We report on infrared (IR) absorption and dc electrical measurements of thin films of poly(3-hexylthiophene) (P3HT) that have been modified by a fluoroalkyl trichlorosilane (FTS). Spectra for FTS-treated films were compared to data for electrostatically-doped P3HT in an organic field-effect transistor (OFET). The appearance of a prominent polaron band in mid-IR absorption data for FTS-treated P3HT supports the assertion of hole doping via a charge-transfer process between FTS molecules and P3HT. In highly-doped films with a significantly enhanced polaron band, we find a monotonic Drude-type absorption in the far-IR, signifying delocalized states. Utilizing a simple capacitor model of an OFET, we extracted a carrier density for FTS-treated P3HT from the spectroscopic data. With carrier densities reaching , our results demonstrate that FTS doping provides a unique way to study the metal-insulator transition in polythiophenes.
REFERENCES
1.
A. J.
Heeger
, Rev. Mod. Phys.
73
, 681
(2001
).2.
R. D.
McCullough
, Adv. Mater.
10
, 93
(1998
).3.
M. J.
Panzer
and C. D.
Frisbie
, Adv. Funct. Mater.
16
, 1051
(2006
).4.
H.
Yang
, S. W.
LeFevre
, C. Y.
Ryu
, and Z.
Bao
, Appl. Phys. Lett.
90
, 172116
(2007
).5.
C. H.
Ahn
, J. -M.
Triscone
, and J.
Mannhart
, Nature (London)
424
, 1015
(2003
).6.
C. H.
Ahn
, A.
Bhattacharya
, M.
Di Ventra
, J. N.
Eckstein
, C. D.
Frisbie
, M. E.
Gershenson
, A. M.
Goldman
, I. H.
Inoue
, J.
Mannhart
, A. J.
Millis
, A. F.
Morpurgo
, D.
Natelson
, and J. -M.
Triscone
, Rev. Mod. Phys.
78
, 1185
(2006
).7.
G.
Brocks
, J.
van den Brink
, and A. F.
Morpurgo
, Phys. Rev. Lett.
93
, 146405
(2004
).8.
A. S.
Dhoot
, J. D.
Yuen
, M.
Heeney
, I.
McCulloch
, D.
Moses
, and A. J.
Heeger
, Proc. Natl. Acad. Sci. U.S.A.
16
, 1051
(2006
).9.
J. D.
Yuen
, A. S.
Dhoot
, E. B.
Namdas
, N. E.
Coates
, M.
Heeney
, I.
McCulloch
, D.
Moses
, and A. J.
Heeger
, J. Am. Chem. Soc.
129
, 14367
(2007
).10.
M. J.
Panzer
and C. D.
Frisbie
, J. Am. Chem. Soc.
129
, 6599
(2007
).11.
L.
Herlogsson
, Y. -Y.
Noh
, N.
Zhao
, X.
Crispin
, H.
Sirringhaus
, and M.
Berggren
, Adv. Mater.
20
, 4708
(2008
).12.
T.
Mills
, L. G.
Kaake
, and X. -Y.
Zhu
, Appl. Phys. A: Mater. Sci. Process.
95
, 291
(2009
).13.
M. F.
Calhoun
, J.
Sanchez
, D.
Olaya
, M. E.
Gershenson
, and V.
Podzorov
, Nature Mater.
7
, 84
(2008
).14.
C. Y.
Kao
, B.
Lee
, L. S.
Wielunski
, M.
Heeney
, I.
McCulloch
, E.
Garfunkel
, L. C.
Feldman
, and V.
Podzorov
, Adv. Funct. Mater.
19
, 1906
(2009
).15.
M.
Pope
and C. E.
Swenberg
, Electronic Processes in Organic Crystals and Polymers
(Oxford University Press
, New York
, 1999
).16.
Z. Q.
Li
, G. M.
Wang
, N.
Sai
, D.
Moses
, N. C.
Martin
, M.
Di Ventra
, A. J.
Heeger
, and D. N.
Basov
, Nano Lett.
6
, 224
(2006
).17.
Z.
Bao
, A.
Dodabalapur
, and A. J.
Lovinger
, Appl. Phys. Lett.
69
, 4108
(1996
).18.
N.
Sai
, Z. Q.
Li
, M. C.
Martin
, D. N.
Basov
, and M.
Di Ventra
, Phys. Rev. B
75
, 045307
(2007
).19.
Z.
Bao
and J.
Locklin
, Organic Field-Effect Transistors
(Taylor & Francis
, Boca Raton
, 2007
).20.
A.
Assadi
, G.
Gustaffson
, M.
Willander
, C.
Svensson
, and O.
Ingans
, Synth. Met.
37
, 123
(1990
).21.
P. J.
Brown
, H.
Sirringhaus
, M.
Harrison
, M.
Shkunov
, and R. H.
Friend
, Phys. Rev. B
63
, 125204
(2001
).22.
L.
Bürgi
, R. H.
Friend
, and H.
Sirringhaus
, Appl. Phys. Lett.
82
, 1482
(2003
).23.
A. S.
Dhoot
, G. M.
Wang
, D.
Moses
, and A. J.
Heeger
, Phys. Rev. Lett.
96
, 246403
(2006
).24.
D.
Braga
and G.
Horowitz
, Adv. Mater.
21
, 1473
(2009
).25.
Th. B.
Singh
and N. S.
Sariciftci
, Annu. Rev. Mater. Res.
36
, 199
(2006
).26.
Z. Q.
Li
, V.
Podzorov
, N.
Sai
, M. C.
Martin
, M. E.
Gershenson
, M.
Di Ventra
, and D. N.
Basov
, Phys. Rev. Lett.
99
, 016403
(2007
).27.
M.
Fischer
, M.
Dressel
, B.
Gompf
, A. K.
Tripathi
, and J.
Pflaum
, Appl. Phys. Lett.
89
, 182103
(2006
).28.
T. J.
Lenk
, V. M.
Hallmark
, C. L.
Hoffmann
, J. F.
Rabolt
, D. G.
Castner
, C.
Erdelen
, and H.
Ringsdorf
, Langmuir
10
, 4610
(1994
).29.
M. -W.
Tsao
, C. L.
Hoffmann
, J. F.
Rabolt
, H. E.
Johnson
, D. G.
Castner
, C.
Erdelen
, and H.
Ringsdorf
, Langmuir
13
, 4317
(1997
).30.
F.
Sinapi
, T.
Issakova
, J.
Delhalle
, and Z.
Mekhalif
, Thin Solid Films
515
, 6833
(2007
).31.
X. M.
Jiang
, R.
Österbacka
, O.
Korovyanko
, C. P.
An
, B.
Horovitz
, R. A. J.
Janssen
, and Z. V.
Vardeny
, Adv. Funct. Mater.
12
, 587
(2002
).32.
R.
Österbacka
, X. M.
Jiang
, C. P.
An
, B.
Horovitz
, and Z. V.
Vardeny
, Phys. Rev. Lett.
88
, 226401
(2002
).33.
A. J.
Heeger
, S.
Kivelson
, J. R.
Schrieffer
, and W. -P.
Su
, Rev. Mod. Phys.
60
, 781
(1988
).34.
Y. H.
Kim
and A. J.
Heeger
, Phys. Rev. B
40
, 8393
(1989
).35.
B.
Horovitz
, Solid State Commun.
41
, 729
(1982
).36.
B.
Horovitz
, R.
Österbacka
, and Z. V.
Vardeny
, Synth. Met.
141
, 179
(2004
).37.
R.
Österbacka
, C. P.
An
, X. M.
Jiang
, and Z. V.
Vardeny
, Science
287
, 839
(2000
).38.
Y. H.
Kim
, D.
Spiegel
, S.
Hotta
, and A. J.
Heeger
, Phys. Rev. B
38
, 5490
(1988
).39.
M.
Dressel
and G.
Grüner
, Electrodynamics of Solids
(Cambridge University Press
, Cambridge
, 2002
).40.
M. M.
Qazilbash
, M.
Brehm
, G. O.
Andreev
, A.
Frenzel
, P. -C.
Ho
, B. -G.
Chae
, B. -J.
Kim
, S. J.
Yun
, H. -T.
Kim
, A. V.
Balatsky
, O. G.
Shpyrko
, M. B.
Maple
, F.
Keilmann
, and D. N.
Basov
, Phys. Rev. B
79
, 075107
(2009
).41.
42.
H.
Sirringhaus
, P. J.
Brown
, R. H.
Friend
, M. M.
Nielson
, K.
Bechgaard
, B. M. W.
Langeveld-Voss
, A. J. H.
Spiering
, R. A. J.
Janssen
, E. W.
Meijer
, P.
Herwig
, and D. M.
de Leeuw
, Nature (London)
401
, 685
(1999
).43.
M.
Wohlgenannt
, X. M.
Jiang
, and Z. V.
Vardeny
, Phys. Rev. B
69
, 241204
(R) (2004
).44.
V.
Cataudella
, G.
De Filippis
, and G.
Iadonisi
, Eur. Phys. J. B
12
, 17
(1999
).45.
S.
Ciuchi
and S.
Fratini
, Phys. Rev. B
79
, 035113
(2009
).46.
K.
Lee
, S.
Cho
, S. H.
Park
, A. J.
Heeger
, C. -W.
Lee
, and S. -H.
Lee
, Nature (London)
441
, 65
(2006
).© 2010 American Institute of Physics.
2010
American Institute of Physics
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