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High-brightness Perovskite Light-emitting Diodes Using a Printable Silver Micro-flake Contact
摘要： Achieving efficient devices while maintaining a high fabrication yield is a key challenge in the fabrication of solution-processed, perovskite-based light-emitting diodes (PeLEDs). In this respect, pinholes in the solution-processed perovskite layers are a major obstacle. These are usually mitigated using organic electron-conducting planarization layers. However, these organic interlayers are unstable under applied bias in air, and suffer from limited charge-carrier mobility. In this work, we present a high brightness p-i-n PeLED based on a novel blade-coated silver micro-flake (SMF) rear electrode, which allows for a low-cost and high performance nanocrystalline ZnO inorganic electron transporting layer to be used. This novel SMF contact is crucial for achieving high performance as it prevents the electrical shorting suffered when standard thermally evaporated silver rear contacts are used. The fabricated PeLEDs exhibit an excellent maximum luminance of 98000 cd/m2, a maximum current efficiency of 22.3 cd/A, and high external quantum efficiency of 4.6% under 5.9 V forward bias. The SMF rear contact can be printed and scaled at low cost to large areas and applied to flexible devices.
关键词： leakage current,light emitting diodes,nanocrystalline ZnO,silver micro-flakes,perovskite materials
更新于2025-09-19 17:13:59
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20.1: <i>Invited Paper:</i> Monolithic Full‐color Quantum Dot Nanoring Micro LEDs with Improved Efficiency
摘要： BiMeO3 (where Me denotes a transition metal) is often used as a chemical modifier to form the Bi0.5Na0.5TiO3‐based solid solutions and to improve the electromechanical properties of the materials. In this study, BiMnO3 was selected as a chemical modifier, and (1 ? x)(0.94Bi0.5Na0.5TiO3‐0.06BaTiO3)–xBiMnO3 thin films with x = 0, 0.005, 0.01, and 0.015 were fabricated using the metal organic decomposition method to study the contributions of the third end‐member BiMnO3 to the reduction in the leakage current and the enhancement of the piezoelectric properties of Bi0.5Na0.5TiO3‐BaTiO3 thin films. Thin films with 1 mol% BiMnO3 exhibit a lower leakage current, and a better piezoelectricity and ferroelectricity, whose Smax/Emax, Pmax, 2Ec, and εr are 100.4 pm/V, 48.0 μC/cm2, 54.9 kV/cm, and 942, respectively.
关键词： metal organic decomposition,piezoelectricity,BNT–BKT–BMO thin films,leakage current
更新于2025-09-19 17:13:59
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Improving Output Power of InGaN Laser Diode Using Asymmetric In0.15Ga0.85N/In0.02Ga0.98N Multiple Quantum Wells
摘要： Herein, the optical ?eld distribution and electrical property improvements of the InGaN laser diode with an emission wavelength around 416 nm are theoretically investigated by adjusting the relative thickness of the ?rst or last barrier layer in the three In0.15Ga0.85N/In0.02Ga0.98N quantum wells, which is achieved with the simulation program Crosslight. It was found that the thickness of the ?rst or last InGaN barrier has strong e?ects on the threshold currents and output powers of the laser diodes. The optimal thickness of the ?rst quantum barrier layer (FQB) and last quantum barrier layer (LQB) were found to be 225 nm and 300 nm, respectively. The thickness of LQB layer predominantly a?ects the output power compared to that of the FQB layer, and the highest output power achieved 3.87 times that of the reference structure (symmetric quantum well), which is attributed to reduced optical absorption loss as well as the reduced vertical electron leakage current leaking from the quantum wells to the p-type region. Our result proves that an appropriate LQB layer thickness is advantageous for achieving low threshold current and high output power lasers.
关键词： asymmetric multiple quantum wells,optical absorption loss,InGaN laser diodes,barrier thickness,electron leakage current
更新于2025-09-16 10:30:52
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Pixel Circuit With Leakage Prevention Scheme for Low-Frame-Rate AMOLED Displays
摘要： This work proposes a new pixel circuit for active-matrix organic light-emitting (AMOLED) smartwatch displays with a low frame rate. Within the long emission period, the leakage current of a low-temperature polycrystalline silicon thin-film transistor (LTPS TFT) is reduced to suppress the distortion of the driving voltage at the gate node of the driving TFT. Based on the measured electrical characteristics of a fabricated p-type LTPS TFT, the HSPICE model is established to verify the feasibility of the proposed circuit. The analytical results indicate that the relative OLED current error rates are all below 4.73%, as the threshold voltage of TFT varies by ±0.5 V. Notably, the OLED current varies by only 2.94% during the emission period of 66.7 ms at a medium gray level, demonstrating the effectiveness of the leakage prevention scheme.
关键词： low-temperature polycrystalline silicon thin-film transistors (LTPS TFTs),Active-matrix organic light-emitting diode (AMOLED),leakage current prevention
更新于2025-09-16 10:30:52
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Integrated step-up non-isolated inverter with leakage current elimination for grid-tied photovoltaic system
摘要： This study presents a non-isolated step-up inverter without leakage current for low-voltage renewable energy generation such as photovoltaic (PV) cells grid connection. From the structure of the proposed inverter, the negative terminal of the PV array is directly linked with the grid neutral, so the common mode voltage of the parasitic capacitance can be kept constant and the leakage current will not be generated in theory. Moreover, this transformerless inverter can produce an AC output voltage higher than the input DC voltage, which will reduce the sizes of the generation system. A switching modulation strategy carrier-based is analysed in detail when the input inductor current is operated in discontinuous conduction mode. The operation modes of the proposed inverter are also discussed, respectively, in positive and negative half line cycles. Finally, a digital experimental prototype is tested in the laboratory, and the experimental results are consistent with the theoretical analysis.
关键词： leakage current elimination,non-isolated inverter,transformerless inverter,step-up inverter,grid-tied photovoltaic system
更新于2025-09-16 10:30:52
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Influence of active layer thickness on photovoltaic performance of PTB7:PC70BM bulk heterojunction solar cell
摘要： In this paper, we studied the effect of active layer thickness on the photovoltaic performance of inverted bulk heterojunction (BHJ) organic solar cell (OSC). The capacitance-voltage (C–V), dark current-voltage (I–V) and impedance spectroscopy (IS) analysis were carried out to explain the active layer thickness dependence on the photovoltaic performance. The OSC with an active layer thickness of 150 nm achieved the best power conversion efficiency (PCE) of 5.87%, while the OSC of 200 nm active layer thickness yielded the worst PCE. Reduction in the fill factor (FF) was the main reason for the reduction in the PCE at large active layer thickness. The dark I–V analysis revealed large defect density for the OSC with active layer thickness of 200 nm, which raised the charge recombination and leakage current and consequently reduced the FF. IS analysis predicted that the charge transport became the serious limitations for the OSC with 200 nm thick active layer, which can be attributed to the weakening of electric field as well as creation of field-free regions. It mainly caused a drastic drop in the fill factor by reducing the charge collection efficiency, consequently deteriorated the photovoltaic performance.
关键词： Charge recombination,Bulk heterojunction solar cell,Ideality factor,Photovoltaic performance,Charge transport resistance,Leakage current
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE PES Innovative Smart Grid Technologies Europe (ISGT-Europe) - Bucharest, Romania (2019.9.29-2019.10.2)] 2019 IEEE PES Innovative Smart Grid Technologies Europe (ISGT-Europe) - A New Transformerless Configuration for Grid-Connected Photovoltaic Inverters
摘要： Due to high efficiency, low cost and weight, inverters are widely used to deliver the transformerless photovoltaic (PV) energy to the grid. On the other hand, due to VDE standards, the leakage current between the stray capacitance of the PV array and the ground should be limited for the grid connected PV systems. In this case, some transformerless structures have been presented to restrict the leakage current. This paper presents a new transformerless structure for the PV inverters. The proposed structure keeps the common mode voltage constant in all switching periods and will suppress the leakage current. The performance of the proposed structure is verified by both mathematical and simulation (MATLAB/Simulink and PLECS Blockset) results.
关键词： Common mode (CM) voltage,Photovoltaic (PV),Leakage current,Transformerless inverter
更新于2025-09-12 10:27:22
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Aqueous-processed insulating polymer/nanocrystal solar cells with effective suppression of the leakage current and carrier recombination
摘要： As one of the most environmentally friendly photovoltaic (PV) conversion equipments, aqueous-processed CdTe nanocrystal solar cells (NC SCs) have attracted great interest in recent years because of their excellent properties such as high charge-carrier mobility and broad absorption. However, two issues including interfacial recombination and leakage current seriously restrict their performance. In this paper, insulating polymer poly(vinyl pyrrolidone) (PVP) is introduced into CdTe NC SCs to solve the problems. The experimental results of transmission electron microscopy (TEM), atomic force microscopy (AFM) and dark current measurements, etc., demonstrate the leakage current is effectively suppressed by introducing PVP. Through further designing device structure, the reduction of interfacial recombination after introducing PVP is confirmed. By strategically taking the advantages of PVP properties (e.g., water solubility and thermostability), the power conversion efficiency of the devices with PVP is enhanced by almost 37% compared to pure CdTe devices. This work demonstrates an effective and low-cost method to fabricate NC SCs via aqueous route. Moreover, it also proves that appropriate content of insulating polymer is of beneficial in promoting the PV performance.
关键词： Aqueous-processed,Polymer,Recombination,Leakage current,Nanocrystal
更新于2025-09-12 10:27:22
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Origin of Bypass Diode Fault in c-Si Photovoltaic Modules: Leakage Current under High Surrounding Temperature
摘要： Bypass diodes have been widely utilized in crystalline silicon (c-Si) photovoltaic (PV) modules to maximize the output of a PV module array under partially shaded conditions. A Schottky diode is used as the bypass diode in c-Si PV modules due to its low operating voltage. In this work, we systematically investigated the origin of bypass diode faults in c-Si PV modules operated outdoors. The temperature of the inner junction box where the bypass diode is installed increases as the ambient temperature increases. Its temperature rises to over 70 ?C on sunny days in summer. As the temperature of the junction box increases from 25 to 70 ?C, the leakage current increases up to 35 times under a reverse voltage of 15 V. As a result of the high leakage current of the bypass diode at high temperature, melt down of the junction barrier between the metal and semiconductor has been observed in damaged diodes collected from abnormally functioning PV modules. Thus, it is believed that the constant leakage current applied to the junction caused the melting of the junction, thereby resulting in a failure of both the bypass diode and the c-Si PV module.
关键词： diode junction melt,bypass diode of PV module,leakage current,temperature inside the junction box
更新于2025-09-12 10:27:22
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H-Bridge Zero-Voltage Switch Controlled Rectifier (HB-ZVSCR) Transformerless Mid-Point-Clamped Inverter for Photovoltaic Applications
摘要： A single-phase transformerless mid-point clamped H-bridge zero-voltage switch-controlled rectifier inverter topology is proposed in this paper for photovoltaic (PV) systems to address the issue of common mode (CM) voltage and leakage currents. Apart from the full H-bridge inverter, the proposed voltage clamping circuit consists of two switches and a full-bridge diode which clamps the AC terminal to the DC midpoint (consisting of two DC-link capacitors) during the freewheeling period. As a result, the common mode voltage is held constant which makes it suitable for the grid-connected PV system. The operating principle and CM effect of the proposed topology are analysed and compared with the conventional topologies. This is followed by the thermal analysis and loss calculation, which shows that the proposed circuit is more efficient over the conventional topologies. Validation is carried out using MATLAB-Simulink using the PLECS toolbox followed by a scale down prototype of 1.5 kW. It is shown that the proposed inverter has the 98±1% efficiency over a wide range of loads with a peak efficiency of 98.96%, and the total harmonic distortion of the output current relatively low (≤1.8 %). The leakage current (??????) is measured for different values of parasitic capacitance that reaches a maximum of 16.65 ???? for 330 ???? capacitor under consideration which is well below the limit set by different safety standards.
关键词： photovoltaic system,Common mode voltage (CMV),mid-point clamping,leakage current
更新于2025-09-12 10:27:22