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Nd3+ as effective sensitizing and deactivating ions for the 2.87?μm lasers in Ho3+ doped LaF3 crystal
摘要： The efficient 2.87 μm emission of Ho3+: 5I6 → 5I7 transition via Nd3+ sensitization in Nd,Ho:LaF3 crystal was obtained under 808 nm LD excitation for the first time. The lifetime of Ho3+:5I7 decreases dramatically from 26.28 ms to 6.41 ms via Nd3+ co-doping. The mechanism of sensitization and deactivation by Nd3+ was investigated compared with the Ho:LaF3 crystal. The absorption cross-section, emission cross-section, and fluorescence quantum efficiency were estimated and discussed. All the results indicate Nd,Ho:LaF3 crystal an attractive gain medium for solid-state lasers around 2.87 μm under an 808 nm LD pump.
关键词： Spectroscopy,Energy transfer,Nd,Ho:LaF3
更新于2025-10-22 19:40:53
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Enhanced absorption of Sr3Lu2(BO3)4:Ce3+,Tb3+ phosphor with energy transfer for UV-pumped white LEDs
摘要： A series green emission phosphors Sr3Lu2(BO3)4:Ce3+,Tb3+ (denoted as SLBO:Ce3+,Tb3+) with broad absorption band matching well with UV LED chip were synthesized by the solid–state reaction method. The phase and structure were analyzed with XRD, EDX, FT-IR measurements. The energy transfer between Ce3+ and Tb3+ in SLBO was proved by spectra and decay curves detailedly. The emission colors vary from blue to green by adjusting the ratio of Ce3+/Tb3+ doped concentration. With temperature increasing, SLBO:Ce3+,Tb3+ phosphor shows well thermal stability that emission intensity retains 70% of its initial at 25 oC even temperature rising to 150 oC. The internal and external quantum efficiency of SLBO:3%Ce3+,8%Tb3+ are 77.5% and 34.8% under 340 nm excitation, respectively. Combining the as-synthesized SLBO:Ce3+,Tb3+ and red emission phosphor CaAlSiN3:Eu2+ coated on a 365 nm UV chip, a warm white LEDs device with CRI of 83 was achieved. All the results indicate that the SLBO:Ce3+,Tb3+ phosphor has potential application in UV pumped white LEDs.
关键词： phosphor,thermal stability,energy transfer,UV LED
更新于2025-10-22 19:38:57
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Regulating Charge-Transfer in Conjugated Microporous Polymer for Photocatalytic Hydrogen Evolution
摘要： Band gap engineering in donor-acceptor conjugated microporous polymers is a potential way to increase the solar energy harvesting towards photochemical water splitting. Herein, we report design and synthesis of a series of donor-acceptor CMPs [tetraphenylethylene (TPE) = donor and 9-fluorenone (F) = acceptor], F0.1CMP, F0.5CMP and F2.0CMP which exhibit tunable band gaps and photocatalytic hydrogen evolution from water. The donor-acceptor CMPs exhibit intramolecular charge transfer (ICT) absorption in the visible region (λmax=480 nm) and their band gap is finely tuned from 2.8 eV to 2.1 eV by increasing the 9-fluorenone content. Interestingly, they also show charge transfer emissions (in 540 -580 nm range), assisted by the energy transfer from the other TPE segments (not involved in CT interaction) as evidenced from fluorescence lifetime decay analysis. By increasing the 9-fluorenone content the emission color of the polymer is also tuned from green to red. Photocatalytic activities of the donor-acceptor CMPs (F0.1CMP, F0.5CMP and F2.0CMP) are greatly enhanced compared to the 9-fluorenone free polymer (F0.0CMP) which is essentially due to improved visible light absorption and low band gap of donor-acceptor CMPs. Among all the polymers F0.5CMP with an optimum band gap (2.3 eV) shows highest H2 evolution under visible light irradiation. Moreover, all the polymers show excellent dispersibility in organic solvents and also they are easily processed onto solid substrates.
关键词： Visible-light absorption,Conjugated polymers,Photocatalysis,Charge transfer,Energy transfer
更新于2025-09-23 15:23:52
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Handling Electromagnetic Radiation beyond Terahertz using Chromophores to Transition from Visible Light to Petahertz Technology
摘要： An increase of the operating frequencies of electromagnetic waves leads from the well-established terahertz technology to the visual and reaches petahertz radiation. It is shown that electromagnetic radiation close to petahertz is attractive for technology where knowledge about radio waves can be applied. The dimensions of such radiation are still classically macroscopic; however, molecular components such as resonators were used where quantum mechanics rules have to be considered. Constructions of coupled resonators for energy transfer are as well demonstrated as molecular components for optical metamaterials.
关键词： Dyes,FRET,Energy transfer,Reflectance,Petahertz,Visible light,Resonators,Metamaterials,Terahertz,Electromagnetic radiation
更新于2025-09-23 15:23:52
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Quantumness in light harvesting is determined by vibrational dynamics
摘要： We demonstrate for the multi-level spin-boson (MLSB) Hamiltonian, typically used to describe biological light-harvesting, that the distinction between quantum and classical dynamics is determined entirely by the thermal environment. In particular, any MLSB model featuring classical interactions with a classical bath is exactly equivalent in its absorption and energy transfer dynamics to a classical model involving coupled harmonic oscillators. This result holds in the linear response regime for both pulsed and incoherent excitation. In the biological context, this finding highlights the centrality of vibrational dynamics in determining the 'quantumness' of photosynthetic light-harvesting, particularly in the creation of the photosynthetic energy funnel where excitation energy concentrates near the reaction center via a series of downhill energy transfer events. These findings support the idea that this energy funnel is exclusively quantum-mechanical in origin, although it need not rely on entanglement.
关键词： vibrational dynamics,energy transfer,photosynthesis,quantumness,light harvesting,spin-boson model
更新于2025-09-23 15:23:52
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Self-Luminescing Theranostic Nanoreactors with Intraparticle Relayed Energy Transfer for Tumor Microenvironment Activated Imaging and Photodynamic Therapy
摘要： The low tissue penetration depth of external excitation light severely hinders the sensitivity of fluorescence imaging (FL) and the efficacy of photodynamic therapy (PDT) in vivo; thus, rational theranostic platforms that overcome the light penetration depth limit are urgently needed. To overcome this crucial problem, we designed a self-luminescing nanosystem (denoted POCL) with near-infrared (NIR) light emission and singlet oxygen (1O2) generation abilities utilizing an intraparticle relayed resonance energy transfer strategy. Methods: Bis[3,4,6-trichloro-2-(pentyloxycarbonyl) phenyl] oxalate (CPPO) as a chemical energy source with high reactivity toward H2O2, poly[(9,9’-dioctyl-2,7-divinylene-?uorenylene)-alt-2-methoxy-5-(2-ethyl-hexyloxy)-1,4-phenylene] (PFPV) as a highly efficient chemiluminescence converter, and tetraphenylporphyrin (TPP) as a photosensitizer with NIR emission and 1O2 generation abilities were coencapsulated by self-assembly with poly(ethyleneglycol)-co-poly(caprolactone) (PEG-PCL) and folate-PEG-cholesterol to form the POCL nanoreactor, with folate as the targeting group. A series of in vitro and in vivo analyses, including physical and chemical characterizations, tumor targeting ability, tumor microenvironment activated imaging and photodynamic therapy, as well as biosafety, were systematically investigated to characterize the POCL. Results: The POCL displayed excellent NIR luminescence and 1O2 generation abilities in response to H2O2. Therefore, it could serve as a speci?c H2O2 probe to identify tumors through chemiluminescence imaging and as a chemiluminescence-driven PDT agent for inducing tumor cell apoptosis to inhibit tumor growth due to the abnormal overproduction of H2O2 in the tumor microenvironment. Moreover, the folate ligand on the POCL surface can further improve the accumulation at the tumor site via a receptor-mediated mechanism, thus enhancing tumor imaging and the therapeutic effects both in vitro and in vivo but without any observable systemic toxicity. Conclusion: The nanosystem reported here might serve as a targeted, smart, precise, and noninvasive strategy triggered by the tumor microenvironment rather than by an outside light source for cancer NIR imaging and PDT treatment without limitations on penetration depth.
关键词： chemiluminescent imaging,H2O2,self-luminescing theranostic nanoreactors,intraparticle relayed energy transfer,PDT
更新于2025-09-23 15:23:52
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Self-electrochemiluminescence of poly[9,9-bis(3‘-(N,N- dimethyl amino)propyl)-2,7-fluorene]-alt- 2,7-(9,9- dioctylfluorene)] and resonance energy transfer to aluminum tris(8-quinolinolate)
摘要： In this paper, the electrochemiluminescence (ECL) behavior of a hole-transport polymer, poly [9,9-bis(3'-(N,N-dimethylamino) propyl)-2,7-fluorene]-alt-2,7-(9,9-dioctylfluorene)] (PFN) was examined with the purpose of finding a novel organic ECL emitter. It was found that the PFN exhibits self-electrochemiluminescence (self-ECL) without any exogenous co-reactants. Quite different from the traditional ECL, the addition of tripropyl amine (TPA) quenched the self-ECL of PFN. PFN ECL intensity reaches a peak during electrochemical oxidation process due to the superposition of self-enhanced ECL, and aggregation quenching of excited state by PFN excimer formation. Aluminum tris(8-quinolinolate) (AlQ3) doped with PFN recovers luminescence intensity with restraining quenching effect via ECL resonance energy transfer from PFN to AlQ3, giving rise to a stable luminescence signal, and hence sensory detection of nitroaromatics. The limits of detections for nitroaromatics can reach down to a level of 10^-22 M. This work sets the stage for a novel organic polymer-based ECL emitter without using any toxic exogenous co-reactant, and presents a practical avenue for a prototype of realising sensory detection through signal stabilization via energy resonance energy transfer (ERET).
关键词： poly[9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene]-alt-2,7-(9,9-dioctylfluorene),Sensor,Resonance energy transfer,Self-electrochemiluminescence
更新于2025-09-23 15:23:52
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Influence of the intramolecular donor-acceptor distance on the performance of double-cable polymers
摘要： A series of double-cable polymers PFT-C4-PDI, PFT-C6-PDI and PFT-C8-PDI, composed of the poly(fluorene-alt-thiophene) (PFT) backbone, the perylene diimide (PDI) pendants and the length-various (four-, six- and eight-carbon) covalent alkoxy linkers, were presented. The backbone polymer chain created the hole-transporting channel and the inner-chain aggregation of PDI units created the electron-transporting channel, but the aggregation became weaker along with the longer linker, as proven by the UV-Vis absorption and fluorescence quenching. The polymers were non-conducting, but functioned as efficient compatibilizers. The doping of the polymers induced the formation of the bi-continuous networks inside P3HT:PCBM blends, facilitated photo-generated exciton dissociation and charge transporting. PFT-C4-PDI more efficiently increased the absorption coefficient and the charge-carrier mobility of the P3HT:PCBM film. The power conversation efficiency (PCE) of the P3HT:PCBM bulk-heterojunction solar cells with 3 wt% PFT-C4-PDI, PFT-C6-PDI and PFT-C8-PDI doping were improved by 16.9%, 9.2% and 8.0%, respectively, relative to the non-doped reference device.
关键词： Structure-property relationships,Energy transfer,Double-cable polymer,Polymer solar cells,Bi-continuous networks
更新于2025-09-23 15:23:52
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A New Biscarbazole-Based Metal-Organic Framework for Efficient Host-Guest Energy Transfer
摘要： A new metal–organic framework (MOF), [Zn6L4(Me2NH2+)4·3 H2O] (1) was constructed based on [9,9’-biscarbazole]-3,3’,6,6’-tetracarboxylic acid (H4L) and Zn2+ ions. The porous framework and intense blue fluorescence of the MOF based on the biscarbazole moiety of the ligand could facilitate efficient host to guest energy transfer, which makes it an ideal platform for the tuning of luminescence.
关键词： in situ encapsulation,metal–organic frameworks,energy transfer,host–guest systems,fluorescence
更新于2025-09-23 15:23:52
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Tunable photoluminescence properties and energy transfer of Ca5(BO3)3F: Tb3+/Eu3+ phosphors for solid state lighting
摘要： A series of Ca5(BO3)3F: Tb3+/Eu3+ phosphors have been prepared via solid-state reaction. Phase purity and crystal structure of as-prepared samples are confirmed by X-ray diffraction measurements. The emission intensity of Ca5(BO3)3F: Tb3+ with Li+, Na+, K+ as charge compensators are remarkably enhanced, and the sample in presence of Na+ exhibits the strongest emission intensity. The emission spectra and fluorescence decays confirm the presence of efficient energy transfers from Tb3+ to Eu3+ in Ca5(BO3)3F: Tb3+/Eu3+ phosphors. The energy transfer mechanism between Tb3+ and Eu3+ has been proven to be resonant type via the electric dipole-dipole interaction. The thermal quenching temperature T50 obtained from the temperature-dependent emission spectra is 478 K, demonstrating a high thermal stability of the as-obtained Ca5(BO3)3F: Tb3+/Eu3+ phosphors. Moreover, by increasing the molar ratio of Eu3+ to Tb3+, the emission colors of Ca5(BO3)3F: Tb3+/Eu3+ phosphors can be tuned from green to orange, and then to red. These results demonstrate that the as-obtained Ca5(BO3)3F: Tb3+/Eu3+ phosphors may have potential applications in solid-state lighting fields.
关键词： Energy transfer,Ca5(BO3)3F,Phosphors,Tunable luminescence,Solid-state reaction
更新于2025-09-23 15:23:52