Applications in Theranostics Guanying Chen,*,†,‡ Hailong Qiu,†,‡ Paras N. Prasad,*,‡,§ and Xiaoyuan Chen* †School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin, Heilongjiang 150001, China ‡Department of Chemistry and the Institute for Lasers, Photonics, and Biophotonics, University at Buffalo, State University of New York, Buffalo, New York 14260, United States Department of Chemistry, Korea University, Seoul 136-701, Korea Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland 20892-2281, United States

Upconversion Nanoparticles: Design, Nanochemistry, and Applications in Theranostics

Upconversion luminescent materials: advances and applications.

Photovoltaic (PV) technologies for solar energy conversion represent promising routes to green and renewable energy generation. Despite relevant PV technologies being available for more than half a century, the production of solar energy remains costly, largely owing to low power conversion efficiencies of solar cells. The main difficulty in improving the efficiency of PV energy conversion lies in the spectral mismatch between the energy distribution of photons in the incident solar spectrum and the bandgap of a semiconductor material. In recent years, luminescent materials, which are capable of converting a broad spectrum of light into photons of a particular wavelength, have been synthesized and used to minimize the losses in the solar-cell-based energy conversion process. In this review, we will survey recent progress in the development of spectral converters, with a particular emphasis on lanthanide-based upconversion, quantum-cutting and down-shifting materials, for PV applications. In addition, we will also present technical challenges that arise in developing cost-effective high-performance solar cells based on these luminescent materials.

Enhancing solar cell efficiency: the search for luminescent materials as spectral converters

Synthesis, Luminescent Properties, and Biomedical Applications Shili Gai,†,‡ Chunxia Li,† Piaoping Yang,*,‡ and Jun Lin*,† †State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China ‡Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, Harbin Engineering University, Harbin, 150001, P. R. China

Recent Progress in Rare Earth Micro/Nanocrystals: Soft Chemical Synthesis, Luminescent Properties, and Biomedical Applications

Lanthanide Nanoparticles: From Design toward Bioimaging and Therapy

Optical sensing plays an important role in theranostics due to its capability to detect hint biochemical entities or molecular targets as well as to precisely monitor specific fundamental psychological processes. Rare-earth (RE) doped upconversion nanoparticles (UCNPs) are promising for these endeavors due to their unique frequency converting capability; they emit efficient and sharp visible or ultraviolet (UV) luminescence via use of ladder-like energy levels of RE ions when excited at near infrared (NIR) light that are silent to tissues. These features allow not only a high penetration depth in biological tissues but also a high detection sensitivity. Indeed, the energy transfer between UCNPs and biomolecular or chemical indicators provide opportunities for high-sensitive bio- and chemical-sensing. A temperature-sensitive change of the intensity ratio between two close UC bands promises them for use in temperature mapping of a single living cell. In this work, we review recent investigations on using UCNPs for the detection of biomolecules (avidin, ATP, etc.), ions (cyanide, mecury, etc.), small gas molecules (oxygen, carbon dioxide, ammonia, etc.), as well as for in vitro temperature sensing. We also briefly summarize chemical methods in synthesizing UCNPs of high efficiency that are important for the detection limit.

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Sensing using rare-earth-doped upconversion nanoparticles.

Photovoltaic cells are able to convert sunlight into electricity, providing enough of the most abundant and cleanest energy to cover our energy needs. However, the efficiency of current photovoltaics is significantly impeded by the transmission loss of sub-band-gap photons. Photon upconversion is a promising route to circumvent this problem by converting these transmitted sub-band-gap photons into above-band-gap light, where solar cells typically have high quantum efficiency. Here, we summarize recent progress on varying types of efficient upconversion materials as well as their outstanding uses in a series of solar cells, including silicon solar cells (crystalline and amorphous), gallium arsenide (GaAs) solar cells, dye-sensitized solar cells, and other types of solar cells. The challenge and prospect of upconversion materials for photovoltaic applications are also discussed.

https://www.mdpi.com/2079-4991/5/4/1782/pdf

Enhancing Solar Cell Efficiency Using Photon Upconversion Materials

Ultrasmall upconversion (UC) nanoparticles with efficient multicolor photoluminescence (PL) are quite desirable for high contrast in vitro and in vivo bioimaging. Here, we present a simple and reproducible thermolysis approach to synthesize 3.7 nm sized lanthanide-doped YF3 UC nanocrystals. The PL intensity of these ultrasmall nanoparticles was found to be about ten times brighter than that of 4.5 nm sized CaF2 counterparts, which were reported to be one of the smallest efficient upconversion nanoparticles. We also showed that the color output of these nanocrystals can all be simply modulated by adjusting the sensitizer Yb3+ concentration. Moreover, to further enhance the PL output, a one nm thick epitaxial layer was grown onto the YF3 nanocrystals. These lanthanide-doped ultrasmall upconversion YF3 nanocrystals with modulated and enhanced multicolor output are ideal for a variety of in vitro and in vivo biological imaging applications.

Lanthanide-doped ultrasmall yttrium fluoride nanoparticles with enhanced multicolor upconversion photoluminescence

The inability to utilize near infrared (NIR) light has posed a stringent limitation for the efficiencies of most single-junction photovoltaic cells such as dye-sensitized solar cells (DSSCs). Here, we describe a strategy to alleviate the NIR light harvesting problem by upconverting non-responsive NIR light in a broad spectral range (over 190 nm, 670–860 nm) to narrow solar-cell-responsive visible emissions through incorporated dye-sensitized upconversion nanoparticles (DSUCNPs). Unlike typically reported UCNPs with narrow and low NIR absorption, the organic dyes (IR783) anchored on the DSUCNP surface were able to harvest NIR photons broadly and efficiently, and then transfer the harvested energy to the inorganic UCNPs (typically reported), entailing an efficient visible upconversion. We show that the incorporation of DSUCNPs into the TiO2 photoanode of a DSSC is able to elevate its efficiency from 7.573% to 8.568%, enhancing the power conversion efficiency by about 13.1%. We quantified that among the relative efficiency increase, 7.1% arose from the contribution of broad-band upconversion in DSUCNPs (about ∼3.4 times higher than the highest previously reported value of ∼2.1%), and 6.0% mainly from the scattering effect of DSUCNPs. Our strategy has immediate implications for the use of DSUCNPs to improve the performance of other types of photovoltaic devices.

Enhancing dye-sensitized solar cell efficiency through broadband near-infrared upconverting nanoparticles.

Here lanthanide-doped tetragonal nanocrystals of BaYF5 with strong near infrared-to-visible multicolor upconversion emissions have been controllably synthesized by a hydrothermal method Opposite to well-established NaYF4 nanocrystals, we found that the sizes of the BaYF5 nanocrystals increase in proportion to that of the molar ratios of EDTA to lanthanide nitrates and decrease as the pH value of the precursor solution increases in presence of EDTA These findings reveal that the nucleation process of BaYF5 nanocrystals is governed by the pH-sensitive chelating ability of EDTA with both Ba2+ and Ln3+ Additionally, it was found that single wavelength laser excitation of 980 nm can induce strong red, green, and blue upconversion emissions in BaYF5 nanocrystals doped with 18%Yb3+/2%Er3+, 18%Yb3+/2%Ho3+, and 18%Yb3+/2%Tm3+, respectively Furthermore, after a facile surface poly(acrylic acid) ligand exchange reaction, such multicolor nanoparticles can be transferred into water and multiple other solvents for applications in biology and materials science

Shuwei Hao

Papers

Sensing using rare-earth-doped upconversion nanoparticles.

Enhancing Solar Cell Efficiency Using Photon Upconversion Materials

Lanthanide-doped ultrasmall yttrium fluoride nanoparticles with enhanced multicolor upconversion photoluminescence

Enhancing dye-sensitized solar cell efficiency through broadband near-infrared upconverting nanoparticles.

Ethylenediaminetetraacetic acid (EDTA)-controlled synthesis of multicolor lanthanide doped BaYF5 upconversion nanocrystals