Graphene benefits

1. Graphene
A modern material with unique physical
and electrical properties that could
reshape our future.
By: Steven Douglas
4/24/15

2. Outline:
• Introduction to graphene.
• History.
• Physical properties.
• Electrical properties.
• Other properties.
• How graphene is created.
• Graphene’s current uses.
– Batteries
– Capacitors
– Transistors
• Graphene’s future.
• Challenges surrounding graphene.
• Summary/Conclusion
• Key concepts.
• References.

3. Introduction to Graphene
• The first 2-dimensional material ever discovered.
• One-atom thick of carbon atoms arranged in a
hexagonal lattice.
• Found in graphite, coal, and created in other
fashions.
• Hard to manufacture in large quantities, just
about all graphene produced is used for R&D
within companies and universities.
• The strongest, lightest, and most conductive
material known to man.

4. Graphene’s short history:
• Discovered by Andre Geim and Konstantin
Novoselov in 2004, however this is apparently
debatable.
• First conceived in 1946. But they didn’t believe it
could be created at room temperature.
• Graphene as we know it was theoretically
mentioned as recent as 1984 to describe the
layers of graphite.
• The term “Graphene” was used mainly In
working with Carbon Nano-tubes.

5. Amazing Physical Properties:
• The strongest material
ever measured. Up to
150X stronger than the
equivalent weight of steel.
• Pliable as rubber and has
the ability to stretch up to
120% of its length then
recover its original shape.
• Extremely light weight, its
said that a single sheet of
Graphene covering a
whole football field would
weigh less than 1g.

6. Electrical Properties
• Graphene is classified as a zero-overlap semi-
metal, which means that either holes or
electrons are charge carriers.
• Very high electrical conductivity when exposed
to an electric field.
• In a vacuum, it had a mobility that was up to
250X that of Si. Out conducts copper by a
thousand times.
• Effective mass at the Dirac point is zero for both
electrons and holes.

7. Other Properties:
• Only known substance that is completely
impermeable to gas.
• Graphene oxide reportedly has the ability to
attract radioactive material.
• Safer creation of “Quantum Dots”. Reduces the
price from $1million a kg to $100 a ton.
• Also has some optical properties that are being
tested as we speak.
• Graphene has the ability to transmit up to 98% of
light.

8. How graphene is created:
Mechanical Exfoliation
• Typically involves scotch
tape.
• Stick the tape to a
graphite block.
• Use another piece of tape
and stick the two sticky
sides together. Repeat
this process 20-100x
• Press the piece of tape
with the graphene on a
substrate.

9. Chemical exfoliation
• The block graphite is
submerged into a solvent.
• An ultrasound is used to
cause a splitting effect
within the graphite
structure.
• Prolonged exposure
causes little platelets to
be formed.
• Enriched by a centrifuge.

10. CE via graphene oxide
• Uses the same
process as chemical
exfoliation but
graphene is oxidized.
• After the CE process,
it is then deposited on
substrate and reduced
to parent graphene in
some fashion.

11. Chemical Vapour Deposition
• The most common practice in
creating graphene today.
• Typically a copper substrate is
exposed to a low pressure,
1000˚C annealing process.
• Methane and Hydrogen gas
flows through the furnace.
• Carbon atoms from Methane
deposite on the copper,
creating a continuous
graphene sheet.

12. Silicon Carbide
• A small amount of silicon
carbide is placed in a box
with a hole in it.
• The box is sealed in a
vacuum or argon gas and
heated to 1500˚C.
• Si molecules evaporate
from the surface leaving a
layer of graphene.

13. Graphene’s current uses:
• In early 2014 I.B.M announced that it had built
the first integrated circuit for wireless devices.
• Today a tennis racquet with a graphene layer has
been manufactured.
• Graphene is an ingredient to conductive inks for
printing circuitry.
• Samsung is reportedly releasing a screen that
employs Graphene to deliver current to the
display.

14. Optical Electronics
• Believed to mainly
be used in
touchscreens,
OLED, and LCD.
• Graphene matches
Indium-Tin Oxide
performance in its
basic state.

15. Energy storage
• Graphene is being
experimented in
both
supercapacitor and
battery
construction.

16. Energy storage cont.
• Graphene based
supercapacitors have
potential to replace small
batteries.
• Uses the chemical
exfoliation discussed
earlier.
• Was able to light LED’s
with a two minute charge
for around twelve hours.

17. Graphene & Transistors
• Clocked at 427
Ghz.
• Create a false band
gap by employing
“Negative”
resistance.
• Another type of
FET uses dual gate
construction.

18. Graphene’s future
• Biomedical
Engineering
• Optical Electronics
• Ultra-Filtration
• Composite Materials
• Photo-Voltaic cells
• Energy Storage
• Radioactive Clean-up

19. Challenges Surrounding Graphene
• Graphene has no bandwidth, which means it
cannot be shut off.
• A very hydrophobic material
• Very expensive and hard to manufacture for
most companies.
• When deployed it seemed that the results
weren’t duplicated.
• Graphene is hard to produce in large usable
sheets. Small flakes are what we use to test
usually.

20. Conclusion
• Graphene has many obstacles to work
around before it can be implemented into
today’s technology.
• Researchers are suggesting that it’s a
matter of months rather than years for the
next graphene break through.
• Graphene has so many amazing
properties, so expect it to impact many
types of technologies.

21. References:
• http://www.sciencedaily.com/releases/2012/09/120910082304.htm
• De la Fuente, Jesus. www.graphene.com.13 April 2015
• Colapinto, John. “Graphene may be the most remarkable substance
ever discovered. But what is it for?”.The New Yorker, 22 December,
2014.Web.13 April, 2015
• Wang, Brian.”Graphene Hybrid Supercapacitors storing as much as
lead acid batteries which is six times commercial supercapacitors”
www.nextbigfuture.com 17 April, 2015. Web 20 April, 2015.
• Johnson, Dexter. “Graphene circuit competes head to head with Si
technology.”www.spectrum.ieee.org 3 February, 2014.Web.20 April,
2014.
• Malasarn, Davin. “UCLA Researchers develop new technique to
scale up production of graphene micro super capacitors”.
www.newsroom.ucla.edu. 19 February, 2013.Web. 20 April, 2015

22. Key Concepts
• The first 2-D material ever discovered, only
measuring 1-atom thick.
• Lightest material ever discovered.
• Strongest material ever discovered per unit
weight.
• Best electrical/thermal conductivity discovered at
room temperature.
• Currently does not possess a band-gap like a Si
gate does.

23. Questions?