OK so today.

I'll talk about something
we were working on for

several years which we tentatively
called glue molecules to surfaces

through the use of sub nanometer
oxide coatings from spruced ability

of molecular sensitize devices that just
have to be kind of a mouthful to say.

So we actually take sort of

this idea from you know what
we did as little kids gluing

things together my toddlers now they just
learned about glue a couple days ago and

they just glued paper on top
of paper on top of paper.

We're trying to be a little more
precise perhaps with our glowing This

is an image here.

This actually this layer here is actually
about an animator thick on some nano

particles where we pollute some molecules
on the surfaces nanoparticles But

oftentimes these these layers
are even less than an ammeter so

I know we're the nanotech seminar but

we're going to be talking about some
things that are even sub nanometer

scale and still providing some useful
useful functionality to some devices.

So this work a lot of it was done
was still research faculty at N.C.

State collaboration with a number of
folks both that you can see the group

who is experts in creating
functional molecules.

Ken Hanson was a close collaboration
on his now faculty at Florida State and

is well we've we've continued this
research now with research groups at Emory

both Craig Hill and Tim Williams Group.

So first I'll just give
an introduction to our lab.

This is our current lab
here at Georgia Tech.

In fact this is a picture even those
taken about a month ago is old because

now we've added a few more
grad students to the group.

So generally what our lab is good at
is materials processing that's really

the focus of our lab understanding
how we can fabricate materials at

the name of scale with three dimensional
structure and the two important

things that we like to investigate
are materials that combine organic and

inorganic components and materials
that have three dimensionality and

we apply our ability to control both
the three dimensionality and the organic

an organic composition of these materials
to variety of different applications.

Making hybrid materials making
traditional more traditional electronic

oxide materials interface with novel
substrates including copper foil.

Gallium nitride semiconductors or

what I'll be talking about today in terms
of molecular functionalize devices.

We've worked in optical materials making

photonic structures this is actually
a tungsten structure that we created.

So an interesting three
dimensional metallic structure and

we actually do a lot of work
chance talk today on fabrics.

So how can we functionalize
fabrics by putting

nano scale coatings on these
fabrics to modify their properties.

So not only do we we make materials but
we also make the equipment that makes

material so we make the stuff that makes
the stuff makes the stuff possible.

So this is just pictures of equipment in
our lab we now operate this is one of our

L.D. reactors we operate to the reactors
one is a third one is under construction.

A fourth one.

As in design of a sputtering tool and a
variety of chemical synthesis equipment as

well as well as a variety of measurement
systems like Helix on a tree and

property measurements like
electrical property measurements.

So briefly some of the material
synthesis techniques

that we're interested in currently
are vapor phase deposition methods

especially chemical vapor
deposition methods.

One of those methods is
atomic layer deposition

in atomic layered up positions a chemical
vapor deposition method except for

sequentially delivering the precursor So
we're not delivering both the precursor

and Korea who the same time is
an attrition traditional C.B.D. process.

Instead we deliver one precursor we
purge remove that precursor we deliver

the second precursor and so that confines
our reactions just to the surface so

that we get a single reaction layer
of our molecule on the surface and

then we purge off any excess and
deliver a CO reactant and

get again layer by layer deposition.

That's conformal over complex
three dimensional architecture so

this is an example of crystal where we had

bunch of colloidal Spears on the micro
scale that had been assembled.

We then infiltrated with our gases in the
process to conform we coat those fears and

then we etched away those fears so
now the spheres are gone and

we're just seeing the skeleton.

That's remaining the photon a crystal
skeleton that's remaining And so

we can use these coatings for a variety of
things including adjusting the wet ability

of for example fabrics changing
light absorption properties in

in this case if he's in mechanical
strength and other properties the other

thing that we're really interested in this
is more on the organic in again a hybrid

material side is if we apply these
these vapor phase precursors to

organic material to Paul America materials
they don't always behave as nicely as

shown in this cartoon they don't always
just react right at the surface.

Instead they can actually do.

Fuse into the subsurface of the polymer
and generate organic in again a hybrid

layers and so we're very interested in the
kinetics of this process and this is one

big effort in our lab and happy to
talk to people about that afterwards.

We're find a lot of interesting
properties with these new hybrid

materials that were created.

OK But today's talk will focus on
a different type of hybrid material really

that interface will hybrid mature we look
at molecules on surfaces and applying our

vapor phase deposition techniques alle the
techniques to formally code around these

molecules and stabilize the attachment
of the molecules to the surface so I'll

begin to talk this is the introduction
I'll begin with the motivation for

why we do this and talk about
the importance of performance and

stability for
these molecularly functionalize devices.

I'll show you sort of our preliminary
successes that are naive at this point

chemical understanding of these interfaces
because a very complex interface we're

talking about you know a molecule that's
maybe one to two nanometers thick and

then the layer that we're depositing
that's only a few angstroms thick So

how do we understand how we probe
the chemistry and in the electronic

transport process these are occurring
at the interface it's very challenging.

And they don't give you two technological
case studies where we've applied this

technology and looked at the device
performance one is a Dyson solar cell and

the other is a water oxidation cathode So

it's basically this process electric
process and then I'll show sort of where

our work fits in perspective with other
groups that have now picked up and

then starting to look at using
this similar technology for

gluing molecules to surfaces for
other applications.

OK So first let's talk about
what they're functionality.

So we're with these projects we're
interested in working collaborating with

chemists we're developing new molecules to
do a variety of different things right so

chemists have become over
the last thirty years or

so very good at designing molecules that
can either absorb light over very specific

wavelengths can emit light over
a specific wavelengths can.

Create electron transfer between
that molecule and some inner

Gaelic substrate to specifically
catalyze certain certain reactions or

to bind molecules for by molecular
sensory and other applications.

So they're very good at this.

And in fact when we take these
molecules we put them in solution.

And we test their properties we
can often record record beating

functionalities because we
can design the chemistry.

So precisely.

The challenge is often that
when we do it in solution.

We really can't couple
it to the outside world.

And so the couple you know the
functionality the outside world world we

often have to attach these molecules
to some sort of solid state device and

that's really a challenge that we've
been looking at how do we attach these

molecules effectively and robustly to
a solid state device that we can interact.

You know with with with with
with the exterior world.

So this requires both creating maintaining
the performance of the molecule and

maintaining the attachment to
reliability of such a device so me just

just go back for a little bit and talk
about you know performance reliability.

If we look in the literature performance
really get all the glamour and

really is as often forgotten about.

So this is a nice review article from
it's a few years old now two thousand and

ten where they talk they
actually do discuss a bit about

reliability particularly
the most famous probably

molecular functionalize devices a Dyson
style solar cell in this review.

They say there is there is certainly been
few published results contain module

fission seeds in combination with data
from accelerator outdoor testing of D.S.C.

modules an interesting trend is
that the publications dealing

with module stability generally have lower
module efficiencies in publications where

stability is not mention So
people often report performance and

not reliability in fact they go on to
say that the devices offering the best

long term stability are often different
from those exhibiting the highest.

Vice efficiencies.

The stability of a D.S.C. module.

They've concluded strongly related
not to how it's designed but

rather how the device is in capsulated So
we'll talk a little bit more about

the importance of encapsulation
up to this point and why that's

been used really to get reliability
not inherently changing the devices.

OK So before we do that let's think
about let's look at what causes

degradation in these molecular
functionalize devices.

So first a bit of an overview for

a Dyson site solar cells
everyone's on the same page here.

So that's inside solar cells
are nanostructure devices

where you attach dye molecules that
absorb light the light comes in and

the electronic orbitals electron gets
excited from the homo to the loo and

it gets injected into the into the inner
again at me in a structure and so

this process needs to occur to then
collect the charge on the electrode and

run the place whatever the load
happens to be so if you look at this.

There's a number of mechanisms for
degradation.

But probably the most important
fundamentally is the desertion of the dye

from the surface.

So if we lose the dye we're no longer
going to be able to transport transfer

that charge upon light absorption from
the dye to the Inner Game six pieces

and the reason dies does or
primarily is due to water water attacks

the binding chemistry between the dye
molecule and the inner game except for us.

OK so there's been many
studies not just chosen to

demonstrate the importance of
water attack causing this or

passion of of like their species
on inner Gammick surfaces.

This is a nice.

Set of ab initio simulations showing
the molecular dynamics of this process

where they have a square rain die
molecule attached to the surface.

With a car box a look as a group of
believe in this case they've placed it in

basically in a quiz that environment
right these are all these water molecules

running around in the environment and when
they look at this event you get hydraulic

attack of one of these attachment
chemistries which can be a problem but

even in the case of a multi
Dentate binding of a molecule So

in this case we have to binding sites you
might expect that this might reattach

at some point before this one detaches.

The problem they found in this
particular simulation study was that

once this detaches the water
molecules start to surround this and

sort of prevented from
reattaching to the surface and

so this drives it or
makes it even more unstable and so

eventually gives a sufficient time than
other water molecule can attack the second

site and sort of the molecule
another another issue.

The can happen is really a bounce
of charge that occurs and so

this is an experimental study where
they're looking at the surface coverage of

different diet molecules
as a function of PH So

you get some Vironment changing the PH and
as you change ph you're going to change

the Zeta potential the surface
essentially the surface charge.

Right.
So in this case we're looking at a T O two

surface and when you go below about PH six
you get a positive charge on the surface

above ph six you get a negative charge
these these species are predominantly

negatively charged species but as we sow

as we go to lower ph is we expect that
the positive charge on the surface will

start to attract these molecules to
the surface and create attachment.

So in this case B. and C.
are these core box elated.

Species we see we don't have sufficient
silica assets here to neutralize charge.

So in this case we don't have
electric stack attraction.

Ever attached for the case of B.

we do see attachment of a fuss
phonic acids are known to

statically it's even better
attachment to higher PH is but

even eventually with strong chemical
binding we get this type of attack

where we get detachment of the molecules
so effectively what we're seeing here is

that as we go to higher PH
experimentally to lecture

the analytically strip molecules from
the surface you go to higher PH is and

you can completely remove any sort of
dye molecule attached to an inner again

exorcise OK so
this problem even becomes more complicated

when we add other stimuli including
light or electricity so we want to put

this into a real device where we either
want to run current through the device or

we want to expose it to light to absorb
light for example for a solar cell.

Well this causes even
more attachment points so

this was a study done by my colleague
Ken Hansen prior to us collaborating where

he was looking at these die molecules
acid bound to an oxide substrate and

he looked at their detachment as he
was exposing them to blue light and

so not only were we in
some ways environment but

we were also exposing them to light and
he tracked then using you even is

how much die was on the surface as
a function of time exposure to light and

we see rapid detachment
within sixteen hours and so

in this particular case I believe
we're we're a very low ph ph one.

So you'll see from the previous
study that you have

Ph One we should be well attached to the
surface especially for FOSS phonic acid.

But here as soon as we extend
it to expose it to light.

We lose.

And we detach the small.

Kills within a period
of less than one day.

So this is this is really a challenge
as we add additional stimuli so

the system but this point might say wait.

If I go into Amazon.

I can buy Di sensitize solar cells.

So why is that OK So this is a for

example keyboard for
your laptop it has three and

a half stars on Amazon must
not fail real immediately.

So certainly there has been some
commercial of ation of these dice or

solar powered backpacks and the key there
was to improve the efficiency it's about

greater than eight percent but also to
create reliable performance of these

devices and the way they've gotten to
reliable performance is not really

an elegant way rather
it's through brute force.

It's really just using very good sealants

on the exterior of these
devices to take your device and

then it capsulated it with a really
good glue a really good poxy the case.

So it's better than Elmer's There's
in fact an entire industry

surrounding the design of the Z.
poxy is to encapsulate

these die sensitized types of devices
the other trick here of course

is that the electrolyte they're
using is non-equal is right.

Synonymous with electrolyte and

then seal it to prevent any
ambient water from getting in.

OK but
what if the device that we want to use

the device design necessitates
exposure Damis fear war for

example if we're doing some
sort of catalytic process.

It was environment we must have
it you know in in water itself.

And there's certainly
a number of molecular or

functional molecules that chemists
are designing to do just that whether it

be water based Dyson size solar cells
fuel cell catalysts water splitting

catalysts for hydrogen fuel generation
C O two reduction biological protection.

And so on and so forth.

So if the chemists aren't wasting their
time designing these we should we

must find a way to attach them in
a real environment because our approach

has been instead of gluing on the X. here
what if we were able to glue the molecule

right at the site of attachment and
that's really been been the revolution

the that we've created is attaching
the molecules right at the surface.

And so our approach again has been using
these days deposition techniques atomic

layer deposition so
we've gone over the process.

This is one of the reactors in in our
in our system again I remind you that

we can can formally coat these
nanostructures with no problems.

So ten twenty nanometer particles we've
shown that we can formally coat those

you saw that on the first
slide of this talk.

The other important thing here is we
can deposit these materials with about

one angstrom percent.

So you'll see in a few minutes

that obviously we don't want to hurt
the performance of these devices so

we need to be very precise and
how much material.

We're encapsulating these molecules with.

Because I will say.

To be very clear there has been work
done previously were people taken

nano porous man a porous oxide scaffold.

Applied to nail the coding and then
attaching a molecule in this really to

understand the photo physics of
electron transfer between the molecule

in your nano oxide scaffolds or
putting in Slayer's or

conductors in between changing
the thickness of people done that.

Previously would had not been done
previously was to take the scaffold

apply your molecules and
then do the deposition and

the reason that people didn't do that
was because they assume that these very

reactive precursors would react with their
molecular functionality and we kind of

thought that might happen as well it turns
out that so far we haven't really seen my.

Dacian or much less degradation that
we would have expected when we do these

processes and so there really were usually
not very limited most of these reactions

occur below well below two hundred
degrees Celsius so we're not hurting

the organic molecules thermally but
we were concerned with with reactions.

Between our vapor phase precursors and
the surface of our molecules.

So this is an example here of a common
dye molecule using the S.S.E.

devices N seven one thousand this
is the molecular structure here.

But if we look at the U.V.
visit absorption especially

Just where does the DI absorb light
that's its prime functionality.

We see that the black curve is just the
bare die on a nano porous substrate and

then if we coat with two three cycles
that's about one half angstroms or

aluminum three cycles or
about three angstroms we

still see a fairly strong absorption and
maybe a slight blue shift.

So we do lose some absorption but
not that much and slight blue shift in

the absorption we believe that's some
modification to these groups and

we've also looked at this catalytic
molecule that use for water oxidation we

thought for sure that this one would react
we have an actual Aqua Ligon here on

the site and many of our precursors
react with water that's the CO react and

so we actually went through a whole
protection chemistry on one of the first

experiments we did which it turns out
that using protection chemistry or

not using protection chemistry.

We got the same results.

The material was still
catalytically active and

likely what's happening is
that we're hydrogenated.

The catalyst prior to doing it because
we're being done in a vacuum environment

essentially no water environment so
we're driving that water molecule off.

Prior to doing the deposition.

So this is an example here it will show
you just a quick movie of if we take

these these these slides of the dyed
slides and we place them in a high ph.

So we know high ph and strip the surface
of all the molecules and so you'll see we

have one that has just been dyed and then
to the been ale be treated after dying.

And we'll see the dye molecules in real
time actually being stripped off of

of the electrodes so the bare here.

Treated.

OK performance illuminance
even better performance.

So after about ten minutes we
start seeing dye coming off

of the untreated and really no diet
coming off so it's pretty obvious even

just visually that we're
losing dye in these devices.

So if we actually look at this

quantitatively we can track the U.V.
visible.

Of these slides in this ph ten
environment as a function of time.

And we see that.

Yes without a coating we can strip off all
of the die within about twelve hours or so

the T O two code in this case.

I gave us some improved stability
the aluminum coating gave us a very

good stability.

We retain about ninety percent of the dye
molecules after even fifty hours in this

very aggressive high ph environment.

So we gone a bit further to look at
again if we expose this to light.

So this was ten ran these experiments
now or is he had done before.

When we expose these to light.

We saw even faster detachment
of these molecules so

without a coating if we can plot the
desertion concert for these materials we

see that as we add this aluminum
coating even just one angstrom ones.

Like all of this material we can in prove
the attachment by about in order to

terms of decreasing the coefficient for
these molecules and we've also

looked a little bit at trying to analyze
the chemistry that's occurring in situ so

this was a system set up at N.C. State
where we had an actual In Situ F.B.I.

Our with with our a reactor and
so we were doing in situ I.R.

spectroscopy while we were doing it and
we could look at each half cycle so

each exposure of a precursor we could
see was occurring in our reaction so

these are the spectra that we collected as
we dose the alumina precursor the aluminum

precursor then the water aluminum
water etc etc for three cycles.

Your initial spectra here is shown as
the spectra each of these specter shown is

a different specter from
the immediately prior spectra and

so features like this indicate
a shift in the peak position.

Features like this indicate just
the elimination of a particular stretch.

OK So we see for example.

These are stretches from these unbound

carb oxalic acid groups and
within a single exposure to R T M A.

We see a removal of those sorts of
stretches in the material the size sign

a group we see this back and forth motion
so we're somehow modifying the thought

with each precursor Co reactant cycle and
then

these C.E.O.'s stretches we actually also
see you'll see up down up down up down and

then sort of the reverse of that on
the other side if you look very closely.

It's actually a shift that we're seeing.

So we're seeing these these these
asymmetric and symmetric stretches sort

of getting closer and farther away from
each other so we plotted that difference

in the symmetric an asymmetric stretch
stretching those of these C.E.O.'s.

Groups and we see with each half cycle.

We're sort of oscillating back and
forth with both precursor chemistries that

we're using and what that sort of
indicates and this is somewhat

interpretive what we're observing is a
change in the binding state of the C.E.O.

group from Amman and then Tate to buy
Dentate so the water is probably releasing

this from a mana Dentate to a book by
Dentate a sort of binding group so we

have some understanding we know there are
some modifications going on but the exact

chemical physics that are happening here
are still pretty difficult to ascertain.

So me show you now sort of if we take
this this this idea and we apply it to

two different devices the type of
performance that we can we can achieve.

So the first example or for
Dyson inside solar cells.

And so we might imagine that if we start
applying a nail the layer to a Dyson sized

solar cell that it may act or may somehow
manipulate the transfer of electrons

that needs to occur from the dye molecule
into the name of scaffold it's and

so this is what we would expect to
occur and it is what we observe.

So this is just again a band
energy diagram all the prophecies.

There are occurring and we can look at
some of these processes using transit

absorption spectroscopy right so
we look at the rate at which each of these

processes occur so we can look at this
recombination process where if we excite

the the electron into the Lumo of
the dime all the Kulin it can't enter for

whatever reason it can't inject it decides
instead to recombine we can see that

with fluorescents the transit fluorescence
measurement injection we actually weren't

able to directly measure
we're doing that right now.

Tim leans group at Emory but we can infer
that from some other measurements and

then we can look at back electron transfer
using transit absorption spectroscopy

looking at different.

Excited modes on the molecules.

OK so I won't go I have the details
of someone to talk afterwards

I can show you the details
of those measurements.

This is sort of the picture that we've
created based on those measurements so

without a coating we know that
there's high injection that occurs and

there's some back electron transfer so

we want mostly injection we want to be
collected by the device we don't want it

to the lecture come back into the die but
in fact even at.

Even for a standard device we
actually have more injection

injections even faster than we
need then we need it to be so

we could take a bit of a hit to injections
still have a high performing device.

Unfortunately when we add the alumina
code even at three anx terms or so

we really really hurt the injection
in the device but also prevents

back electron transfer so it's really
acting as it insulators one might expect.

And we can't inject nor can we can we do
we have electrons coming back with the T.

out to coding we still we found as
we maintain about the same high

injection rate is as far as we
could detect and what we see even

higher back electron transfer
rates than we had seen previously.

So he had to just seems to
be acting as a conductor

because often the scaffold
itself is T O two.

So we're just making the scaffold
closer to the molecule itself.

Now as you'll recall the alumina
has great stability.

OK stability.

So we came up with this very naive
hypothesis that what if we mix

the aluminum with the two could we get
sort of a synergy of these properties or

an averaging of these properties.

OK So we actually went ahead and
made some dice and

sell devices this is
a control device with no L.D.

coatings we get about seven and a quarter
percent efficiency so reasonable fission

see dies as I solar cells if we just go
ahead and put three cycles of alumina to

we take quite a hit in efficiency maybe
thirty percent to fifty percent reduction.

Efficiency.

So this is the pure the pure case however.

If we now do mixtures we did a couple
different ways we did mixtures and this is

two cycles of alumina the one cycle two
are we versus those we can actually get

within ninety percent of the initial
efficiency of the unmodified device so

now we're we're pretty
close to where we were.

And if we look at the efficiency.

As we age.

These devices so

this is a standard aging test where we
do eighty degree C. in the dark side and

of an eight degree C. we find and
this is again it would help a lot.

I'll point out here.

Oftentimes people normalize
these sorts of plots.

We're not normalizing this data here this
is actual fission see of the devices and

so we see after about one hundred hours.

Our devices are equivalent
to our control devices and

beyond that they show a higher
efficiency in the control so

the control has degraded at a faster
rate and ends up being lower performing

then our coated devices stuff we can
pair this to the literature data.

So this is our uncoded our
control device we see this

almost a forty percent drop in
efficiency over four hundred hours.

This is our OP sort of our optimized
device and with this mix alumina

to we get about twenty percent drop in
efficiency again this is this is true.

Fission C.

This is a gradual device so aggressive
devices they have their magic command of

structuring that reproduce anywhere else
in the world and they get you know upwards

of twelve percent efficiency and
this is what and seven thousand so

no one of their fancy that's still
not as good as their best devices.

But when they test that for four hundred
hours it drops to about seven low under

seven percent efficiency so we're you know
we're pretty close to that efficiency even

though our starting fish and see is much
lower and they obviously lose a lot more

efficiency when they do this sort of
aging test and we do so if we can get a.

All of their devices we can probably
improve their their door ability

much better.

This is a comparable study from another
group that makes nice devices and

they get about the same efficiency as we
do initially when they age theirs they

lose about sixty percent.

So we think we're doing very
good in terms of improving

the reliability of these
molecularly functionalized devices.

So the second example is water
oxidation catalyst molecule.

So the Meier group.

They've been working working
on these molecules I think for

twenty to thirty years now making these
receiving molecules that are used for

water oxidation catalysts for
for solar fuel applications.

OK so here we need to be
in a quiz environment so

we can take the water molecules and
convert them into oxygen.

And this particular case we're not
doing it and we're just doing it.

Driven So it's just an electrolyzer but

instead of having platinum
as your catalyst.

We're using this molecular species
as a catalyst on the OK so

this is the picture of the chemical
route that you used for

the station it's a multi-step
process that will go and

that will look at the details
a little a little bit but

what we can see when we you know
when we do cyclical Tammy tree.

We can see this redux couple
related to this process here and

that indicates that the that that that
we're getting catalytic activity.

Now if we run the cyclical to metry
you know multiple times we start

to see a reduction in
the currents indicating

that these molecules are coming off of
the surface and they're detaching So

this loss in current is indicative
of degradation of the device.

So increasing number of cycles
loss of catalytic molecules.

So we went ahead and took.

A control device and then we started

coding these devices with increasing
cycle numbers of T.-O. to what we saw

was improved stability less loss of
current eventually at about twenty cycles.

We essentially see no loss of
our electric catalyst current.

However if we go to thick thirty forty
cycles we're now this layer is now

about one and a half to two nanometers
these molecules are also about one and

a half to two nanometers So
we're actually coding.

Now we've actually are coding is
reached the top of the molecule and

we're coding over the molecule and
so these particular molecules.

We're going to they're going to lose their
activity because we're now no longer able

to access the reaction sites for
these devices so we eventually see a loss

in our redux couple because we're
coding basically the entire molecule.

So this is just a plot of surface
coverage from integrating

the docs couple that C.V. curve.

We can track the percentage of molecules
on the surface as a number of cycles.

No L.D. code and we see loss of
surface coverage with an algae coating

of optimize of twenty cycles.

We see great stability for a variety of
PH is from neutral ph up to PH of eleven.

Now this is important because we can
actually access different reaction

kinetics based on the Ph.

We're working at so if we go back and
look at the mechanism for for

this oxidation catalyst.

This is the rate limiting step rate here.

So the rate let me step is essentially
when you add the second water molecule to

your catalyst site and during this process
you're forming the oxygen oxygen bond.

So you need to add an O. H.
Group to this receiving five complex.

OK so so it ph is less than five
this is really this is the.

Ism for this reaction is just
direct attack of a water molecule

to the writhing in five
complex as we increase the Ph.

We now have some species in
there some sort of conjugate

based species that's creating you know
our increase in PH They can then active

Stracke the hydrogen from a water molecule
creating an atom proton transfer process

that facilitates the attachment of
the group to the thinning five so

that's of course an easier
process to facilitate and so

has faster reaction kinetics or even
faster would be if we get a high enough

ph is where we just have a lot of
hydroxyl ions floating around in solution

then we can directly attack a hydroxyl
eye on earth in five complex.

So what we're actually able to do by
stabilizing these devices is to push

our reaction mechanisms to different to
different mechanisms right so Ph seven

we start to see the atom transfer proton
transfer process and as we increase Ph.

We can actually get to direct attack from.

And so
we're showing here are just the curves and

the same over potential So as we change ph
that over potential is going to shift and

so if we go to the same over potential
we should see the same current but

because we're seeing increasing currents
that's indicating there we're getting

different reaction processes that are in
fact have faster reaction kinetics

and so we can actually verify that these
highs ph is we are getting direct attack

from hydroxyl by looking at the reaction
rate I.E. the electric chemical current

as a function of ph which is essentially
just the concentration of the O. H.

on and so we see a linear reaction
kinetic reaction rate as a function of

zero eight species which is what we
would expect for a first order reaction.

With the Hydrox on.

OK And so what that allows us to
do is we've actually increased

reaction kinetics by a couple
of words of magnitude.

This is actually one hundred thousand
times faster than the process these occur.

Lois ph is and
that's really prior to demonstrating this

the only reactions they could run or
at PH is less than five

because the molecules just don't
don't don't adhere to the surface.

Except for
at the lowest those lowest ph is.

So let me show just our
work in perspective.

So there's Michael Rose's group at U.T.

Austin is now begun looking at using email
deed to attach molecules to surfaces

to use to shift electronic
band structure of interfaces.

There's also a very nice work from the hop
group up at Northwestern where they're

using these ale detached
die molecules for.

Dye sensitize solar cells so not only
are they getting increased ability but

they're also improving the wet ability
of the wet ability to manage structure

to allow your age with electrolyte
to permeate the entire structure.

And so I think there's a lot of
opportunity actually in a quiz die

sense type solar cells.

Not only because of our
stability demonstrations but

also there's been work coming out
about new redux couples that work more

efficiently in the Queen's environments.

So to summarize today's talk

is the first of all that surface bound
functional molecules Who great promise for

a variety of devices whether it
be in catalytic applications or

bio sensing or energy applications
like I sensed a solar cells.

The challenge with these devices the.

Versal challenge is maintaining
attachment of our molecular species to

a device scaffold.

And what we shown is about using L.
do you.

We can effectively glue these
molecules to a surface.

And still remain tain the properties
of these materials I've lost some

texture it looks like but you'll see that
you know through continue understanding of

the interface chemistry and
the electronic transfer process is there

curry at these interfaces we can create
a set of rational design principles for

understanding how to design these
complex organic inner Gaelic devices and

not only can we improve the build
up of tension we can access.

New reaction pathways that also enhanced
the performance of our devices.

So that our knowledge number funding
sources as well as our collaborators

both in the Research Triangle Park as well
as now here in Georgia Tech and angry.

So thank you for your

attention.

I would love to find
someone who does that and

collaborate with them because I
think there's opportunity there.

But I don't know that field.

So I'm definitely looking for
a collaborator.

And we you know.

And we and we can do a potters'
we can do lots of things.

So it doesn't need to be a flat
substrate or a nano scaffold.

So I'd love to

talk.

So it's faster.

It's still not fast platinum.

It's still orders of magnitude slower but
the surface area there is a strict

they play with surface area to
try to get it closer to platinum.

So this is another.

Another secret of the molecular
catalyst folks is that

a lot of these things are still
not as fast as the inner game but

you can get away with loading
nanostructures and getting pretty close.

And so
I don't think there's an issue with heat.

I think there is an issue with the nano
structures in the gas transport once you

form these bubbles.

I'm not sure if he does an issue

that you raise here.

So you know our best guess is it's
just Eric just preventing it from.

Attacking.

We know you know you can look up in Port
Bay diagrams what the electro chemical

stability of different oxides are.

And so we know we'll use some
other oxide that will dissolve and

basically detach see do we have any other.

Evidence.

That's so that is your question.

I mean that's our best understanding
we would love to understand we've been

doing some studies with Tim leans group.

So we think there may
there's this question right.

And we're talking about and
sure as a material whether or

not it's going over top or underneath or
how much of that is occurring we have some

indications that in terms of the lecture
on transfer that we might gain just

a little bit underneath because we see
some differences in the injections.

And we're doing work with tens
group at Emory where they're doing.

Measurements some frequency
generation measurements where

they can track the spatial orientation
of molecule before and after alle D.

and so we do see rearranging
somehow modifying its position.

This is one of the things that to me isn't
one of the biggest challenges how do we

characterize the structure

of the bank.
I mean we've we've done a lot of I mean

I can if you want.

We have trays absorption measurements
we've done is that what.

You're asking

your.

So you know we have a number of
measurements that we've done said transits

or some measurements and we could I
could have them all hidden here but.

We've done in terms of looking
at electron transfer rates.

You know we've looked at so
this is the simplest example right

where we've we've taken with this is for
alumina.

And as we this is basically these
are the trans absorption spectra for

increasing aluminum thickness more
centrally seeing this is tracking back

electron transfer so higher.

So if we if this if the states retained
it means the electron is as not

transmitted back and so a higher.

Higher signal here higher that
in this direction from zero

indicates that slower back electron
transfer rate this decays this is a slower

decay than this is so without any L D.

We see a fast decay fast back electron
transfer here slow back electron transfer.

And so we have a number of a measure to
we actually don't see much of a change.

And we some see some interesting things
in the four essence which tells us about

the process and so we've interpreted some
of this we've not measured this directly.

This is the thing that we're
working with him now big.

We need to get to pico second measurements
these are named all nano second

measurements these transit absorption
measurements so we need a faster

measurement system to probe that directly
but I sort of summarize this does that.

Does that does that give you that so
I've summarize it all here in one

slide to make it very simple and
not to go into all the details but

I'm happy to discuss more and
we have some publications on that.