Yes or got arrested in

the house or senator or

as you already learned
quite a bit about like and

desires and

the same highest

levels but also he's one of few

highly successful companies for instance

in terms of yourself you words of that so

doing that

in Germany one of five founders of and

you know or so

I'd like to leave
the floor to an exciting.

Well thanks for that very Thanks for
the very kind of know that

the invitation to it to present I was very
impressed with the Talk to have taken.

And I had very nice discussions
to be as you might notice.

Maybe not from the distance.

I'm even wearing a tie which is
actually caused by the simple

reason that my luggage got lost the when
I arrived this morning at the airport.

Gave me the.

Title with the B. is it to be.

OK.

So I'll talk today about

organic solar cells which is one of
the many nice things you can do with.

I'll take the liberty to a few slides
of what I'm doing currently at

least in Saudi Arabia.

It's as you probably know
a very new university and

she can we did in the light
a little bit in the front

of

me.
So my office is up there with a nice view

on the Red Sea and I'm currently
setting up the Solar Center and

that's how I look at work usually And
that is in the back is

one small this is this this my office here
this is the if you will from the harbor.

Now there's a law and
photo to take engine you researched and

as it's called has at the moment
eight faculty we are hiring

additional faculty it has a very extensive
laboratories and a very nice clean room.

What we want to do is to bring
world class photo it takes research

to Saudi Arabia it's an ideal country for
this later on we also work on storage and

conversion and train the people for
the whole this technology and

I think the unique point about the cost is
that we have a very broad array of humor.

T.V. taken on the G.'s organic sparrows
kite oxides in quantum dots and

also some copper.

I selenite work and
in another special point is that for

several of these materials we combine
either wake him processing all liquid face

the opposition so that you can understand
the difference in these two things.

OK But
now let me come to the main talk and

I start with we've thinking the people
who were involved in this work.

This is a joint work of.

At the would present several is all.

It's one for me honest with you from
because additional Christof you know mine

was going to this and I'm out in Helmand
now and this is done in collaboration

with the company you mentioned he had
take with pay the Polish coupe and

it would amend a little bit talk
about modeling of it if in the group

of ten is on the ankle but this will
be one be very brief in this talk.

Now if you if you look at
organic semiconductors

from a product perspective there is
one very successful product this

is the small mobile phone display I'm
carrying once the once in my pocket and

it made me from a takes P.R.

spender since the two years ago to
a taxpayer takes money generator.

You know and this is this is for me at
least it was a very nice point when I

was able to go to an electronics shop and
show to my kids what I'm doing.

Now what what's what's
will be the next step.

I think we'll see.

Very soon the large tv's there
are first T.V.'s on the market but

the the pricing is prohibitive.

Lighting is that if you
go to field in terms of

efficiency in pricing
the hurdles are very high.

I also see organic P.V.

still as a difficult field I'll
explain the reasons in the second and

maybe unfortunately the most difficult
field this is again a Gallup poll.

Transistors logic because

they have the competition from from
Silicon the sometimes overwhelming.

So step by step by them.

I'm sure we'll see more products and
maybe in twenty years.

We'll have all these electronics
around us in every day

in our jackets in our cars and
everywhere and.

Now when we come to organic photo with
takes the potential is immediately clear.

It's a flexible technology.

It's a potentially transparent technology.

It can it can have different
attractive colors.

So in many respects is specs
it's a very nice technology.

It should be a long material and energy
consumption short energy payback time and

at the end of the pricing should
be should be very attractive.

Unfortunately most of these potential
points is not really realized and

for several reasons we still have to work
a lot to it to really be the expectation

the one issue with this organic P.V. is
that when you're when you look at this and

well part of the efficiency of order
would take systems the organics is still

down here in the noise so to speak as
you can see there's a gradient but

still we are in the ten percent
range with efficiencies and

the established order would
take to get all the G.'s R.

in the laboratory at least
well above twenty percent.

Now the other big issue is as you know the
the pricing and there's a learning curve.

Which says that when you double production
you price goes down by about twenty

percent and we're somewhere still Asians
this is now followed for thirty years and

his specially in the last few years.

We actually went went
under the average and

they are very reasonable put it
projections that in the next five years or

so or silicon modules will go down
to forty cents below what peak.

And this is a price which many people
never thought to be possible with still.

And then the question is
Is there any space left for

Game weeks and the answer is yes but
it's not easy.

The question is what do we need to
do to make organic Peavy successful

if you go to conferences and organic P.V.
many people stop their parks with which

they've been it's like you know we've If
we make it cheap enough efficiencies not

that important or I have heard statements
you know five years lifetime is OK.

If it doesn't last long that we simply
exchanging modules I doubt that very much

and I would say the minimum we need
is fifteen percent in the model

of more than twenty years lifetime and
well below fifty cents per watt peak

and the key point actually
is the efficiency

because efficiency pays off in many
respects efficiency we do is the cost of

electricity generation clearly by the to
do it is the energy payback time and

it also helps to to realise
this on small area.

Sorry that's not a little bit more
extensively with economic points but

I simply want to go to a show where the
challenges are this is a paper which was

published a few years ago which calculates
the the cost estimates for organic P.V.

and as you see per square meter depending
on whether you are aggressive or

less aggressive you have twenty to forty
dollars approximately proscribe meter.

Now imagine you have a five percent
module then even with the aggressive

as the Met you are already
more expensive than silicon.

So at low efficiency there's no way to go
all but when you look at the numbers for

instance for the moment when you buy
an organic material for four production.

You don't pay two dollars you
pay two hundred dollars So

this is pretty much both estimates
are pretty much aggressive.

And as I said the total shows
really that even from pricing you

need high efficiency to keep the area
small the other point is energy payback.

This was published in the patent.

Paper in twenty twelve.

It shows the harvesting of a module or

worse is the efficiency and this is
what you harvest typically in Germany.

Maybe in Atlanta twice as much or
significantly more but

the basic message is that organics is
quite good compared to various inorganic

technologies but even at low

efficiencies you still have several years
under at least under German circumstances.

However this curse clearly
goes one over X. and you can

see if you go to ten zero even fifteen
percent then you reach very very short

paper times which can be even in Germany
on the order of two or three months.

So again this is an argument for
high efficiency.

Now if you look at
the efficiency predictions for

again next we did some calculations in the
days in the Ph D. thesis of twenty my law

and the basic result was that for
a single junction cell you can reach.

Something like fifteen percent and make
some woman efficiency which means they

have ten to twelve in the more doeth which
tells you immediately that with a single

junction cell organics probably
doesn't reveal reach ever a market and

the way to go is like discussed recently
in the paper by Michael Grade so

to harvest we're several junctions
the larger part of the solar spectrum and

then from the sharply acquires
a limit of thirty one percent for

attendant to forty two went for
triple to forty nine.

And another point is that when
you go to ten the more Triple

you actually to do with
the lower the current and

therefore you have in a way like take
the losses so we need to go to ten them or

even triple and when you go to attend
them we did again some calculations.

You'll find out that something like twenty
percent is absolutely reasonable and

that's the way to go and that's also my
personal goal to say to each in the next

ten years efficiencies of twenty
percent in the laboratory.

And it's you know.

The progress has been enormous.

We started with a result I
thought arc of about a percent.

And now this so if I enlarge ourselves in
the last few years have flown from about

three percent to He'd taken away twelve
percent taken in almost development

and that is really the question that
how long can we continue to have and

how much time will it take to
come to these twenty percent.

OK But now after this somewhat lengthy
into a doctrine that may come to do

the science and the biggest challenge
in my opinion inorganic piece to find

the right materials because the search for
materials this is difficult and.

There are many properties
which which need to be met.

Why is it difficult to find materials
while an organic solar cell has a somewhat

more complicated chain of events from from
absorption of a forward on to a charge

of extraction you don't generate
immediately carious by the exit ones they

have to diffuse to a hetero junction
because they have to be separated here or

they have to a drunk.

And then you need to transport again in
this time the charger and then you need to

extract it and the working structure as
you probably know with more complicated

than an additional solar cell because
you have to have a head production.

The one issue is that if you want Lang's
these are some measurements we did

in Britain some time ago for a pebble
in the rivet if as a model material and

by changing the layout thickness and
modeling and

you can very precisely determine
the exact one diffusion of things and

the very disappointing result
is that it's a proton one and

this is very typical There are some
materials which might have a little

more some have a little less but for
the moment we have typical numbers like

this whether this is extreme as you
go interesting is not known and

it's a good question whether we
can raise that for instance by.

More highly pure material.

The other issue is is the fact that the.

Except on his very tightly bound
this is a nice informal its leader

chose an organic exit on which is
basically and then I meet all so large.

It's on one molecule and it's binding
energy something like ten times K.

T. compared to one two and except on in
Silicon the gallium arsenide which is

twenty nine the meter is also large and
is much less think a T.

You have a problem here you can
of really separate the charges.

Now the way to proceed this is
known since many years the first

the discovery was from Ching Ting
who had the idea to use

a hetero drunks into two
separate electrons and holes.

So the ones diffused to this head
to a junction get separated.

Now because the exit points do not like
to diffuse You can also bring that chunks

into the exit on.

And this is done in the junction which was
actually many people will look at that

invented by here from zero to in Japan
already in nine hundred ninety one.

And this way using this morphology you
can get the junction to the except one.

So at the end what we would we do
have is the nominal morphology of

domains of a donor and then accept
a material the energetics must be OK.

The transport in this
morphology must be OK.

The orientation of the molecule must be
controlled and this altogether it's a very

difficult and challenging issue as
I'll show you in some some details.

Now when we come to organic P.V.
there are kind of two schools

the school i'm so
to speak member office is

the ONLY go mail a small molecule school
which is either done by bake him or by

Solution processing and the other school
is the part of my school which is done.

Usually by solution solution processing.

The physics at the end
are very similar but

in many respects
the differences in processing.

For the moment I personally believe
that the all of them approach

has has advantages as you
know in the mobile phone.

We talk about only governments for
the same reason.

These materials have
a fairly simple synthesis

with defined Monica a way that
we can purify them simply and

in the molecules we always use
the fuel fuel already in C sixty

which is which is very cheap and
easy to to obtain whereas most of

the polymers although it actually usually
done with P.C.B. and mostly seventy.

Now if there were less to it to give you
a flavor where we are I cite some little

of efficiency problem out there are some
proprietary results beyond ten percent.

The paper which I follow in which.

It has been published
in Nature photonics and

which reported also results about nine
percent and as you can see these these

are fairly good solar cells with also
fairly good external quantum efficiency

in the small molecule field there's
also a lot of work on materials and

people have explored a lot of
materials and the power for

in square in the body dies and
tile fiends.

I will in the following mainly talk
about because the that's where

most of the work was done then this is
the compound cost which take is using but

it looks like that there are many
molecules which work and there's not

really a quiet area and why a certain
materials class is better or worse.

Again in the small molecule field people
have either use solution processing or

evaporation and their solution processing
has some advantages like a you

can actually make fairly thick actively
else as you'll see in my experiments they

are much thinner because you can make good
transport properties especially this is so

this also on the group showed that
by adding in a bit if you can

control the morphology and by a by
using a suitable concentration of the.

If the morphology is obviously much
better and the cells are much better.

And there are some recent results I found
a result with more than eight percent now

using the seventy one P.C. B.M..

And the most reason result is
now far from the H.R. recently

from getting getting screwed which I had
for it and then sell at ten percent.

So far.

The problem us the numbers of are quite
good and are almost as good as for

the small molecules.

That would let me come in more detail to
what we we need we have this junction and

that what we need to do is we must form
a network with high end balance mobility.

We must adjust the domain sizes
to have to have that the same

time good separation and
good transport in the calculations so show

that we need to mobility is of a tenth of
a minus three which sounds fairly low but.

Actually in this market a junction
is already a pretty high value.

Now even the faked than optimum
mobility is not clear and

I want to discuss that with some
results I'm sure in a second.

But the key challenge at the moment is
actually that ideally we would define

a solar cell by designing
a high efficiency wise and

then we would go this way we would go back
and tell the synthetic chemist please

make this in this model molecule
molecule to have the right properties at

the moment we go the other way we
make a molecule go all this way and

then we judge the quality of the molecule
and I'll show you later in my pocket

that going this way is very difficult
because the device you get at the end

is not only depending on the molecular
structure but also in much

detail on how you would process
the devices and what the conditions are.

Now one spec to two of these mobility
question these are some calculation.

One of contested in his Ph D. thesis
he made a drift if you should model and

calculated the simple bottle trying to
use some different combination models

a very simple direct by
Mother combination model and

a somewhat more involved launch of a model
which is probably more appropriate for

where the diffusion of the carriers
This is also important.

When he uses the simple recombination
model it actually turns out

that the efficiency of the device as a
function from abilities for other cons and

holds is increasing and reaches at
about a tenth of the minus three

apply towards your then you are not
is limited by mobility is anymore.

So the basic conclusion would be you
have to have ten to the minus three and

bever in mobility S..

Now if you takes the more appropriate.

Valter of a theory things look
more complicated you again

increase them the efficiency with
mobility about ten to the minus three

is now it makes a moment and when you go
high end mobility efficiency quiz down.

If you look at the details it
turns out that very simply

the higher mobile the carriers
are the more a combination you have.

Unfortunately we couldn't get
experimentally test this because we cannot

reach this regime we are we have moved
up here that seems to be true but

we haven't had this mobility
materials to move around.

And the other issue is actually to
measure these mobility is in the pocket

of the action most people measure mobility
as using field effect transistors.

But that is not what we need because we
need to vertical transport in a device and

we need to know the fuel dependence and
the carrier density

dependence which is typically present
in these organic materials and

recently in his speech
theses is found in my

opinion a beautiful new method to
measure field dependent and then to.

Dependent mobility is what this
measurement to leave us at the end is such

a plot where you plot the field and the
whole density and the mobility is color

coded so you can see these dependencies
directly he called this method.

Poem for
potential mapping by thickness variation.

The idea behind the model is very simple.

Let's assume you have a homogeneous.

Film of material and you and
your transport carry us through it.

And now you start to slice.

So to speak this material.

When you keep the constant current for
different thicknesses For

instance when you go down far far far this
fitness you you need this wall ditch and

if you go down in thickness to within
a sample to have the same car and

you actually need this wall ditch.

If you go down here you need for instance
this world which you can actually plot

the electric potential in the sample
of what you do is you make a series of

sample of different thicknesses and then
you measure always the same current and

the voltage is directed tell you
the potential in the in the sample.

And from that from the potential
power file you can get the electric

field PA fallen from the electric field

using the current you can get
the carrier density profile.

So what you want you simply do is you will
make it the riveted of the potential then

you have the field and then they will make
it this deliver day for the field and this

way you can you can get the density and
if you know the current and the field and

the density you can actually calculate the
mobility at each location of the sample

and since you also know the the field and
the carrier density at this location.

You'll get what you need that is
mobility is a function of field and

aerial density this series extremely
simple you don't need to transform a model

the experiment is more complicated
because you need a certain

definition of your sample what
we use is typically people.

I peel and I ensamples where we have
a material on the investigation between

two dolefully Yes.

The reason is that by using this
structure we have to find injection and

extraction that is what you need for
the more you need to cement to

decide the device design because you
should not have a built in field that

would disturb this analysis and clearly
you have to have either electrons on hold.

So you need selective contacts and

such a structure to a large degree
fulfills all these requirements and

this way we have to know what a very
nice and precise method to determine

mobility is you can check the method
I don't want to go into much detail.

By using a certain transport model and
then do in America and that list is of

the I.V. curves and then do the do
the analysis using his is approach and

we tested that and

did that we've various transport models
and the agreement was very very good.

So we operate issue of that the model and
the approach is correct.

I want to show you on only one example.

This is a junction of the sync
tell us line and the rivet

if we sixty and what you are basically
observe here is that in this material.

There is a quite field dependence
if you go for a sconce and

carry a density to a high all fields.

You see that the mobility
significantly increasing.

Whereas if you go at the certain.

Field to a higher carrier densities you
can see that the color code is virtually

unchanged.

So there's very little field dependence.

However of the invent
measurement the density was

somewhat lower than it would
be in that he'll be wise.

But given that model now you are able
to to analyze the mobility is and

look at the very disappointing
results that was a prepared.

On the usual way we put solar
cell in the mobility south into

the minus six in the tent and
a minus three and that's the main power.

And we have in these materials.

OK Now in the second part of the talk
when two were to come to our

investigations of what we call the fire
fiends who we call it the fire because

it's full of animals and
these different animals is a very large

number of molecules which we hope
pain from from paid about as group.

The basic idea is that you have to handle
the one handle is actually the backbone

length in units we typically
look at three to sixty.

And the second handle now
is the type groups of

the molecule either simply hydrogen or
up to Boot Hill groups.

And now what what what are the effects
of this this handle actually changes

directly the electronic properties of the
molecule this handled thousand not change

the electronic properties but it changes
the crystal picking this way again.

It changes the electronic
properties in the solid state.

This is nicely visible These are simply
the energy levels versus the back bone and

as you can see the the level is fairly
unchanged as a function of the new and

it's with the whole more level
can be nicely shifted and

this way we can actually shift the the
energy gradient at the Hitler junction

we can optimize the Baltics and

it turns out that we've Pfeiffer in
the wises we have the optimal well teach.

However if you look in more detail.

Now as as the energy shifts for
the different number of the new one.

It's but also for the site groups and

to compare here measurements in
solution and in this whole bit.

Stage of this they have other rates data
you see that the solution measurements

cannot only little as a function of
sight group the basically change here by

the length of the backbone length but
this only state results in red.

You see they make significant fluctuations

with the site groups because you
change the solid state morphology.

So it is very complicated and
very difficult to really

control the energy levels and we have
observed I would don't want to go into any

detail about that you get a completely
different crystal structures the bend.

Depending on the site and

it's not possible at the moment
to predict that in any way.

So although these materials
should allow a systematic

variation in practice
when you really do it.

You have already in the extreme
really complicated a system.

And I will not talk about
what it is today but

I'm actually using one he'll take
slide here to show that all these most

recent take material which is again it's
probably our proprietary if I offend or

if it if that voltage is very good.

Basically what you want is
the difference between optical gap and

the U.S.C.
which is as small as possible and the tech

materials are now are actually these
are not really the best we have today.

Today we had about point six walls
between optically Keppen viewers see and

if you do some theoretical considerations.

It looks like that is close to the optimum
with what you can do in an organic solar

cell in an inorganic solar cell you
would have something like point.

That's what we lose in organics.

But now I let me come back to the question
of crystal structure and morphology.

And that we studied in more detail in
a paper which we published already one and

a half years ago we took five fields
which have the optimum voltage and

we took the method of site groups and

this case we used all method by
the different locations of the molecule.

So one structure called one two and
three and

when you look at the the solution spectra
are they look fairly similar there's

a small difference for the materials
the solid state spect eyes to see

are massively red shifted
which they should be.

Or there is good.

Coupling between the molecules and here
you see the differences become larger and

especially the compound as the largest
redshift which says it has

seems to have the largest taking.

Now I when we looked at
the the the ordering using a scattering.

It turns out that there's a quite
complicated behavior at room temperature

come upon number one has the highest
ordering and the most clear reflects this

but at the temperatures where we usually
deposit the solar cells the company

number has now with the highest ordering
So those two results this year and

this year tend that compound number for
he seems to be the compound of choice and

indeed at that time when we measure
out the efficiencies we turned

we notice that combine number
three brought the best results.

And so the message was clear.

OK this is the best picking and it's
the best molecule that was our conclusion.

Keep in mind that when you look at
the saw last last six point nine percent.

It has negatively only
thirty nine a meter and

that is because we have insufficient
mobility if you would have a mobility one

up toward As of May need to have high
are we could do they are one hundred then

to me then would be well above ten percent
and but so far we haven't missed that yet.

In the meantime we've
done a little better.

We reached over seven and in some
some internal results we have now and

we are now at eight percent but still not
really at the potential of the material.

However we have reason to visit it that
story we persist once more the materials

and we confirmed the efficiency
that the compound free was better

than the compound one.

But then we looked in more
detail at the structure and

for that purpose in his speech he
did some measurements in Stanford.

At the sink.

Using a grazing incidence wide angle X.
ray scattering and

what he observed is that if you do.

The enemy this was the thing
the layoffs that the this

catering images in the synchrotron for
both compounds for slightly more almost

the same there was a slightly less all
the structure for all the compound one.

But it was fairly similar.

However when he then began measurements
of the junction D.C. five and C sixty.

He noticed that we had
overlooked a subtle effect and

that is when you go for
the compound free for and

from from room temperature to one and then
ten degrees you see that is a much higher.

Although at one hundred ten degrees but
this absolutely

the same effect is happening for
compound one by that higher temperature.

So the problem was that we had overlooked
that you would do this small difference in

the methyl site groups the materials
obviously needed different temperatures

fall to my ization And
the problem is that this compound

one is already at that temperature which
is critical for Gannett solar cells.

So we didn't simply didn't go to
the temperature when we did the devices

because of the fusion effects and
the whole morphology developed

as a function of temperature turned out to
be a rather complex at room temperature.

You have various small domains Crystal
linearity and when you go to higher

temperatures the domain is called larger
the salinity actually wasn't much higher.

So the main effect of the better reflects
this was the high up on the larger domain

size at the same time the films start to
be rough and at the highest temperature

actually the films itself were that rough
that they couldn't be used for devices

anymore and the efficiencies in it when
it goes down very quickly even you exceed

a certain temperature could actually
shore that very high temperatures that.

You we're seeing in this these warm like
crystals which were if you were in which

was kind of growing out of the LEOs and
formed crystals on top of the bucket or

junction so
the the dynamics of the formation

is a very complex function of temperature.

So that's that's what we learned and
the basic message is

it is very difficult to judge
whether a molecule is good or not.

And by simply missing some parameters you
can come to completely wrong conclusions.

OK so the final part of my talk I
want to spend on ten themselves

as I'm motivated in the beginning you
need them and on energy harvesting and.

The ideas is probably well known to you.

You basically combine two photo active
materials at different wavelengths.

There are now two of challenges in these
organic saw lots of the one challenges if

you combine two cells you need a so-called
recombination conduct about electrons and

holes we combine and the other challenges
since we have thin film devices.

We have optical standing waves and
we need to generate.

The cells in the way that the standing
waves fit through the absorbedly us

fortunately a couple of years ago we
had published a paper where we do these

so-called instruction of these P.
and N. they have been transparent

globally us and first of all they
form a P.N. junction which is a very

good recombination contact and secondly
you can actually bury the thickness of

these window layers beautifully and you
can really adjust that and this was a key

point in forty also we follow this as
a pet and this one of the key piece.

It's quite interesting to look at the
physics of this we combination can take

that is a diagram I took from
a an article about free fives and

you know that the most efficient solar
cells we have two days are these three

five mile the junction cells which
are about forty percent and the.

Exactly the same principle they use
these highly Torpey injunctions and

since I started or

did much of my as a scientific career in
basic transport effects in brief ice.

It was really nice for

me to come back to these this good old
days when we looked at more detail at

these junctions this was the work which
was done by his claim on in this.

Thesis he looked at these organic and
I was he made an intrinsic

to really look at these ideas and
threw it into control of the fields.

And what he did is the very
the in the layer of fitness and

looked at the that he burst breakdown and

the basic message was that in
the forward curve this this in the layer

thickness is not of the leavened which
we expect for a forward P. A injunction.

But for
the worst breakthrough every nanometer so

to speak our minds and what he did
basically was making scene the diode so

you may die or it's which has a very
nicely controlled breakthrough and

which I actually useful for
many applications like like memory.

The basic point is if you make
the intrinsically thin enough

say six nanometers or less you get almost
symmetric I send that is what you need for

this would come in nation contact.

And he also was able to look
at the transport mechanism and

could clearly show that this is indeed
Wayland's to conduction band tunneling.

By looking at the temperature dependence
the reverse current is always not almost

not temperature dependent which you
would expect for a tunneling process and

together with the group of
Johnny Quinn about the in the.

We could actually make a theoretical
model they set up a molecular model Well

the calculated the tunneling rates from
the home or levels to the levels in

a fairly simple way he and they fitted.

All I recurse and

they distinguish the two approximations
The one is where the motion for

molecule to molecule in this
chain is is spy hopping and

the other where you have a really coherent
States over these few molecules and

their somewhat surprising
result was that the key here.

The model fits the data and
hoping model but at least on this

kind of one to free molecule reverse
tunneling you seem to have clear and

transponder you can also analyze
the the mass of the carrier us and

it turned out that we got masses which
are way below one which was quite

surprising and this was all of this not
fully understood we have published it but

the so far we don't have an explanation
for this very small masses.

OK That was a very short excursion and
I'm coming back now to the solar cells and

just show you some results
which we have published already

some time ago where we did such
a tandem sell using a fire fee in and

taken a tell us in both cases we
see sixty as you can see in this

case where we use open materials
the overlap is significant and this

is not ideal that we would actually need
a larger gap between the two materials but

producing this Ellice is fairly simple
you have to do individual cells and

you simply as they come and
on top of each other.

What do you see and always that these
devices are fairly complicated.

You have something like ten or
twelve layouts but

using this make him think all of
this is not difficult to do and

you can nicely double
the voltage you get very high.

Phil Spector's higher than for
the individual cells.

What we didn't really achieve
in this case was good color and

matching because of the spectral
properties of the two materials and

working together with the field Outtake.

We optimize that step by step and

then the latest result published
by he had take is this Velcro.

Called of twelve percent as you can see
from the wall digits already a triple sell

and.

It shows the potential but
it's not really what is relevant for

four production elements for production
this is what they did on models these

are models on glass and already some
time ago they had nine percent.

The more recent results is almost
ten percent for the active area and

that is that I should mention that a big
difference to the palm of your P.V.

technology because the current
record polymers or

using C seventy one the use
poisonous solvents and

rather complicated synthesis whereas
these materials are sixty and absolutely

production ready and at the moment you
get take as putting that into products.

Now one factor which also
helps a lot is harvesting and

we call that the the all factor.

What is what do I mean with harvesting
when you talk about us all of the you

would talk about one sun
twenty five degrees and

perpendicular perpendicular incidents
that sustain of measurement conditions.

However in the reality typically
all models are much more talk and

not only in the morning in the evening but
if there's bad weather.

You have less than one sun and
it can be diffused.

And fortunately organics is in
all of these points favorable

in temperature on less than one sun and
the issue is light.

We have observed an improvement and
then in total we had up

to a third if percent better harvest
things were twelve percent means that

it harvests better than the say
fifteen percent also silicon module

to show you a part of these data
these these are measurements

by a by he had pick on the ten percent
cells and as you can see the organic

cell this is getting significantly
better to the operation temperature.

Whereas all of our P.V. take moment.

He's going down.

And same for intensity if you go
down from from one thousand to

the point two sons also organic
school is that if you can be up and

all the other technologies go down and
all together we can angle a factor.

You have this nearly thirty percent think
this button however the better ourselves

will be the less this effect it will be.

Finally a few comments about lifetime.

And manufacturing clearly it's a big

issue of whether these organic materials
can be stable enough and last year.

Christiane if I submitted this thesis
on a new electron transport materials

she wasn't looking for a long life time
but she wanted to replace the sixty.

Because we've always speculating that
sixty should be a source of instability

in organic solar cells.

We were actually proven wrong any of these
is she found some materials which came

replace the sixty in terms of efficiency
but when she did the lifetime measurement

unfortunately and disappointingly the C
sixty still gave the best lifetime

results and she was measuring
this under an intensity of two

thousand as we use simple glass glass and
capsulated devices and

stability is defined as a lifetime
as it is a twenty percent.

DK and when she did the very rough
example Asian for her thesis.

It would have been at least
under German conditions.

It would have been a lifetime I
would also thirty seven years now.

This is not really politically irrelevant
because we won't do it says substrates but

it tells that the intrinsic stability
of these are getting the organic

materials is excellent.

One comment is that you first of all need
to encapsulate very well the second point

is you need to block you be if you don't
block you read these lifetimes go down but

in practice you need to block you
each can be done at technically.

Also I want to show a mall.

Our practical level of end result which
is again taken from here you have take

this so-called Stand up the M.P.
test in P.V.

and that means that all molecules that
Dell that Dell models and on Monday.

Calls must so wife and
eighty five eighty five humidity test.

For one thousand dollars.

You should have at most ten percent.

And as you can see the head out take
module's had a bug free press and

efficiency drop So the uptake modules
now pass this test which every P.V.

more dual must pay is and the outdoor

life times are now about ten years on for
all.

So I'm very optimistic that these twenty
years lifetime of named will be made.

Now about what action is this what

action he had take is doing the pile
up with auction is an old old coder

Unfortunately it's a proprietary tool and
when he introduced the the tool

at the inauguration of the facility they
made a big paper wall in front of it.

So you can't see anything.

How it looks really so I'm not throwing
you in the pile of production tool if he

didn't take but I'm showing you with
a research tool we are operating at

the phone often see to it indecent and
the way it works is quite simple.

You have a big vacuum tank and
in that vacuum tank at the door.

You have here the plastic for oil.

This is thirty's and they meet a fall and
you unwind it and pull it around the big

cylinder which is rotating and
around the cylinder not really visible

they are up here you have the organic
salsas these are linear else Also this and

they are put next to each other and
there what you do is to

evaporate all these ten or twelve layouts
in one run while you pull around why.

Once you evaporate all the layers so
it's very efficient doable to code and.

You need only one run around at
the desired speed would be that do it.

We each several meters per minute and
then you can produce these

cells very efficiently and there's one
a very economically important point.

If you scale such a tool
with the weight of the bend.

It's chaos with the square root of
the cost scaling is only a square root so

if you go from thirty centimeters to
two metre the tool is not really much

more expensive and these are examples not
forgetting solar cells but fog and they.

And this is they actually
know the place they fall

about the in this case we use
the lumen them for you can also do it.

These are going to go ladies and so
a lot sells on a new minimum for

all which is mechanically very robust and
also a good encapsulation

in one direction so this would all
production basically works and

at the moment here I
think is ramping it up.

So finally is light to
the applications and

I've ordered a little
demonstrator to show.

The key application.

If you if you look at
the different markets fall for

Gainey P.V. They markets and

then the basic result
it's a very small market.

You know that there has been a bank with
organic solar cells of Kanaka and cannot

cover and bankrupt so this probably was
all some of the very attractive market.

The first market where I think we'll see
him take product is in an automotive and

the key point why people
pay a lot of money for

a fairly low efficiency
structure is transparency so

this is a model that
the transparency you need for

this application is only
about twenty percent.

This is because a project that comes
from here not very good to see and

it's a it's a fairly homogeneous
looking base color of a cell and.

And therefore we see the first
application in this market.

The second interesting market identified
by he I take is the building integrated

four door takes imagine that you would
have in all we know is such such a foil he

would shade and at the same time
produce electricity the market which

they didn't they have to make a rod square
red square around this is what the market.

I would love to see that is
the power plant market which is at

the moment completely dominated by silica
and I think organics has the potential but

it will be very hard work to achieve
the efficiencies and lifetimes for

this market but
even the fact that this is only carbon.

It's simply would be
a beautiful Go to achieve that.

So let me come to the conclusions.

I think the organic
previous although it's.

Has improved a lot still needs
an efficiency breakthru.

We probably cannot work with
single chunks of the wisest we

probably need to at least ten of them or
even triple structures.

The most in my opinion most
difficult challenge of organic piece

are the design rules for materials we have
a complex stone except I have no junction

structure and to find the design
rules this is very challenging and

especially the fact that this all
depends in a very subtle manner and

process variations make makes this very
difficult and the the manufacturing

technologies are they are they haven't
been leading in that low price but

it will be possible to have to
manufacture all of that low price and

the dream is that in twenty thirty years
if you drive through a city or for

the countryside your eyes should be
always on an organic solar cell.

Thank you.

One of the things that
I ask you when you use

that with respect to

seventy six.

Yeah I mean this is producing a very

simple industrial process you're
basically create a special kind of suit.

And then you're purified and

therefore you can project that it
will be very cheaply available.

That's the biggest advantage of
using C sixty were so for the P.C.B.

I mean you need another synthesis step.

And especially that at
least at the moment.

C seventy and P.C.B. seventy one.

This is very expensive and
it's very difficult to clean it.

So for the moment it's much more
advantageous to use the sixty

one year for going.

Well you change you can change a little
bit the energetics of the C sixty

by choosing the the Synthesis
the force on your ability.

That's another handle you have which we

don't have the sixty
this is the benchmark and

they must address the dawn of the material
to add to the energy levels of C sixty.

So you don't have this handle.

That's an advantage of using P.C.B.
them other compounds that.

No.

It's a very good question whether
I found tops in the idea that.

That is true.

And that is true or not

I mean

this opens in the in
the final production step.

They have they have to quit they go
appoint someone if they do use them.

And usually or pump them away because
you know you have your deposit and

then you need to Throop to pump it off
clockwork so wherever you do it but

the second point is that you keep
some solvent in the solar cell and

that is the stability issue.

So if you if you do try this
problem is not the area but

that's what.

Your

eyes.

Both of you know you always need both.

I mean we tried to keep the backbone
constant in this case because

our main goal was to really have these two
different handles electronic properties by

backbone length only and
a crystal structure by a by site groups.

Length and position and
however in the meantime

we have also looked at some other
molecules which had a different backbone.

And they're clearly US use.

You see this potential for
improvement but the other point is always

that unfortunately when you want to
optimize the sort of cell structure

the optimization is different for
every molecule.

Yet we did.
We did some estimates and

a very simple message is if you if
you do all that all of production and

your band speed is larger than
about a meter per minute then

you you get from the I mean
you have a depreciation

depreciation range full of slow speeds and
the material limit for

higher speeds and when you are above about
a meter up a minute to get into the tool

in the materials cost limit and
at the moment we have reached

rates which give about this one meter and
I would personally expect that in the long

term point auction we will be at the at
a level of several meters per minute.

And then that will cost is a few percent.

And the materials cost
dominate the production cost.

Well the the the very big
issue when you do such

all it all process is you have
ten sources and things are.

Go forth and back.

You have to have the rates adjusted
that every Les I think knows this

is correct and the material
which has the smallest budget.

What we call thermal badgered
between evaporation temperature and

decomposition temperature
is limiting the rate.

So you know that the materials
if there are some of which.

Have been kind of two hundred degree but
should you know they represent two hundred

degrees and decompose at four hundred but
they're also materials which evaporated

three fifty and decompose at four hundred
and those materials limit the process.

So one of the challenge is to search for

materials which have a very large project
between the start of a reparation and

decomposition and
that has also proven to be too

difficult for

us as we

like this thing through.