Carbon sheets could save Earth's limited Indium supply

Posted by Rick C. Hodgin

Mainz (Germany)  - It is estimated that there is only a 10 years supply of indium left on the entire planet.  Indium is a crucial resource in creating solar cells, LCD and other devices which must have transparent electrodes to carry out their function.  However, a new discovery related to single atomic layer sheets of carbon (graphene) could prove to be a better replacement, according to researchers at the Max Planck Institute for Polymer Research in Germany.

Prototype
Researchers have been able to take graphene, single layer 2D sheets extracted from the common material graphite, and build a electrode 10 layers thick, or about 5nm.  Such small electrodes are 80% transparent to visible light, and 100% transparent to infrared light.  The team believes that with this level of transparency, it could prove to be just the alternative manufactures need for the dwindling indium supply.  In fact, the researchers believe they could get it down even thinner with continued experiments, allowing for 90% transparency or higher.

Currently, the team has created the prototype with this process.  They coated some cells with a solution of graphite oxide flakes, which are not true graphene sheets, but close to it.  They were each about 10 to 100 nm across, creating a solid coating of flakes on the surface.  The cell was subjected to intense heating to remove the oxygen, which then caused the "sheets" to merge together, leaving a solid sheet of thick graphene.

Solar cells
The big bonus here is for solar panels.  Since the graphene electrodes are completely transparent to infrared light, solar cells could absorb energy from more of the EM spectrum.  This would allow for more efficient solar cells, provided the rest of the technology can also be worked out to use graphene in production.  The researchers claim this process would also cost less than silicon solutions for mass production.

Very stable
According to Linjie Zhi of the Max Planck Institute, "It is very stable in the face of heat and acidic conditions, which makes fabrication much easier."  Some problems remain, however.  The team is not getting a sheet that is completely smooth.  The manufacturing process they are using today results in periodic creases, which alter the way the materials function.  Their goal is to get a single atomic layer of graphene.  If they could achieve that, they'd have a nearly 100% transparent material, one which is completely suitable for replacing indium.
 

Author's opinion
I read a lot of science journals, and discoveries like these are always "5-10 years out".  It's just a given because people like to report on their early findings to keep the grants rolling.  Still, consider that five years ago that most of us were using a Pentium III or Athlon K7 processor, most likely with 256MB or less memory, and maybe a 20 GB hard drive.  Five years can make a huge difference in terms of technology.

It would be very nice in 5-10 years to have affordable solar cells, powerful batteries, and the ability to be largely energy-grid free.  Clean, renewable energy sources, the kind that can not only power our homes, but also our electric vehicles.  That would be oh so nice.