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Fabrication and electroluminescence of sheet-like ZnO/Si light-emitting diodes by radio frequency magnetron sputtering method
摘要： Sheet-like ZnO/Si light emitting diodes (LEDs) have been fabricated through depositing nanoscale ZnO on the p-type single crystal silicon by using a radio frequency (RF) magnetron sputtering method. From XRD patterns, the (100), (002) and (101) diffraction peaks can be observed. Through increasing the sputtering time, however, the intensity of (100) and (101) diffraction peaks has gradually decreased and the intensity of (002) diffraction peak has gradually enhanced. With decreasing the sputtering powers, the fabricated ZnO films have been observed to show better (002)-orientation growth. Electroluminescence (EL) from ZnO/Si LEDs have been decomposed into three emission bands, i.e., UV, green and orange emissions, which origin from the band gap, zinc interstitial or vacancies oxygen and shallow level, respectively. Under the lower sputtering power, orange emission is disappeared. It is indicated that the structures and EL properties are sensitive to the fabrication conditions. It is important to optimize and tune the fabrication conditions for purposeful applications in the future works.
关键词： ZnO/Si LED,Crystal growth,Electroluminescence,Orientation growth,Luminescence
更新于2025-09-16 10:30:52
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Fast extraction of front ribbon resistance of silicon photovoltaic modules using electroluminescence imaging
摘要： A fast and non-destructive method based on electroluminescence (EL) imaging is presented to extract the front side resistive loss for individual cells within a crystalline silicon photovoltaic module. As the local luminescence intensity of a solar cell is an exponential function of local voltage, the voltage distribution along individual ribbons within the solar cell can be extracted. The front side resistance can then be computed using the distributive nature of current flow along the ribbon. As the soldering ribbons are much more conductive than the cell busbars, and due to the contact resistance between the cell busbars and soldering ribbons, the extracted front-side resistance describes mainly the front ribbon resistance. The method requires only two EL measurements on finished modules, which makes cell-to-module resistive loss analysis simple and fast. The proposed method is then compared with the measured and predicted voltage difference along the ribbon for individual solar cells. Simulation results are also presented and compared with our proposed method.
关键词： Front-side ribbon resistance,c-Si PV modules,Voltage distribution,Electroluminescence
更新于2025-09-16 10:30:52
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Synthesis and properties of hyperbranched polymers for white polymer light-emitting diodes
摘要： In this work, a series of hyperbranched copolymers with fluorene-alt-carbazole as the branches, three-dimensional-structured spiro[3.3]heptane-2,6-dispirofluorene (SDF) as the core, and iridium 1-(4-bromophenyl)-isoquinoline (acetylacetone) (Ir(Brpiq)2acac) as the dimming group were synthesized by one-pot Suzuki polycondensation for white emission. All copolymers show great thermal stabilities and high hole-transporting ability due to the introduction of the carbazole unit. The hyperbranched structures for copolymers can suppress the interchain interactions efficiently, and help to form amorphous films. The fabricated polymer light-emitting devices (PLEDs) based on the above synthesized copolymers realize good white light emission, and achieve high electroluminescence (EL) performance. For example, for the optimized PLED, the maximum luminance and current efficiency reach 6210 cd m?2 and 6.30 cd A?1, respectively, indicating the synthesized hyperbranched copolymers have potential application in solution-processable white polymer light-emitting diodes.
关键词： hyperbranched copolymers,electroluminescence,white emission,Suzuki polycondensation,polymer light-emitting devices
更新于2025-09-16 10:30:52
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Pyrenylpyridines: Sky-Blue Emitters for Organic Light-Emitting Diodes
摘要： A novel sky-blue-emitting tripyrenylpyridine derivative, 2,4,6-tri(1-pyrenyl)-pyridine (2,4,6-TPP), has been synthesized using a Suzuki coupling reaction and compared with three previously reported isomeric dipyrenylpyridine (DPP) analogues (2,4-di(1-pyrenyl)pyridine (2,4-DPP), 2,6-di(1-pyrenyl)pyridine (2,6-DPP), and 3,5-di(1-pyrenyl)-pyridine (3,5-DPP)). As revealed by single-crystal X-ray analysis and computational simulations, all compounds possess highly twisted conformations in the solid state with interpyrene torsional angles of 42.3°?57.2°. These solid-state conformations and packing variations of pyrenylpyridines could be correlated to observed variations in physical characteristics such as photo/thermal stability and spectral properties, but showed only marginal influence on electrochemical properties. The novel derivative, 2,4,6-TPP, exhibited the lowest degree of crystallinity as revealed by powder X-ray diffraction analysis and formed amorphous thin films as verified using grazing-incidence wide-angle X-ray scattering. This compound also showed high thermal/photo stability relative to its disubstituted analogues (DPPs). Thus, a nondoped organic light-emitting diode (OLED) prototype was fabricated using 2,4,6-TPP as the emissive layer, which displayed a sky-blue electroluminescence with Commission Internationale de L’Eclairage (CIE) coordinates of (0.18, 0.34). This OLED prototype achieved a maximum external quantum efficiency of 6.0 ± 1.2% at 5 V. The relatively high efficiency for this simple-architecture device reflects a good balance of electron and hole transporting ability of 2,4,6-TPP along with efficient exciton formation in this material and indicates its promise as an emitting material for design of blue OLED devices.
关键词： Suzuki coupling reaction,tripyrenylpyridine derivative,OLED,electroluminescence,dipyrenylpyridine,sky-blue-emitting
更新于2025-09-16 10:30:52
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Model for electroluminescence in single-walled carbon nanotube field effect transistor under transverse magnetic field
摘要： Electroluminescence spectrum and radiative recombination rate of short channel single-walled carbon nanotube field effect transistor in presence of transverse magnetic field is calculated by using non-equilibrium Green’s function method. Significant enhancement in radiative recombination rate and red shift in electroluminescence spectrum are observed with increase in the strength of magnetic field. The band gap suppression estimated from energy position resolved local density of states calculation plays a dominant role in transport mechanism under the influence of external magnetic field. The tuning of electroluminescence spectrum of single-walled carbon nanotube by transverse magnetic field can be employed as nanoscale optical source in next generation optoelectronic and photonic devices.
关键词： electroluminescence,single-walled carbon nanotube,optoelectronics,radiative recombination rate,plasmonics,field effect transistor
更新于2025-09-16 10:30:52
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GAN-Based Augmentation for Improving CNN Performance of Classification of Defective Photovoltaic Module Cells in Electroluminescence Images
摘要： Electroluminescence (EL) imaging is an effective way for the examining of photovoltaic (PV) modules. Compared with manual analysis, using Convolutional Neural Network (CNN) for classification is much more convenient but it requires a certain amount of annotated training samples which cannot be acquired handily. In this paper, we present a method for augmenting the existing dataset of EL images using Generative Adversarial Networks (GANS) and propose a model called AC-PG GAN aiming at this. Three chosen CNN models are used to examine the effectiveness of the proposed GAN model and have achieved an improvement of the classification accuracy with the augmented dataset after some adjustment and the maximum improvement is up to 14%.
关键词： Data Augmentation,Electroluminescence,Photovoltaic Modules,GAN,CNN
更新于2025-09-16 10:30:52
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Photo- and electroluminescence features of films and field effect transistors based on inorganic perovskite nanocrystals embedded in a polymer matrix
摘要： The optical and electrical properties of films and field-effect transistors (FETs) based on pure MEH-PPV, neat CsPbBr3 nanocrystals (NCs), and MEH-PPV:CsPbBr3 NCs composites with different contents of CsPbBr3 NCs are investigated. The films were characterized by absorbance, atomic-force microscope and current-voltage characteristics (I-Vs) techniques. Relative PL and EL intensities and PL spectra of the pure MEH-PPV, neat CsPbBr3 NCs and MEH-PPV:CsPbBr3 NCs films were measured at 300 K at various levels of optical and electrical excitation power; these dependencies of the PL and EL intensities turned out to be sublinear and superlinear respectively. FETs based on MEH-PPV:CsPbBr3 NCs (1:1) films exhibit I-Vs at 290 – 100 K a dominant hole transport mechanism. The mobility of charge carriers was determined at 290 K for neat CsPbBr3 NCs (for electrons: 2.7 10-2 cm2/Vs) and MEH-PPV:CsPbBr3 NCs (1:1) (for holes: 9 cm2/Vs). The temperature dependence of the hole mobility μFET(T) of FETs based on MEH-PPV:CsPbBr3 NCs (1:1) films characteristic of the hopping mode. It was found that the superlinearity of the dependence of EL of MEH-PPV:CsPbBr3 NCs LE-FETs at 290 K increases with increasing concentration of CsPbBr3 NCs due to efficient energy transfer between CsPbBr3 NCs and the MEH-PPV polymer matrix, and also because of the probability of electron tunneling through the potential barrier to electrode. It is expected that the obtained MEH-PPV:CsPbBr3 NCs nanocomposite films will be useful for efficient applications in nanotechnology LEDs, FETs and LE-FETs.
关键词： Energy transfer,Field-effect transistors,Semiconducting polymers,Photo- and electroluminescence,Charge carrier mobility,Inorganic perovskite nanocrystals
更新于2025-09-16 10:30:52
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Efficient perovskite solar cells through suppressed non-radiative charge carrier recombination by processing additive
摘要： It was reported that non-radiative charge carrier recombination in hybrid perovskite materials restricted device performance of perovskite solar cells. In this study, we report efficient perovskite solar cells through suppressed non-radiative charge carrier recombination by processing additive, aminopropanoic acid. It is found that aminopropanoic acid not only modulate the crystal growth processes, but also minimize defects of CH3NH3PbI3 thin films. Moreover, the CH3NH3PbI3 thin films processed with addition of aminopropanoic acid exhibit both enhanced photoluminescence and electroluminescence, elongated charge carrier lifetime, indicating that non-radiative charge carrier recombination within CH3NH3PbI3 thin films is drastically suppressed. As a result, perovskite solar cells fabricated by CH3NH3PbI3 thin films processed with addition of aminopropanoic acid exhibit approximatively 15% enhanced efficiency as compared with that by pristine CH3NH3PbI3 thin film. All these results demonstrate that our finding provides a facial way to improve efficiency of perovskite solar cells.
关键词： open-circuit voltage loss,perovskite solar cells,photoluminescence,electroluminescence,non-radiative charge carrier recombination
更新于2025-09-16 10:30:52
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Recent advances in circularly polarized electroluminescence based on organic light-emitting diodes
摘要： Since the first attempt that was made to obtain direct circularly polarized (CP) light from OLEDs by Meijer et al. in 1997, considerable efforts have been devoted to the development of circularly polarized organic light-emitting diodes (CP-OLEDs), particularly in the recent years. Circularly polarized electroluminescence (CPEL) based on OLEDs has attracted increasing interest for its efficient ability to generate CP light directly and wide potential applications in 3D displays, optical data storage, and optical spintronics. In this review, we systematically summarize the recent progress in chiral emitter based OLEDs with CPEL properties including CPEL based on chiral conjugated polymers, CPEL based on chiral metal complexes, and CPEL based on chiral simple organic molecules, especially chiral thermally activated delayed fluorescence (TADF) molecules. We believe that this review will provide a promising perspective of chiral emitter based OLEDs with CPEL properties for a broad range of scientists in different disciplinary areas and attract a growing number of researchers to this fast-growing research field.
关键词： chiral simple organic molecules,circularly polarized electroluminescence,thermally activated delayed fluorescence,chiral conjugated polymers,organic light-emitting diodes,chiral metal complexes
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