Transcriber: Qirui Jiang Reviewer: lisa thompson
I reckon most of you reading my name
can easily guess that I’m Italian.
I have indeed a very typical Italian name,
with my last name being one of the most common in the country.
But what my name cannot reveal
is where exactly in Italy I’m from.
I was born and bred
in a lovely city on the southern coast of Italy,
Naples, better known as the city of the pizza and the sun.
So, the memories of this delicious pizza are always in the back of my mind.
But what brings me here today is the love for the sun and sunshine.
And today, I want to tell you why the sun is so important to me as a scientist.
Right now, we are all thrilled to be inspired
by letting new ideas floating in our mind.
But can you imagine for just one minute, if these very same theaters,
you will have been on a rooftop overlooking skylines like those?
This would have been amazing.
I honestly believe that no other human-made scenarios can be so iconic --
all the excitement, happening and adrenaline.
Looking at those, I just feel I want to have fun; I want to mingle.
They make us feel so alive.
But nothing comes for free.
And indeed, these bright and attractive metropolises
are also highly energy-consuming.
Actually, these growing cities,
together with the explosion of industrial activities,
the continuous traveling around the globe,
are driving a continuous increase
of the energy demand, and this demand is foreseen to grow in the future.
So, why we think that the increase of energy demand is a problem,
and mostly why should we care about this?
The problem is that our society
rely for more than 80%
on the combustion and fuels.
And in doing so,
we are generating tons of CO2 emissions,
which drive climate change, floodings, temperature rising,
and many other natural disasters.
This is a crime which is affecting the future of that upcoming generation.
So,
the clock is ticking.
On one side, we love our dynamic lifestyle,
and we actually hope that more and more people all around the globe
will be able to access a comfortable lifestyle and technologies;
on the other side, we are destroying our planet day by day.
How can we solve this dilemma?
Renewable energy are the answer, and solar is in a prime position.
Indeed, when we look at the energy resources
that we have on earth --
we can see that non-renewable energy like fuels, coals, uranium
and renewable energy like solar, wind, and tide --
it becomes very obvious
that solar is by far the most abundant energy resource that we have.
Just to give you an idea,
the solar radiation shining on earth in one hour
is already larger
than the whole energy consumed by the whole world in one year.
So, one hour in one entire year. You got it right.
Can you imagine working one hour tomorrow and then you’re all done for one year?
Wow. We all wish it could be possible.
But despite having all the solar energy available for us,
we are not making a good use of it right now.
Even if solar cells have been around for more than 50 years,
we do need a change of direction.
So, what are these solar cells?
A solar cell, or solar panels when they become larger,
is a device which is able to absorb the sunlight
and to transform it into electricity.
So, the most important part of it is the absorbing material.
Almost all the solar cells that you see around us are based on silicon,
crystalline silicon.
And these silicon solar cells are becoming cheaper and cheaper with the time.
And so, more and more solar cells
and solar panels’ installation are coming into the world.
This is brilliant.
But even with this rate of installation,
all the new solar cells that will appear in the world
will not be able to match the energy demand
for the next 70 or 80 years.
So,
silicon solar cells
are based on a very established and trustable technology.
And we don’t want to get rid of them,
but we do want to complement it
and go beyond them to be able to meet our energy demand.
So, let’s see which are the limitations right now
of the state of the art of the silicon cells.
So, first of all,
silicon solar cells are based on crystalline silicon,
so they require high temperature to be produced.
This means that still a considerable amount of CO2 is produced.
Just to give you an idea,
it means that we need to run continuously our silicon solar cells
for at least three or five years
just to compensate for the CO2 that is generated during this production.
Secondly, this technology is quite close to the efficiency limits.
But mostly, number three, these silicon solar cells
are all big, are heavy, are bulky,
so their installation and maintenance can be costly,
and they require large space to be stored,
so they cannot be really used everywhere or brought everywhere we go.
Solar farms, they may appear beautiful in the countryside, as you can see,
but in the city, in the sparkling and attractive cities we have seen before,
there is not enough space for them.
Indeed, these cities are full of high buildings and skyscrapers.
So, silicon solar cells, they work very nicely on the rooftops.
But these rooftops represent just five percent of the total surface.
If we want to make progress, we need to make use of the facades,
which are, instead, 95% of the surfaces that are available for us.
So, the question is, how can we exploit the facades?
How can we exploit all the surfaces that are around us?
And I mean
the bridges, the road, the bus stop,
the trucks, the cars, your backpack,
your purse, your hat: all of them --
how can we make solar energy reach everyone everywhere?
We need to have
solar cells that are light, lightweight, transparent.
They can be adjustable to different surfaces
so we can customize them where we need them.
In the last 30 years,
scientists have been exploring many different options
by working on organic, inorganic and hybrid materials,
and they obtained very promising results.
All these discoveries, they’ve paved the way.
And one decade ago,
a game-changer for solar energy has been discovered:
perovskite.
Perovskites are wonder materials and they are the ideal candidate
to change,
to transform the way we maximize solar energy on earth.
These perovskites are human-made ionic minerals
which are made from abundant and inexpensive powders.
Their fabrication happens at low temperature.
This means that they have a very small CO2 footprint.
And their fabrication is simple,
so it means they can be dissolved to form an ink, and then we can print it.
We can print our solar panels exactly as we print our newspapers.
Also, they can be evaporated, at low temperature again,
exactly as we do to create the screen of our TV
or our tablet or our mobile phone.
So, with these methods, we can create solar panels
in a variety of shapes, of colors, of patterns.
And we can also make them transparent and flexible.
Moreover, perovskite solar cells in ten years have reached an efficiency
in converting the solar energy into power of about 25%.
This is incredible.
Just to give you a reference,
silicon solar cells to reach a similar level of efficiency
took 30 years, almost 30 years.
This is all very beautiful, and that’s not all.
Indeed, perovskite materials are astonishing light absorbers.
This means that we can have solar cells
which are 100 times thinner than a human hair.
So, our perovskite panels can be extremely light.
These light solar panels, they can be placed everywhere.
First of all, we will put on top of our silicon solar panels,
and by combining these two technology,
we can create tandem solar cells
which are able to achieve much higher efficiency
than each of the two technologies.
But also, we can place them on the building, on the roads,
on the consumer goods,
on the backpack and the hat that we mentioned before.
Also, this means that when you are working in the office
or when you are coming to the theater, like today,
you can charge your phone
just bringing a solar panel that is as light and thin as a tinfoil.
Also, you can charge it when you are in the street in the sunlight,
but you can also charge it when you are in the underground or in the bus.
Yes, indeed, these perovskite solar cells,
they can work very nicely, also, with indoor lighting.
So,
how far are we from having this dream becoming true?
We are not very far.
Many scientists around the world,
and also here in Singapore, just like myself,
have been demonstrating
highly efficient
and enlarged perovskite solar cells and panels.
Also, we made them flexible and vividly colored
to be integrated in buildings, for example,
in a way that is a pleasure looking at them.
Moreover, last year, the fantastic team at NTU and I,
we went a little bit further, bringing these solar cells
one step out of our laboratories and closer to our homes.
We scaled up the perovskite solar cells,
which are typically very, very small when they are created in the lab,
and demonstrated the most efficient perovskite mini panels,
that you can see there.
We used fabrication techniques that are already available
in many production lines.
This means that many companies can already be ready
to produce these panels and cells in a short time.
This was exciting news and indeed has travelled the world very fast,
from east to west, west to east.
We, as scientists and engineers, we still have work to do,
luckily for us, to make these solar cells more reliable, larger,
and really customize them to many different surfaces.
But we are getting closer
to seeing beautiful and energy-producing buildings
and bridges like those all over in our city.
These are beautiful.
But also, this means that we are getting closer to save our planet
and meet our energy demand
by transforming the way we exploit the sun.
And that’s why I believe
that the best compliment that you might wish to receive is “You are my sunshine.”
The future is more than bright; the future is sunny.
Thank you.
(Applause)