Behind the secret life of materials – Solar Energy

Behind the secret life of materials – Solar Energy


My name is Michael Graetzel
and I am a professor at the École Polytechnique
Fédérale de Lausanne. I am working on systems
that mimic photosynthesis to produce fuels
and electricity from sunlight. The oil crisis in the seventies… I realised that
there was not really much oil left. I was passionate
about finding systems that would use fuels
from light, electricity from light. It took kind of a stroke of genius. We call this
the Graetzel genius sort of. Dye-sensitized solar cells are much closer to
the natural photosynthetic system than silicon, PN junction and so on cells. They use a molecular dye
and chlorophyll, a pigment, to absorb sunlight and then the molecule
produces electric charges. So the construction
of the Graetzel cell goes like following. We have a piece of glass. Titanium oxide …coated with a dye. And there is a second piece
of conducting glass to complete the device. Electrolyte
that completes the circuit. Electrons are generated
inside the titanium oxide, goes through the electrical circuit. Electrolyte brings back
the electron to the dye who lost it previously. That’s how the circuit works. It took about 10 years of work to ascertain that what we had
in our head was rugged and could be made
into a practical system that the world could use. This technology offers
advantages compared to the silicon cells. They collect light
from both sides, it’s very important
in the desert because panels
will be vertically mounted. They collect very well
the diffused radiation, they can be used indoors. They are unbeatable indoors. They have much higher efficiency
in the ambient condition indoors than the silicon cells. And there is the big market
of the building integration a transparent aesthetic nice looking
that’s like art. Part. Not only solar
but it has an aesthetic function. And now there is a new hope coming in
with what is called a perovskite cell which is a derivation
of the dye sensitised cell and there the hope is
to get very high efficiency at super low cost as there is a very small amount
of materials involved. The legacy is
that he has kind of initiated this avalanche of development
in that field and made many thousands
of young scientists to work with enthusiasm
with this promise of solar energy. Helping the world. It’s a huge success
for all the people who have helped. It should be a good encouragement
for the young people to pick that up
and follow similar strategies, similar ways.

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