Nanocrystal Quantum Dot Fluorophores: Fine-Tuning Optical Properties Through Chemistry
Dr. Jennifer Hollingsworth
Technical Staff Member
Los Alamos National Laboratory
Semiconductor nanocrystal quantum dots (NQDs) have attracted much interest in recent years due to their potential as enabling technologies for applications requiring bright, stable emission, such as in optoelectronics (e.g., LEDs, lasers, and photodetectors) and biology (e.g., optical labels for single-particle tracking). NQDs are near ideal flourophores, as they are characterized by high photo-bleaching thresholds, molar extinction coefficients (~10-100x that of organic dyes) and quantum yields in emission, as well as broadband absorption and narrow-band emission. Significantly, absorption onsets and emission energies are tunable from the ultraviolet (UV) to the infrared (IR) as a function of particle composition and size. Despite these numerous enabling characteristics, NQD optical properties are frustratingly sensitive to their surface chemistry and chemical environment. In this talk, I will discuss recent efforts to control NQD optical properties through solution-based synthetic chemistry strategies, with an emphasis on environmental robustness and single-NQD optical properties. Most notably, I will present our “all-inorganic” approach to suppressing “blinking” (fluorescence intermittency) in CdSe NQDs.
Figure: (left) Standard CdSe/ZnS core/shell NQD showing typical blinking behavior. (right) “Giant” CdSe-based NQD showing suppressed blinking.