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High-Performance Free-Standing Flexible Photodetectors Based on Sulfur-Hyperdoped Ultrathin Silicon
摘要： Flexible photodetectors (PDs) prepared with silicon-based materials have received considerable attention for use in a wide range of portable and wearable applications. In this study, we present the first free-standing flexible PD based on sulfur-hyperdoped ultrathin silicon, which was fabricated using a femtosecond laser in SF6 atmosphere. It is found that the fabricated device exhibits excellent performance of broadband photoresponse from 400 to 1200 nm, with peak responsivity of 63.79 A/W @ 870 nm at a low bias voltage of -2 V, corresponding to an external quantum efficiency reaching 9092%, which surpasses most values reported for silicon-based flexible PDs. In addition, the device shows a fast response speed (rise time τr=68 μs) and stable detection performance with good mechanical flexibility. The high-performance PD described here suggests a promising way in flexible applications for sensors, imaging systems, and optical communication systems.
关键词： flexible photodetector,ultrathin silicon,black silicon,sulfur-hyperdoped,femtosecond laser
更新于2025-09-19 17:13:59
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Enhanced Light Absorption and Charge Carrier Management in Core‐Shell Fe2O3@Nickel Nanocone Photoanodes for Photoelectrochemical Water Splitting
摘要： Solar driven photoelectrochemical (PEC) water splitting is a clean and sustainable approach to generate green fuel, Hydrogen. Hematite (Fe2O3) is considered as potential photoanode because of its abundance, chemical stability and suitable band gap, though its short carrier diffusion length puts a limit on the film thickness and subsequent light absorption capability. In this regard, here we have designed and constructed a unique photoanode by depositing ultrathin films of Fe2O3 on purpose-built three-dimensional (3D) nickel nanocone arrays. In this design, 3D nanostructures not only provide ameliorated surface area for PEC reactions but also enhance light absorption capability in ultrathin Fe2O3 films, while ultrathin films promote charge carrier separation and effective transfer to the electrolyte. The 3D electrodes exhibit a substantial improvement in light absorption capability within the entire visible region of solar spectrum, as well as enhanced photocurrent density as compared to the planar Fe2O3 photoelectrode. Detailed investigation of reaction kinetics suggests an optimum Fe2O3 film thickness on 3D nanocone arrays obtained after 6 deposition cycles in achieving maximum charge carrier separation and transfer efficiencies (82% and 88%, respectively), mainly ascribable to the increased charge carrier lifetime overcoming recombination losses.
关键词： photoanode,nanocones,water splitting,ultrathin,photoelectrochemical
更新于2025-09-19 17:13:59
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An improvement on the conversion efficiency of Si/CZTS solar cells by LSPR effect of embedded plasmonic Au nanoparticles
摘要： In this work, Au/Si/CZTS/Ag and Au/Si/plasmonic-CZTS/Ag solar cells have been produced using PLD technique. These CZTS solar cells have been produced based on p-type CZTS ultrathin films at different thicknesses of 61 nm, 112 nm and 210 nm which were grown on an n-type Si wafer. Morphologic and crystalline structures as well as optical characteristics of CZTS ultrathin films have been investigated by courtesy of AFM, XRD and UV–vis spectra. J-V characteristics of CZTS solar cells have been obtained under AM 1.5 solar radiation of 80 mW/cm2. It has been observed that Jsc, Voc and η values of CZTS solar cells increase as thickness of CZTS ultrathin films are diagnosed to an optimum thickness. But, CZTS ultrathin films at thickness of 61 nm and 112 nm have low absorption rate and it was observed that absorption rate of CZTS ultrathin films increase dramatically in visible and NIR regions after Au plasmonic nanoparticles were embedded in these CZTS ultrathin films. Furthermore, Jsc and η values of plasmonic CZTS solar cells increase and that increase can be attributed to the transfer of electrons from the plasmonic Au NPs to the conduction band of CZTS semiconductor, the photon absorption of CZTS ultrathin films from visible to NIR region in the wide spectral region, and the increase in the path length of light through in CZTS semiconductor by photon scattering of Au nanoparticles.
关键词： Ultrathin film,CZTS,Au,LSPR,PLD,Efficiency
更新于2025-09-19 17:13:59
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Low-temperature chemical vapor deposition growth of graphene films enabled by ultrathin alloy catalysts
摘要： This report introduces a method for fabricating graphene at low temperatures via chemical vapor deposition enabled by ultrathin (～1 nm) nickel-gold (Ni-Au) catalysts. The unique combination of high carbon (C) solubility Ni, low C solubility Au, and an ultrathin layer of a catalyst demonstrates the effectiveness to produce graphene at 450 °C with the layer number independent of growth duration. In contrast to grain-boundary defined catalyst morphology found in thicker (>20 nm) metal catalysts, the ultrathin catalyst morphology leads to the formation of nanoscale metal “islands” during the growth process, which results in curved graphene covering the catalyst. To test the effect of preactivation of the ultrathin catalyst for the formation of graphene, a preanneal process of the catalyst followed by the introduction of a carbon precursor was also investigated. The preanneal process resulted in the formation of carbon nanotubes (CNTs) in lieu of graphene, displaying the impact of the catalytic surface treatment in relation to the produced materials. The results and discussion presented here detail a low-temperature nanoscale manufacturing process that allows for the production of either graphene or CNTs on an ultrathin catalyst.
关键词： graphene,low-temperature growth,nickel-gold catalysts,chemical vapor deposition,ultrathin alloy catalysts
更新于2025-09-19 17:13:59
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Band engineering of III-nitride-based deep-ultraviolet light-emitting diodes: A review
摘要： III-nitride deep ultraviolet (DUV) light-emitting diodes (LEDs) are identified as the promising candidate for energy-efficient, environment-friendly and robust UV lighting source in the application of water/air purification, sterilization, and bio-sensing. However, the state-of-art DUV LED performance is far from satisfaction for commercialization owing to its low internal quantum efficiency, large current leakage and efficiency droop at high current injection, etc. Extensive efforts have been devoted to properly designing the band structures of such luminescent devices to enhance their output power. In this review, we summarize the recent progress on various energy band designs and engineering of DUV LEDs, with particular of interest is paid on the various approaches in band engineering of the electron-blocking layer, quantum well, quantum barrier and the implementation of many novel structures such as tunnel junctions, ultrathin quantum heterostructures to enhance their efficiency. Those inspirational approaches pave the way towards the next generation of greener and efficient UV sources for practical applications.
关键词： Quantum well,Quantum barrier,Deep ultraviolet light-emitting diode,Ultrathin quantum heterostructures,Band engineering,Electron-blocking layer,Tunnel junctions,III-nitride
更新于2025-09-19 17:13:59
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[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - Plasmonics in Atomically Thin Crystalline Silver
摘要： We report on the fabrication of few-atomic-layer-thick wafer-scale crystalline silver films, along with the observation of plasmons in the near-to-mid infrared spectral regions upon lithographic structuring. Our measured optical spectra reveal narrow plasmons (quality factor ~ 4), further supported by a low sheet resistance comparable to bulk metal in few-atomic-layer silver films down to 7 Ag(111) monolayers. Good crystal quality and plasmon narrowness are obtained despite the addition of a thin passivating dielectric, which renders our samples resilient to ambient conditions.
关键词： 2D materials,ultrathin plasmonics,2D plasmonics,atomically thin silver,crystalline metal films
更新于2025-09-16 10:30:52
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Ultrathin Nano-Absorbers in Photovoltaics: Prospects and Innovative Applications
摘要： Approaching the first terawatt of installations, photovoltaics (PV) are about to become the major source of electric power until the mid-century. The technology has proven to be long lasting and very versatile and today PV modules can be found in numerous applications. This is a great success of the entire community, but taking future growth for granted might be dangerous. Scientists have recently started to call for accelerated innovation and cost reduction. Here, we show how ultrathin absorber layers, only a few nanometers in thickness, together with strong light confinement can be used to address new applications for photovoltaics. We review the basics of this new type of solar cell and point out the requirements to the absorber layer material by optical simulation. Furthermore, we discuss innovative applications, which make use of the unique optical properties of the nano absorber solar cell architecture, such as spectrally selective PV and switchable photovoltaic windows.
关键词： switchable solar cell,spectrally selective solar cell,absorption enhancement,ultrathin absorber,amorphous germanium
更新于2025-09-16 10:30:52
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Photocatalytic producing dihydroxybenzenes from phenol enabled by gathering oxygen vacancies in ultrathin porous ZnO nanosheets
摘要： As an energy-efficient and environmental friendliness method, solar sunlight-driven photo-oxidation catalysis process for organic chemicals synthesis has gained enormous attention, but still faces huge challenge in developing highly-efficient photocatalysts material. Two-dimensional materials engineering and surface defect engineering of photocatalysts both provide an effective strategy to improve the catalytic activity. Inspired by these pathway, we design and synthesize ultrathin porous ZnO nanosheets featuring abundant oxygen vacancies specific to producing dihydroxybenzenes based on a photocatalytic oxidation process. Several valid characterizations had been employed to discern the structural character of the obtained model catalyst, revealing that the resultant ZnO sheets afford an average thickness of 3 nm, and abundant surface porosity, thereby contributing to the rich oxygen vacancies. Such a structure could generate a synergistic effect to enhance the optical absorption and improve the transportation rate of photogenerated charge carriers from the materials design. As expected, the specific ultrathin ZnO nanosheets exhibited a greatly-improved photocatalytic activity for oxidation of phenol to dihydroxybenzenes (31.5% conversion & almost 76.7% selectivity of DHB), near 3 and 4 times higher, respectively than its counterparts that one with few oxygen vacancies and Bulk-ZnO. Impressively, the obtained catalyst showed durable catalytic activity without any activity loss during the five recycling. Finally, the feasible oxidation mechanism was proposed and testified by the controlled scavenger experiments. This study provides a novel reference on how to design high-performance photocatalytic material.
关键词： oxygen vacancies,ZnO,ultrathin nanosheets,oxidation of phenol,photocatalytic
更新于2025-09-12 10:27:22
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Adjusting Interfacial Chemistry and Electronic Properties of Photovoltaics Based on a Highly Pure Sb <sub/>2</sub> S <sub/>3</sub> Absorber by Atomic Layer Deposition
摘要： The combination of oxide and heavier chalcogenide layers in thin film photovoltaics suffers limitations associated with oxygen incorporation and sulfur deficiency in the chalcogenide layer or with a chemical incompatibility which results in dewetting issues and defect states at the interface. Here, we establish atomic layer deposition (ALD) as a tool to overcome these limitations. ALD allows one to obtain highly pure Sb2S3 light absorber layers, and we exploit this technique to generate an additional interfacial layer consisting of 1.5 nm ZnS. This ultrathin layer simultaneously resolves dewetting and passivates defect states at the interface. We demonstrate via transient absorption spectroscopy that interfacial electron recombination is one order of magnitude slower at the ZnS-engineered interface than hole recombination at the Sb2S3/P3HT interface. The comparison of solar cells with and without oxide incorporation in Sb2S3, with and without the ultrathin ZnS interlayer, and with systematically varied Sb2S3 thickness provides a complete picture of the physical processes at work in the devices.
关键词： interfacial layer,extremely thin absorber,transient absorption,atomic layer deposition,antimony sulfide,ultrathin layer
更新于2025-09-12 10:27:22
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Double-sided pyramid texturing design to reduce the light escape of ultrathin crystalline silicon solar cells
摘要： Reducing the light absorption loss of ultrathin crystalline silicon (c-Si) solar cells is significant to achieve high photocurrent density and photoelectric conversion efficiency. Here, we designed and simulated ultrathin c-Si cells with front pyramids and double-sided pyramids. By adjusting the shape of pyramids, the maximum photocurrent densities reach 36.23 and 37.71 mA/cm2 for the cells with front pyramids and double-sided pyramids, respectively. The reflectivity spectrum indicates that the double-sided pyramidal architecture remarkably suppresses light escape and then enhances the light absorption in long wavelength range, which makes the absorption approach the Yablonovitch limit. The calculated conversion efficiencies of planar, front and double-sided textured cells are 16.94%, 19.65% and 20.45% respectively. Additionally, the difference between randomly and periodically textured cells was investigated and the results show that although the randomly front pyramid texture has a better light absorption in the range of 900–1200 nm, the periodically double-sided pyramids texture exhibit almost the same light absorption in the whole range as the random one. Besides, the solar cells with double-sided pyramids show extremely small angular dependence of incident light. Thus, the double-sided light trapping structure designed in the present work provides an alternative pathway to improve the performance of ultrathin c-Si cells.
关键词： Conversion efficiencies,Double-sided texture,Angular dependence,Ultrathin c-Si solar cells,Photocurrent density
更新于2025-09-12 10:27:22