title: Precise Tuning of Surface Quenching for Luminescence Enhancement in Core-Shell Lanthanide-Doped Nanocrystals.
abstract: Lanthanide-doped nanocrystals are of particular interest for the research community not only due to their ability to shape light by downshifting, quantum cutting, and upconversion but also because novel optical properties can be found by the precise engineering of core-shell nanocrystals. Because of the large surface area-to-volume ratio of nanocrystals, the luminescence is typically suppressed by surface quenching. Here, we demonstrate a mechanism that exploits surface quenching processes to improve the luminescence of our core-shell lanthanide-doped nanocrystals. By carefully tuning the shell thickness of inert β-NaLuF4around β-NaYF4nanocrystals doped with Yb3+and Er3+, we unravel the relationship between quantum yield and shell thickness, and quantify surface quenching rates for the relevant Er3+and Yb3+energy levels. This enhanced understanding of the system's dynamics allowed us to design nanocrystals with a surface quenching-assisted mechanism for bright NIR to NIR downshifting with a distinctive efficiency peak for an optimized shell thickness.
authors.affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.|Department of Chemistry, University of California-Berkeley , Berkeley, California 94720, United States.
authors.forename: Stefan
authors.initials: S
authors.lastname: Fischer
authors.affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.|Department of Chemistry, University of California-Berkeley , Berkeley, California 94720, United States.
authors.forename: Noah D
authors.initials: ND
authors.lastname: Bronstein
authors.affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.|Department of Chemistry, University of California-Berkeley , Berkeley, California 94720, United States.
authors.forename: Joseph K
authors.initials: JK
authors.lastname: Swabeck
authors.affiliation: Molecular Foundry, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: Emory M
authors.initials: EM
authors.lastname: Chan
authors.affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.|Department of Chemistry, University of California-Berkeley , Berkeley, California 94720, United States.|Department of Materials Science and Engineering, University of California-Berkeley , Berkeley, California 94720, United States.|Kavli Energy NanoScience Institute , Berkeley, California 94720, United States.
authors.forename: A Paul
authors.initials: AP
authors.lastname: Alivisatos
keywords: NIR; Upconversion; core−shell; downshifting; lanthanide; nanocrystals; photoluminescence; quantum yield; surface quenching