A procedure that reliably produces perfect quantum dots, each doped with exactly four copper ions, has opened up possibilities for fine-tuning the nanocrystals’ optical properties and producing spectacular colors. Incorporating “guest” ions into the crystal lattice of QDs can be very challenging, and adding only an average number of ions does not produce QDs with optimal electrical and optical properties, said Ali Jawaid, a graduate student at the University of Illinois at Chicago and first author of a paper on the research. To achieve these desired properties — which could find use in dye production, bioimaging and solar energy production — the researchers introduced four copper ions into each QD, yielding the perfect nanocrystal. Researchers at the University of Illinois at Chicago have developed quantum dots doped with copper. The discovery opens up possibilities for fine-tuning the optical properties of the quantum dots and producing spectacular colors. Courtesy of the University of Illinois at Chicago. “When the crystallinity is perfect, the quantum dots do something that no one expected — they become very emissive and end up being the world’s best dye,” said Preston Snee, assistant professor of chemistry at UIC and principal investigator of the study, which appeared in ACS Nano (doi: 10.1021/nn305697q). Snee believes that the method will enable the investigators to substitute other guest ions with the same consistent results. “This opens up the opportunity to study a wide array of doped quantum dot systems,” he said. Donald Wink and Leah Page of UIC and Soma Chattopadhyay of Argonne National Laboratory in Lemont also contributed to the study. For more information, visit: www.uic.edu