The last couple of years have seen the emergence of a new “wonder material” in photovoltaics: perovskite. Recently, we’ve seen that perovskite’s wonders are not limited to just solar cells; they can create 100-percent efficient lasers and can be manipulated to carry both electric and magnetic polarization.
Even without any particular manipulation, perovskites are a class of material with attractive PV properties such as high charge-carrier mobility, long diffusion lengths, and low cost. With these as motivation, research has pushed perovskite energy conversion efficiency up from 5 percent to 20 percent in just a few years.
Despite its spectacular development in photovoltaics, there has been no way to directly measure perovskits charge-transport properties for other applications. Now a team of researchers from both Wake Forest University and the University of Utah has overcome this limitation. The researchers have shown that it’s possible to make a field-effect transistor (FET) out of perovskite, showing for the first time that anyone can directly measure the material’s electronic properties at room temperature.
"We designed the structure of these field-effect transistors that allowed us to achieve electrostatic gating of these materials and determine directly their electrical properties," said lead author, Oana Jurchescu, an assistant professor of physics at Wake Forest, in the press release. (Electrostatic gating is the use of a static electric field on the gat of an FET to control the flow of current through the transitor channel.) "Then we fabricated these transistors with the Utah team and we measured them here in our lab."
Prior to this work, which was published in the journal MRS Communications, there were some who believed that the fact that nobody had been able to produce electrostatic gating in perovskites was an indication that field-effect modulation was not possible with them.
Not only was the gating proven possible, but with this perovskite-based FET, the researchers were able to determine that such devices are ambipolar: both electrons and holes can carry current through them.
With these results perovskites might move beyond just photovoltaics and branch out into integrated optoelectronic systems and pumped lasers. "This work shows that in addition to solar cell technologies, the hybrid perovskites have potential to be used in a variety of optoelectronic applications,” said Zeev "Valy" Vardeny, physics professor at the University of Utah, in the press release.
Dexter Johnson is a contributing editor at IEEE Spectrum, with a focus on nanotechnology.