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Microwave-assisted synthesis of FexZn1?xO nanoparticles for use in MEH-PPV nanocomposites and their application in polymer light-emitting diodes
摘要： A one-step microwave-assisted polyol method was used to fabricate FexZn1?xO (x = 0.01, 0.05, 0.10) nanoparticles. Zinc acetate dihydrate, iron (III) acetylacetonate, oleic acid and diethylene glycol were placed in a Teflon-lined reaction vessel. The reaction mixture was heated up to 250 °C for 15 min in a microwave reactor. The surface modification with oleic acid prevented agglomeration of the nanoparticles. The X-ray diffraction analysis revealed characteristics wurtzite hexagonal structure of ZnO and successful incorporation of the Fe dopant into the host crystal lattice. Doping of ZnO by Fe led to bandgap modification as estimated by Tauc plot. The as-prepared nanopowders were dispersed in toluene and mixed with a poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) polymer to make stable homogenous dispersions. Then, the FexZn1?xO/MEH-PPV nanocomposite thin films were prepared by spin coating and used as thin active layers in polymer light-emitting diodes. The thickness of deposited FexZn1?xO/MEH-PPV film was ca. 30 nm and that of reference neat MEH-PPV film was ca. 25 nm. The electroluminescent spectroscopy study showed that direct blending of MEH-PPV with Fe-doped ZnO nanoparticles is a simple and effective approach to significantly increase the luminance intensity of the diode in comparison to the diode fabricated by neat MEH-PPV.
关键词： Polymer light-emitting diodes,FexZn1?xO nanoparticles,Microwave-assisted synthesis,MEH-PPV nanocomposites
更新于2025-10-22 19:40:53
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Green and Stable Processing of Organic Light-Emitting Diodes from Aqueous Nanodispersion
摘要： An imminent show-stopper for up-scaled production of printed thin-film electronics are the flammable and environmentally hazardous solvents used to dissolve the organic semiconductors. Especially in the case of wide-web large-area coating the development of toxic and flammable vapour during coating and drying poses serious health and safety risks. Processing the active materials from aqueous nanodispersion therefore offers a highly attractive alternative. In contrast to thin-film organic photovoltaics (OPV), nanoparticle-based organic light-emitting diodes (OLEDs) have so far received only little attention. The very high electrical field (~0.1 GV/m) poses rather “unforgiving” requirements regarding the topology, integrity and chemistry of the active layer, seemingly difficult to achieve using aqueous nanodispersions. In this work we show that it can be done. We present polymer light-emitting diodes (PLEDs) with active layers processed from nanodispersion. Through thorough optimization of the particle preparation and casting procedures, we obtain smooth, dense and intergral light-emitting nanoparticle films compatible with stable PLED operation. The performance of the nanoparticle PLEDs is on par with that of solution-cast reference devices. The devices exhibit low leakage current and turn-on voltage, no sign of degradation through voltage cycling, no current hysteresis and similar efficiencies.
关键词： organic light-emitting diodes,aqueous nanodispersion,green processing,nanoparticle films,polymer light-emitting diodes
更新于2025-09-23 15:21:01
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[IEEE 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Bengaluru, India (2018.12.17-2018.12.19)] 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Development of New Blue-Light Emitting PPV Block Copolymer: Synthesis, Characterization and Electro-Optical Studies
摘要： New soluble intense blue light emitting bulky ring substituted segmented PPV block copolymer was synthesized by synthesized condensation polymerization. Rigid cyclohexyl methoxy group substituted distyrylbenzene unit was the chromophore group present in the synthesized segmented block copolymer. The obtained copolymer was dissolved in all common organic solvents. The structure of the copolymer was characterized by using FT-IR, NMR techniques, and elemental analysis. GPC analysis shows that the copolymer has narrow polydispersity index. Thermal gravimetric analysis shows it has excellent thermal stability with maximum decomposition temperature obtained as 4220C. The HOMO and LUMO values of copolymer were estimated from the cyclic voltammograms. Photoluminescence studies show that copolymer gives blue emission. XRD and DSC studies give information about the semi-crystalline nature of the present copolymer. Overall results such as thermal properties, photoluminescence characteristics and low onset voltage from Voltage vs. Current data are confirmed the suitability of the copolymer for fabricating PLEDs.
关键词： polymer light emitting diodes,light emitting polymers,segmented block copolymer
更新于2025-09-23 15:21:01
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Improving the out-coupling efficiency of polymer light-emitting diodes with soft nanoimprinted random corrugated structures
摘要： A simple method is demonstrated in this study by applying random corrugated structures into the polymer emitting layer via soft nanoimprint technology to enhance the light out-coupling efficiency of polymer light-emitting diodes (PLEDs). The device with the random corrugated structures presents high efficiency and stable emission close to the Lambertian pattern. Compared with the flat device, about 52% efficiency enhancement is achieved in the PLEDs with the random corrugated structures, which can be understood by extraction of waveguide mode and surface plasmon polariton mode losses simultaneously. With these advantages, the simple random corrugated structures have the potential to stimulate the development of low-cost and large-area flexible PLEDs with high efficiency in the applications of solid-state light sources and full-color displays.
关键词： surface plasmon polariton mode,soft nanoimprint,light out-coupling efficiency,random corrugated structures,polymer light-emitting diodes,waveguide mode
更新于2025-09-23 15:21:01
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Conducting Polymers || Electrical Properties of Polymer Light-Emitting Devices
摘要： In this chapter, we present a brief introduction to semiconducting properties of conjugated polymers and the motivation to apply this class of materials in electronic/optoelectronic devices such as polymer light-emitting diodes (PLEDs). We describe, in detail, the operating mechanisms of PLEDs, with particular focus on the effects of charge injection and transport and their dependence on the external electric field and temperature. The mechanisms of current injection from the electrodes into the organic semiconductor are initially treated using traditional models for thermionic emission and tunnelling injection. More recent models considering the influence of metal/semiconductor interface recombination and of energetic and spatial disorder in the injection currents are also introduced and discussed. In addition, models considering space-charge-limited currents and trap-filling-limited currents are employed to describe the charge transport characteristics in the bulk. Furthermore, we present a brief discussion on ideas concerning the effects of the disorder on the charge-carrier transport behaviour.
关键词： space-charge-limited currents,conjugated polymers,polymer light-emitting diodes,organic semiconductors,electrical properties
更新于2025-09-19 17:15:36
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Solution-processed, top-emitting, microcavity polymer light-emitting diodes for the pure red, green, blue and near white emission
摘要： Top-emitting microcavity polymer light-emitting diodes (TMPLEDs) are of great significance for active matrix PLED displays with high color purity. However, the complex device structures of high efficiency microcavity organic light-emitting diodes fabricated by the full vapor deposition technology are not suitable to the solution processed PLEDs. The solution-processed TMPLEDs with simple device structures are promising candidates as the large-area, mass production display techniques. In this work, three strategies were used to apply microcavity into PLEDs: (1) double Ag electrodes performed as the mirrors of cavity, instead of multi-layer Bragg reflector, which simplified the device structure and fabrication process; (2) three solution processed functional layers were specially designed for avoiding the inter-infiltration between the different solution and improve the interface contacts; (3) high order microcavities were utilized according to the optical simulation results, in which thick EMLs benefited to thickness control and reproductivity. As results, the full-color emission including pure red, green, blue was realized, and quasi-white light was also achieved from single polymer emitting material. The achievement of color purity always sacrifices part of current efficiency (CE) due to the spectra narrowing, while the higher CE of green TMPLED (10.08 cd/A) than that of non-cavity PLED (∽8.60 cd/A) cast lights on the future improvement.
关键词： Top-emitting,Interface Engineering,Color Tuning,Polymer Light-Emitting Diodes,Solution-processed,Microcavity
更新于2025-09-16 10:30:52
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Pyrene-based hyperbranched porous polymers with doped Ir(piq)2(acac) red emitter for highly efficient white polymer light-emitting diodes
摘要： Here, we designed and prepared a series of hyperbranched porous polymers constructed using fluorene branches and pyrene core, and all hyperbranched porous polymers exhibit intense blue fluorescence, good morphological stability, and high thermal stability. Further, it is found that the aperture sizes for hyperbranched porous polymers can be adjusted by simply changing the content of pyrene and fluorene in the synthesis process. When the feed ratios of pyrene in the total polymers is 15 mol%, the optimized aperture size was obtained, which is slightly larger than the maxlength of complementary red emitter Bis(1-phenylisoquinoline)(acetylacetonate) iridium (III) (Ir(piq)2acac), indicating the Ir(piq)2acac can well distributed in the apertures of hyperbranched porous polymers in co-doped film of Ir(piq)2acac and hyperbranched porous polymers. The fabricated polymer-light-emitting diode (PLED) with such co-doped film as light-emitting layer realizes good white emission with almost equal blue and red emission intensity from hyperbranched porous polymers and Ir(piq)2acac. The balanced electroluminescent (EL) spectra contribute to ideal Commission Internationale de l’Eclairage (CIE) coordinate of (0.326, 0.374) located at white light zone. In addition, the device also achieves high device performance with maximum luminance and current efficiency reaching 5369 cd/m2 and 8.35 cd/A, respectively. We believe that such porous-structure polymers have huge potential applications in the development of highly efficient white PLEDs with reducing production cost.
关键词： White light,Electroluminescence spectra,Polymer light-emitting diodes,Hyperbranched porous polymers
更新于2025-09-16 10:30:52
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Flexible ITO-free sky-blue polymer light-emitting diodes and printed polymer solar cells based on AgNW/PI transparent conductive electrode
摘要： In this work, transparent and conductive as well as flexible silver nanowire/polyimide (AgNW/PI) composite film with an average figure of merit as high as 111.3, which is the ratio of electronic conductivity to optical conductivity, is produced by a simple peel-off method without any post treatments. When employing the AgNW/PI composite film as the flexible transparent conductive anode in blue polymer light-emitting diodes (PLEDs), the device shows a high external quantum efficiency of 3.42% which is comparable to the rigid ITO-based control device with an efficiency of 3.96%. Moreover, for the flexible printed polymer solar cell (PSCs) with AgNW/PI as the transparent conductive anode, a high power conversion efficiency of 4.01% is achieved, which is also comparable to that of the rigid ITO-based PSC. This work systematically demonstrates that AgNW/PI composite film has a promising prospect for application in all kinds of flexible optoelectronic devices, such as light-emitting diodes, solar cells, flat panel displays, and so on.
关键词： Printing,ITO-free,Flexible Ag nanowire/polyimide,Polymer solar cells,Polymer light-emitting diodes
更新于2025-09-12 10:27:22
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Polymer light emitting diodes (PLEDs): An update review on current innovation and performance of material properties
摘要： Conventional lighting systems, such as the incandescent light bulbs used on the offshore oil rigs are becoming obsolete due to high energy consumption, poor life span and additional costs of waste treatment and disposal. Furthermore, they are susceptible to fire when exposed to an oxygen rich environment, posing a threat to the oil rig workers. Recent advances have led to the development of polymer light emitting diodes (PLEDs) as substitutes to these prevailing light sources. The PLEDs have advantages over the incandescent bulbs, for being durable, low energy consumption and environmental friendly. Consequently, the increasing research collaborations among the academic researchers and industrial stakeholders are gaining momentum in ensuring the advancements of PLEDs in terms of economic value and performance. This paper is aimed at reviewing the recent advances in the field of current innovation and performance of PLEDs materials. The paper focuses on the important experiments on the PLEDs materials towards the upgrading and modification of anode and holes injection/transporting layer and the influence of doping effect. In spite of that, this paper discovered that synthetic materials, such as synthetic silicates are the commonly used materials in the current PLEDs, and recommends the incorporation of cost effective inorganic clay-polymer nanocomposite-based LEDs as a way forward to reducing the material costs and provide more environmental friendly PLEDs materials.
关键词： doping,insertion,Polymer light emitting diodes,intercalation,materials
更新于2025-09-12 10:27:22
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Influence of the Silver Nanocrystal Shape on the Luminous Efficiency of Blue-Emitting Polymer Light-Emitting Diodes
摘要： Truncated silver nanodecahedrons (TAgNDs) and truncated silver nanoplates (TAgNPs) fabricated via chemical reduction and photochemical methods were added to poly[3,4-ethylenedioxythiophene]:poly[styrenesulfonate] (PEDOT:PSS) as a dopant to promote the luminous efficiency of blue-emitting polymer light-emitting diodes (PLEDs). The differences in shape between TAgNDs and TAgNPs result in better dispersion of TAgNDs in PEDOT:PSS. Therefore, at an optimal doping concentration (the distributed density in the light-emitting region is 6.88 μg cm?2 for TAgNDs and 5.16 μg cm?2 for TAgNPs), the average current efficacy and maximum electroluminescence intensity enhancement factor for TAgNDs-doped PLED were 4.18 cd A?1 and 420% respectively, which are much higher than those for TAgNPs-doped PLED (1.83 cd A?1 and 200%) at a luminescence wavelength of 440 nm.
关键词： truncated silver nanoplates,blue-emitting polymer light-emitting diodes,luminous efficiency,truncated silver nanodecahedrons
更新于2025-09-11 14:15:04