| Autor: |
Brittman S; U.S. Naval Research Laboratory , 4555 Overlook Avenue SW , Washington , D.C. 20375 , United States., Colbert AE; U.S. Naval Research Laboratory , 4555 Overlook Avenue SW , Washington , D.C. 20375 , United States., Brintlinger TH; U.S. Naval Research Laboratory , 4555 Overlook Avenue SW , Washington , D.C. 20375 , United States., Cunningham PD; U.S. Naval Research Laboratory , 4555 Overlook Avenue SW , Washington , D.C. 20375 , United States., Stewart MH; U.S. Naval Research Laboratory , 4555 Overlook Avenue SW , Washington , D.C. 20375 , United States., Heuer WB; Chemistry Department , U.S. Naval Academy , 572M Holloway Road , Annapolis , Maryland 21402 , United States., Stroud RM; U.S. Naval Research Laboratory , 4555 Overlook Avenue SW , Washington , D.C. 20375 , United States., Tischler JG; U.S. Naval Research Laboratory , 4555 Overlook Avenue SW , Washington , D.C. 20375 , United States., Boercker JE; U.S. Naval Research Laboratory , 4555 Overlook Avenue SW , Washington , D.C. 20375 , United States. |
| Abstrakt: |
The size of a quantum-confined nanocrystal determines the energies of its excitonic transitions. Previous work has correlated the diameters of PbS nanocrystals to their excitonic absorption; however, we observe that PbS quantum dots synthesized in saturated dispersions of PbCl 2 can deviate from the previous 1S h -1S e energy vs diameter curve by 0.8 nm. In addition, their surface differs chemically from that of PbS quantum dots produced via other syntheses. We find that these nanocrystals are coated in a shell that is measurable in transmission electron micrographs and contains lead and chlorine, beyond the monatomic chlorine termination previously proposed. This finding has implications for understanding the growth mechanism of this reaction, the line width of these quantum dots' photoluminescence, and electronic transport within films of these nanocrystals. Such fundamental knowledge is critical to applications of PbS quantum dots such as single-photon sources, photodetectors, solar cells, light-emitting diodes, lasers, and biological labels. |
