MULTI-BLOC COPOLYMER BASED TUNABLE LIGHT EMITTING DIODE, POLYMERS SUITABLE THEREFOR AND OLIGOMERS

DIODE ELECTROLUMINESCENTE REGLABLE A BASE DE COPOLYMERE MULTISEQUENCE, POLYMERES APPROPRIES A LADITE APPLICATION ET OLIGOMERES

English Abstract

The invention is directed to a light emitting diode (LED) emitting light having a wavelength from 400 to 850 comprising an
electroluminescing material, electrodes and optionally carrier material and/or reflecting material, said electroluminescing material comprising
at least one block copolymer consisting of at least two types of blocks, active blocks sandwiched between non-active blocks, said active
blocks being a .pi.-conjugated block of at least 2 and at most 16 monomeric units, said .pi.-conjugated block having a substantially uniform
block length throughout the copolymer, and said non-active block having no .pi.-conjugated, optionally with additional electron and/or hole
transport properties, to polymers suitable for preparing such LED, to oligomers for preparing said multiblock copolymers and to various
processes.

Claims

NEW CLAIMS
1. Light emitting diode (LED) emitting light having a
wavelength between 400 to 850 nm comprising a layer of an
electroluminescing material, electrodes and optionally carrier
material and/or reflecting material, said electroluminescing
material comprising at least one block copolymer consisting of
at least two types of blocks, active blocks sandwiched between
non-active blocks, said active blocks being a .pi.-conjugated
block of at least 2 and at most 16 monomeric units, said .pi.-
conjugated block having a substantially uniform block length
throughout the copolymer, and said non-active block having no
.pi.-conjugation.
2. LED according to claim 1, wherein the monomeric units of
the .pi.-conjugated block have been selected from the group
consisting of thiophene, alkylated, alkoxylated and arylated
thiophene, vinylene, optionally substitued phenylene,
optionally substitued p-phenylene-vinylene, vinylene-
thiophene, alkylated, alkoxylated and arylated vinylene-
thiophene, and combinations of two or more of these monomeric
units.
3. LED according to claim 2, wherein the monomeric units of
the .pi.-conjugated block have been selected from the group
consisting of substituted and unsubstituted thiophene,
alkylated, alkoxylated and arylated thiophene.
4. LED according to any one of the claims 1-3, wherein the
non-active, non-.pi.-conjugated block has been selected from the
group consisting of .alpha.,.beta.-unsaturated organic compounds like
vinyl and alkylene compounds, oligovinylenes and derivatives
thereof, germanium compounds, silicium compounds and carbon
compounds.
5. LED according to any one of the claims 1-4, wherein the
at least one block copolymer comprises as at least one third
block a hole or electron transport controlling block.

6. LED according to any one of the claims 1-5, wherein an
additional layer is present having hole and/or electron
transport controlling properties.
7. LED according to claim 6, wherein the material of the
said additional layer is polysilane.
8. LED according to any one of the claims 1-7, wherein the
said electroluminescing material is used in admixture with a
material influencing the hole transport properties, for
example a polysilane.
9. LED according to any one of the claims 1-8, wherein a
thin layer of polymer forming a hole injecting electrode,
transparent in the region of emission, is applied to a
flexible substrate, for example a polyester.
10. Block copolymer particularly suitable for use in a light
emitting diode according to claim 1-9, consisting of at least
two groups of blocks, thiophene blocks A sandwiched between
non-thiophene blocks B, of the formula [(-Ax-By-)]z, wherein
Ax and By respectively denote the thiophene and the non-
thiophene blocks, x and y being the respective block-lengths
and z being the number of -Ax-By- blocks in the polymer, said
thiophene blocks Ax having the formula 1,
<IMG>
wherein m, n and p are integers having a value of 0-9, the
sum of m, n and p being at least 4 and wherein the blocks Ax
contain at least one ring wherein at least one of R1-R6 is
different from H.

11. Block copolymer according to claim 10, wherein the
substituents R1-R6 are selected from H and alkyl, aryl,
alkaryl, aralkyl, alkoxy, aralkoxy, preferably from H,
optionally branched, lower alkyl, i.e. C1-C15 and optionally
branched, lower alkoxy.
12. Block copolymer according to claim 10 or 11, wherein the
values of x, y and z are such that the molecular weight of the
polymer will be between 2500 and 500,000.
13. Block copolymer according to claim 10-12, wherein at
least two of the rings in each block are substituted with
alkyl, aryl, alkaryl, aralkyl, alkoxy, aralkoxy and the like,
each substituent containing one to 15 carbon atoms.
14. Block copolymer according to claim 10-13, wherein the
number of substituents on each thiophene ring does not exceed
one.
15. Block copolymer according to claim 10-14, wherein the
group B is selected from the group consisting of .alpha., .beta.-
unsaturated organic compounds like styrene and derivatives
thereof, germanium compounds and silicium compounds.
16. Block copolymer according to claim 15, wherein the group
B is
<IMG>
R7 and R8 being identical or different, each denoting a liniair
or branched alkyl radical having 1-6 carbon atoms or a phenyl
radical, optionally substituted with one or more alkyl and/or
alkoxy groups.
17. Thiophene oligomer, suitable for preparing a
multiblock copolymer according to claim 10, wherein said
thiophene oligomer has the formula 1,

<IMG>
wherein m, n and p are integers having a value of 0-9, the sum
of m, n and p being at least 4 and wherein in at least one
ring in the block at least one of R1-R6 is different from H.
18. Thiophene oligomer according to claim 17, wherein the
substituents R1-R6 are selected from H and alkyl, aryl,
alkaryl, aralkyl, alkoxy, aralkoxy, preferably from H,
optionally branched, lower alkyl, i.e. C1-C15 and optionally
branched, lower alkoxy.
19. Thiophene oligomer according to claim 17 or 18, wherein
at least two of the rings in each block are substituted with
alkyl, aryl, alkaryl, aralkyl, alkoxy, aralkoxy and the like,
each substituent containing one to 15 carbon atoms.
20. Thiophene oligomer according to claim 17-19, wherein the
number of substituents on each thiophene ring does not exceed
one.
21. Process for preparing a block copolymer consisting of at
least two groups of blocks, thiophene blocks A sandwiched
between non-thiophene blocks B, of the formula [(-Ax-By-)]z,
wherein Ax and By respectively denote the thiophene and the
non-thiophene blocks, x and y being the respective block-
lengths and z being the number of -Ax-By- blocks in the
polymer, said thiophene blocks Ax having the formula 1,

<IMG>
wherein m, n and p are integers having a value of 0-9, the sum
of m, n and p being at least 4 and wherein the blocks Ax
contain at least one ring wherein at least one of R1-R6 is
different from H, substantially as described herein.
22. Process for preparing a thiophene oligomer, wherein an
oligomer is prepared having the formula 1,
<IMG>
wherein m, n and p are integers having a value of 0-9, the sum
of m, n and p being at least 4 and wherein in at least one
ring at least one of R1-R6 is different from H, substantially
as described herein.
23. Use of the multiblock copolymers according to anyone of
the claims 10-16 in optoelectronics.
24. Film, optionally on a substrate, of a multiblock
copolymer according to any one of the claims 10-16.

Description

~ 094/15368 2 ~ 5 ~ ~ 2 PCT~L93/00280
Title: Multi-block copolymer based tunable light emitting
diode, polymers suitable therefor and oligomers.
The present invention is directed to a tunable light
emitting diode (LED) based upon multi-block copolymers, to
novel thiophene multi-block copolymers, to thiophene olig~mers
suit ble for preparing said polymers, to processes for
preparing said oligomers and said polymers and to the use of
said polymers in opto-electronics.
Commercial LED devices are made of inorganic
semiconductors e.g. GaAs, GaP etc. which cover almost the
whole spectral region. It would be advantageous to have an
organic material with electroluminescence in the blue region,
as the organic materials are usually more easy to process.
The production of an effective blue LED using
organic materials has however not been aCcompl;she~ yet, which
is one of the reasons for the search for alternative
materials. Although low molecular weight organic materials are
known to give lllm;nPscence even with high efficiencies, only
recently the use in electroluminescent devices was reported. A
disadvantage of the use of low molecular wei.ght organic
materials in devices is their tPn~PnCy to recryst~ e.
The use of organic materials in the production of
LED has certain advantages, especially from the viewpoint of
processability.
One of the important advantages of the polymer LED
is its ease of fabrication. The active polymer or prepolymer
can be cast from solution on a substrate which makes it
possible to fabricate large-area devices. Conjugated polymers
can cover the whole spectral region by chemical tuning of the
wavelength of the emission by choice of the polymer and
control of the conjugation length of the polymer. Another
promising feature is the additional use of a conducting

WO 94/15368 PCT/NL93/00280--
~ 529~2 2 -
polymer as the hole-injecting electrode resulting in a fully
flexible LBD.
Suitable candidates for applications in stable
optoelectronic devices are conjugated polymers. Polymers can
be processed relatively easily and especially large area
structures are feasible. The first encouraging results were
L~oLLed by Burroughes et al ~Nature, 347, 477 (1992)), Braun
et al. (Appl. Phys. Lett. ~, 1982 (1992)) and Grem et al.(Adv.
Mater.4, 36 (1992)), using poly(p-phenylene vinylene)s and
poly(p-phenylene) as the electroluminescent layer.
The basic element giving rise to injection
ll~m~nescence is that of a p-n junction diode operated under
forward bias as is illustrated in fig. 1.
The electrons recambine with holes and give rise to
bounded excitons, which radiatively decay to photons. In the
ideal case each injected electron takes part in the radiative
recombination but in practice this is not the case. The
quantum efficiency of a device made of an inorganic
semiconductor emitting in the visible region lies in the range
0.05 to 496. The wavelength of the emitted photon is det~rm~ne~l
by the energy band gap ~ideal case). For example GaAs has a
band gap of 1.43 eV. In order to obtain visible radiation the
energy gap has to be larger than 2 eV. For a blue LE~ a band
gap of 3.4 eV is required. Inorganic semiconductors like SiC
with these large band gaps tend to have high resistivities
next to fabrication problems because of high melting
temperatures and structural stability.
A large nun~ber of organic materials have extremely
high fluorescent quantum efficiencies in the whole visible
spectral region. The major problem with organic crystals is
the high vo~tage needed to inj ect charges. The drive voltage
to obtain a significant light output is in the order of 100 V
or above. The use of thin solid films lowers the drive voltage
but the efficiency still is extremely low.
Recently it has been reported that LED's can be made
of organic thin films by using a multilayer structure. An

2 ~ 2 2
094/15368 pcTn~L93loo28o
- 3
emitting layer is combined with or sandwiched between a hole
and an electron injecting layer.
A LED emitting bright blue light was achieved, thus
with a ll~min~nce of 700 cd/m2 at a DC drive voltage of lO V.
Unfortunately the stability of the cell is not good yet.
Probably recrystallization of the organic layers due to
produced heat causes degradation of the cell.
Burroughes et al. (loc.cit.) and Braun et al. (loc.
cit.~ clearly demonstrated that LEDs can be made with
conjugated polymers. Their main advantage over non-polymeric
(in)organic semiconductors is the possibility of processing to
form large area structures. The structure of such a LED is
shown in figures 2 and 3.
A substrate, usually glass is covered with the
transparent electrode, e.g. indium/tin oxide (ITO) ~unctioning
as the hole injecting cathode. The emitting layer or a
prepolymer is spincoated on top of this layer and covered with
a top electrode e.g. Al or Ca, the electron injecting anode.
The choice of the electrodes is important. Metals with a low
work function give higher efficiencies. Disadvantage of these
electrodes is the oxidative instability. By choosing a
polymeric substrate polyethylenetererhthAl~te (PET) covered
with transparent processa~le polyaniline as the hole injecting
electrode, G. Gustafsson et al., Nature, 357 477 (l992) even
fabricated a fully flexible ~ED. The electroluminescent
polymer used by the above mentioned scientists is poly(p-
phenylene vinylene~ or a soluble alkoxy derivative thereof.
The electroluminescence spectra of these materials
are very simila~ to their photoluminescence spectra. ~he
ph~tol7lmin~.sce1ce of PPVIs is assigned to ra~iative
co~binat}on- of the singlet polaron exciton ~also called
neutral bipolaron) formed by intrachain excitation.
The electrolllmin~scence is assigned to the sa~e
excited state and is generated by recombinations of holes and
electrons in}ected ~ro~ opposite sides o~ the structure. The
charge carriers are pro~ably polarons. ~ecause the quantum

WO94/15368 21~ 2 ~ 2 ~ PCTA~L93/00280 -
yield of photoluminescence of PPV is about 4%, the non-
radiative processes limit the efficiency of L~Ds. This is
caused by mlgration of the excited states to defect sites
which act as non-radiative recombination centres. Burn et al.
synthesized a copolymer that can be converted by heat
treatment from a conjugated/non-conjugated polymer into a
fully conjugated polymer. The ~l~ntllm yields for
electroluminescence of the coniugated/nonconjugated polymers
were strongly ~nh~nced. The non-conjugate part acting as a
trap for the excitons, ~Le~ Ling the migration to ~lPnch;ng
sites.
The invention is aimed at providing a light emitting
diode (LED) emitting light having a wavelength from 400 to 850
comprising an electroluminescing material, electrodes and
optionally carrier material and/or reflecting material, said
LED being tunable, stable and easy to manufacture at low cost.
According to the ir.vention said electrolllm;nescing
material comprises an electrolnm;ne~cing material, electrodes
and optionally carrier material and/or reflecting material,
said electrolnm;n~cing material comprising at least one block
copolymer consisting of at least two types of blocks, active
blocks sandwiched between non-active blocks, said active
blocks being a ~-conjugated block of at least 2 and at most 16
mon~m~ric units, said ~-conjugated block having a
substantially uniform blocklength throughout the copolymer,
and said non-active block having no ~-conjugation.
The invention is based thereon that it has been
found to be possible to tune the wavelength of the emitted
light by sandwiching ~-conjugated blocks having subst~nt;~lly
uni~orm block length between blocks having no ~-conjugation,
whereby the length of the ~-conjugated blocks mainly
det~rm;nPs the wavelength of the emitted light. According to
the invention this definition of sandwiching ~-conjugated
blocks between blocks having no ~-conjugation is intended to
include the situation that both blocks have ~-conjugation,
whereby there is a large difference in band gaps between the

~ WO94/15368 21~ 2 ~ 2 ~ PCT~L93/00280
blocks, resulting therein that there is no ~-conjugation
between the blocks.
Examples of the components of both the ~-conjugated
blocks and the ~-conjugated blocks, which may be combined in
every possible combination, can be found on the form~ sheet
tFig. 4~. It is to be noted, that in case the multi-block
copolymer is based upon two types of ~-conjugated blocks
having large difference in band gaps, it is possible to make
com.binations of two or more of the ~-conjugated block
materials.
A series of multi-block copolymers with blocks made
out of oligothiophenes (~-conjugated) and oligosilane blocks
(~-conjugated) have been tested for the electrolllm;nescence
thereof. Data on adsorh~nce and photoluminescence as a
function of conjugation lengths for the oligothiophenes and
for oligosilanes respectively, show that with this type of
materials the colour of an electroluminescence device can be
controlled, not only by a~iusting the conjugation length of a
~-system, but also by adj~sting the conjugation length of a ~-
system.. (polys;lAnes). Besides, these materials have theadvantage that they can be processed with deep W-
photolithography, since the polysilanes are deep- W
photoresists. The stability of the above materials under
envilo.".,~ l conditions and under the influence of optical
and electric fields used, is comparable to that of PPV, the
first polymer material used for electroll~m;n~scence device
applications.
It is worth noticing that although the me~h~n~cal
properties of the olig~mer blocks are poor, the m~h~n; cal
properties of the multi-blocks made out of these oligomers
generally are excellent and easy to control by adjusting the
number of blocks. Further, the solubility as well as some of
the electrical and optical properties are controllable by the
substituents on the non-active blocks and the ~-conjugated
blocks. Thus, the above approach gives ample flexibility to
tune not only the mechanical, but also the optical and

WO94/lS368 PCT~L93/00280
~ 9 2 2 - 6
electrical properties by tuning the length of the oliyull~Ls
and the number of blocks in the multi-block copolymers and the
chemical nature of the side-groups.
Suitable ~-conjugated blocks can be based upon all
types of components that result in ~-conjugation after
polymerization to short blocks. Examples thereof are i.a.
thioph~n~s, suitably substltuted thioph~n~s, vinylene,
arylene, vinylene-arylene, thioph~n~-vinylene and thiophene-
arylene.
A preferred group of oligomers to be used for the
present invention are the, optionally substituted, oligo-
thiophenes.
Other suitable oligomers are based upon the various
components given in the form~ sheet (Fig. 4).
According to the invention it is essential to use a
well-defined ~-conjugated block having a substantially uniform
block length. This means that all or substantially all ~-
conjugated blocks in the polymer have the same number of
units. In practise this will mean that at least about 90'~,
preferably at least 98~ of the ~-conjugated blocks will have
the same length. Optionally it is also possible to prepare a
block copolymer based upon a mixture two or three different
blocks. In that case each of the components will have
substantially the same block length.
The ~-conjugated blocks can be prepared from the
components that give said ~-conjugated blocks upon
polymerization. Essential is the factor that the block length
is subst~nt;~lly uniform. There are various methods in which
to obtain said substantially uniform block length. Generally
these methods are all based thereon that first an oligomer is
obt~;ne~ having a subst~nt;~lly uniform block length. This can
for example be acc~mplished by oligomerising the mnn~m~rs in a
controlled m~nner to give rise to a product that is already
relatively uniform, optionally followed by purification to
obtain the required uniform block length. Another approach is

094/15368 ~1 ~ 2 ~ 2 ~ PCTn~L93/00280
to control the reaction in such way, that the components can
only react to give a well-defined product.
An example of this latter approach is to provide a
starting material R having two reactive groups, which reactive
groups each react with one other reactant, S, to give a
product S-R-S that possesses the required block length and ~-
con~ugation (optionally after further treatment, for example
removing or adding substituents).
The non-active blocks that can be sandwiched between
the ~-conjugated blocks can have any composition, provided
that they do not provide ~-conjugation and that they can be
sandwiched between the ~-conjugated blocks. Examples thereof
are oligo organo-silanes, substituted silicium blocks and
oligo styrene and derivatives thereof.
The choice of the intermediate group has influence
on the properties of the multiblock copolymer. Preferred
groups are i.a. , ~-unsaturated organic compounds like vinyl
and alkylene compounds, oligovinylenes and derivatives
thereof, g~rm~n;llm compounds, silicium compounds and carbon
compounds.
Suitable materials for said blocks are based on
silicium, g~rm~n;um or on carbon-carbon oligomers. Of the
latter group, especially the styrenic materials, like
oligostyrene, and oligomers of styrene derivatives, as well as
vinyl compounds such as vinylc~rh~701e are suitable. The
silicium, carbon or g~rm~n;um based materials are preferably
of the type.
IR7
x--
R8
0
wherein X denotes Si, Ge, C, SiO, or CO, R7 and R8
being identical or different, each denoting a l;n~i r or
br~nche~ alkyl substituent having 1-6 carbon atoms or a

WO94/15368 21~ ~ 9 ~ 2 8 - PCT~YL93/00280 -
phenyl, optionally substituted with one or more alkyl and/or
alkoxy groups.
The non-active, or ~-conjugated blocks do not have
such a strong influence on the wavelength of the hED, although
the choice of the blocks and the length thereof certainly
influences the behaviour of the LED. Suitable block lengths
vary between ~ and 8, said block length being based upon the
number of atoms in the ~-conjugated block that become part of
the polymer chain.
The silicon-based blocks have the advantage that
they can be processed with deep W-photolithography, since the
polysilanes are deep- W photoresists. The blocks based upon
silicium and g~rm~nlumn act also as intrinsic hole transport
material, ilLL~loving thus the quantum efficiency. It is thus
possible to prepare a three block copolymer, wherein two types
of non-~-conjugated blocks are present, namely one type having
hole and another having electron transport properties.
The non-~-conjugated blocks are either directly
available chemicals, like vinyl or vinylene oligomers, or can
be prepared separately or in situ, i.e. during the assembly of
the block copolymer.
According to the present invention new semi-
conduct~ing organic and/or organic-inorganic block copolymers
can be used, (s~me of which are shown in ~igure 4) said
polymers being obt~'n~hle by making various combinations for
the optionally alkylated or alkoxylated active blocks of
oligothiophenes, oligovinylenes, oligophenylenes and
oligo(p-phenylenevinylene)s (~-conjugated blocks) with
oligosilanes (~-conjugated blocks), oligosiloxanes,
oligovinypyridine, oligostyrene non-active blocks in order to
obtain a heterostructure based on the principal of the
selfassembly of the block copolymers.
The active block will be sandwiched between the non-
active blocks [(-AX-By-)]z, wherein Ax and By respectively
denote the ~-conjugated and the non ~-conjugated blocks, x and
y being the respective block-lengths and z being the number of
-AX-By~ blocks in the polymer. The values of x, y and z are

~ 094/15368 21 S 2 9 ~ 2 PCT~L93/00280
preferably such that the molecular weight of the polymer will
be between 2500 and 500,000. Lower values may lead to problems
in the processing to films, whereas higher values do not
provide additional advantages in terms of polymer properties
and may lead to processing difficulties, due to the high
molecular weight.
The proposed block copolymers provide various
chemical and physicochemical tuning capabilities and improve
the properties that have been described previously, concerning
the tunable LEDs. Depending on the length of the J~- conjugated-
blocks and the non-active blocks the wave length of the
emitted light is tuned to a value between 400 and 850. The
block length, preferably varies between 2 and 16 units, each
unit comprising two double and two single C-C bonds. With
shorter block lengths the emitted light is more in the
blue/green area, ~hereas larger block lengths lead to a more
reddish colour.
Further the ability of the block copolymers to self
assemble, thus producing microphase separated ordered
structures at the su~l~L.~lecular level, gives the opportunity
to obtain new device architectures or even new devices.
Recently P.L Burn et al.(Nature, 356, 47 tl992))
have ~e~olLed an increase in the efficiency of the LEDs by the
use of copolymers of conjugated/non-conjugated blocks (PPV-
precursors). The synthesis of the copolymers was accomplishedby the use of two different leaving groups (methoxy,
slllphonium) into a precursor copolymer, from which they can
el-m~n~te selectively one of these, or both, to give a fully
conjugated copolymer of poly(p-phenylenevinylene) (PPV). A
severe disadvantage of the system of Burn et al lies therein
that their system cannot provide a well-defined block-length,
and thus no well-defined tunable wave length of the LED due to
the random character of the ~l;min~tion reaction.
The a-conjugated blocks are either directly
available chemicals, like vinyl or vinylene oligomers, or can

WO94/15368 PCTn~L93/00280 -
10 -
be prepared separately or in situ, i.e. during the assembly of
the block copolymer.
The blocks can be assembled into one polymer by
known techniques, for example by reaction between the blocks,
either directly into one copolymer or in two or more steps.
One of the further objects of the present invention
is to provide a novel class of multiblock copolymers
cont~l n; ng short blocks of thiophene and derivatives thereof,
which multiblock copolymers are suitable for use in opto-
electronics and more in particular in LED's, as describedherein.
A further object is to provide a novel class of
multiblock copolymers cont~;n;ng short blocks of thiophene and
derivatives thereof, which multiblock copolymers are easy to
process, for example by spin coating, into a thin layer on a
substrate.
This block copolymer consists of at least two groups
of blocks, thiophene blocks A, sandwiched between
non-thiophene blocks B, said thiophene blocks A having the
fgrm~
R R
R1 R2 R5 R6
wherein m, n and p are integers having a value of
0-9, the sum of m, n and p being at least 3 and wherein at
least one of Rl-R6 is different from H. This means that at
least one of the rings in each block has at least one R
different from H.

~ 094/1~368 ~ I S 2 ~ 2 2 PcTn~Lg3l00280
The substituent R1-R6 may each be selected from H,
optionally branched, lower alkyl, i.e. C1-C15 and optionally
branched, lower alkoxy.
It is to be noted, that the substituents R1-R6 in
the blocks may vary within each block.
The block A, the thiophene block, will be sandwiched between
the non-thiophene blocks in the m~nn~r [(-Ax-By~)]z, wherein Ax
and By respectively denote the ~-conjugated and the non ~-
conjugated blocks, x and y being the respective block-lengths
and z being the number of -AX-By- blocks in the polymer. The
values of x, y and z are preferably such that the molecular
weight of the polymer will be between 2500 and 500,000. hower
value may lead to problems in the processing to films, whereas
higher values do not provide additional advantages in terms of
polymer properties and may lead to processing difficulties,
due to the high molecular weight.
Depending on the required properties the number of
thiophene units can be selected, as well as the type and
number of substituents. It is preferred that at least one of
the thiophene rings has to be substituted as otherwise the
processability, especially in spin-coating, is insufficient.
Preferably at least two of the rings in each block are
substituted with alkyl, aryl, alkaryl, aralkyl, alkoxy,
aralkoxy and the like, each substituent cont~nlng one to 15
carbon atoms. In practising the invention the substituents R1
and R2 will generally be identical to R5 and R6, whereas R3 and
R4 may be different. Preferably the number of substituents on
each ring will not exceed one, that means that in each ring at
least one of the R-groups will denote H. The selection of the
substituents influences the electroluminescent properties of
the material to some degree. For the processing properties of
- the materials the presence of substituents, like butyl, octyl
and dodecyl, is very important.
Suitable multiblock copolymers preferably contain 2
to 16 or more thiophene units in each thiophene block.

WO94115368 2 ~S 2 ~ 2 ~ PCTA~L93/0028~
It is to be noted that when using these multiblock.
copolymers of the present invention in opto-electronics and
more in particular in electro-luminescent devices, the length
of the blocks has a profound influence on the wave length of
the light. Also important is the choice of the various
substituents.
Suitable multiblock copolymers preferably C~nt~ i n 5
or more thiophene units.
The choice of the int~rm~ te group, group B, has
also influence on the properties of the multiblock copolymer.
In case of use in optoelectronics preferred groups are i.a.
a, ~-unsaturated organic compounds like styrene and
derivatives thereof, g~rm~n;um compounds and silicium
compounds.
Suitable materials for said blocks are those
described hereinbefore in relation to the LED.
The blocks can be assembled into one polymer by
known techniques, for example by reaction between the blocks,
either directly into one copolymer or in two or more steps.
According to the invention new LED's are provided
based upon novel semi-conducting organic and/or organic-
inorganic block copolymers, said polymers being obtAinAhle by
making various combinations of ~-conjugated and non-~-
conjugated blocks in order to obtain a heterostructure based
25 on the principal of the selfassembling of the block
copolymers.
The materials for the electrodes n~e~ for the LEDs
and quantum-well devices are chosen a~u~iately following
the work function of the active multi-block copolymers. These
materials are well-known in the art of LED's. Suitable
materials are described ln the literature and can be selected
by a person skilled in the art based upon the actual
configuration to be used.
Generally the T-~n comprises two layers of
35 electrodes, such as indium-tinoxide and a conducting metal,
between which layers the electrolllminescent material has been

WO94/15368 ~ 9 ~ ~ PCTn~L93/00280
- 13 -
sandwiched. The electroluminescent material is preferably
spun-coated on the surface of an electrode. In case a flexible
LED is required a thin layer of polymer forming a hole
injecting electrode, transparent in the region of emission,
may be applied to a flexible substrate, for example a
polyester. This two layer material forms the cathode of the
LED, which is placed in contact with the electroluminescent
material. The anode can advantageously be evaporated at low
pressure onto the surface of the electroluminescent material.
Suitable metals are calcium, indium, aluminium, tin, magnesium
and alloys of those materials.
In the figures some aspects of the invention have
been elucidated.
In figure l the basic element giving rise to
injection luminescence, a p-n junction diode operated under
forward bias, is illustrated.
In figures 2 and 3 the schematic set-up of an LED is
shown and in figure 4 the general structure of so~e the multi-
block copolymers is given.
Figure 5 gives the spectroscopic characterization of
thin films of multiblock copolymers with varying ~lock length.
Figures 6-9 give some of the reactions that may be
used to prepare the block copolymers used in the invention.
Finally Figure lO shows the wave length pattern of
the electroluminescence of two different multiblock
copolymers.
The present invention is elucidated on the basis of
the following examples and reaction schemes, without being
limited thereto.
General Structure of Poly[(Silanylene~Thiophene]s
Route A. Polycon~en~tion of dilithiumsalt of
- oligothienylene and oligosilanylene. (fig 9)
Route B. Cross coupling of digrignard-
bisthienylsilanylene and dibromooligothienylene. (fig 9)

WO 94/15368 '2~S 2 ~ ~ 14 PCT/NL93/00280--
Rl, R2, R3, R4, R5, R6 = H, Cl-C20 l;n~3r or br~nrh,~
alkyl or alkoxyalkyl; R7, R8 = Cl-C20 1 ~n~r or br~nchefl alkyl,
aryl; n = 0-3; m= 0-4; q= 1-8.
Example 1
Synthesis o~ poly[(dibutylsilanylene)terthiophene] .
Dibutyldichlorosilane (5 mmol) in 10 ml of
10 diethylether was added to the dilithiumsalt of 2,2l:5l,5ll-
terthiophene (5 mmol) in 25 ml of dimethoxyethane. Refluxing
for 1 hour and precipitation from chloroform in cold methanol,
acetone and methanol again, gave pure pale yellow product
(50%).
Example 2
Synthesis of (T60ct2Si2Me4)n.
Two ec~uivalents n-BuLi were added to 1.41 g (5 mmol)
of bisthienyltetramethyldisilane dissolved in 50 ml THF. By
adding two equivalents of MgBr2.Et20 in Et20 the dilithiumsalt
was converted to the diGrignard. Subsequent addition of an
equimolar amount of dibromodioctyltetrathienylene and 1%
NiC12.dppp afforded a dark red solution which was stirred
overnight The crude reaction mixture was precipitated in
excess methanol. The precipitate, a dark red solid, was vacuum
dried yielding 3.46 g (83%) polymer.
Synthesis of 3,3"'-di-n-octyltetrathiophène.
2-Iodo-3-octylthiophene (112.8 g, 0.35 mol) in 250
ml of diethylether was slowly added to 0.70 mol of magnesium
turnings in 50 ml of diethylether (1 hour). This mixture was
refluxed for 2 hours. The Grignard was decanted and added to
0.14 mol of dibromobithienyl (45.4 g, 0.14 mol) and 1.5 g of

~ 094/15368 21 ~ ~ 9 ~ ~ PCT~L93/00280
- 15 -
NiC12.dppp in 200 ml of diethylether. The mixture was stirred
overnight, poured into 1000 ml of a cold 5% aqueous NH4Cl
solution. The a~ueous layer was extracted with CH2C12. The
combined organic layers were washed with water and brine and
dried over MgSO4. Removal of the solvent afforded a brown
viscous oil, that was purified by flash chromatography
(aluminiumoxide / pentane). Repeated crystalli2ation from
acetone (5~ ml) yielded 50.5 g (66%) of a yellow solid.
Synthesis of 5,5"'-dibromo-3,3"'-di-n-octyltetrathienyl.
3,3'll-di-n-octyltetrathiophene (20 g, 36 mmol) was
dissolved in acetlc acid/chloroform (150 ml). To this mixture
Nn3s (12.8 g, 72 mmol) was added. The mixture was stirred for
1.5 hours at ~5 C. After addition of chloroform (200 ml), the
mixture was neutralized with a KOH solution. The organic layer
was washed with water and brine and dried over MgSO4. After
removal of the solvent, the crude product was crys~ ed
from CH2C12 / acetone (2/1). Yielding 20.2 g (79%) of pure
brown-yellow product.
Preparation of films
Thin films of the polymers were prepared by spincoating
5-15% solutions of the various polymers in an organic solvent
on a glass slide covered with Indium Tin Oxide (ITO). Various
metal electrodes (Ca,Al,In,Sn,Mg and alloys of these metals)
were evaporated at low pressure (10-6 torr). The films were
assembled into an LED. The wave length pattern of the
electroluminescence of two different multiblock copolymers has
been given in Fig. 10.