TY - JOUR

T1 - Bulk-like emission in the visible spectrum of colloidal LiYF4:Pr nanocrystals downsized to 10 nm

AU - Komban, Rajesh

AU - Spelthann, Simon

AU - Steinke, Michael

AU - Ristau, Detlev

AU - Rühl, Axel

AU - Gimmler, Christoph

AU - Weller, Horst

N1 - Funding Information: R. K., C. G. and H. W. would like to thank Free and Hanseatic City of Hamburg, Germany for the financial support. The work of S. S., M. S., A. R. and D. R. was partly funded by: Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy - EXC-2123 Quantum Frontiers - 390837967. D. R. would like to thank the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) for partly funding this work under Germany's Excellence Strategy within the Cluster of Excellence PhoenixD (EXC 2122, Project ID 390833453). The publication of this article was funded by the Open Access Fund of the Leibniz Universität Hannover. Dr Michael Zopf, Institute of Solid State Physics at Leibniz University Hannover, Germany helped with the fitting procedure of multi-exponential decays. Pascal Rusch, Institute of Physical Chemistry and Electrochemistry at Leibniz University Hannover, Germany performed the quantum yield measurement. Dr Christian Kraenkel, Leibniz-Institut für Kristallzüchtung Berlin, Germany provided absorption and emission cross section data for LiYF4:Pr bulk crystals. The authors also thank Ms Andrea Koeppen and Mr Stefan Werner, University of Hamburg (UHH), Germany for their supports for the microscopic and XRD analyses. Special thanks go to Mr Andreas Kornowski, a long-term collaborator and expert in the field of electron microscopy of nanoscopic materials at UHH. His contribution by material characterization greatly helped in shaping this publication. Unfortunately, he passed away before this paper could be submitted/published. Funding Information: R. K., C. G. and H. W. would like to thank Free and Hanseatic City of Hamburg, Germany for the financial support. The work of S. S., M. S., A. R. and D. R. was partly funded by: Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy – EXC-2123 Quantum Frontiers – 390837967. D. R. would like to thank the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) for partly funding this work under Germany's Excellence Strategy within the Cluster of Excellence PhoenixD (EXC 2122, Project ID 390833453). The publication of this article was funded by the Open Access Fund of the Leibniz Universität Hannover. Dr Michael Zopf, Institute of Solid State Physics at Leibniz University Hannover, Germany helped with the fitting procedure of multi-exponential decays. Pascal Rusch, Institute of Physical Chemistry and Electrochemistry at Leibniz University Hannover, Germany performed the quantum yield measurement. Dr Christian Kraenkel, Leibniz-Institut für Kristallzüchtung Berlin, Germany provided absorption and emission cross section data for LiYF:Pr bulk crystals. The authors also thank Ms Andrea Koeppen and Mr Stefan Werner, University of Hamburg (UHH), Germany for their supports for the microscopic and XRD analyses. Special thanks go to Mr Andreas Kornowski, a long-term collaborator and expert in the field of electron microscopy of nanoscopic materials at UHH. His contribution by material characterization greatly helped in shaping this publication. Unfortunately, he passed away before this paper could be submitted/published. 4

PY - 2022/4/25

Y1 - 2022/4/25

N2 - Though Pr3+ doped LiYF4 (LiYF4:Pr3+) bulk crystals are a well-known laser gain material with several radiative transitions, their nanocrystal counterparts have not been investigated with regards to these. Through downsizing to the nanoscale, novel applications are expected, especially in composite photonic devices. For example, nanocrystals in stable colloidal form with narrow size distribution are highly desirable to reduce scattering in such composites. Herein, we synthesized monodispersed LiYF4:Pr3+ nanocrystals having a size of 10 nm resulting in colorless clear stable colloidal dispersions and conducted an extensive optical characterization for the first time. We observed unexpected yet intense emission with excited state lifetimes comparable to bulk crystals in the visible spectrum through excitation at 444 nm and 479 nm. In macroscopic bulk crystals, this emission is only exploitable through excitation of a different, subjacent energy level. A comprehensive comparison to the bulk crystals provides deeper insight into the excitation mechanism and performance of these nanocrystals. The presented results pave the way for developing application-oriented LiYF4:Pr3+ nanocrystals as emitters with tailored properties for quantum optics or biomedical applications.

AB - Though Pr3+ doped LiYF4 (LiYF4:Pr3+) bulk crystals are a well-known laser gain material with several radiative transitions, their nanocrystal counterparts have not been investigated with regards to these. Through downsizing to the nanoscale, novel applications are expected, especially in composite photonic devices. For example, nanocrystals in stable colloidal form with narrow size distribution are highly desirable to reduce scattering in such composites. Herein, we synthesized monodispersed LiYF4:Pr3+ nanocrystals having a size of 10 nm resulting in colorless clear stable colloidal dispersions and conducted an extensive optical characterization for the first time. We observed unexpected yet intense emission with excited state lifetimes comparable to bulk crystals in the visible spectrum through excitation at 444 nm and 479 nm. In macroscopic bulk crystals, this emission is only exploitable through excitation of a different, subjacent energy level. A comprehensive comparison to the bulk crystals provides deeper insight into the excitation mechanism and performance of these nanocrystals. The presented results pave the way for developing application-oriented LiYF4:Pr3+ nanocrystals as emitters with tailored properties for quantum optics or biomedical applications.

UR - http://www.scopus.com/inward/record.url?scp=85135864739&partnerID=8YFLogxK

U2 - 10.1039/d2na00045h

DO - 10.1039/d2na00045h

M3 - Article

AN - SCOPUS:85135864739

VL - 4

SP - 2973

EP - 2978

JO - Nanoscale Advances

JF - Nanoscale Advances

IS - 14

ER -