Exciton-phonon coupling in InP quantum dots with ZnS and (Zn,Cd) Se shells

Annalisa Brodu, Mariana V. Ballottin, Jonathan Buhot, Dorian Dupont, Mickael Tessier, Zeger Hens, Freddy T. Rabouw, Peter C.M. Christianen, Celso De Mello Donega, Daniel Vanmaekelbergh

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

InP-based colloidal quantum dots are promising for optoelectronic devices such as light-emitting diodes and lasers. Understanding and optimizing their emission process is of scientific interest and essential for large-scale applications. Here we present a study of the exciton recombination dynamics in InP QDs with various shells: ZnS, ZnSe, and (Zn,Cd)Se with different amounts of Cd (5, 9, 12%). Phonon energies extracted from Raman spectroscopy measurements at cryogenic temperatures (4-5 K) are compared with exciton emission peaks observed in fluorescence line narrowing spectra. This allowed us to determine the position of both the bright F=±1 state and the lowest dark F=±2 state. We could identify the phonon modes involved in the radiative recombination of the dark state and found that acoustic and optical phonons of both the core and the shell are involved in this process. The Cd content in the shell increases electron wave-function delocalization, and thereby enhances the exciton-phonon coupling through the Fröhlich interaction.
Original languageEnglish
Article number125413
Pages (from-to)1-7
Number of pages7
JournalPhysical Review B
Volume101
Issue number12
DOIs
Publication statusPublished - 13 Mar 2020

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