Bright, Mechanosensitive Upconversion with Cubic-Phase Heteroepitaxial Core–Shell Nanoparticles
- Stanford Univ., Stanford, CA (United States)
- Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kavli Energy NanoScience Institute, Berkeley, CA (United States)
Lanthanide-doped nanoparticles are an emerging class of optical sensors, exhibiting sharp emission peaks, high signal-to-noise ratio, photostability, and a ratiometric color response to stress. The same centrosymmetric crystal field environment that allows for high mechanosensitivity in the cubic-phase (α), however, contributes to low upconversion quantum yield (UCQY). In this work, we engineer brighter mechanosensitive upconverters using a core-shell geometry. Sub-25 nm α-NaYF4:Yb,Er cores are shelled with an optically inert surface passivation layer of ~4.5 nm thickness. Using different shell materials, including NaGdF4, NaYF4, and NaLuF4, we study how compressive to tensile strain influences the nanoparticles' imaging and sensing properties. All core-shell nanoparticles exhibit enhanced UCQY, up to 0.14% at 150 W/cm2, which rivals the efficiency of unshelled hexagonal-phase (β) nanoparticles. Additionally, strain at the core-shell interface can tune mechanosensitivity. In particular, the compressive Gd shell results in the largest color response from yellow-green to orange or, quantitatively, a change in the red to green ratio of 12.2 ± 1.2% per GPa. For all samples, the ratiometric readouts are consistent over three pressure cycles from ambient to 5 GPa. Therefore, heteroepitaxial shelling significantly improves signal brightness without compromising the core's mechano-sensing capabilities and further, promotes core-shell cubic-phase nanoparticles as upcoming in vivo and in situ optical sensors.
- Research Organization:
- Energy Frontier Research Centers (EFRC) (United States). Light-Material Interactions in Energy Conversion (LMI); SLAC National Accelerator Lab., Menlo Park, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- AC02-05CH11231; AC02-76SF00515; SC0001293; FI 2042/1-1; 2013156180
- OSTI ID:
- 1464057
- Alternate ID(s):
- OSTI ID: 1532327
- Journal Information:
- Nano Letters, Vol. 18, Issue 7; ISSN 1530-6984
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Accurate Control of Core–Shell Upconversion Nanoparticles through Anisotropic Strain Engineering
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journal | August 2019 |
Stimuli‐Responsive Hybridized Nanostructures
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journal | August 2019 |
Are lanthanide-doped upconversion materials good candidates for photocatalysis?
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journal | January 2019 |
Defect-induced abnormal enhanced upconversion luminescence in BiOBr:Yb 3+ /Er 3+ ultrathin nanosheets and its influence on visible-NIR light photocatalysis
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journal | January 2020 |
Design of Layer‐Structured KAlF 4 :Yb/Er for Pressure‐Enhanced Upconversion Luminescence
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journal | November 2019 |
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