(dreamy, upbeat music)
– [Xiaolin] The first time I was in California
when I got off the airplane, I saw the sun.
Energy from the sun is infinite.
The hard part is to figure out how to use it efficiently.
I always wanted to be an engineer
because I think engineers are the people
who had build things, and that’s cool.
– [Christopher] Xiaolin Zheng is an associate professor
of mechanical engineering at Stanford University
working in the field of nanoscience,
the study of structures and materials
on the scale of nanometers.
– [Xiaolin] Nanoscience studies material
that are extremely tiny.
A human hair is about 50,000 nanometer.
– [Christopher] It’s difficult to think about things
on such a micro scale,
but a meter is about 39 1/2 inches long.
So if we pretend that the entire Earth
is the size of one meter,
– [Xiaolin] The one nanometer will be the size
of probably like a tennis ball.
So, that’s the scale we are working with.
And for my research, I focus on nanomaterials
and energy conversions,
particularly how to use sunlight
to generate renewable energy
using solar cells to convert sunlight to electricity.
– [Christopher] These, of course, are solar panels.
You can think about them as a sort
of sun-powered battery that’s usually made
of a semiconductor material called silicon.
Materials that easily transmit energy,
such as heat or electricity, are called conductors,
while an insulator is a material
that is a poor conductor of electricity.
Semiconductors are materials that are sort of in the middle,
as conductivity changes based
on environmental factors like light or heat.
Like a battery, a solar cell has a positive
and a negative side made of metallic layers
with semiconductors sandwiched in between.
When energy flows from the sun into this material,
electrons are put into motion.
The movement of electrons creates a current
that can be converted into usable electricity.
– [Xiaolin] There are two things
that nanoscience can do to solar cells.
One is to increase efficiency.
The other is to lower the cost.
When people think about traditional solar panels,
they are quite expensive.
Installation is quite difficult.
We figured out a way to make solar cells
as flexible and light as stickers.
The solar sticker can be sticked to the back of a cellphone
and that serve as a charger for your cellphone,
just constantly charging whenever the sun is there.
My dream is that those type
of solar stickers can be used anywhere.
What I hope the most is to put on buildings.
That will have the largest surface area very close
to people’s home so they can power their home.
Working on renewable energy is not a choice.
We have to do it
because we are going to run out of fossil fuels.
One day, maybe not tomorrow, but maybe 100 years,
we have to rely on renewable energy.
(gentle music)
For me, it’s the simple desire
to provide electricity for regular people.
That keeps me motivated.
People feel better if they know
they’re doing something good for the Earth.
If you realize the electricity you are using
does not generate pollutions and is renewable,
I think people will be happier.
