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Ionic occupation sites, luminescent spectra, energy transfer behaviors in Y3MgAl3SiO12: Ce3+, Mn2+ phosphors for warm white LED
摘要： The Ce3t and Mn2t doped Y3MgAl3SiO12 (YMAS) phosphors were synthesized by the high-temperature solid-state reaction in 5%H2–95%N2 reduced atmosphere. Rietveld refinement of X-ray diffraction data indicated that co-doped YMAS phosphors had a garnet type cubic structure with the Ia3d space group. Ce3t occupies the lattice sites of Y3t. Mn2t occupies both lattice sites of MgO6 octahedron and AlO4 tetrahedron, emitting optical lights centered at 613 nm (Mn2t (I)) and 723 nm (Mn2t (II)), respectively. The orange-yellow light with the range of 450 nm–750nm was obtained by the energy transfer of Ce3t(cid:0) Mn2t with a maximum value of 69.2% of energy transfer efficiency. The integrated warm white LED produced white light with CRI of 85.4, CCT of 4502 K, and a CIE color coordinate (0.3542, 0.3269). It indicated that the phosphor might be suitable for blue light-excited white LEDs.
关键词： Phosphor,Y3MgAl3SiO12,White LED,Energy transfer,Garnet
更新于2025-09-16 10:30:52
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Fluorescence resonance energy transfer effect enhanced high performance of Si quantum Dots/CsPbBr3 inverse opal heterostructure perovskite solar cells
摘要： CsPbBr3 based perovskite solar cells draw boosted investigation benefitting from their simplified preparation property and outstanding stability against moist and heat while the photo-electrical conversion efficiency (PCE) is still worth promotion. In addition, relatively wide band gap limits the light utilization ability of pristine CsPbBr3 which leads to insufficient photo-induced charge carrier population thereby a low photocurrent density. Herein, we for the first time demonstrate a strategy to combine crystalized Si quantum dots (QDs) with CsPbBr3 inverse opal (IO) which significantly enhances the solar energy utilization efficiency by virtue of providing an additional fluorescence resonance energy transfer (FRET) process from Si QDs to CsPbBr3 IO. Acting as donor, the emitted photoluminescence from Si QDs can be absorbed by CsPbBr3, which serves as acceptor, leading to an increased carrier population in the system. Meanwhile, the multi-dimensional heterojunction between Si QDs and CsPbBr3 IO effectively facilitates the system bulk charge transfer process. A greatly improved PCE up to 8.31% with an obviously enhanced photocurrent density up to 7.8 mA?cm?2 can be obtained with a competitive IPCE up to 81%. This strategy provides a new alternative method to develop high-performance perovskite solar cells and other photo-electronic devices.
关键词： Perovskite solar cells,CsPbBr3,Heterostructure,Fluorescence resonance energy transfer
更新于2025-09-16 10:30:52
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Design and Synthesis of a Well-Controlled Mechanoluminescent Polymer System Based on Fluorescence Resonance Energy Transfer with Spiropyran as a Force-Activated Acceptor and Nitrobenzoxadiazole as a Fluorescent Donor
摘要： Colorimetric mechanophores, which change color through force-induced covalent bond breakage, have been incorporated into polymer chains to create mechanochromic materials. However, the color change of most mechanophores is a turn-on response. In this work, we designed and synthesized a novel mechanoluminescent polymer system, PBA-SP-P(MMA-co-NBD), based on fluorescence resonance energy transfer (FRET) with spiropyran (SP) as a force-activated "on/off" mechanophore acceptor and nitrobenzoxadiazole (NBD) as a fluorescent donor. It is a comb polymer having NBD-bearing poly(methyl methacrylate) (PMMA) side chains grafted onto a poly(butyl acrylate) (PBA) backbone through SP groups. The processed polymer yields a morphology having NBD-containing PMMA nanodomains embedded into a PBA matrix with SP at the interface. The distance between NBD and SP functionalities is less than 10 nm with confinement of the nanophase separation, which effectively facilitates their fluorescence resonance energy transfer. Under uniaxial stretch, the materials change color at strains as low as about 18% and undergo a green-to-red fluorescence color switch. The two colors are ratiometric, exhibiting a linear correlation with strain after the onset of mechanoactivation. The color change is greatly enhanced right after failure. The fluorescence emission performance can be well controlled through regulating the PMMA/PBA and SP/NBD ratios in the synthesis. The synthesized polymer system exhibits a good potential as an indicator in monitoring microscale cut damages.
关键词： mechanochromic materials,nitrobenzoxadiazole,spiropyran,fluorescence resonance energy transfer,mechanoluminescent polymer
更新于2025-09-16 10:30:52
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Corea??shell polymeric nanoparticles co-loaded with photosensitizer and organic dye for photodynamic therapy guided by fluorescence imaging in near and short-wave infrared spectral regions
摘要： Background: Biodistribution of photosensitizer (PS) in photodynamic therapy (PDT) can be assessed by fluorescence imaging that visualizes the accumulation of PS in malignant tissue prior to PDT. At the same time, excitation of the PS during an assessment of its biodistribution results in premature photobleaching and can cause toxicity to healthy tissues. Combination of PS with a separate fluorescent moiety, which can be excited apart from PS activation, provides a possibility for fluorescence imaging (FI) guided delivery of PS to cancer site, followed by PDT.
关键词： Polymeric nanoparticles,Poly-N-isopropylacrylamide,Electronic excitation energy transfer,Photodynamic therapy,Short wave infrared fluorescence bioimaging
更新于2025-09-16 10:30:52
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Nanococktail Based on AIEgens and Semiconducting Polymers: A Single Laser Excited Image-Guided Dual Photothermal Therapy
摘要： Semiconducting polymers (SPs)-based dual photothermal therapy (PTT) obtained better therapeutic effect than single PTT due to its higher photothermal conversion efficiency. However, most dual PTT need to use two lasers for heat generation, which brings about inconvenience and limitation to the experimental operations. Herein, we report the development of “nanococktail” nanomaterials (DTPR) with 808 nm-activated image-guided dual photothermal properties for optimized cancer therapy. Methods: In this work, we co-encapsulated AIEgens (TPA-BDTO, T) and SPs (PDPPP, P) by using maleimide terminated amphiphilic polymer (DSPE-PEG2000-Mal, D), then further conjugated the targeting ligands (RGD, R) through “click” reaction. Finally, such dual PTT nanococktail (termed as DTPR) was constructed. Results: Once DTPR upon irradiation with 808 nm laser, near-infrared fluorescence from T could be partially converted into thermal energy through fluorescence resonance energy transfer (FRET) between T and P, coupling with the original heat energy generated by the photothermal agent P itself, thus resulting in image-guided dual PTT. The photothermal conversion efficiency of DTPR reached 60.3% (dual PTT), much higher as compared to its inherent photothermal effect of only 31.5% (single PTT), which was further proved by the more severe photothermal ablation in vitro and in vivo upon 808 nm laser irradiation. Conclusion: Such smart “nanococktail” nanomaterials could be recognized as a promising photothermal nanotheranostics for image-guided cancer treatment.
关键词： semiconducting polymers,aggregation-induced emission fluorogens,fluorescence resonance energy transfer,A single laser,dual photothermal therapy
更新于2025-09-16 10:30:52
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Hybrid CdSe/CsPbI <sub/>3</sub> quantum dots for interface engineering in perovskite solar cells
摘要： Hybrid CdSe/CsPbI3 quantum dots (QDs) are selected for incorporation between the perovskite film and the hole transport layer (HTL). Owing to the high absorption coefficient and the suitable band gap of CsPbI3, an optimized energy level structure can be expected. Besides, energy transfer could be realized due to the overlap between the emission spectrum of CdSe QDs and the excitation spectrum of CsPbI3 QDs. Hence, CdSe/CsPbI3 QDs can serve as an interface layer to promote interfacial charge extraction and enhance light harvesting ability simultaneously. Compared with pristine perovskite solar cells (PSCs), hybrid CdSe/CsPbI3 QD incorporated PSCs achieve 21% enhancement in power conversion efficiency (PCE). The enhancement of PCE can be ascribed to the ultrafast charge carrier dynamics and F?rster resonance energy transfer (FRET) effect. The design of hybrid CdSe/CsPbI3 QDs offers an alternative method for interfacial engineering to enhance optical properties and facilitate the charge transport process in PSCs.
关键词： interface engineering,charge transport,perovskite solar cells,Hybrid CdSe/CsPbI3 quantum dots,F?rster resonance energy transfer
更新于2025-09-16 10:30:52
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F?rster Resonance Energy Transfer between Colloidal CuInS2/ZnS Quantum Dots and Dark Quenchers
摘要： F?rster resonance energy transfer (FRET) using colloidal semiconductor quantum dots (QDs) and dyes is of importance in a wide range of biological and biophysical studies. Here, we report a study on FRET between CuInS2/ZnS QDs and dark quencher dye molecules (IRDye QC-1). Oleate-capped QDs with photoluminescence quantum yields (PLQYs) of 55±4% are transferred into water by using two types of multifunctional polymer ligands combining imidazole groups and specific moieties with amine or methoxy groups as the terminal sites. The resulting water-dispersible QDs show PLQYs as high as 44±4% and exhibit long-term colloidal stability (at least 10 months at 4 °C in the dark) with a hydrodynamic diameter of less than 20 nm. A side-by-side comparison experiment was performed using the amine or methoxy-functionalized QDs for coupling to dark quencher dye molecules. The amine-functionalized QDs bind to the dye molecules via covalent bonds while methoxy-functionalized ones bind only weakly and non-specifically. The progressive quenching of the QD emission and shortening of its photoluminescence decay time upon increasing the number of conjugated dye molecules demonstrate that the QD acts as the energy donor and the dark quencher dye as the energy acceptor in a donor-acceptor FRET pair. The FRET dynamics of the QD-dye conjugates are simulated using two different models based on the possible origin of the multiexponential PL decay of the QDs (i.e., variations in nonradiative or radiative decay rates). The model based on the radiative decay rates provides a better fit of our experimental data and estimates a donor–acceptor distance (6.5 nm) that matches well the hydrodynamic radius of the amine-functionalized QDs.
关键词： dark quencher dye molecules,energy acceptor,multifunctional polymer ligands,CuInS2/ZnS,F?rster resonance energy transfer,colloidal semiconductor quantum dots,energy donor,photoluminescence quantum yields
更新于2025-09-12 10:27:22
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Enhanced Energy Transfer in Doped Bifluorene Single Crystals: Prospects for Organic Lasers
摘要： Organic single crystals with long-range molecular order ensure enhanced carrier mobility and stability as well as emission outcoupling, which makes them attractive as gain medium for electrically pumped organic lasers. Unfortunately, effects of excitonic coupling introduce losses degrading optical performance in crystals, hence higher lasing thresholds are observed compared to amorphous films. Here, crystal doping strategy is investigated as a method to avoid pronounced reabsorption and annihilation losses associated with J-type excitonic coupling, while taking advantage of enhanced exciton transport for efficient energy transfer. Bifluorene-based derivatives linked with acetylene and ethylene rigid bridges are suitable as host and dopant system forming high-quality crystals doped at various concentrations (0.5–11.0%). Enhanced exciton transport in host crystal mediates picosecond host–dopant energy transfer enabling 100% transfer efficiency at lower doping concentrations compared to amorphous films. Amplified spontaneous emission threshold of 1.9 μJ cm?2 in 3.5% doped crystal is enabled by minimized exciton annihilation and emission reabsorption losses at optimal doping concentration.
关键词： long-range energy transport,organic single crystals,organic laser gain materials,amplified spontaneous emission,F?rster resonant energy transfer
更新于2025-09-12 10:27:22
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Effect of energy transfer on the optical properties of surface-passivated perovskite films with CdSe/ZnS quantum dots
摘要： Surface passivation is an effective method to protect the surfaces and improve the luminescence properties of perovskite (PS) films. CdSe/ZnS core-shell quantum dots (QDs) have been employed for surface passivation of PS films because of their size-dependent tunable bandgaps. Herein, the energy transfer (ET) behavior of CH3NH3PbI2Br PS films covered with CdSe/ZnS QDs (QD/PS hybrid structures) is characterized by using photoluminescence (PL) and time-resolved PL spectroscopy. The PL decay time and the integrated PL intensity of the QD/PS hybrid structure increase compared with those of the bare PS films, owing to ET from the QDs to the PS and reduced charge traps. The ET efficiency increases from ~7% to 63% for the QD/PS hybrid structure when the core diameter of the QDs decreases from 6.5 to 2.7 nm, respectively. This can be explained by the charge transfer rate enhancement due to the control of energy level alignment of QDs. These results allow us to understand fundamental mechanisms such as ET from QDs to PS films as a function of the size of the QD.
关键词： CdSe/ZnS quantum dots,perovskite films,energy transfer,photoluminescence,surface passivation
更新于2025-09-12 10:27:22
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All-solution processed inverted QLEDs with double hole transport layers and thermal activated delay fluorescent dopant as energy transfer medium
摘要： Highly efficient, all-solution processed inverted quantum dot light-emitting diodes (QLEDs) with high performance are demonstrated by employing poly(9-vinlycarbazole) (PVK) as additional hole transport layer (HTL) and doping it with a blue thermal activated delay fluorescent (TADF) material, 4,5-bis(carbazol-9-yl)-1,2-dicyanobenzene (2CzPN). This PVK: 2CzPN composite layer not only optimizes hole injection, but also utilizes the leaked electrons to enhance device luminance by energy transfer process from 2CzPN to quantum dots (QDs). These benefits enable a 20-fold increment for the device current efficiency (from 0.523 cd/A to 11 cd/A) and a 9.9-fold improvement for the maximum luminance (from 3220 cd/m2 to 35352 cd/m2), compared with those of the standard QLED with poly[(9, 9-dioctylfluorenyl-2,7-diyl)-alt-(4,4'-(N-(4-butylphenyl) (TFB) single HTL. In comparison with the QLED with TFB/pristine PVK double HTLs, the device performance of the optimal QLED with PVK: 2CzPN additional HTL are still 40.8% and 61.7% higher in luminance and current efficiency, respectively.
关键词： Thermally activated delayed fluorescence,Quantum dot light-emitting diode,All-solution process,Energy transfer,Double hole transport layers,Inverted structure
更新于2025-09-12 10:27:22