Electrical and Related Properties of Organic Solids

441 Pages·1997·18.602 MB·English

by  M. Kryszewski (auth.), R. W. Munn, Andrzej Miniewicz, Bogdan Kuchta (eds.)

Electrical and Related Properties
of Organic Solids
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3. High Technology - Vol. 24
Electrical and Related
Properties of Organic Solids
edited by
R. W. Munn
Department of Chemistry, UMIST,
Manchester, United Kingdom
and
Andrzej Miniewicz
Bogdan Kuchta
Institute 01 Physical and Theoretical Chemistry,
Technical University of Wroctaw, Poland
Springer Science+Business Media, B.V.
Proceedings of the NATO Advanced Advanced Research Workshop
ERPOS-7: Electrical and Related Properties of Organic Solids
Polanica Zdr6j, Poland
18-22 June 1996
A C.I.P. Catalogue record for this book is available from the Library of Congress
ISBN 978-94-010-6444-6 ISBN 978-94-011-5790-2 (eBook)
DOI 10.1007/978-94-011-5790-2
Printed on acid-free paper
AII Rights Reserved
© 1997 Springer Science+Business Media Dordrecht
Originally published by Kluwer Academic Publishers in 1997
Softcover reprint of the hardcover 1st edition 1997
No part of the material protected by this copyright notice may be reproduced or
utilized in any form or by any means, electronic or mechanical, including photo
copying, recording or by any information storage and retrieval system, without written
permission from the copyright owner.
CONTENTS
Some applications of organic conductors
M. Kryszewski 1
Hole transport in triphenylmethane doped polymers
P. M. Borsenberger 25
Photoconductivity of polymers: Influence of the photoinduced charge transfer
S. Ne.spurek and M. Mensik 39
Intermediate excited states in photoconductivity and luminescence of PPY:
Study by spin-dependent techniques
E. L. Frankevich 55
Electroluminescence in polymeric systems with defined chemical and
morphological structure
D. Neher, M. Remmers and Y. Cirnrova 79
Theoretical characterization of electroluminescence in semiconducting
conjugated polymers and oligomers
J.-L. Bredas 101
Calculation of charge-transfer states in molecular crystals
R. W. Munn 117
Charge carriers as electronic and molecular polarons in organic crystals:
Formation and transfer processes
E. A. Silinsh 133
Molecular electronic relaxation in organic solids
N. Sato 157
Electron processes in organic e1ectroluminescence
J. Kalinowski 167
Time-resolved fluorescence quenching and carrier generation in titanyl
phthalocyanine (TiOPc)
Z. D. Popovic, M. I. Khan, S. J. Atherton, A.-M. Hor and
J. L. Goodman 207
Gallium phthalocyanine thin films studied by electroabsorption
K. Yamasaki and M. Kotani 219
vi
Three component organic semiconductors, conductors and superconductors
H. Inokuchi and K. Imaeda 227
Conductivity of the ET polyiodides crystalline networks transformed into
superconducting phase
J. U1anski, A. Tracz, J. K. Jeszka, E. Laukhina, A. Khomenko,
P. Polanowski, D. Staerk and H. W. Helberg 241
Electron donor-acceptor interactions of C60 with tetraphenylphosphonium
and tetraphenylarsonium halides
A. Graja, V. N. Semkin, N. G. Spitsina and S. Kr61 259
Novel organic crystals for nonlinear and electro-optics
C. Bosshard, M.-S. Wong, F. Pan, R. Spreiter, S. Follonier,
U. Meier and P. Gunter 279
Heterocyclic squaraines: Second-harmonic generation from Langmuir-Blodgett
films of a centrosymmetric donor-acceptor-donor molecule
G. J. Ashwell and P. Leeson 297
Photorefractive polymers for digital holographic optical storage
D. M. Burland 305
Dye-doped liquid crystal for real-time holography
A. Miniewicz, S. Bartkiewicz, A. Januszko and W. Turalski 323
Nonlinear spectroscopy in conjugated molecules
S. Delysse, J.M. Nunzi, P. Raimond and F. Kajzar 339
Fluorescence microscopy of single molecules: Temperature dependence
of linewidths
T. Imgartner, H. Bach, A. Renn and U. P. Wild 359
Proton tunnelling in molecular crystals: Translational tunnelling along
hydrogen bonds and rotational tunnelling of methyl groups as studied by
optical spectroscopy, NMR, and neutron scattering
H. P. Trommsdorff, M. Johnson, M. Neumann, L. von Laue,
D. F. Brougham and A. J. Horsewill 369
Ab initio molecular dynamics simulation of condensed molecular systems
M. Sprik 395
VB
Electron-proton co-operation in I-D metallic states
T. Mitani and H. Kitagawa 403
The influence of electronic changes on structural phase transformations
in solid iodine under pressure
B. Kuchta, T. Luty, K. Rohleder and R. D. Etters 415
Theory of optical switching in a model based on electron transfer in H2 +
E. Cane) 423
Langmuir-Blodgett films of archaeal lipids: Properties and perspectives
S. Dante, M. G. Ponzi-Bossi and F. Rustichelli 431
Index 445
PREFACE
As its acronym indicates, ERPOS-7 was the seventh in a series of conferences.
Like the first meeting in 1974 and most of its predecessors, it was held in the
Lower Silesia region of south-west Poland. Also like its predecessors, the
conference had two aims. The first aim, essential to all successful conferences, was
to bring together authoritative speakers and critical listeners so that the current state
of knowledge of organic solids could be expounded and tested in debate. The
second aim, specific to this series, was to bring together participants satisfying the
first aim drawn from a balance of eastern and western countries so that knowledge
and understanding of scientific and other matters could be shared.
However, the circumstances for achieving the latter aim have changed markedly
since earlier conferences in the series. Political upheavals in eastern Europe
including the break-up of the Soviet Union have made it easier in some ways to
achieve this aim, though no less desirable. In particular, the countries of eastern
Europe have changed from being members of a pact confronting NATO to being
Cooperating Partners of NATO. It is this change which has allowed ERPOS-7 to
be supported as a NATO Advanced Research Workshop. The organisers and
participants are very grateful for this scientific and financial support.
These proceedings are also a reflection of NATO support. Following the NATO
guidelines, we have tried to make the contributions together a retlection of the
current state of the art in electrical and related properties of organic solids. This
too has changed over the years. The first conferences were predominantly
concerned with electrical properties, but with time the title changed to reflect the
increasing importance of related (mainly optical) properties. Optical properties
continue to constitute a significant part of the proceedings, but maintaining the
balance with electrical properties has remained important. Few conferences
combine such a breadth of properties with such a breadth of materials, and hence
few conferences offer such a wealth of opportunities for cross-fertilization of ideas.
We hope that will be evident from these Proceedings, which have been assembled
from camera-ready manuscripts prepared by the authors. (Contributed papers will
appear in the journal Advanced Materials for Optics and Electronics.)
We gratefully acknowledge the NATO support already mentioned, the guidance and
support of the publishers Kluwer, the hard work put in during the conference by
the team of referees and editorial workers in helping to prepare the contributions
for publication, and of course the contributors from whose researches and writings
those Proceedings derive all their value. In the local vernacular, dzi~kujemy!
Bob Munn, Andrzej Miniewicz and Bogdan Kuchta
ix
SOME APPLICATIONS OF ORGANIC CONDUCTORS
M.KRYSZEWSKI
Center of Molecular and Macromolecular Studies, PAS, 90-363 L6dt,
Poland; Polymer Institute, Technical University of Mdt, 90-924 Poland
1. Introductions
A novel class of electronic materials:. inherently conducting charge transfer
complex (CT complexes) emerged in the 1960's and in the late 1970's when highly
conducting doped polyacetylene was discovered. This conjugated organic polymer can
be oxidized or reduced (doped) to exhibit metallic conductivity of the order of 200 s/cm
[1,2]. For over a decade, this polymer has been the subjected of intense scientific
research, however its general lack of processability and environmetal instability has
hindered its technical applicability.
It is not possible to try to understand the properties of conducting polymers
without considering the strong development of the studies on crystalline charge transfer
complexes which has been carried out during last three decades. It is out of the general
scope of our discussion to describe these results but the considerable body of
informations obtained should be briefly mentioned here because the progress in the
study of these materials had an deep influence on the progress in the studies and
application of organic conductors.
It have been shown that these systems consist of organic donors combined with
inorganic or organic acceptors. In Bechgaard salts organic donors are combined with
inorganic acceptors. There is a certain amount of charge transfer from the organic
donor to the inorganic acceptor. Because of this charge transfer the electronic bands are
only partially filled and the Bechgaard salts are metalic. At low temperatures some of
them become superconducting, others undergo a metal-to-insulator transition via the
Peierls mechanism.
Bechgaard's salts show another interesting behavior ego (fluoranthenyl)2SbF6
shows very narrow SRR lines which makes it a very sensitive magnetic fields probe.
This is due to the charge delocalization of fluoroanthenyl stacks which is usually the
case of good one -dimensional metals.
All organic CT complexes are obtained by combination of an organic donor
with organic acceptor. A very well and often investigated is the complex of
tetrathiafulvalene with tetracyanochinodimethane (TTF-TCNQ) [3]. One can consider
it as the model substance for all fully organic CT complexes. The crystal structure of
this complex shows that TTF and TCNQ units are arranged in a hearing bone pattern.
R. W. Munn et at. (eds.), Electrical and Related Properties ojOrRanic Solids, 1-23.
© 1997 Kluwer Academic Publishers.
2
Because of the tilt, the units are more densely packed with larger overlap between the
molecules in the stack. Thus it is the charge transfer from the TTF stacks to the TCNQ
stacks which makes the TTF-TCNQ complexes well conducting. TCNQ and TTF also
crystallizes separately fonning insulating solids. TTF-TCNQ complexes show very
interesting solid state effects e.g. high anisotropic electrical conductivity and Peierls
transition (metal-to-insulator) but it dose not become superconducting.
In the 1970's reports have been published concerning the superconductivity
with Tc as high as 58°C for some of the TTF-TCNQ complex samples. Today we know
that the samples showed tricky artifacts caused by the high, very much temperature
dependent anisotropy of the electrical conductivity.
It is not possible to discus here the details of structure, properties and complex
transition in one - two and three dimensional organic superconductors. The organic
charge transfer salt of tetramethylselenofulvalene (TMTSF) with PF is the first one
6
dimensional organic material in which the superconductivity was observed [4].
Under the pressure of 12 kbar the superconductivity occurred at Tc =0. 9K.
TMTSF is related to TTF in which the sulfur atoms are replaced by selenium atoms and
four methyl groups are added. The PF6 AsF6, TaF6, Re04 or CI04 act as electron
acceptors. Conductivity in these materials is exclusively due to overlapping of the
7['
orbitals of the cation. It seems necessary to note that it is different from the p-orbital
overlap fonning the bonds in conjugate polymers occurs sidewise along the polymer
7['
axis which leads to wide bands W - IOeV. Overlapping in CT-salts is top to bottom,
extends along the stacking axis and leads to narrow bands, W - leV. Conjugated
polymers are intra-molecular one-dimensional conductors. Charge-transfer salts are
inter-molecular conductors. It should be mentioned that there is also an inter-molecular
interaction e.g. inter-chain overlapping in conjugated polymers with W::; leV and an
inter-stack overlap in TMSTF charge transfer salts with W ~ leV.
The studies on TMTSF compounds have shown how important is the one
dimentionality temperature and pressure to control the phenomenon of superconductivity
e.g. (TMTTFhBr2 is the first superconductor in the (TM)2X2 series under the pressure
of 26kbar [4]. In one dimensional superconductors the critical temperature is limited by
the competition between various instabilities. Stronger inter-stack lateral coupling
between the cations causes that they are two-dimensional rather then linear. Such
requirements are fulfilled by BEDT-TTF or ET - bis(ethylenedithio)tetrathiafulvalene.
It is a sulfur-based relative of TTF which contains four chalcogen atoms. (ET)2R04 is
the first sulfur based organic superconductor (Tc=2K at p>4,5 kbar. ET donor can be
combined with a very large variety of acceptors. This system exhibits a rich diversity
in structures. There are two main groups of structures the {3 and K-family. ET layers
exist in both families. In the {3-family the ET molecules fonn a honeycomb -like sulfur
network, while the structure of K-family is more complicated. The (ET)2 CU[(CN)2]Br
is the organic-inorganic superconductor with highest Tc= 12.8 at a pressure of 0.3 kbar.
It seems interesting to note that ET -salts are somehow in the vicinity if high temperature
ceramic copper semiconductors. Those materials consists of "metalic" layers e.g. CU02