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[SpringerBriefs in Applied Sciences and Technology] Air-Stable Inverted Organic Light-Emitting Diodes ||
摘要： We introduce the importance of air stability on the basis of the principles and the history of organic light-emitting diodes (OLEDs), and the way of realising air-stable OLEDs finally. OLEDs are current-driven self-emitting devices that, in principle, have the features of lightness and thinness. Therefore OLEDs are expected to have unprecedented flexibility. However, it is difficult to achieve air stability in OLEDs, which is the key property for the realisation of flexible devices, because it has been essential to use air-active materials in consideration of the operational mechanism.
关键词： organic electronics,air stability,OLEDs,encapsulation,flexibility
更新于2025-09-23 15:21:01
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[IEEE 2019 Compound Semiconductor Week (CSW) - Nara, Japan (2019.5.19-2019.5.23)] 2019 Compound Semiconductor Week (CSW) - 2Gps OFDM Visible Light Communication Using Light-emitting Diodes with Photonic Crystals
摘要： Nowadays, enhanced knowledge of the nature of the electricity demand is achieved through the progressively increasing deployment of smart meters and advanced data analysis techniques. One of the major challenges is to exploit this knowledge to support the introduction of strategies to modify the demand according to relevant objectives to be achieved, like users’ participation in demand response programmes. A key point for facing this challenge is to characterize the demand flexibility. In spite of many discussions about the concept of flexibility, the few mathematical definitions of flexibility available do not address the variation in time of the overall demand aggregation. This paper starts from the analysis of time-variable patterns of aggregate residential customers, ending up with suitable definitions of expected flexibility for aggregate demand. These definitions are based on assessing positive and negative pattern variations and are identified from the analysis of the collective behavior of the aggregate users. A set of results is shown for different numbers of aggregate customers, by considering different values of the averaging time step for load pattern representation.
关键词： demand response,binomial probability,maximum likelihood estimation,customers,demand flexibility,electrical load,Aggregate demand,load variation pattern
更新于2025-09-23 15:19:57
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Pulsed-grown graphene for flexible transparent conductors
摘要： In the race to find novel transparent conductors for next-generation optoelectronic devices, graphene is supposed to be one of the leading candidates, as it has the potential to satisfy all future requirements. However, the use of graphene as a truly transparent conductor remains a great challenge because its lowest sheet resistance demonstrated so far exceeds that of the commercially available indium tin oxide. The possible cause of low conductivity lies in its intrinsic growth process, which requires further exploration. In this work, I have approached this problem by controlling graphene nucleation during the chemical vapor deposition process as well as by adopting three distinct procedures, including bis(trifluoromethanesulfonyl)amide doping, post annealing, and flattening of graphene films. Additionally, van der Waals stacked graphene layers have been prepared to reduce the sheet resistance effectively. I have demonstrated an efficient and flexible transparent conductor with the extremely low sheet resistance of 40 Ω sq?1, high transparency (Tr ≈90%), and high mechanical flexibility, making it suitable for electrode materials in future optoelectronic devices.
关键词： doping,flexibility,chemical vapor deposition,graphene,transparent conductors,sheet resistance
更新于2025-09-19 17:15:36
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Flexible and recyclable SERS substrate fabricated by decorated TiO2 film with Ag NPs on the cotton fabric
摘要： Flexible and recyclable surface-enhanced Raman scattering (SERS) substrate was fabricated based on woven cotton fabric by grafting Ag nanoparticle on the TiO2 film which was deposited on the cotton fabric. Due to the synergetic effect of heterostructure Ag/TiO2 and superior adsorption capacity of fabrics, recyclable SERS cotton fabric (RSCF) possessed excellent SERS sensitivity with a detected concentration of p-Aminothiophenol as low as 10-12 M. Furthermore, SERS performance of RSCF can be recovered after 180 min in the presence of UV light illumination, resulting from the photocatalytic property of TiO2 on the surface of RSCF. It can be further utilized to reproduce SERS performance of the RSCF through the UV-assisted cleaning. As a trial for potential application, based on the flexibility of cotton fabric, RSCF was employed to detect a pesticide (carbaryl) on the surface of a pear by simply swabbing and low concentration down to 10-4 M was reached. This work provides a potential guide towards the universal design of the flexible and recyclable SERS substrates for a promising application in the SERS rapid detection of trace-level toxic pollutants on the food.
关键词： Recyclability,Cotton fabric,SERS substrate,Swabbing,Flexibility
更新于2025-09-19 17:15:36
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Laser-induced photothermal generation of flexible and salt-resistant monolithic bilayer membranes for efficient solar desalination
摘要： Harvesting solar energy and generating steam through solar thermal energy are viable approaches with diverse applications such as power generation, desalination, and water purification. Particularly, for efficient and stable solar desalination, hierarchically porous materials are desired to enable the required multiple functionalities. However, high thermal/chemical energy required and time consumed remain roadblocks. In this study, a facile, fast, and scalable laser-induced photothermal method to achieve flexible monolithic bilayer sheets (MBS) of hierarchically porous graphitic carbon (HPGC) and polymeric foam for use in salt-resistant and flexible solar steam generators is reported. The MBS-based self-floating solar steam generator shows outstanding solar desalination performance with a solar thermal efficiency of 83.2% (1-sun) and a high salt-rejection ratio (99.9%). Efficient solar thermal energy transformation is achieved by the versatile multi-functionalities of the MBS, including broad-spectrum solar light absorption, heat localization, and capillary action. Anisotropic wetting properties of hydrophobic HPGC and hydrophilic polyimide (PI) foam effectively prevent salt accumulation on the HPGC surface. The salt-resistant MBS enable long-term stability for solar desalination with actual seawater. Our laser-based photothermal method has potential in the development of high-performance solar thermal systems with substantial cost reduction by scalable production of multiscale hierarchically structured materials from micro-structured polymers.
关键词： monolithic bilayer structures,solar evaporation,porous polyimide,salt-resistant solar steam generators,self-floating,flexibility,laser-induced graphene
更新于2025-09-19 17:13:59
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Freestanding and supported processing of sub-70 μm kerfless epitaxial Si and thinned Cz/FZ Si foils into solar cells: An overview of recent progress and challenges
摘要： Utilisation of expensive silicon (Si) material in crystalline Si modules has come down to 4 g Si per watt-peak in 2018, mainly as a result of reduction in wafer thickness and kerf losses as well as increase in module efficiencies. With continued progress in conventional multi-wire sawing of ingots, wafers as thin as 100 μm could eventually be produced. Beyond this, kerfless lift-off technologies are being investigated which enable wafer thicknesses well below 100 μm with negligible Si kerf waste. Such thin Si wafers and foils would be much lighter in weight than today's standard 165-180 μm-thick wafers and would exhibit considerable flexibility and fragility. This necessitates a rethink about how to handle and process thin Si into solar devices in a manufacturing line with high mechanical yield and high throughput. This paper gives a broad overview of the different approaches for fabricating solar cells on thin Si foils. In particular, three routes are discussed in detail, namely (1) freestanding processing of thin Si, (2) processing of thin Si supported mechanically on a conductive low-cost Si substrate (“wafer-equivalent” approach) and (3) processing of thin Si bonded to a transparent glass superstrate. In each case, the main challenges are explained and the recent progress in addressing them are summarised. Kerfless 50 μm-thick epitaxial Si foils lifted-off using porous Si and thinned-down Si wafers (below 70 μm) are used as model substrates for this work.
关键词： Fragility,Layer transfer,Breakage,Lift-off,Glass superstrate,Thin silicon foils,Supported processing,Epitaxial silicon,Bonding,Adhesive,Wafer-equivalent,Low-cost silicon substrate,Flexibility,Kerfless,Freestanding
更新于2025-09-16 10:30:52
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Stretchable and colorless freestanding microwire arrays for transparent solar cells with flexibility
摘要： Transparent solar cells (TSCs) are emerging devices that combine the advantages of visible transparency and light-to-electricity conversion. Currently, existing TSCs are based predominantly on organics, dyes, and perovskites; however, the rigidity and color-tinted transparent nature of those devices strongly limit the utility of the resulting TSCs for real-world applications. Here, we demonstrate a flexible, color-neutral, and high-efficiency TSC based on a freestanding form of n-silicon microwires (SiMWs). Flat-tip SiMWs with controllable spacing are fabricated via deep-reactive ion etching and embedded in a freestanding transparent polymer matrix. The light transmittance can be tuned from ~10 to 55% by adjusting the spacing between the microwires. For TSCs, a heterojunction is formed with a p-type polymer in the top portion of the n-type flat-tip SiMWs. Ohmic contact with an indium-doped ZnO film occurs at the bottom, and the side surface has an Al2O3 passivation layer. Furthermore, slanted-tip SiMWs are developed by a novel solvent-assisted wet etching method to manipulate light absorption. Finite-difference time-domain simulation revealed that the reflected light from slanted-tip SiMWs helps light-matter interactions in adjacent microwires. The TSC based on the slanted-tip SiMWs demonstrates 8% efficiency at a visible transparency of 10% with flexibility. This efficiency is the highest among Si-based TSCs and comparable with that of state-of-the-art neutral-color TSCs based on organic–inorganic hybrid perovskite and organics. Moreover, unlike others, the stretchable and transparent platform in this study is promising for future TSCs.
关键词： Silicon microwires,High-efficiency,Flexibility,Transparent solar cells,Color-neutral
更新于2025-09-12 10:27:22
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[IEEE 2019 IEEE Milan PowerTech - Milan, Italy (2019.6.23-2019.6.27)] 2019 IEEE Milan PowerTech - optimising Load Flexibility for the Day Ahead in Distribution Networks with Photovoltaics
摘要： In this paper a methodology is proposed to calculate the load demand ?exibility that could be activated within the next 24-hours for solving the technical impacts of contingencies that may come up in an unbalanced low voltage distribution networks with high penetration of intermittent DG sources. The methodology is formulated within a Demand Response program environment via load shifting as ?exibility enabler mechanism. To achieve that, a non-linear optimisation problem is formulated based on an unbalanced optimal power ?ow, which allows the determination of the load ?exibility that each Demand Response customer could provide at the request of the Distribution System Operator. The demand as well as weather conditions are forecasted for the day ahead. The optimisation problem is solved in a sequence fashion, within a daily framework, splitting the whole problem in optimisation blocks. In each block, the ?exible load demand is obtained and the load demand forecasting its updated for the upcoming blocks based on the changes in the scheduled load demand. The methodology is applied to a real distribution network with the load data received from the smart metering infrastructure. The results obtained show the strength of the methodology in solving the technical problems of the network under high unbalanced operation.
关键词： Photovoltaics,Demand Response,Load Flexibility,Distribution Networks,Optimal Power Flow
更新于2025-09-12 10:27:22
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Efficient stable graphene-based perovskite solar cells with high flexibility in device assembling <i>via</i> modular architecture design
摘要： Carbon-based perovskite solar cells (C-PSCs) are emerging as low-cost stable photovoltaics. However, their power conversion efficiency (PCE) still lags behind that of devices based on Au or Ag as the current collector. Here, we introduced an innovative modular PSC design using a carbon back electrode, whose sheet resistance and thickness were greatly reduced by covering it with another carbon-coated FTO glass that was applied under pressure. We showed that these two individual elements could be assembled and separated repeatedly. Moreover, among the various commercial carbon sources (carbon black, graphite sheet, and graphene), graphene exhibited the best overall performance, showing the crucial importance of graphene as a charge collector. Power conversion efficiency (PCE) of 18.65% was achieved for graphene-based PSCs (G-PSCs), which was among the highest efficiency reported so far for C-PSCs. Moreover, the optimized devices without encapsulation retained 90% of their initial PCE after aging at an elevated temperature of 85 1C for 1000 h. Remarkably, G-PSCs showed significant structural flexibility; there was negligible degradation in PCE after repeated disassembling and assembling for more than 500 cycles. Our system provides a promising prospect for the facile repair and maintenance of PSCs via modular interconnections; related strategies may be extended to other devices.
关键词： modular architecture,stability,carbon-based,perovskite solar cells,flexibility,graphene
更新于2025-09-12 10:27:22
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Printable materials for printed perovskite solar cells
摘要： Since it’s introduced in 2009, the power conversion efficiency (PCE) of perovskite solar cells (PSCs) has increased from about 3% at the beginning to 24.2% at present, which is the fastest developing new generation solar cell. However, there are still some bottlenecks to be overcome for its industrialization, including both materials and fabricating technologies. In this paper, research progresses and existing problems of PSCs related materials which can be used for printing in recent years were reviewed. The characteristics, improvement and optimization of various new materials were introduced in details. Finally, the research prospects of printing large area PSCs, improving device stability and reducing fabricating costs was pointed out, which provides some suggestions for future researches on printing efficient and stable PSCs.
关键词： perovskite,solar cells,flexibility,printable materials
更新于2025-09-12 10:27:22