Visible emissions through upconverting nanodots of NaYF4:Er3+; Yb3+ nanocrystals: a brief study in their upconversion mechanism and energy transfers
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Monami Das Modak
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Pradip Paik
Abstract
Here we report the formation of upconverting nanodots of Er3+/Yb3+ codoped NaYF4 nanocrystals confining diameter as calculated to be 3.4 ± 0.15 nm and are evolved as single crystalline particles with monodisperse particle size distribution. These nanodots are obtained with appearance of major cubic phases and minor prehoxagonal phases via thermal decomposition heat treatment. The bright green visible emissions for 2H11/2–4I15/2/4S3/2–4I15/2 energy transfers resulting from a three-photon excitation process, are obtained under 980 nm laser diode excitation sources, employed with an inexpensive diode laser with a maximum power density of about 150 mW/cm2. The synthesized nanodots are well characterized by high resolution transmission electron microscopy (HRTEM), X-ray diffraction study (XRD), Raman spectroscopic analysis, fluorescence spectroscopy for confirming their sizes, shapes; crystallinity; phases present and emissions respectively. Additionally, we also report the vis-vis photoluminescence (PL-study) under 450 nm excitations followed by two-photon excitation process. These nanocrystals are efficient enough to be dispersed in nonpolar organic solvents and could be of a great potential candidate for using as imaging probes or in fluorescent labels.
Acknowledgments
M. D. Modak would like to thank DST, Ministry of Science and Technology for financial support and University of Hyderabad (SEST -UoH) for carrying out several experimental investigations. P. Paik also acknowledges DST, Science and Engineering Research Board (SERB), India and they also wish to acknowledge the Defence Research and Development Organizations (DRDO), Ministry of Defence, and Government of India for providing instrument facility.
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Research ethics: Not applicable.
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Informed consent: Not applicable.
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Author contributions: All authors have accepted responsibility for the entire content of this manuscript and approved its submission.
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Use of Large Language Models, AI and Machine Learning Tools: None declared.
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Conflict of interest: The authors state no conflict of interest.
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Research funding: None declared.
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Data availability: Not applicable.
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