@article{61427cf62c5e48658d2558f472e321fb,
title = "Cubic versus hexagonal - phase, size and morphology effects on the photoluminescence quantum yield of NaGdF4:Er3+/Yb3+ upconverting nanoparticles",
abstract = "Upconverting nanoparticles (UCNPs) are well-known for their capacity to convert near-infrared light into UV/visible light, benefitting various applications where light triggering is required. At the nanoscale, loss of luminescence intensity is observed and thus, a decrease in photoluminescence quantum yield (PLQY), usually ascribed to surface quenching. We evaluate this by measuring the PLQY of NaGdF4:Er3+,Yb3+ UCNPs as a function of size (ca. 15 to 100 nm) and shape (spheres, cubes, hexagons). Our results show that the PLQY of α-phase NaGdF4 Er3+,Yb3+ surpasses that of β-NaGdF4 for sizes below 20 nm, an observation related to distortion of the crystal lattice when the UCNPs become smaller. The present study also underlines that particle shape must not be neglected as a relevant parameter for PLQY. In fact, based on a mathematical nucleus/hull volumetric model, shape was found to be particularly relevant in the 20 to 60 nm size range of the investigated UCNPs.",
author = "Marta Quintanilla and Eva Hemmer and Jose Marques-Hueso and Shadi Rohani and Giacomo Lucchini and Miao Wang and Zamani, \{Reza R.\} and Vladimir Roddatis and Adolfo Speghini and Richards, \{Bryce S.\} and Fiorenzo Vetrone",
note = "Funding Information: The authors appreciate the valuable comments of Dr Ian Howard and Dr Damien Hudry (both at KIT, Karlsruhe, Germany) during the final stages of the manuscript. Also, the authors thank Gwena{\"e}l Chamoulaud (UQAM, Montreal, Canada) for experimental support with the thermogravimetric measurements and gratefully acknowledge the use of equipment in the “Collaborative Laboratory and User Facility for Electron Microscopy” (CLUE, http://www.clue.physik.uni-goet-tingen.de). Prof. F. Vetrone is grateful for financial support from the Natural Sciences and Engineering Research Council (NSERC) of Canada and the Fonds de Recherche du Qu{\'e}bec – Nature et Technologies (FRQNT) for supporting their research. E. Hemmer is thankful to the Alexander von Humboldt Foundation for financial support in the frame of the Feodor Lynen Research Fellowship. J. Marques-Hueso thanks the UK Engineering and Physical Sciences Research Council for support (EP/T013680/1). M. Quintanilla acknowledges the financial support of the Spanish Ministerio de Ciencia e Innovaci{\'o}n through the project COLUMNAS (PID2019-110632RB-I00). B. S. Richards would like to acknowledge the financial support provided by the Helmholtz Association via (i) the Recruitment Initiative Funding; and (ii) the Research Field Energy – Program Materials and Technologies for the Energy Transition – Topic 1 Photovoltaics. Publisher Copyright: {\textcopyright} The Royal Society of Chemistry.",
year = "2022",
month = jan,
day = "28",
doi = "10.1039/d1nr06319g",
language = "English",
volume = "14",
pages = "1492--1504",
journal = "Nanoscale",
issn = "2040-3364",
publisher = "Royal Society of Chemistry",
number = "4",
}