Tag Archives: Igor Shvets

Transforming flat screens with P-type conductors at CRANN

I’m not sure about window-integrated flat screens as one of the applications for this technology breakthrough at Trinity College Dublin’s (TCD) CRANN (Centre for Research on Adaptive Nanostructures and Nanodevices). I think there’s enough signage and video being beamed at me everywhere I go but all indications are that more and more surfaces are going to become display and/or communication devices and these researchers seem to have found a way to speed that process.

From the March 21, 2012 news item on Nanowerk,

Researchers at CRANN, the Science Foundation Ireland funded nanoscience institute based in Trinity College Dublin (TCD), have discovered a new material that could transform the quality, lifespan and efficiency of flat screen computers, televisions and other devices (see paper in Applied Physics Letters: “Magnesium, nitrogen codoped Cr2O3: A p-type transparent conducting oxide”).

The research team was led by Prof Igor Shvets, a CRANN Principal Investigator who has successfully launched and sold two spin out companies from TCD and who is involved in the Spirit of Ireland energy project. A patent application protecting the new material was filed by TCD. Commenting on the research, Prof Igor Shvets said, “This is an exciting development with a range of applications and we are hopeful this initial research will attract commercial interest in order to explore its industrial use. The new material could lead to innovations such as window-integrated flat screens and to increase the efficiency of certain solar cells, thus significantly impacting on the take-up of solar cells, which can help us to reduce carbon emissions.” [emphasis mine]

The application for solar cells sounds a lot more appealing to me. CRANN issued a March 21, 2012 press release which included some technical details,

Devices that the new material could be used with such as solar cells, flat screen TVs, computer monitors, LEDs all utilise materials that can conduct electricity and at the same time are see-through.  These devices currently use transparent conducting oxides, which are a good compromise between electrical conductivity and optical transparency. They all have one fundamental limitation: they all conduct electricity through the movement of electrons. [emphasis mine] Such materials are referred to as n-type transparent conducting oxides. Electricity can also be conducted through as p-type materials.  Modern day electronics make use of n-type and p-type materials.  The lack of good quality p-type transparent conducting oxides, however, led the research team to develop a new material – a p-type transparent conducting oxide.

I wish I better understood the fundamental limitation of an n-type transparent conducting oxide and how the new p-type transparent conducting oxide addresses that limitation.

After reading the description of p-type materials, it seems to me that electrons also move in that material. From the Wikipedia essay on p-type materials,

The dopant atom accepts an electron, causing the loss of half of one bond from the neighboring atom and resulting in the formation of a “hole”. Each hole is associated with a nearby negatively charged dopant ion, and the semiconductor remains electrically neutral as a whole. However, once each hole has wandered away into the lattice, one proton in the atom at the hole’s location will be “exposed” and no longer cancelled by an electron. [emphasis mine] This atom will have 3 electrons and 1 hole surrounding a particular nucleus with 4 protons. For this reason a hole behaves as a positive charge. When a sufficiently large number of acceptor atoms are added, the holes greatly outnumber thermal excited electrons. Thus, holes are the majority carriers, while electrons become minority carriers in p-type materials.

Well, I am interpreting the “wandering away” bit as a type of movement so I find the descriptions just a bit confusing. As for the holes being the majority carrier in p-type materials, perhaps the electrons in the n-type materials are the majority carriers?

If there’s anyone out there who could help lift the veil of confusion, I would much appreciate it.

For those who don’t need as much handholding as I do, you can find out more about Shvets and his work here.