Colloidal Tm3+/Yb3+‐Doped LiYF4 Nanocrystals: Multiple Luminescence Spanning the UV to NIR Regions via Low‐Energy Excitation

Mahalingam, Venkataramanan; Vetrone, Fiorenzo; Naccache, Rafik; Speghini, Adolfo; Capobianco, John A.

doi:10.1002/adma.200901174

Cited by 412 publications

(325 citation statements)

References 26 publications

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“…The devices comprising the silicon cells, the dye-sensitized cells, the polymer-PCBM and the polymer-nanocrystals heterojunction solar cells, encounter with spectral mismatch [12][13][14][15], thereby leading to loss of energy. The upconversion materials which possess the optical property of converting long-wavelength photons into shorter ones [16][17][18], gives rise to a promising method to harvest the solar energy. Provided that the short-wavelength emissions from the upconversion materials can overlap the absorption region of the photosensitizer in the photovoltaic cell, the device is probably able to utilize the short-wavelength photons when coupled with the upconversion materials.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of polythiophene–TiO2 heterojunction solar cells coupled with upconversion nanoparticles

Zhang

2014

J Mater Sci: Mater Electron

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We introduce lanthanide-doped LiYF 4 upconversion nanoparticles into TiO 2 film and use the obtained composite film to photocatalyze the polymerization of thiophene, developing a polythiophene-TiO 2 heterojunction coupled with upconversion nanoparticles. The upconversion nanoparticles, which are capable of converting long-wavelength photons into shorter ones, aim to broaden the light-harvesting of the heterojunction films. Solar cells are fabricated from the heterojunction films coupled with different contents of upconversion nanoparticles, and measured in respect to the incident photon-electron conversion efficiencies and the current density-voltage curves. It is revealed that the upconversion nanoparticles enable the devices to utilize the long-wavelength photons, and thus, the photovoltaic performances are enhanced. Moreover, by employing Raman spectroscopy, we monitor the process of polymerization on the TiO 2 substrate and put deep insight into the interfacial interaction of the heterojunction.

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Section: Introductionmentioning

confidence: 99%

Fabrication of polythiophene–TiO2 heterojunction solar cells coupled with upconversion nanoparticles

Zhang

2014

J Mater Sci: Mater Electron

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“…15 Our group has recently synthesized LiYF 4 :Tm 3+ /Yb 3+ -UCNPs that showed stronger UV/blue emission following NIR excitation with 980 nm light compared to NaYF 4 . 16 Taking advantage of the high penetration depth and minimal autofluorescence of the NIR excitation light, LiYF 4 :Tm 3+ /Yb 3+ -UCNPs can be used as UV/blue excitation sources in biological applications.In this study we report on the functionalization of LiYF 4 :Tm 3+ / Yb 3+ -UCNPs with m-THPC to demonstrate the generation of singlet oxygen by this nanoconstruct using the blue light obtained following NIR excitation of the nanoparticles. In order to generate singlet oxygen from the upconverted blue light emission of the LiYF 4 :Tm 3+ /Yb 3+ -UCNPs, it was necessary to modify m-THPC using 4-(bromomethyl)benzoic acid (BMBA), which facilitated grafting of m-THPC onto the LiYF 4 :Tm 3+ /Yb 3+ -UCNPs, and induced a bathochromic shift of the m-THPC blue absorption peak.…”

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confidence: 99%

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confidence: 99%

Chemical modification of temoporfin – a second generation photosensitizer activated using upconverting nanoparticles for singlet oxygen generation

Rodriguez

Naccache

et al. 2014

Chem. Commun.

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In photodynamic therapy (PDT), the destruction of a target tissue (localized tumor) involves the combination of light of a specific wavelength, oxygen and a photosensitizer (PS). 1-3 Individually, these components are harmless; however, when combined, a putative cytotoxic agent, singlet oxygen ( 1 O 2 ), is generated. It is the 1 D g form of singlet oxygen that induces oxidation damages on cell components, resulting in cytotoxic reactions in the cells via necrosis or apoptosis, the self-destruction mechanisms of cells.The second generation PS, 5,10,15,20-tetra(m-hydroxyphenyl)-chlorin 4-6 (m-THPC, Foscan s , Temoporfin), with enhanced absorption of light in the red region (l max = 652 nm) has been found to be more specific than conventional porphyrins where skin photosensitization, usually a side effect of PDT, has been reported to be shorter. However, m-THPC does not make use of the optimal spectral biological window for tissue penetration in the 700-1000 nm range. Unfortunately, photons in this region are energetically too low for 1 O 2 generation. In addition to the band at 652 nm, which has a high molar extinction coefficient (e = 2.9 Â 10 4 cm À1 M À1 ), m-THPC has another absorption band in the blue region centered at 417 nm with a much higher molar absorption coefficient (e = 2.3 Â 10 5 cm À1 M À1 ). Excitation of m-THPC at 417 nm would eliminate the problem of low photon energy; however, direct excitation with high-energy blue light limits the use in biological applications due to its low tissue penetration depth. 7Lanthanide-doped upconverting nanoparticles (Ln 3+ -UCNPs) have been intensively studied in recent years. These nanoparticles can emit UV, visible and/or near-infrared (NIR) light upon NIR excitation (typically 980 nm) via a multiphoton process known as upconversion. The application of Ln 3+ -UCNPs as an energy source for exciting photosensitizers has been proposed. [8][9][10][11][12][13] The nanoconstructs, which were prepared using upconverting nanoparticles for the excitation of different photosensitizers, made use of the Er 3+ transitions, 2 H 11/2 , 4 S 3/2 -4 I 11/2 and 4 F 9/2 -4 I 11/2 . The transitions have one major disadvantage, the emission from these transitions does not overlap with the strongest absorption peak, the Soret band, of the photosensitizer presently used, which is at B400 nm. 14 The ideal modification would be to shift the Soret band of the photosensitizer to obtain the maximum overlap with the emission band(s) of the Ln 3+ -UCNPs. Temoporfin is one example of an approved second-generation photosensitizer. 15 Our group has recently synthesized LiYF 4 :Tm 3+ /Yb 3+ -UCNPs that showed stronger UV/blue emission following NIR excitation with 980 nm light compared to NaYF 4 . 16 Taking advantage of the high penetration depth and minimal autofluorescence of the NIR excitation light, LiYF 4 :Tm 3+ /Yb 3+ -UCNPs can be used as UV/blue excitation sources in biological applications.In this study we report on the functionalization of LiYF 4 :Tm 3+ / Yb 3+ -UCNPs with m-THPC to d...

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“…10 A straightforward solution to this problem came with the development of fluoride-based matrices, which showed a high luminescent efficiency due to their low phonon energies. 11 Most reports in the literature have been focused on the development 18 based on the use of microwaves as the heating source, which did not produce discrete BaLuF 5 nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

Crystal structure, NIR luminescence and X-ray computed tomography of Nd³⁺:Ba_0.3Lu_0.7F_2.7 nanospheres

González-Mancebo¹,

Becerro²,

Cantelar

et al. 2017

Dalton Trans.

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Colloidal Tm³⁺/Yb³⁺‐Doped LiYF₄ Nanocrystals: Multiple Luminescence Spanning the UV to NIR Regions via Low‐Energy Excitation

Cited by 412 publications

References 26 publications

Fabrication of polythiophene–TiO2 heterojunction solar cells coupled with upconversion nanoparticles

Fabrication of polythiophene–TiO2 heterojunction solar cells coupled with upconversion nanoparticles

Chemical modification of temoporfin – a second generation photosensitizer activated using upconverting nanoparticles for singlet oxygen generation

Crystal structure, NIR luminescence and X-ray computed tomography of Nd³⁺:Ba_0.3Lu_0.7F_2.7 nanospheres

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Colloidal Tm3+/Yb3+‐Doped LiYF4 Nanocrystals: Multiple Luminescence Spanning the UV to NIR Regions via Low‐Energy Excitation

Cited by 412 publications

References 26 publications

Fabrication of polythiophene–TiO2 heterojunction solar cells coupled with upconversion nanoparticles

Fabrication of polythiophene–TiO2 heterojunction solar cells coupled with upconversion nanoparticles

Chemical modification of temoporfin – a second generation photosensitizer activated using upconverting nanoparticles for singlet oxygen generation

Crystal structure, NIR luminescence and X-ray computed tomography of Nd3+:Ba0.3Lu0.7F2.7 nanospheres

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Colloidal Tm³⁺/Yb³⁺‐Doped LiYF₄ Nanocrystals: Multiple Luminescence Spanning the UV to NIR Regions via Low‐Energy Excitation

Crystal structure, NIR luminescence and X-ray computed tomography of Nd³⁺:Ba_0.3Lu_0.7F_2.7 nanospheres