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Flexible organic light-emitting diodes for antimicrobial photodynamic therapy
摘要： Bacterial infection and the growth of antibiotic resistance is a serious problem that leads to patient suffering, death and increased costs of healthcare. To address this problem, we propose using flexible organic light-emitting diodes (OLEDs) as light sources for photodynamic therapy (PDT) to kill bacteria. PDT involves the use of light and a photosensitizer to generate reactive oxygen species that kill neighbouring cells. We have developed flexible top-emitting OLEDs with the ability to tune the emission peak from 669 to 737 nm to match the photosensitizer, together with high irradiance, low driving voltage, long operational lifetime and adequate shelf-life. These features enable OLEDs to be the ideal candidate for ambulatory PDT light sources. A detailed study of OLED–PDT for killing Staphylococcus aureus was performed. The results show that our OLEDs in combination with the photosensitizer methylene blue, can kill more than 99% of bacteria. This indicates a huge potential for using OLEDs to treat bacterial infections.
关键词： Photodynamic therapy,Flexible organic light-emitting diodes,Staphylococcus aureus,Antimicrobial,Methylene blue
更新于2025-09-12 10:27:22
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Deep Red Iridium(III) Complexes Based on Pyrene-Substituted Quinoxaline Ligands for Solution-Processed Phosphorescent Organic Light-Emitting Diodes
摘要： In this paper, we systemically investigated the photoelectric properties of three new deep-red quinoxaline-based iridium(III) complexes: Ir-0, Ir-1, and Ir-2. (MPQ)2Ir(dpm) (Ir-0) bore a 2-methyl-3-phenyl-quinoxaline cyclometalated ligand, while (c-PyMPQ)2Ir(dpm) (Ir-1) and (t-PyMPQ)2Ir(dpm) (Ir-2) possessed a 1-pyrene substituent that connected at the 6/7 position of the corresponding ligands. The configurations of the latter two complexes were well-confirmed by single-crystal X-ray diffraction, and both of them had large dihedral angles between the quinoxaline and pyrene units, preventing the emission peaks of the three complexes from being altered too much. Based on the density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations, we concluded that the emission of all complexes originated predominantly from the triplet metal-to-ligand/intraligand charge transfer (3MLCT/3ILCT) state of the non-pyrene-substituted counterpart Ir-0 core. Interestingly, we also obtained another type of pyrene-stacking characteristic crystal of Ir-1, which had an emission resembled the phosphorescence observed in thin film. The easily formed pyrene-stacking configuration would most probably limit their device performance at a higher concentration. Moreover, the fabricated organic light-emitting diodes (OLEDs) using these materials achieved considerable device performance at a low doping concentration of 0.5 wt %. This work provides an approach for reasonably designing large fused-ring-substituted quinoxaline ligands of iridium complexes.
关键词： Pyrene-Substituted Quinoxaline Ligands,Deep Red Iridium(III) Complexes,Solution-Processed Phosphorescent Organic Light-Emitting Diodes
更新于2025-09-12 10:27:22
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Luminescent and Structural Properties of Electron-Irradiated Silicon Light-Emitting Diodes with Dislocation-Related Luminescence
摘要： Electroluminescence (EL) from light-emitting diodes (LEDs) at wavelengths in the range 1000-1650 nm, current densities of up to 10 A/cm2, and temperature of 64 K has been studied. p-Cz-Si wafers were irradiated with low-energy electrons (a variant of the technique based on rapid thermal annealing) and annealed in a chlorine-containing atmosphere at 1100°C. To obtain p-n junctions and ohmic contacts, layers of polycrystalline silicon doped with phosphorus and boron were deposited by vapour-phase epitaxy onto the opposite sides of the wafers. The dislocation structure in the samples under study consists of gliding 60?- dislocations and perfect and faulted dipoles. An analysis showed that the transformation of EL spectra with current is precisely described by six Gaussian lines. The peak wavelengths are current-independent and equal to 1235, 1309, 1369, 1414, 1472, and 1515 nm. The current dependences of the intensity of the EL lines have been determined.
关键词： dislocation-related luminescence,electron microscopy,silicon light-emitting diodes,extended and point defects
更新于2025-09-12 10:27:22
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J-aggregation Enhances the Electroluminescence Performance of Sky-blue TADF Emitter in Non-doped OLEDs
摘要： A pivotal thermally activated delayed fluorescence (TADF) emitter DspiroAc-TRZ was developed, and it exhibits greatly enhanced electroluminescence performance in non-doped organic light-emitting diodes (OLEDs) owing to the concurrent manipulation of aggregation behavior and monomolecular structure. The delicate non-planar packing pattern in DspiroAc-TRZ crystal can not only lead to highly efficient solid-state luminescence, but also form loose intermolecular packing pattern, greatly decreasing the HOMOs or LUMOs overlaps in dimers and shortening triplet exciton diffusion length. In addition, the rigid donor and acceptor moieties in DspiroAc-TRZ can rigidify the molecular backbone, resulting in tiny geometry vibrational relaxation in excited state. Impressively, high photoluminescent quantum yields (PLQYs) of 78.5% and 83.7% were achieved for DspiroAc-TRZ single-crystal and non-doped film. A high external quantum efficiency (EQE) of 25.7% was achieved in non-doped sky-blue TADF-OLED, which is higher than any reported EQE values of non-doped sky-blue TADF-OLEDs so far.
关键词： molecular orientation,non-doped,thermally activated delayed fluorescence,organic electronics,organic light-emitting diodes
更新于2025-09-12 10:27:22
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High transmittance Er-doped ZnO thin films as electrodes for organic light-emitting diodes
摘要： Rare earth element-Erbium (Er) doped ZnO (ErZO) thin films were deposited on glass substrates by pulsed laser deposition (PLD). The effect of the Er doping concentration on photoelectric properties of ErZO thin films was investigated in the range of 0–2.0 wt. %. The Er doping resulted in the improvement of n-type conductivity as compared with intrinsic ZnO thin films. The optimized ErZO thin films present the low resistivity of 3.4 (cid:2) 10(cid:3)4 X/cm, high carrier concentration of 5.9 (cid:2) 1020/cm3, and high visible optical transmittance ((cid:4)93%) when the Er content is 1.0 wt. %. The ErZO thin films were used as transparent anodes to fabricate organic light-emitting diodes (OLEDs). Impressively, with ErZO as the anode, the current efficiency of the OLED device can reach as high as 86.5 cd/A, which was increased by 14% when compared with the reference OLED device (76.0 cd/A) using indium tin oxide as the anode.
关键词： Er-doped ZnO,transparent conducting oxides,pulsed laser deposition,thin films,organic light-emitting diodes
更新于2025-09-12 10:27:22
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[IEEE 2019 IEEE 12th International Symposium on Diagnostics for Electrical Machines, Power Electronics and Drives (SDEMPED) - Toulouse, France (2019.8.27-2019.8.30)] 2019 IEEE 12th International Symposium on Diagnostics for Electrical Machines, Power Electronics and Drives (SDEMPED) - Parametric degradation model of OLED using Design of Experiments (DoE)
摘要： This article presents an original parametric degradation model using Design of Experiments. This method is based on the estimation of a Weibull function under accelerated conditions. It is applied on cold white organic light emitting diodes OLEDs from Philips with a 10000 hrs theoretical lifetime. Accelerated degradation using thermal and electrical stress is tested. The predicted degrading model is a function of time, temperature, current density and their interaction. It illustrates the behaviour of the degradation of the OLED using multiple stress factors without really knowing the physics of these degradations. The proposed model is tested on experimental data for different luminances. The average error of the predicted model compared to real values is around 3 %. The proposed model is then compared to a previously developed lifespan model. The results obtained with the present approach are closer to the real values.
关键词： Degradation,Electrical stresses,Modeling,Thermal stresses,Design for Experiments,Accelerated aging,Organic light emitting diodes,Weibull distribution,Lifetime estimation
更新于2025-09-12 10:27:22
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Control of carrier injection and transport in quantum dot light emitting diodes (QLEDs) via modulating Schottky injection barrier and carrier mobility
摘要： Carrier injection and transport in the quantum dot (QD) layer was modulated by tuning the Schottky injection barrier and mobility of charge transport layers. The analyses indicate that stages of the J-V curve for hole injection must match with those of electron injection to achieve the charge balance in the QD layer. In addition, it was demonstrated that not only the parameters investigated but also other parameters such as charge trap density and energy levels must be considered to enhance the e?ciency of the QLEDs. With the improved charge balance in the QD layer, the current e?ciency of the quantum dot light-emitting diode display was improved from 26 to 40 cd/A.
关键词： Schottky injection barrier,light emitting diodes,quantum dot,charge balance,carrier mobility
更新于2025-09-12 10:27:22
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Wireless phototherapeutic contact lenses and glasses with red light-emitting diodes
摘要： Light-mediated therapeutics have attracted considerable attention as a method for the treatment of ophthalmologic diseases, such as age-related macular degeneration, because of their non-invasiveness and the effectiveness to ameliorate the oxidative stress of retinal cells. However, the current phototherapeutic devices are opaque, bulky, and tethered forms, so they are not feasible for use in continuous treatment during the patient’s daily life. Herein, we report wireless, wearable phototherapeutic devices with red light-emitting diodes for continuous treatments. Red light-emitting diodes were formed to be conformal to three-dimensional surfaces of glasses and contact lenses. Furthermore, fabricated light-emitting diodes had either transparency or a miniaturized size so that the user’s view is not obstructed. Also, these devices were operated wirelessly with control of the light intensity. In addition, in-vitro and in-vivo tests using human retinal epithelial cells and a live rabbit demonstrated the effectiveness and reliable operation as phototherapeutic devices.
关键词： wearable healthcare,phototherapies,red light-emitting diodes,transparent electronics
更新于2025-09-12 10:27:22
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Ultraefficient Green LEDs Using Quantum Dots in Liquid Matrix
摘要： Green spectral range, which has the highest human eye sensitivity, is one of the most fundamental colors in lighting and display. Quantum dots (QDs) offer exceptional optical properties including high quantum yield (QY), strong absorption, and narrow emission linewidths for efficient green-emitting diodes. In this article, we demonstrated QD-based light-emitting diodes (QD-LEDs) that operate at a luminous efficiency (LE) level of 95 lumens per electrical watt, the luminous efficacy of optical radiation of 409 lumens per optical watt, and external quantum efficiency (EQE) of 23.3% in the green spectral region. For that, we synthesized 1-octanethiol-capped CdSe/ZnS QDs with an absolute QY of 91% and integrated them in a liquid matrix that allows conservation of the QD efficiency in device architecture. Our simulations were in agreement with the performance of the fabricated QD-LEDs, and they showed that the QD-LEDs can be further improved to reach LE levels over 250 lm/W.
关键词： light-emitting diodes (LEDs),luminous efficiency (LE),liquid-state integration,quantum dots (QDs),External quantum efficiency (EQE)
更新于2025-09-12 10:27:22
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Modulation of F?rster and Dexter Interactions in Single‐Emissive‐Layer All‐Fluorescent WOLEDs for Improved Efficiency and Extended Lifetime
摘要： White organic light-emitting diodes (WOLEDs) with thermally activated delayed fluorophor sensitized fluorescence (TSF) have aroused wide attention, considering their potential for full exciton utilization without noble-metal containing phosphors. However, performances of TSF-WOLEDs with a single-emissive-layer (SEL) still suffer from low exciton utilization and insufficient blue emission for proper white balance. Here, by modulating F?rster and Dexter interactions in SEL-TSF-WOLEDs, high efficiencies, balanced white spectra, and extended lifetimes are realized simultaneously. Given the different dependencies of F?rster and Dexter interactions on intermolecular distances, sterically shielded blue thermally activated delayed fluorescence (TADF) emitters and orange conventional fluorescent dopants (CFDs) with electronically inert peripheral units are adopted to enlarge distances of electronically active chromophores, not only blocking the Dexter interaction to prevent exciton loss but also finely suppressing the F?rster one to guarantee balanced white emission with sufficient blue components. It thus provides the possibility to maximize device performances in a large range of CFD concentrations. A record high maximum external quantum efficiency/power efficiency of 19.6%/52.2 lm W?1, Commission Internationale de L’Eclairage coordinate of (0.33, 0.45), and prolonged half-lifetime of over 2300 h at an initial luminance of 1000 cd m?2 are realized simultaneously for SEL-TSF-WOLEDs, paving the way toward practical applications.
关键词： sensitizing process,thermally activated delayed fluorescence,exciton interactions,white organic light-emitting diodes,sterically inert substituents
更新于2025-09-12 10:27:22