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Title: Effect of Interfacial Alloying versus “Volume Scaling” on Auger Recombination in Compositionally Graded Semiconductor Quantum Dots

Auger recombination is a nonradiative three-particle process wherein the electron–hole recombination energy dissipates as a kinetic energy of a third carrier. Auger decay is enhanced in quantum-dot (QD) forms of semiconductor materials compared to their bulk counterparts. Because this process is detrimental to many prospective applications of the QDs, the development of effective approaches for suppressing Auger recombination has been an important goal in the QD field. One such approach involves “smoothing” of the confinement potential, which suppresses the intraband transition involved in the dissipation of the electron–hole recombination energy. Here, the present study evaluates the effect of increasing “smoothness” of the confinement potential on Auger decay employing a series of CdSe/CdS-based QDs wherein the core and the shell are separated by an intermediate layer of a CdSe xS 1–x alloy comprised of 1–5 sublayers with a radially tuned composition. As inferred from single-dot measurements, use of the five-step grading scheme allows for strong suppression of Auger decay for both biexcitons and charged excitons. Further, due to nearly identical emissivities of neutral and charged excitons, these QDs exhibit an interesting phenomenon of lifetime blinking for which random fluctuations of a photoluminescence lifetime occur for a nearly constant emission intensity.
Authors:
ORCiD logo [1] ; ORCiD logo [1] ;  [2] ; ORCiD logo [2]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of New Mexico, Albuquerque, NM (United States). Center for High Technology Materials (CHTM)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Report Number(s):
LA-UR-17-26004
Journal ID: ISSN 1530-6984
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Nano Letters
Additional Journal Information:
Journal Volume: 17; Journal Issue: 9; Journal ID: ISSN 1530-6984
Publisher:
American Chemical Society
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division; USDOE Laboratory Directed Research and Development (LDRD) Program
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; Material Science; semiconductor nanocrystal; quantum dot; suppression of Auger recombination; interfacial alloy layer; lifetime blinking
OSTI Identifier:
1469533