“…Interestingly, lifetimes obtained upon both excitation conditions are considerably longer than those obtained in the case of 20% Yb 3+ content. The decrease in lifetime correlates with the differences in emission intensity and is due to significant concentration quenching 7, 14, 22, 38 for high Yb 3+ concentrations.Figure 5( a ) Decay curves of 2-hydroxyperfluoroanthraquinone-capped 10% Yb 3+ -doped NaYF 4 nanoparticles (chromophore/nanoparticle suspension concentration ratio of 0.44) with 460 nm and 960 nm OPO excitations. ( b ) I(t) decay curve and fittings for the 1030 nm emission at the 460 nm OPO excitation for the 0.37 mg/ml chromophore functionalized nanoparticle at the high chromophore/NaYF 4 : Yb 3+ nanoparticles suspension concentration ratio of 1.04.…”
Section: Resultsmentioning
confidence: 99%
“…However, exposure of the NIR-emitting lanthanides to an environment rich in C-H, O-H or N-H groups 19, 20 (as is usual in organic compounds) results in strong vibrational quenching of the emission, due to the comparable energies of the gaps and the 3rd-5th overtones of hydrogenated groups’ vibrational quanta 19, 20 . A number of alternatives, including fluorination 21, 22 or chlorination 12 of the organic groups have been proposed, some of them resulting in considerable increases of the emission with relatively high emission efficiencies and correlated long lifetimes allowing, for instance, NIR to visible upconversion in organic environments 22 .…”
Infra-red emission (980 nm) of sub 10 nm Yb3+-doped NaYF4 nanoparticles has been sensitized through the excitation of 2-hydroxyperfluoroanthraquinone chromophore (1,2,3,4,5,6,7-heptafluro-8-hydroxyanthracene-9,10-dione) functionalizing the nanoparticle surface. The sensitization is achieved with a broad range of visible light excitation (400–600 nm). The overall near infra-red (NIR) emission intensity of Yb3+ ions is increased by a factor 300 as a result of the broad and strong absorption of the chromophore compared with ytterbium’s intrinsic absorption. Besides the Yb3+ NIR emission, the hybrid composite shows organic chromophore-based visible emission in the orange-red region of the spectrum. We observe the energy migration process from the sensitized Yb3+ ions at the surface to those in the core of the particle using time-resolved optical spectroscopy. This highlights that the local environments for emitting Yb3+ ions at the surface and center of the nanoparticle are not identical, which causes important differences in the NIR emission dynamics. Based on the understanding of these processes, we suggest a simple strategy to control and modulate the decay time of the functionalized Yb3+-doped nanoparticles over a relatively large range by changing physical or chemical parameters in this model system.
“…Interestingly, lifetimes obtained upon both excitation conditions are considerably longer than those obtained in the case of 20% Yb 3+ content. The decrease in lifetime correlates with the differences in emission intensity and is due to significant concentration quenching 7, 14, 22, 38 for high Yb 3+ concentrations.Figure 5( a ) Decay curves of 2-hydroxyperfluoroanthraquinone-capped 10% Yb 3+ -doped NaYF 4 nanoparticles (chromophore/nanoparticle suspension concentration ratio of 0.44) with 460 nm and 960 nm OPO excitations. ( b ) I(t) decay curve and fittings for the 1030 nm emission at the 460 nm OPO excitation for the 0.37 mg/ml chromophore functionalized nanoparticle at the high chromophore/NaYF 4 : Yb 3+ nanoparticles suspension concentration ratio of 1.04.…”
Section: Resultsmentioning
confidence: 99%
“…However, exposure of the NIR-emitting lanthanides to an environment rich in C-H, O-H or N-H groups 19, 20 (as is usual in organic compounds) results in strong vibrational quenching of the emission, due to the comparable energies of the gaps and the 3rd-5th overtones of hydrogenated groups’ vibrational quanta 19, 20 . A number of alternatives, including fluorination 21, 22 or chlorination 12 of the organic groups have been proposed, some of them resulting in considerable increases of the emission with relatively high emission efficiencies and correlated long lifetimes allowing, for instance, NIR to visible upconversion in organic environments 22 .…”
Infra-red emission (980 nm) of sub 10 nm Yb3+-doped NaYF4 nanoparticles has been sensitized through the excitation of 2-hydroxyperfluoroanthraquinone chromophore (1,2,3,4,5,6,7-heptafluro-8-hydroxyanthracene-9,10-dione) functionalizing the nanoparticle surface. The sensitization is achieved with a broad range of visible light excitation (400–600 nm). The overall near infra-red (NIR) emission intensity of Yb3+ ions is increased by a factor 300 as a result of the broad and strong absorption of the chromophore compared with ytterbium’s intrinsic absorption. Besides the Yb3+ NIR emission, the hybrid composite shows organic chromophore-based visible emission in the orange-red region of the spectrum. We observe the energy migration process from the sensitized Yb3+ ions at the surface to those in the core of the particle using time-resolved optical spectroscopy. This highlights that the local environments for emitting Yb3+ ions at the surface and center of the nanoparticle are not identical, which causes important differences in the NIR emission dynamics. Based on the understanding of these processes, we suggest a simple strategy to control and modulate the decay time of the functionalized Yb3+-doped nanoparticles over a relatively large range by changing physical or chemical parameters in this model system.
“…Introduction of dopants in active layer is easy to implement due to its simple process and low cost. Some organic molecules, 18,19 metal nanoparticles (NPs), 20,21 rare-earth NPs, 22,23 and inorganic quantum dots 24,25 have been doped into PSCs and further advanced their PCEs.…”
The highly efficient polymer solar cells were realized by doping poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) dots into active layer. The dependence of doping amount on devices performance was investigated and a high efficiency of 7.15% was obtained at an optimal concentration, accounting for a 22.4% enhancement. The incorporation of PFO dots (Pdots) is conducted to the improvement of Jsc and fill factor mainly due to the enhancement of light absorption and charge transport property. Pdots blended in active layer provides an interface for charge transfer and enables the formation of percolation pathways for electron transport. The introduction of Pdots was proven an effective way to improve optical and electrical properties of solar cells.
“…It is called cooperative energy transfer (CET), where at least two Yb 3+ ions simultaneously transfer energy to one Tb 3+ ion [21][22][23][24][25][26][27]. CET based upconversion occurs when the energy gap between the highest lying component of the ground state of Ln 3+ ion and its first excited state is too large to be bridged by a single, excited Yb 3+ ion.…”
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