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Note: Complementary approach for radiation dosimetry with Ag <sup>+</sup> -activated phosphate glass
摘要： Silver ion-activated phosphate glass (Ag+-glass) has a good potential for application to radiation dosimetry in various radiation fields due to its multifunctional properties as a detector. The Ag+-glass provides three independent signals of radiophotoluminescence, optical absorption, and nuclear track. The combination of these signals allows the dynamic range of the measured dose (10 μGy–10 kGy) and linear energy transfer (<10 keV/μm and >1 MeV/μm) to be widened.
关键词： optical absorption,radiophotoluminescence,Ag+-activated phosphate glass,radiation dosimetry,nuclear track
更新于2025-09-23 15:21:01
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Red-Emitting Thermally Activated Delayed Fluorescence Polymers with Poly(fluorene- <i>co</i> -3,3′-dimethyl diphenyl ether) as the Backbone
摘要： A series of red-emitting thermally activated delayed ?uorescence (TADF) polymers have been designed and synthesized based on poly(?uorene-co-3,3′-dimethyl diphenyl ether) (PFDMPE) as the backbone. Compared with poly?uorene (PF, 2.16 eV), the introduction of 3,3′-dimethyl diphenyl ether into the main chain of PFDMPE leads to the increased triplet energy of 2.58 eV, which is higher enough than the tethered red TADF guest (2.13 eV) to prevent the unwanted triplet energy back-transfer. Meanwhile, there is a good overlap between the absorption spectrum of the red guest and the photoluminescence (PL) spectrum of the polymeric host, ensuring the e?cient energy transfer from host to guest. Consequently, the resultant polymers PFDMPE-R01 to PFDMPE-R10 in solid states show obvious red TADF properties with delayed ?uorescence lifetimes of 126?191 μs and PL quantum yields of 0.18?0.55. Among them, PFDMPE-R05 obtains the best device performance, revealing a bright red electroluminescence peaked at 606 nm and a promising current e?ciency of 10.3 cd/A (EQE = 5.6%). The results compete well with those of red phosphorescent polymers and indicate that PFDMPE other than PF is a suitable polymeric host for the construction of e?cient red TADF polymers.
关键词： PFDMPE,electroluminescence,polymers,poly?uorene,triplet energy,PF,energy transfer,red-emitting,thermally activated delayed ?uorescence,poly(?uorene-co-3,3′-dimethyl diphenyl ether)
更新于2025-09-23 15:21:01
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Organic Upconversion Display with an over 100% Photon-to-photon Upconversion Efficiency and a Simple Pixelless Device Structure
摘要： Comparing to traditional near infrared (NIR) imaging devices, NIR-to-visible upconversion display which integrated a NIR photodetector with a visible light-emitting diode have merits of simple device structure, low cost, high resolution, and a simple pixelless structure. However, photon-to-photon upconversion efficiencies of these devices are typically much lower than unity. Here we report an all-organic NIR-to-visible upconversion display with a photon-to-photon upconversion efficiency higher than 100% by integrating a photomultiplying organic NIR photodetector with a high-efficiency thermally activated delayed fluorescent organic light-emitting-diode. To the best of our knowledge, this is the first report showing a photon-to-photon upconversion efficiency over 100% without using a built-in transistor for current amplification.
关键词： organic photodetector,NIR-to-visible upconversion,photon-to-photon efficiency,thermally activated delayed fluorescence,organic light-emitting diode
更新于2025-09-23 15:21:01
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High External Quantum Efficiency in Fluorescent OLED by Cascade Singlet Harvesting Mechanism
摘要： The cascade singlet harvesting (CSH) organic light-emitting diodes (OLEDs) are devised to resolve the low quantum efficiency issue of fluorescent OLEDs by efficient singlet exciton harvesting of the fluorescent emitters. The CSH mechanism is realized by doping a fluorescent emitter in the singlet exciton harvesting matrix consisted of high energy exciplex and low energy exciplex. The high energy exciplex serves as the main component of the emitting layer and the low energy exciplex is a medium harvesting the singlet excitons of the fluorescent emitter. Both exciplexes are thermally activated delayed fluorescence type exciplexes to effectively harvest singlet excitons by reverse intersystem crossing process. The singlet excitons of the low energy exciplex are harvested by the high energy exciplex through F?rster energy transfer and then the singlet excitons of the fluorescent emitter are harvested by the low energy exciplex through the second F?rster energy transfer process. The CSH mechanism maximizes the singlet exciton formation in the fluorescent emitter, which significantly enhances the external quantum efficiency (EQE) of the fluorescent OLEDs. The optimization of the emitting layer structure provides high EQE of 19.9% in the fluorescent OLEDs compared with 10.4% of a conventional singlet harvesting fluorescent OLED.
关键词： energy transfer,external quantum efficiency,fluorescent OLEDs,thermally activated delayed fluorescence,cascade singlet harvesting,exciplex
更新于2025-09-23 15:19:57
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Effects of post bonding annealing on GaAs//Si bonding interfaces and its application for sacrificial-layer-etching based multijunction solar cells
摘要： By using the sacrificial layer (SL) etching, GaAs substrates are separated from III–V epi substrate//Si substrate junctions that are made by surface activated bonding (SAB) technologies. The post-bonding low-temperature (300-?C) annealing plays an essential role in achieving a promising (～90%) bonding yield. The effects of the post-bonding annealing are investigated by hard X-ray photoemission spectroscopy and current–voltage measurements of GaAs//Si bonding interfaces. It is found that the concentration of oxygen atoms at interfaces is reduced and the resistance decreases to 1.6–2.1 m??cm2 by the low-temperature annealing. Aluminum fluoride complexes are not observed by X-ray photoelectron spectroscopy on the exposed surfaces of separated GaAs substrates. The roughness average of the surfaces is ≈0.25–0.30 nm. The characteristics of double junction cells fabricated on the GaAs//Si junctions prepared by the SL etching are almost the same as those of cells fabricated by dissolving GaAs substrates after bonding. These results indicate that multijunction cells could be fabricated in a process sequence compatible with reuse of GaAs substrates by combining the SL etching and SAB.
关键词： Sacrificial layer etching,GaAs//Si double junction cells,Surface activated bonding,Low temperature annealing,Epitaxial lift-off
更新于2025-09-23 15:19:57
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Light-Triggered Dual-Modality Drug Release of Self-Assembled Prodrug-Nanoparticles for Synergistic Photodynamic and Hypoxia-Activated Therapy
摘要： Photodynamic therapy (PDT) leads to tumor hypoxia which could be utilized for the activation of hypoxia-activated prodrugs (HAPs). However, conventional photosensitizer-loaded nanoformulations suffer from aggregation-caused quenching (ACQ) effect, which limits the efficiency of PDT and synergistic therapy. Herein, prodrug-nanoparticles (NPs) are prepared by the self-assembly of heterodimeric prodrugs composed of pyropheophorbide a (PPa), hypoxia-activated prodrug PR104A, and a thioether or thioketal linkage. In addition, a novel dual-modality drug release pattern is proposed on the basis of the structural states of prodrug-NPs. Under light irradiation, PR104A is released via photoinduced electron transfer (PET) due to the aggregating state of prodrugs. With the disassembly of prodrug-NPs, ACQ effect relieves, PPa produces singlet oxygen which further promotes the reactive oxygen species (ROS)-sensitive release of PR104A. Such prodrug-NPs turn the disadvantage of the ACQ effect to facilitate drug release, demonstrating high-efficiency synergy in combination with PDT and hypoxia-activated therapy.
关键词： aggregation-caused quenching,Photodynamic therapy,drug release,photoinduced electron transfer,hypoxia-activated prodrugs,reactive oxygen species
更新于2025-09-23 15:19:57
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Characteristics of Bubble Oscillations During Lasera??Activated Irrigation of Root Canals and Method of Improvement
摘要： Background and Objectives: Laser‐activated irrigation of dental root canals is being increasingly used as its efficacy has been shown to be superior compared with conventional techniques. The method is based on laser‐initiated localized fluid evaporation and subsequent rapid bubble expansions and collapses, inducing microfluid flow throughout the entire volume of the cavity. The irrigation efficacy can be further improved if optimally delayed “SWEEPS” double laser pulses are delivered into the canal. This study aims to show that the irrigation efficacy, as measured by the induced pressure within the canal, is related to the double pulse delay, with the maximal pressure generated at an optimal delay. The second aim is to find a method of determining the optimal delay for different cavity dimensions and/or laser parameters. Study Design/Materials and Methods: Experiments were made in transparent models of root canals where Er:YAG laser (λ = 2.94 μm, pulse duration tp = 25 or 50 microseconds, and pulse energies up to EL = 40 mJ) was used with a combination of cylindrical and conical fiber‐tip geometries (diameters 400 and 600 μm). High‐speed photography (60,000 fps) and average pressure measurements inside the canal were used for process characterization. Results: The results show that a pressure amplification of more than 1.5 times occurs if the laser pulse delay approximately coincides with the bubble oscillation time. Correlations between normalized oscillation time and canal diameter for a wide range of laser pulse energies (R2 = 0.96) and between the average pressure within the canal and the bubble oscillation periods (R2 = 0.90) were found. A relationship between the bubble oscillation time and the diameter of the treated cavity was found depending on the bubble oscillation time in an infinite fluid reservoir. Conclusions: The bubble oscillation time within a constrained volume can be determined based on the known oscillation time in infinite space, which offers a fast and simple solution for optimization of the laser parameters. These findings enable determination of optimal conditions for shock wave generation, and improvement of root canal irrigation at the same dose of laser energy input, leading to improved treatment efficacy and safety.
关键词： constrained environments,cavitation bubble,irrigation,Er:YAG laser,root canals,laser‐activated,laser‐induced cavitation
更新于2025-09-23 15:19:57
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Tert-butyl Substituted Hetero-donor TADF compounds for Efficient Solution-Processed Non-doped Blue OLEDs
摘要： For the development of solution-processed organic light-emitting diodes (OLEDs), it is highly desirable and challenging for releazing solution-processable non-doped thermally activated delayed fluorescence (TADF) emitters due to their high efficiency and excellent compatibility to the wet methods. Herein, two pairs of blue TADF isomers are designed and synthesized with a hetero-donor configuration for the realization of high photoluminescent quantum yield. The incorporation of two tert-butyl groups in the molecules can effectively increase the molecular solubility and reduce the aggregation-caused self-quenching of excitons in neat films by inhibiting the intramolecular vibrational relaxation and the intermolecular π-π stacking. Solution-processed non-doped OLEDs are achieved with these blue TADF emitters, exhibiting the record-high external quantum efficiencies (EQE) of 25.8%. Furthermore, all-TADF white OLED with an EQE of 27.3% is also achieved by employing a single emitting layer with the blue TADF emitter as a host for an orange-red TADF dopant.
关键词： non-doped OLED,blue fluoresecent materials,Organic light-emitting diodes,solution process,thermally activated delayed fluorescence
更新于2025-09-23 15:19:57
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Rotation-restricted thermally activated delayed fluorescence compounds for efficient solution-processed OLEDs with EQEs of up to 24.3% and small roll-off
摘要： Two triphenylamine or 4,4’-di(tert-butyl)triphenylamine groups are introduced at 1,8-positions of 3,6-di(tert-butyl)-9-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)carbazole to yield two emitters containing a cofacial donor-acceptor-donor chromophore, which exhibit strong TADF characteristic dominated by through-space charge-transfer. The solution-processed OLEDs achieve the maximum external quantum efficiencies of up to 17.4% and 24.3% with small efficiency roll-off rate.
关键词： Thermally Activated Delayed Fluorescence,solution-processed,efficiency roll-off,OLEDs
更新于2025-09-23 15:19:57
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Experimental study with analysis for a novel saturated activated alumina photovoltaic thermal system
摘要： This paper presents a novel photovoltaic thermal system based on water absorption-desorption phenomenon using activated alumina. Experimental work for a promising photovoltaic thermal system that utilise activated alumina tablets as heat absorbing and storing element is presented. Based on the experimental results, electrical, thermal and combined energy efficiencies were calculated and compared with the stand-alone PV panel efficiency. Three identical systems -containing 10 cm depth saturated activated alumina mixed with aluminium mesh cuts-were attached to the back surface of simulated solar panel. The three systems were tested at 600, 800 and 1000 W/m2 for 6 consecutive working hours, representing sun shining time. Results showed a net energy efficiency of 57% and 53.6% at 600 W/m2 and 1000 W/m2 respectively. The electrical efficiency increased by 10.4% and 6.7% at 600 W/m2 and 1000 W/m2, respectively, compared with the stand-alone panel. This led to an increase in total energy generation by 309% and 319.5% at 600 W/m2 and 1000 W/m2 respectively, compared with stand-alone solar panel.
关键词： Solar panels,PV/T,Activated alumina,Materials,Saturated,Cooling
更新于2025-09-23 15:19:57