TY - JOUR
T1 - Effect of polarization of surrounding organic molecules on upconversion emission of β-NaYF4 Co-Doped with Er3+ and Yb3+
AU - Nomura, Koki
AU - Umezawa, Masakazu
AU - Tezuka, Keiko
AU - Tasaki, Tomomi
AU - Okubo, Kyohei
AU - Soga, Kohei
N1 - Funding Information:
We thank Mr. Shuya Hasegawa (Department of Materials Science and Technology, Tokyo University of Science) for TEM observation of our ultrasmall NaYF 4 NPs. This research was supported in part by a the MEXT Grant-in-Aid for Scientific Research on Innovative Areas (Resonance Bio), no. 15H05950 , the MEXT Grant-in-Aid for Scientific Research(A), no. 19H01179 , and the Center of Innovation Program “COINS” from Japan Science and Technology Agency , JST.
Funding Information:
We thank Mr. Shuya Hasegawa (Department of Materials Science and Technology, Tokyo University of Science) for TEM observation of our ultrasmall NaYF4 NPs. This research was supported in part by a the MEXT Grant-in-Aid for Scientific Research on Innovative Areas (Resonance Bio), no. 15H05950, the MEXT Grant-in-Aid for Scientific Research(A), no. 19H01179, and the Center of Innovation Program ?COINS? from Japan Science and Technology Agency, JST.
Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2021/11
Y1 - 2021/11
N2 - Rare-earth-doped ceramic nanoparticles (RED-CNPs) have been studied for biological applications because they can convert biopermeable near-infrared light into visible and ultraviolet light. Both the host ceramic and the microenvironment around RED-CNPs may influence their luminescence characteristics; however, the effects of surrounding molecules have not been systematically clarified. In the present study, the effects of dispersion solvents and adsorbed polymers on the upconversion luminescence of Yb3+- and Er3+-doped NaYF4 nanoparticles (NaYF4:Yb3+,Er3+ NPs) were investigated. The effect of polymers was analyzed by encapsulating the luminescent NPs into various hydrophobic particle cores composed of poly(ethylene glycol) block copolymers. NaYF4:Yb3+,Er3+ NPs showed different upconversion spectra under different conditions when excited by 980 nm light. As the polarities of the surrounding organic molecules (solvents and hydrophobic core polymers) on the particle surface decreased, the thermal relaxation (4I11/2 → 4I13/2) was suppressed, whereas the excitation from 4I11/2 to 4F7/2 was enhanced in the upconversion excitation process, and thus, green upconversion luminescence (520–540 nm) increased. The solubility parameter was effective as an index of polarity affecting thermal relaxation. Our results showed the importance of material design considering the molecular polarity of the surrounding microenvironment for obtaining the desired upconversion emission of RED-CNPs.
AB - Rare-earth-doped ceramic nanoparticles (RED-CNPs) have been studied for biological applications because they can convert biopermeable near-infrared light into visible and ultraviolet light. Both the host ceramic and the microenvironment around RED-CNPs may influence their luminescence characteristics; however, the effects of surrounding molecules have not been systematically clarified. In the present study, the effects of dispersion solvents and adsorbed polymers on the upconversion luminescence of Yb3+- and Er3+-doped NaYF4 nanoparticles (NaYF4:Yb3+,Er3+ NPs) were investigated. The effect of polymers was analyzed by encapsulating the luminescent NPs into various hydrophobic particle cores composed of poly(ethylene glycol) block copolymers. NaYF4:Yb3+,Er3+ NPs showed different upconversion spectra under different conditions when excited by 980 nm light. As the polarities of the surrounding organic molecules (solvents and hydrophobic core polymers) on the particle surface decreased, the thermal relaxation (4I11/2 → 4I13/2) was suppressed, whereas the excitation from 4I11/2 to 4F7/2 was enhanced in the upconversion excitation process, and thus, green upconversion luminescence (520–540 nm) increased. The solubility parameter was effective as an index of polarity affecting thermal relaxation. Our results showed the importance of material design considering the molecular polarity of the surrounding microenvironment for obtaining the desired upconversion emission of RED-CNPs.
KW - Hydrophobic polymer
KW - Organic solvent
KW - Polarity
KW - Rare-earth-doped ceramic nanoparticle
KW - Thermal relaxation
KW - Upconversion luminescence
UR - http://www.scopus.com/inward/record.url?scp=85112782067&partnerID=8YFLogxK
U2 - 10.1016/j.jlumin.2021.118394
DO - 10.1016/j.jlumin.2021.118394
M3 - Article
AN - SCOPUS:85112782067
VL - 239
JO - Journal of Luminescence
JF - Journal of Luminescence
SN - 0022-2313
M1 - 118394
ER -