August 4, 2023 — Hebrew University of Jerusalem (HU) researchers developed a nanoscale artificial molecule that facilitates fast switching of colored light, which is essential in lighting, displays, and fast optical fiber-communication networks, as well as biological and neuroscience sensors. 

The study was just published in Nature Materials.  

“Our research is a big leap forward for the use of nanomaterials in optoelectronics,” says Prof. Uri Banin from the Hebrew University Institute of Chemistry and the Center for Nanoscience and Nanotechnology. “This is an important step in our exposition of the idea of “nanocrystal chemistry,” in which nanocrystals are building blocks of artificial molecules with exciting new functionality. The ability to switch colors quickly and efficiently has enormous possibilities for revolutionizing advanced displays and creating color-switchable single photon sources.”  

Until now, color switching required a different nanocrystal for each specific color, and it wasn’t possible to switch colors. When color-emitting semiconductors operate in a nanoscale size ─ 100,000th smaller than a human hair ─ the color of the light emitted can be changed by changing the nanocrystal size.  

Although single colloidal color tuning of single colloidal nanocrystals has been previously investigated and implemented in prototype optoelectronic devices, actively switching colors has been insufficient as color brightness is diminished when changed. 

The Hebrew University research team overcame this limitation by creating a unique molecule with two emission centers. In this model, an electric field can tune the relative emission from each center, changing the color without losing brightness. For example, one nanocrystal can be tuned to emit “green” light, while the other emits “red” light. This new, dual-color-emitting artificial molecule is sensitive to external voltage, which induces an electric field that allows a molecule to emit each of the two colors, or any combination, simply by applying the appropriate voltage.    

The study received financial support from the European Research Council (ERC), under the European Union’s Horizon 2020 research and innovation program (project Coupled NC, grant agreement No [741767], and project CQDplay, grant agreement No [101069322]). 

The research team includes Prof. Uri Banim, Yonatan Ossia, Adar Levi, Yossef E. Panfil, Somnath Koley, Einav Scharf, Nadav Chefetz, Sergei Remennik, and Atzmon Vakahi, from the Institute of Chemistry and the Center for Nanoscience and Nanotechnology at the Hebrew University of Jerusalem.