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Achieving a high open-circuit voltage in inverted wide-bandgap perovskite solar cells with a graded perovskite homojunction
摘要： Wide-bandgap (~1.7-1.8 eV) perovskite solar cells have attracted substantial research interest in recent years due to their great potential to fabricate efficient tandem solar cells via combining with a lower bandgap (1.1-1.3 eV) absorber (e.g., Si, copper indium gallium diselenide, or low-bandgap perovskite). However, wide-bandgap perovskite solar cells usually suffer from large open circuit voltage (Voc) deficits caused by small grain sizes and photoinduced phase segregation. Here, we demonstrate that in addition to large grain sizes and passivated grain boundaries, controlling interface properties is critical for achieving high Voc’s in the inverted wide-bandgap perovskite solar cells. We adopt guanidinium bromide solution to tune the effective doping and electronic properties of the surface layer of perovskite thin films, leading to the formation of a graded perovskite homojunction. The enhanced electric field at the perovskite homojunction is revealed by Kelvin probe force microscopy measurements. This advance enables an increase in the Voc of the inverted perovskite solar cells from an initial 1.12 V to 1.24 V. With the optimization of the device fabrication process, the champion inverted wide-bandgap cell delivers a power conversion efficiency of 18.19% and sustains more than 72% of its initial efficiency after continuous illumination for 70 h without encapsulation. Additionally, a semitransparent device with an indium tin oxide back contact retains more than 88% of its initial efficiency after 100 h maximum power point tracking.
关键词： wide-bandgap perovskite solar cells,perovskite homojunction,guanidinium bromide
更新于2025-10-22 19:40:53
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An Improved Proposed Single Phase Transformerless Inverter with Leakage Current Elimination and Reactive Power Capability for PV Systems Application
摘要： Single-phase transformerless inverters are broadly studied in literature for residential-scale PV applications due to their great advantages in reducing system weight, cost and elevating system efficiency. The design of transformerless inverters is based on the galvanic isolation method to eliminate the generation of leakage current. Unfortunately, the use of the galvanic isolation method alone cannot achieve constant common mode voltage (CMV). Therefore, a complete elimination of leakage current cannot be achieved. In addition, modulation techniques of single-phase transformerless inverters are designed for the application of the unity power factor. Indeed, next-generation PV systems are required to support reactive power to enable connectivity to the utility grid. In this paper, a proposed single-phase transformerless inverter is modified with the clamping method to achieve constant CMV during all inverter operating modes. Furthermore, the modulation technique is modified by creating a new current path in the negative power region. As a result, a bidirectional current path is created in the negative power region to achieve reactive power generation. The simulation results show that the CMV is completely clamped at half the DC link voltage and the leakage current is almost completely eliminated. Furthermore, a reactive power generation is achieved with the modified modulation techniques. Additionally, the total harmonic distortion (THD) of the grid current with the conventional and a modified modulation technique is analyzed. The efficiency of the system is enhanced by using wide-bandgap (WBG) switching devices such as SiC MOSFET. It is observed that the efficiency of the system decreased with reactive power generation due to the bidirectional current path, which leads to increasing conduction losses.
关键词： leakage current,transformerless inverter,reactive power,wide-bandgap (WBG),silicon carbide (SiC),photovoltaic (PV) power system
更新于2025-09-23 15:23:52
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Regional Manufacturing Cost Structures and Supply Chain Considerations for SiC Power Electronics in Medium Voltage Motor Drives
摘要： With the growth in wide bandgap (WBG) semiconductors, specifically Silicon Carbide (SiC), the technology has matured enough to highlight a need to understand the drivers of manufacturing cost, regional manufacturing costs, and plant location decisions. Further, ongoing research and investment, necessitates analytical analysis to help inform development of wide bandgap technologies. The paper explores the anticipated device, module, and motor drive cost at volume manufacturing. It additionally outlines the current regional contributors to the supply chain and proposes how the base models can be used to evaluate the cost reduction potential of proposed research advances.
关键词： Wide bandgap,Supply chain,SiC,Wide-band gap,Wideband gap,Techno-economic,WBG,bottoms-up,Medium voltage,Motor drive,Wide band-gap,Analysis,Power electronics,Cost model
更新于2025-09-23 15:22:29
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Threshold switching and memory behaviors of epitaxially regrown GaN-on-GaN vertical p-n diodes with high temperature stability
摘要： This letter reports the observation of threshold switching and memory behaviors of epitaxially regrown GaN-on-GaN vertical p-n diodes. This mechanism was ascribed to the conductive path formed by traps in the insulating layer at the regrowth interface after soft breakdown. The device can reliably switch more than 1000 cycles at both room temperature and 300 oC with small fluctuation on the set and reset voltage. The set voltage increased with the increasing temperature due to the enhanced thermal detrapping effect that made it harder to form conductive path at high temperatures. Besides, the device showed memory behaviors when the reset voltage was higher than 4.4 V. This work can serve as important references to further developing GaN-based memory devices and integrated circuits.
关键词： memory,breakdown,wide bandgap semiconductor,threshold switching,p-n diodes,Gallium nitride
更新于2025-09-23 15:22:29
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Puzzling robust 2D metallic conductivity in undoped β-Ga2O3 thin films
摘要： Here, we report the analogy of an extremely stable topological-like ultra-wide bandgap insulator, a solid that is a pure insulator in its bulk but has a metallic conductive surface, presenting a two-dimensional conductive channel at its surface that challenges our current thinking about semiconductor conductivity engineering. Nominally undoped epitaxial b-Ga2O3 thin films without any detectable defect (after a range of state-of-the-art techniques) showed the unexpectedly low resistivity of 3 × 10^-2 Ωcm which was found to be also resistant to high dose proton irradiation (2 MeV, 5 × 10^15 cm^-2 dose) and was largely invariant (metallic) over the phenomenal temperature range of 2 K up to 850 K. The unique resilience and stability of the electrical properties under thermal and highly ionizing radiation stressing, combined with the extended transparency range (thanks to the ultra-wide bandgap) and the already known toughness under high electrical field could open up new perspectives for use as expanded spectral range transparent electrodes (e.g., for UV harvesting solar cells or UV LEDs/lasers) and robust Ohmic contacts for use in extreme environments/applications and for novel optoelectronic and power device concepts.
关键词： Electron accumulation,Wide bandgap insulator,Transport properties,Ga2O3
更新于2025-09-23 15:22:29
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GaN Integration Technology, an Ideal Candidate for High-Temperature Applications: A Review
摘要： In many leading industrial applications such as aerospace, military, automotive, and deep-well drilling, extreme temperature environment is the fundamental hindrance to the use of microelectronic devices. Developing an advanced technology with robust electrical and material properties dedicated for high-temperature environments represents a significant progress allowing to control and monitor the harsh environment regions. It may avoid using cooling structures while improving the reliability of the whole electronic systems. As a wide bandgap semiconductor, gallium nitride is considered as an ideal candidate for such environments, as well as in high-power and high-frequency applications. We review in this paper the main reasons that offer superiority to GaN devices over better-known technologies such as silicon (Si), silicon-on-insulator, gallium arsenide (GaAs), silicon germanium (SiGe), and silicon carbide (SiC). The theory of operation and main challenges at high temperature are discussed, notably those related to materials and contacts. In addition, the main limitations of GaN, including the technological (thermal and chemical) and intrinsic (current collapse and device self-heating) features are provided. In addition, the GaN devices recently developed for high-temperature applications are examined.
关键词： wide-bandgap semiconductors,high-temperature electronics,Extreme temperature applications,gallium-nitride technology
更新于2025-09-23 15:22:29
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Heteroepitaxial growth of thick <i>α</i> -Ga <sub/>2</sub> O <sub/>3</sub> film on sapphire (0001) by MIST-CVD technique
摘要： The 8 μm thick single-crystalline α-Ga2O3 epilayers have been heteroepitaxially grown on sapphire (0001) substrates via mist chemical vapor deposition technique. High resolution X-ray diffraction measurements show that the full-widths-at-half-maximum (FWHM) of rocking curves for the (0006) and (10-14) planes are 0.024° and 0.24°, and the corresponding densities of screw and edge dislocations are 2.24 × 106 and 1.63 × 109 cm?2, respectively, indicative of high single crystallinity. The out-of-plane and in-plane epitaxial relationships are [0001] α-Ga2O3//[0001] α-Al2O3 and [11-20] α-Ga2O3//[11-20] α-Al2O3, respectively. The lateral domain size is in micron scale and the indirect bandgap is determined as 5.03 eV by transmittance spectra. Raman measurement indicates that the lattice-mismatch induced compressive residual strain cannot be ruled out despite the large thickness of the α-Ga2O3 epilayer. The achieved high quality α-Ga2O3 may provide an alternative material platform for developing high performance power devices and solar-blind photodetectors.
关键词： chemical vapor deposition,ultra-wide bandgap semiconductor,gallium oxide,epitaxy
更新于2025-09-23 15:22:29
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Room temperature spin injection into SiC via Schottky barrier
摘要： Electrical spin injection into and spin extraction from a wide-bandgap semiconductor SiC at room temperature were demonstrated via Schottky junctions. The spin relaxation time of SiC could reach 300 ps, overwhelming that of Si with similar carrier density due to the smaller atomic number. We also found that there existed two channels in SiC/CoFeB Schottky junctions for spin relaxation, one from bulk SiC and the other from interfacial defect states within the barrier whose spin relaxation times were about 1 ns. The bias condition controlled transport channels via bulk or defect states within the barrier and then affected the effective spin relaxation process. Realization of spin injection into SiC shed light on spintronics of wide-bandgap semiconductors such as spin-resolved blue light emitting diodes and high power/temperature spintronics.
关键词： spintronics,SiC,spin injection,Schottky barrier,wide-bandgap semiconductor
更新于2025-09-23 15:21:21
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[IEEE 2019 3rd International Conference on Circuits, System and Simulation (ICCSS) - Nanjing, China (2019.6.13-2019.6.15)] 2019 3rd International Conference on Circuits, System and Simulation (ICCSS) - Research on Deep-UV Photodetectors Based on Carbon Dots as Reactive Layer
摘要： Deep-ultraviolet photodetectors are attracting attention due to their important applications in various fields. In this paper, carbon dots are used as an active layer to fabricate DUV photodetectors. These devices are capable of detecting UV light at wavelengths below 320 nm. Carbon dots are prepared by electrochemical method using distilled water as the electrolyte and their properties were characterized. A planar photoconductive structure is designed using carbon dots as reactive layer to prepare effective device by processes such as thermal evaporation and the performance of the device was estimated. The results show that the absorption peak of the carbon dots prepared by the electrochemical method is around 230 nm. A photodetector fabricated with carbon dots as an active layer has a good response at 254 nm illumination and the ratio of photocurrent to dark current of the device reaches 188.
关键词： wide bandgap,deep ultraviolet,carbon dots,photodetectors
更新于2025-09-23 15:21:01
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Efficient, stable silicon tandem cells enabled by anion-engineered wide-bandgap perovskites
摘要： Maximizing the power conversion efficiency (PCE) of perovskite-silicon tandem solar cells that can exceed the Shockley-Queisser single-cell limit requires a high performing, stable perovskite top cell with a wide band gap. We developed a stable perovskite solar cell with a band gap of ~1.7 electron volt that retained over 80% of its initial PCE of 20.7% after 1000 hours of continuous illumination. Anion engineering of phenethylammonium (PEA)-based two-dimensional (2D) additives was critical for controlling the structural and electrical properties of 2D passivation layers based on a PbI2-framework. The high PCE of 26.7% of a monolithic two-terminal wide gap perovskite/Si tandem solar cell was made possible by the ideal combination of spectral responses of the top and bottom cells.
关键词： tandem solar cells,anion engineering,perovskite,silicon,wide-bandgap
更新于2025-09-23 15:21:01