Nanocrystal quantum dots (QDs) have large potential as a unique optical material in a broad range of applications that rely on downshifting light, especially in applications that rely on achieving a high level of spectral purity at relatively high optical flux levels. Here, we have newly designed a synthesis that produces high-quality CdSe/CdS core/shell QDs at elevated temperature. The resulting CdSe/CdS core/shell QDs perfectly maintain the original crystal structure of the starting CdSe core. We find that single dot blinking is also significantly suppressed with only a relatively thin shell. These core/shell QDs for the first time simultaneously satisfy the criteria that include high uniformity, high PL QY, very narrow PL peaks, and significantly suppressed blinking (over 90% on-time fractions). In addition, the small size of the shells allows for compact QDs generally preferred for biological imaging applications. We demonstrate that these CdSe/CdS core/shell QDs can be easily brought into water by ligand exchange processes with either polyethylene glycol thiol (PEG-SH) or poly imidazole ligands (PIL). These water-soluble QDs maintain a high PL QY (>70%) and are suitable as in vivo imaging agent. In short, QDs with the combination of properties described here have been sought after for a long time. These QDs should show a significant improvement in the performance of QDs in a variety of applications ranging from solid state lighting and illumination to biological multiplexed labeling and tracking.

New generation of core/shell nanocrystals combines high emission quantum yield, narrow linewidths, suppressed blinking, and a compact size

244th National Meeting (2012)

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