We used time-resolved terahertz spectroscopy to study ultrafast photoconductivity of polycrystalline thin-film silicon solar cells. We selected a series of samples, which exhibited variable conversion efficiencies due to hydrogen plasma passivation under various technological conditions. The decay of the transient terahertz conductivity shows two components: the fast one is related to the charge recombination at interfaces, while the slow nanosecond one is attributed to the trapping of photocarriers by defects localized at grain boundaries or at dislocations in the polycrystalline p layer of the structure. We observed a clear correlation between the open-circuit voltage and the nanosecond-scale decay time of the transient terahertz conductivity of the solar cells. Thus, the terahertz spectroscopy appears to be a useful contactless tool for inspecting the local photoconductivity of solar cells including, in particular, various nanostructured schemes.

1.
R. B.
Bergmann
,
Appl. Phys. A
69
,
187
(
1999
).
2.
M. A.
Green
,
Third Generation Photovoltaics: Advanced Solar Energy Conversion
(
Springer
,
Berlin
,
2006
).
3.
J.
Bisquert
,
Nanostructured Energy Devices: Equilibrium Concepts and Kinetics
(
CRC Press, Taylor & Francis
,
2015
).
4.
P. K.
Nayak
,
G.
Garcia-Belmonte
,
A.
Kahn
,
J.
Bisquert
, and
D.
Cahen
,
Energy Environ. Sci.
5
,
6022
(
2012
).
5.
A.
Fejfar
,
M.
Hývl
,
M.
Ledinský
,
A.
Vetushka
,
J.
Stuchlík
,
J.
Kočka
,
S.
Misra
,
B.
O'Donnell
,
M.
Foldyna
,
L.
Yu
, and
P.
Roca i Cabarrocas
,
Sol. Energy Mater. Sol. Cells
119
,
228
(
2013
).
6.
L.
Carnel
,
I.
Gordon
,
K.
Van Nieuwenhuysen
,
D.
Van Gestel
,
G.
Beaucarne
, and
J.
Poortmans
,
Thin Solid Films
487
,
147
(
2005
).
7.
L.
Carnel
,
I.
Gordon
,
D.
Van Gestel
,
K.
Van Nieuwenhuysen
,
G.
Agostinelli
,
G.
Beaucarne
, and
J.
Poortmans
,
Thin Solid Films
511–512
,
21
(
2006
).
8.
B.
Gorka
,
B.
Rau
,
P.
Dogan
,
C.
Becker
,
F.
Ruske
,
S.
Gall
, and
B.
Rech
,
Plasma Processes Polym.
6
,
S36
(
2009
).
9.
M.
Spiegel
,
C.
Zechner
,
B.
Bitnar
,
G.
Hahn
,
W.
Jooss
,
P.
Fath
,
G.
Willeke
,
E.
Bucher
,
H.-U.
Höfs
, and
C.
Häßler
,
Sol. Energy Mater. Sol. Cells
55
,
331
(
1998
).
10.
G.
Hahn
,
P.
Geiger
,
D.
Sontag
,
P.
Fath
, and
E.
Bucher
,
Sol. Energy Mater. Sol. Cells
74
,
57
(
2002
).
11.
D.
Hiller
,
S.
Gutsch
,
A. M.
Hartel
,
P.
Löper
,
T.
Gebel
, and
M.
Zacharias
,
J. Appl. Phys.
115
,
134311
(
2014
).
12.
S.
Steffens
,
C.
Becker
,
D.
Amkreutz
,
A.
Klossek
,
M.
Kittler
,
Y.-Y.
Chen
,
A.
Schnegg
,
M.
Klingsporn
,
D.
Abou-Ras
,
K.
Lips
, and
B.
Rech
,
Appl. Phys. Lett.
105
,
022108
(
2014
).
13.
I.
Gordon
,
L.
Carnel
,
D.
Van Gestel
,
G.
Beaucarne
, and
J.
Poortmans
,
Thin Solid Films
516
,
6984
(
2008
).
14.
C.
Becker
,
D.
Amkreutz
,
T.
Sontheimer
,
V.
Preidel
,
D.
Lockau
,
J.
Haschke
,
L.
Jogschies
,
C.
Klimm
,
J. J.
Merkel
,
P.
Plocica
,
S.
Steffens
, and
B.
Rech
,
Sol. Energy Mater. Sol. Cells
119
,
112
(
2013
).
15.
S.
Varlamov
,
J.
Dore
,
R.
Evans
,
D.
Ong
,
B.
Eggleston
,
O.
Kunz
,
U.
Schubert
,
T.
Young
,
J.
Huang
,
T.
Soderstrom
,
K.
Omaki
,
K.
Kim
,
A.
Teal
,
M.
Jung
,
J.
Yun
,
Z. M.
Pakhuruddin
,
R.
Egan
, and
M. A.
Green
,
Sol. Energy Mater. Sol. Cells
119
,
246
(
2013
).
16.
N. H.
Nickel
,
N. M.
Johnson
, and
W. B.
Jackson
,
Appl. Phys. Lett.
62
,
3285
(
1993
).
17.
S.
Honda
,
T.
Mates
,
M. L. J.
Oswald
,
A.
Fejfar
,
J. K. T.
Yamazaki
,
Y.
Uraoka
, and
T.
Fuyuki
,
Thin Solid Films
487
,
152
(
2005
).
18.
R. A.
Sinton
and
A.
Cuevas
, in
16th European Photovoltaic Solar Energy Conference, Glasgow, United Kingdom
,
2000
, p.
1152
.
19.
M.
Fehr
,
P.
Simon
,
T.
Sontheimer
,
C.
Leendertz
,
B.
Gorka
,
A.
Schnegg
,
B.
Rech
, and
K.
Lips
,
Appl. Phys. Lett.
101
,
123904
(
2012
).
20.
S.
Steffens
,
C.
Becker
,
J.-H.
Zollondz
,
A.
Chowdhury
,
A.
Slaoui
,
S.
Lindekugel
,
U.
Schubert
,
R.
Evans
, and
B.
Rech
,
Mater. Sci. Eng., B
178
,
670
(
2013
).
21.
R.
Ulbricht
,
E.
Hendry
,
J.
Shan
,
T. F.
Heinz
, and
M.
Bonn
,
Rev. Mod. Phys.
83
,
543
(
2011
).
22.
L.
Fekete
,
P.
Kužel
,
H.
Němec
,
F.
Kadlec
,
A.
Dejneka
,
J.
Stuchlík
, and
A.
Fejfar
,
Phys. Rev. B
79
,
115306
(
2009
).
23.
V.
Zajac
,
H.
Němec
,
C.
Kadlec
,
K.
Kůsová
,
I.
Pelant
, and
P.
Kužel
,
New J. Phys.
16
,
093013
(
2014
).
24.
C. F.
Klingshirn
,
Semiconductor Optics
(
Springer
,
Berlin
,
2007
), p.
201
.
25.
J.
Nelson
,
The Physics of Solar Cells
(
Imperial College Press
,
2003
), p.
145
.
26.
M. J.
Keevers
,
A.
Turner
,
U.
Schubert
,
P. A.
Basore
, and
M. A.
Green
, in
Proceedings of the 20th European Photovoltaic Solar Energy Conference, Barcelona, Spain
,
2005
, p.
1305
.
27.
W.
Beyer
,
Sol. Energy Mater. Sol. Cells
78
,
235
(
2003
).
28.
See supplementary material at http://dx.doi.org/10.1063/1.4937388 for details on the terahertz experimental setup and terahertz photoconductivity spectra.
29.
C.
Jacoboni
,
C.
Canali
,
G.
Ottaviani
, and
A. A.
Quaranta
,
Solid-State Electron.
20
,
77
(
1977
).
30.
W.
Shockley
and
W. T.
Read
,
Phys. Rev.
87
,
835
(
1952
).

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