Once the orientation of the emitters is known, Zia says, it may be possible to design structured devices that maximize those directional properties. In most applications, thin-film materials are layered on top of each other. The orientations of emitters in each layer indicate whether electronic excitations are happening within each layer or across layers, and that has implications for how such a device should be configured.
"If you were making an LED using these layered materials and you knew that the electronic excitations were happening across an interface," Zia said, "then there's a specific way you want to design the structure to get all of that light out and increase its overall efficiency."
The same concept could apply to light-absorbing devices like solar cells. By understanding how the electronic excitations happen in the material, it could be possible to structure it in a way that coverts more incoming light to electricity.
"One of the exciting things about this research is how it brought together people with different expertise," Zia said. "Our group's expertise at Brown is in developing new forms of spectroscopy and studying the electronic origin of light emission. The Kymissis group at Columbia has a great deal of expertise in organic semiconductors, and the Shan group at Case Western has a great deal of expertise in layered nanomaterials. Jon Schuller, the study's first author, did a great job in bringing all this expertise together. Jon was a visiting scientist here at Brown, a postdoctoral fellow in the Energy Frontier Research Center at Columbia, and is now a professor at UCSB.
|Contact: Kevin Stacey|