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Solar 3.0: This New Technology Could Change Everything - YouTube
Channel: Electric Future
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in this video we'll explore the world's
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fastest improving new solar technology
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and provide an exclusive peak inside the
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lab of a team working on this
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breakthrough material
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right now while you're watching this
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video a giant fusion reactor 93 million
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miles away is irradiating the earth
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without as much energy as all of human
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civilization uses in a year so why
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aren't we harnessing this abundant
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renewable energy source to meet all of
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humanity's energy needs it's not an
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issue of physical impossibility if you
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wanted to power the entire us with solar
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panels it would take a fairly small
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corner of nevada or texas or utah you
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only need about 100 miles by a hundred
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miles of solar panels to power the
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entire united states currently only two
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percent of global electricity comes from
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solar power and ninety percent of that
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comes from crystalline silicon based
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solar panels the dominant material
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technology while abundant silicon has
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downsides related to efficiency
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manufacturing complexity and pollution
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that prevent it from being an absolute
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no-brainer
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now what if i told you about a material
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that was lighter more efficient and
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simpler to produce at a lower cost an
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inexpensive solution that can make a
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photovoltaic cell so thin that just half
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a cup of liquid would be enough to power
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a house a solar panel is so lightweight
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that it can be balanced atop a soap
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bubble well that folks is known as the
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holy grail of solar they're called
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perovskites and they might just
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revolutionize how humans generate energy
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from sunlight we headed to silicon
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valley to meet joel gene the ceo of
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swift solar one of the leading teams
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working to bring perovskite solar
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technology to light
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[Music]
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it's a
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new kind of thin film technology so
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you've probably heard of that for for a
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long time different kinds of thin films
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have come and gone over the years what
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we do here is a new kind of material
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it's called perovskites new
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semiconductor material that absorbs
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light really effectively also transports
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charge so it's it just turns out to be
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very efficient material for solar cells
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solar cell technologies can be
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classified into two categories
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wafer-based or thin film cells
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wafer-based cells are fabricated on
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semi-conducting wafers and are usually
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protected by a material like glass these
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are the crystalline silicon cells you'll
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typically find on bulky roof mounted
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solar panels thin film cells are made by
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depositing thin layers of semiconducting
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films onto a glass plastic or metal
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substrate and use ten to a thousand
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times less material than crystalline
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silicon cells these thin film cells are
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light and flexible but have lower
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average efficiencies you can make thin
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film cells from amorphous silicon or
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more complex materials like cadmium
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telluride but scientists have been on
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the hunt for better thin film solar
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technologies that can see more
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widespread use these materials are known
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as emerging thin films currently
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perovskites are the leading contender
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what could you do with a solar panel
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with a hundred times the power to weight
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performance of conventional silicon
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panels a solar material so abundant it
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could be painted on skyscrapers flexible
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lightweight highly efficient cells could
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open up a wide range of applications
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where traditional silicon cells are too
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heavy and rigid but before we cover your
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tesla model s plaid in perovskite solar
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what exactly is this revolutionary
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crystal
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the perovskite crystal structure was
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first discovered as the naturally
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occurring mineral calcium titanium oxide
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but the perovskites used in solar cells
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don't need to be mined from the earth a
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perovskite is any material with a
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crystal structure following the formula
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abx-3 where a and b are two positively
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charged ions often of different sizes
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and x is a negatively charged ion
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scientists realize that they could
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create a diverse range of man-made
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perovskite crystals following the same
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arrangement that have very useful
[209]
properties
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so we use basic you know metal halide
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salts so things like a lead iodide
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or some some organic salts as well and
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we combine them to make these inorganic
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organic
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hybrid perovskites so if you if you can
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form them in solution you can form them
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out of an in vacuum at a vapor phase and
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they condense into form forming these
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perovskite crystals and the thin films
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they're like multi-crystalline which
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means that there's a bunch of little
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crystal domains um they turn out just to
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be really good semiconductors
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so just how efficient are perovskite
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solar cells
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the most efficient modern silicon solar
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panels you'd find on a home only work
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best at around 20 efficiency but the
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theoretical conversion efficiency of
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single junction solar technologies is
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about 33
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called the shockley quasar limit that's
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the fundamental limit for a single solar
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cell single material-based solar cell
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perovskites are the exact same thing
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silicon perovskites cadmium telluride
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cigs all of these technologies have the
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same limit but perovskite solar cells
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can be made in a form factor that's
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capable of much higher efficiency limits
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pushing the boundaries of possibility
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for solar power to understand why
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perovskites hold an advantage over
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traditional silicon solar cells let's
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first do a basic refresh of how
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photovoltaic cells convert sunlight to
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electricity
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[Music]
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the top and bottom parts of a solar cell
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contain semiconductor materials with
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different electrical properties in a
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traditional silicon cell for example
[294]
silicon is used for both layers but each
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layer is modified or doped with tiny
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amounts of different elements to create
[299]
different electrical charges the portion
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that contains a higher concentration of
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free negatively charged electrons is
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called the n-type region and the side
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that contains more positively charged
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holes or missing electrons is known as
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the p-type region the boundary between
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these two layers is known as the p-n
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junction when an n-type and p-type
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material are put in contact free
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electrons from the n-type material and
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free holes from the p-type material move
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across the boundary and cancel each
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other out the electrons fill in the
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holes this uncovers the fixed positive
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and negative charges of the dopant ions
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which creates a built-in electric field
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that stops more electrons and holes from
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moving across the boundary this electric
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field corresponds to a built-in voltage
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and acts like a one-way valve for charge
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carriers the fundamental unit of light
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is the photon which represents the
[343]
smallest packet of electromagnetic
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radiation of a given wavelength when a
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photon from sunlight hits a solar cell
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and gets absorbed it creates an extra
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free electron and hole which are
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separated by the electric field and
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pulled to opposite sides of the cell
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this creates a photo current if
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electrodes are attached to both sides of
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the cell forming the electrical circuit
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an electric current will flow as long as
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the sun is shining
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the magic of perovskite crystals lies in
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their customizability single junction
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solar cells can only absorb a portion of
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the solar spectrum depending on what
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semiconductor material they use the
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lowest energy of light that can be
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absorbed in a semiconductor is called
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its band gap a semiconductor will not
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absorb photons of energy less than the
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bandgap and the useful energy that can
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be extracted from a photon is no more
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than the band gap energy this means much
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of the energy and sunlight goes to waste
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when it hits a single junction solar
[392]
cell but because the bandgap of
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perovskites can be easily changed you
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can stack perovskite layers on top of
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each other that are chemically tuned to
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absorb different parts of the solar
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spectrum this results in a solar cell
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with multiple pn junctions that can
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produce electricity from a broader range
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of light wavelengths or extract more
[408]
energy from each photon improving the
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cell's efficiency
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so when you stack two solar cells on top
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of each other that's called a tandem or
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a multi-junction solar cell and when you
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do that that actually pushes that
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efficiency limit up from 30 to over 40
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about 45 or 46
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theoretically an infinite number of
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junctions would have a limiting
[427]
efficiency of 86.8 percent under highly
[430]
concentrated sunlight and it goes higher
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with more layers but it also becomes
[433]
more expensive and you get diminishing
[435]
returns so generally we talk about doing
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two layers or making a tandem
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and that's kind of the real selling
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point of perovskites so perovskite
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tandems convert more of the sun's energy
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into electricity rather than wasting it
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as excess heat what are the exact
[449]
efficiency percentages we're talking
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about here we shouldn't expect solar
[453]
cells above 40 efficiency this kind of
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solar cell for a long long time i think
[457]
in theory could get there but
[458]
realistically i think in the 30s is
[460]
doable which is still a substantial jump
[463]
from you know what you see out there on
[465]
the market today it's not just
[466]
performance that's improved the nature
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of perovskites allow for manufacturing
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advantages too so you only need
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less than one percent of the material
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that you need for a silicon cell to
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absorb all the sunlight so in theory you
[478]
can save money you can basically make
[480]
this stuff
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a lot cheaper the cool thing about the
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perovskites is that they turn out even
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though it's made of this kind of not
[486]
perfect material you can actually make a
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very very efficient solar cell it's
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formed at low temperatures silicon
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usually you have to crystallize at
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something like 1400 degrees celsius
[495]
with perovskites you can form it at less
[497]
than 100 degrees celsius
[499]
so that means that you can
[500]
actually use smaller equipment and you
[502]
can kind of use more standard chemical
[504]
processes and you can form the these
[506]
solar cells on things like plastics so
[508]
things that would melt under high
[509]
temperatures you can actually use to
[511]
make solar cells on so you can make
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something really lightweight and
[513]
flexible as well
[515]
perovskite thin films can be made by
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synthesizing a solar ink of sorts and
[519]
gently heating it until the perovskites
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crystallize just like salt crystals
[523]
emerging from evaporating seawater now
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let's go deeper into the lab to take a
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rare and exclusive sneak peek behind the
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scenes to see how perovskite solar cells
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are made yeah so this guy is called a
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thermal evaporator so it's it's one of
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many kinds of deposition tools that we
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use to to put down thin films so when
[540]
you look at a perovskite solar cell it's
[542]
like any other thin film device like an
[544]
organic led or a cadmium telluride solar
[546]
cell it's got a lot of thin film
[548]
semiconductor layers and one of the ways
[550]
you deposit some of those layers is
[551]
using techniques like thermal
[553]
evaporation where you heat up a source
[554]
material or maybe it's silver or maybe
[556]
it's a precursor for for one of your
[559]
semiconductors and you melt it you
[560]
evaporate it and then you have a cold
[562]
surface that you condense on and that
[563]
cold surface is actually just at room
[564]
temperature it's a plastic sheet or a
[566]
glass sheet or even a silicon wafer that
[568]
you're trying to deposit a film on the
[570]
substrate sits at the very top of the
[572]
chamber it's under high vacuum and you
[574]
again evaporate this material and it
[576]
condenses and forms this uniform thin
[577]
film and you do that many many times
[579]
with different kinds of techniques and
[581]
that gets you your solar cell
[582]
you can also make perovskite cells with
[584]
spin coating screen printing electrode
[586]
deposition or even printing the material
[589]
on a sheet just like an inkjet printer
[592]
here's the end result a small
[593]
rectangular perovskite solar cell so
[596]
this is the side that's facing the sun
[598]
correct and this is the back of the cell
[600]
yeah the the side facing the sun is
[602]
actually you're looking through the
[603]
glass and on the other side of that
[605]
glass there's a perovskite layer
[608]
kind of sandwiched between
[610]
the contacts so the contacts are will
[612]
pull the charge out of the perovskite
[614]
so there's a transparent conductor on
[615]
that on the close the side closest to us
[618]
then there's the proskate um and then on
[620]
the other side if you look at it from
[622]
you know from the back side there's
[623]
these silver electrodes there could be
[625]
any different kinds of metals but that
[627]
side doesn't have to be transparent
[628]
because you you actually want the light
[630]
to reflect back into the semiconductor
[632]
not go through
[633]
these solar cells are just lab samples
[635]
designed to test different perovskite
[637]
formulas
[638]
and you can see that
[640]
these different pads each of these
[641]
squares is a solar cell so we have six
[644]
different solar cells on one substrate
[645]
for for r d purposes for testing
[648]
swift solar is trying to create a
[650]
perovskite solar cell with a perfect mix
[652]
of longevity and efficiency ready for
[654]
commercialization so how do you test the
[655]
cells if it's a cloudy day the sun can
[657]
be quite unreliable even in california
[660]
we actually use this this machine right
[662]
here so this is a it's called a solar
[664]
simulator so it's actually just a fake
[665]
sun it's an led array that basically
[668]
has uh
[670]
all the colors basically it has a lot of
[672]
different colors of leds something like
[673]
20 different led colors in an array with
[676]
optics to make it really uniform so the
[678]
idea is here we don't want to have to
[679]
take our solar cells outdoors and test
[681]
you know if it's raining we can't test
[683]
ourselves
[684]
what are these here are these the
[685]
circuit boards at the solar panel that
[687]
measure voltage when the solar panels
[688]
sit on top of them yeah it measures the
[689]
voltage and current so this is um you
[691]
can kind of see this it's the same shape
[693]
and it's got a bunch of pads on there
[694]
and each of those like are basically
[696]
leads to to pull out current or measure
[698]
yeah to measure voltage so or apply
[701]
voltage so you can see we can do 20 of
[703]
these at once
[704]
and it basically automatically moves
[707]
around to test the cells each of them
[709]
individually perovskites have improved
[712]
greatly since scientists first began
[713]
testing them and are now beginning to
[715]
surpass mono and polycrystalline silicon
[717]
cells in conversion efficiency as
[719]
perovskites start coming into commercial
[721]
usage where are we most likely to see
[723]
them first all the traditional solar
[725]
applications on your rooftop out in the
[727]
field somewhere in the desert on
[728]
commercial rooftops on residential
[730]
rooftops like those are all fair game
[731]
down the line
[732]
perhaps guys aren't ready for that kind
[734]
of you know prime time yet they
[736]
stability is still a challenge like
[737]
you're getting them to last for 25 years
[739]
we can't no one can say that yet
[741]
confidently we don't have the field data
[743]
to prove that
[744]
so there's a lot of engineering work and
[746]
science to be done to get to that that
[748]
point but there's a lot of applications
[750]
where you don't need 25 year life right
[751]
like a car maybe only needs 10 or 15
[753]
years there's things like high altitude
[755]
drones right which are going to be fully
[757]
powered by solar you know they're flying
[758]
the stratosphere at 65 000 feet beaming
[760]
down internet so that kind of thing is
[763]
needs very very lightweight solar it
[764]
needs very efficient solar it doesn't
[766]
need a 25-year life you maybe only need
[768]
a couple years five years
[770]
so that kind of thing you can imagine
[771]
being powered by perovskites very soon
[773]
same with solar wristwatches or small
[776]
iot internet of things devices there's a
[779]
lot of these kind of mobile applications
[780]
where you can imagine perhaps guys kind
[783]
of coming into the market and then
[784]
eventually improving towards the rooftop
[786]
towards the utility scale applications
[789]
so what exactly are the challenges that
[790]
are preventing perovskites from
[792]
dominating the solar energy landscape
[794]
and changing everything we've spent a
[796]
lot of time in this lab actually working
[798]
on the challenges of of developing this
[800]
technology to a point where it's ready
[802]
for production for scale up there's
[804]
things like stability which is probably
[806]
the core problem for perovskites is how
[808]
do you make these cells last effectively
[811]
for years in the field under high
[813]
temperatures car roof might get up to 80
[815]
degrees celsius right or more on a hot
[817]
day so you need to be able to like
[818]
survive those temperatures for years at
[820]
a time and i think we try to do we do a
[822]
lot of tests and iteration on the
[824]
materials on the device stack the stack
[826]
of materials we use
[827]
on the design of the device itself on
[829]
the packaging to make sure that we can
[831]
survive those kind of temperatures high
[833]
humidities
[834]
the different kind of environments you
[835]
face outdoors
[837]
the relative fragility of the perovskite
[839]
material requires protection to shield
[841]
the semiconductor layer from
[842]
environmental stresses and degradation
[844]
the international standards for
[846]
terrestrial solar panels require harsh
[848]
testing that simulates 25 years of being
[850]
outside in these tests panels are heated
[852]
up and even battered with simulated hail
[854]
stones the problem with perovskites is
[856]
that they're still relatively new we can
[858]
subject them to these harsh simulated
[860]
tests that give us a pretty good idea of
[861]
their longevity but we just don't have
[863]
the real world data yet like we do for
[865]
silicon panels which have been in use
[867]
for decades now
[868]
[Music]
[869]
perovskites are still in the research
[871]
and development phase of the technology
[873]
life cycle there are many teams all over
[875]
the world working on improving their
[876]
efficiency and stability to bring them
[878]
into commercial adoption the raw
[879]
materials for perovskites are abundant
[881]
around the world and the solar cells can
[883]
be made using relatively simple
[884]
manufacturing processes this means that
[887]
perovskites can rapidly scale when
[888]
they're ready for mass-market
[890]
commercialization it's estimated that
[892]
perovskite panels could cost up to 15
[894]
times less per watt than modern
[895]
commercial silicon solar panels in
[897]
addition engineered perovskite materials
[899]
absorb all parts of the solar spectrum
[901]
efficiently to produce the highest
[903]
possible power output and ultra thin
[905]
films open the door to new product
[906]
formats with unprecedented power to
[908]
weight ratios and high flexibility
[912]
a future with cheap abundant solar power
[914]
could open the door for a variety of use
[916]
cases where current photovoltaic
[918]
technology does not yet make sense how
[920]
about these electric yachts i filmed for
[921]
previous electric future videos their
[923]
range could be radically improved with
[925]
higher efficiency lightweight integrated
[927]
perovskite solar panels we could see
[929]
integrated solar panels on trucks buses
[931]
and cars and any other applications
[933]
where sunlight is not yet considered
[935]
energy dense enough to provide
[936]
meaningful power imagine buildings
[938]
covered in transparent photovoltaic
[940]
glass windows that generate electricity
[944]
it's difficult to predict the future of
[945]
solar while perovskites are promising
[947]
serious researchers avoid playing
[949]
favorites instead they view all
[951]
technologies objectively based on
[953]
increased efficiency reduced materials
[955]
usage reduced manufacturing complexity
[957]
and cost
[959]
solar photovoltaics are the fastest
[961]
growing energy technology in the world
[963]
today and a leading candidate for
[964]
terawatt scale carbon free electricity
[966]
generation in our lifetime if you'd like
[968]
to better understand some of the
[970]
concepts we presented in this video it's
[972]
important to first learn the
[973]
fundamentals of solar energy brilliant
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does a great job of taking complicated
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science and breaking it down into
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bite-sized pieces with fun and
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challenging interactive explorations
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master concepts grasp the fundamental
[984]
principles and develop your intuition so
[986]
you can truly understand these
[987]
breakthrough technologies i've taken
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brilliant courses on electricity and
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magnetism and solar energy and was
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impressed with how well they structured
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their lessons with clever analogies
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examples and quizzes to test your
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knowledge brilliant offers a wide range
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of other content and topics from
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learning go to brilliant.org
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