Intrinsically Slow Cooling of Hot Electrons in CdSe Nanocrystals Compared to CdS

Matthew J. Coley-O’Rourke*, Bokang Hou, Skylar J. Sherman, Gordana Dukovic, Eran Rabani

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The utilization of excited charge carriers in semiconductor nanocrystals (NCs) for optoelectronic technologies has been a long-standing goal in the field of nanoscience. Experimental efforts to extend the lifetime of excited carriers have therefore been a principal focus. To understand the limits of these lifetimes, in this work, we theoretically study the time scales of pure electron relaxation in negatively charged NCs composed of two prototypical materials: CdSe and CdS. We find that hot electrons in CdSe have lifetimes that are 5 to 6 orders of magnitude longer than in CdS when the relaxation is governed only by the intrinsic properties of the materials. Although these two materials are known to have somewhat different electronic structure, we elucidate how this enormous difference in lifetimes arises from relatively small quantitative differences in electronic energy gaps and phonon frequencies, as well as the crucial role of Fröhlich-type electron-phonon couplings.

Original languageEnglish
Pages (from-to)244-250
Number of pages7
JournalNano Letters
Volume25
Issue number1
DOIs
StatePublished - 8 Jan 2025

Funding

FundersFunder number
Advanced Scientific Computing Research
National Energy Research Scientific Computing Center
U.S. Department of Energy
University of Colorado Boulder
Office of Science
Air Force Office of Scientific ResearchFA9550-19-1-0083, FA9550-22-1-0347
Division of Materials Sciences and EngineeringDE-AC02-05CH11231
Fundamentals of Semiconductor Nanowire ProgramKCPY23
Basic Energy SciencesDE-SC0022088

    Keywords

    • electron cooling
    • nanocrystals
    • optical phonons
    • quantum dots

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