517
,
2519
2523
(
2009
).
21.
G. A.
Hope
,
C. G.
Munce
,
G. K.
Parker
, and
S. A.
Holt
,
Colloids Surf., A
295
,
152
158
(
2007
).
22.
L. S.
Price
,
I. P.
Parkin
,
T. G.
Hibbert
, and
K. C.
Molloy
,
Chem. Vap. Deposition
4
,
222
225
(
1998
).
23.
X.
Fontane
,
L.
Calvo-Barrio
,
V.
Izquierdo-Roca
,
E.
Saucedo
,
A.
Perez-Rodriguez
,
J. R.
Morante
,
D. M.
Berg
,
P. J.
Dale
, and
S.
Siebentritt
,
Appl. Phys. Lett.
98
,
181905
(
2011
).
24.
P. A.
Fernandes
,
P. M. P.
Salome
, and
A. F.
da Cunha
,
J. Phys. D
43
,
215403
(
2010
).
25.
J. C.
Jamieson
and
H. H.
Demarest
, Jr.
,
J. Phys. Chem. Solids
41
,
963
964
(
1980
).
26.
E. A.
Lund
,
H.
Du
,
W. M.
Hlaing Oo
,
G.
Teeter
, and
M. A.
Scarpulla
,
J. Appl. Phys.
115
,
173503
(
2014
).
27.
M. J.
Romero
,
H.
Du
,
G.
Teeter
,
Y.
Yan
, and
M. M.
Al-Jassim
,
Phys. Rev. B
84
,
165324
(
2011
).
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