2013/07/16 by Young‐Shin Park, Wan Ki Bae, Park, Young-Shin +7
Engineering · Materials Science · Physics and Astronomy · #Chalcogenide Semiconductor Thin Films #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Quantum Dots Synthesis And Properties #Semiconductor Quantum Structures and Devices
paper · pdf · doi:10.48550/arxiv.1307.4433
openalex publication_date 2013/07/16 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Previous single-particle spectroscopic studies of colloidal quantum dots have\nindicated a significant spread in biexciton lifetimes across an ensemble of\nnominally identical nanocrystals. It has been speculated that in addition to\ndot-to-dot variation in physical dimensions, this spread is contributed to by\nvariations in the structure of the quantum dot interface, which controls the\nshape of the confinement potential. Here we directly evaluate the effect of the\ncomposition of the core-shell interface on single- and multi-exciton dynamics\nvia side-by-side measurements of individual core-shell CdSe-CdS nanocrystals\nwith a sharp vs. smooth (graded) interface. To realize the latter type of\nstructures, we incorporate a CdSexS1-x alloy layer of controlled composition\nand thickness between the CdSe core and the CdS shell. We observe that while\nhaving essentially no effect on single-exciton decay, the interfacial alloy\nlayer leads to a systematic increase in biexciton lifetimes. This observation\nprovides direct experimental evidence that in addition to the size of the\nquantum dot, its interfacial properties also significantly affect the rate of\nAuger recombination, which governs biexciton decay. These findings help\nrationalize previous observations of a significant heterogeneity in the\nbiexciton lifetimes across similarly sized quantum dots and should facilitate\nthe development of Auger-recombination-free colloidal nanostructures for a\nrange of applications from lasers and light-emitting diodes to photodetectors\nand solar cells.\n