- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Scattering Effect on Optical Performance of Quantum Dot White Light-Emitting Diodes Incorporating SiOa?? Nanoparticles
摘要： Traditional rehabilitation techniques have limited effects on the recovery of patients with tetraplegia. A brain–computer interface (BCI) provides an interactive channel that does not depend on the normal output of peripheral nerves and muscles. In this paper, an integrated framework of a noninvasive electroencephalogram (EEG)-based BCI with a noninvasive functional electrical stimulation (FES) is established, which can potentially enable the upper limbs to achieve more effective motor rehabilitation. The EEG signals based on steady-state visual evoked potential are used in the BCI. Their frequency domain characteristics identi?ed by the pattern recognition method are utilized to recognize intentions of ?ve subjects with average accuracy of 73.9%. Furthermore the movement intentions are transformed into instructions to trigger FES, which is controlled with iterative learning control method, to stimulate the relevant muscles of upper limbs tracking desired velocity and position. It is a useful technology with potential to restore, reinforce or replace lost motor function of patients with neurological injuries. Experiments with ?ve healthy subjects demonstrate the feasibility of BCI integrated with upper extremity FES toward improved function restoration for an individual with upper limb disabilities, especially for patients with tetraplegia.
关键词： rehabilitation robotics,functional electrical stimulation,human–robot interaction,intelligent control,Brain–computer interfaces
更新于2025-09-19 17:13:59
-
Doping Strategy for Efficient and Stable Triple Cation Hybrid Perovskite Solar Cells and Module Based on Poly(3‐hexylthiophene) Hole Transport Layer
摘要： As the hole transport layer (HTL) for perovskite solar cells (PSCs), poly(3-hexylthiophene) (P3HT) has been attracting great interest due to its low-cost, thermal stability, oxygen impermeability, and strong hydrophobicity. In this work, a new doping strategy is developed for P3HT as the HTL in triple-cation/double-halide ((FA1?x?yMAxCsy)Pb(I1?xBrx)3) mesoscopic PSCs. Photovoltaic performance and stability of solar cells show remarkable enhancement using a composition of three dopants Li-TFSI, TBP, and Co(III)-TFSI reaching power conversion efficiencies of 19.25% on 0.1 cm2 active area, 16.29% on 1 cm2 active area, and 13.3% on a 43 cm2 active area module without using any additional absorber layer or any interlayer at the PSK/P3HT interface. The results illustrate the positive effect of a cobalt dopant on the band structure of perovskite/P3HT interfaces leading to improved hole extraction and a decrease of trap-assisted recombination. Non-encapsulated large area devices show promising air stability through keeping more than 80% of initial efficiency after 1500 h in atmospheric conditions (relative humidity ≈ 60%, r.t.), whereas encapsulated devices show more than >500 h at 85 °C thermal stability (>80%) and 100 h stability against continuous light soaking (>90%). The boosted efficiency and the improved stability make P3HT a good candidate for low-cost large-scale PSCs.
关键词： perovskite interfaces,light soaking,photovoltaic module,polymeric hole transport materials,thermal stability
更新于2025-09-19 17:13:59
-
Effect of the hole transporting / active layer interface on the perovskite solar cell stability
摘要： In the field of photovoltaics, perovskite solar cells have attracted great interest due to their high efficiency combined with a strong potential for low cost and good versatility. One of the main issue concerns the intrinsic stability of these cells. To develop mitigation strategies, there is a critical need for a better understanding of the most plausible degradation mechanisms. This work focuses on the impact of the hole transporting layer (HTL) on the stability of planar NIP perovskite solar cells based on MAPbI3-xClx. From the comparison of two different HTL (P3HT and PTAA), the crucial role of interfacial materials on the stability of a complete device is demonstrated. Even if PTAA-based devices presented better performances in the initial state, their degradation under mild aging conditions (35°C, under dark and inert conditions) is more pronounced than that with the P3HT counterpart. Thanks to complementary characterization tools (infrared spectroscopy, X-ray diffraction, UV-visible absorption, photoluminescence) applied to different stages of the stack assembly (with respectively 3, 4 or 5 layers), a degradation mechanism was identified at the perovskite-PTAA interface. These devices consisting of several extremely thin layers, the interfaces play an important role on the performances and stability of the complete cells. It is a pioneering work in the community, which could be transposed to other devices and architecture.
关键词： Perovskite solar cells,degradation mechanisms,hole transport layer,interfaces,stability
更新于2025-09-19 17:13:59
-
Ultra-Stable Plasmonic Colloidal Aggregates for Accurate and Reproducible Quantitative SE(R)RS in Protein-Rich Biomedia
摘要： Au/Ag colloids aggregated with simple salts are amongst the most commonly used substrates in surface-enhanced (resonance) Raman spectroscopy (SE(R)RS). However, salt-induced aggregation is a dynamic process, which means that SE(R)RS enhancements vary with time and that measurements therefore need to be taken at a fixed time point, normally within a short time-window of a few minutes. Here, we present an emulsion templated method which allows formation of densely-packed quasi-spherical Au/Ag colloidal aggregates. Since the particles in the product aggregates retain their weakly adsorbed charged ligands and the ionic strength remains low these charged aggregates resist further aggregation while still providing intense SE(R)RS enhancement which remains stable for days. This eliminates a major source of irreproducibility in conventional colloidal SE(R)RS measurements and paves the way for SE(R)RS analysis in complex systems, such as protein-rich bio-solutions where conventional aggregated colloids fail.
关键词： self-assembly,interfaces,colloidosomes,SE(R)RS,aggregates
更新于2025-09-19 17:13:59
-
Controlled ultra-thin oxidation of Graphite promoted by cobalt oxides: influence of the initial 2D CoO wetting layer
摘要： The interaction of CoO with highly oriented pyrolytic graphite (HOPG) was studied using a set of complementary techniques. The morphology of the CoO thin film was determined using atomic force microscopy (AFM), whereas the electronic structure was investigated using x-ray absorption (XAS) and photoemission (PES) spectroscopies. The experimental spectra were analyzed using a configuration interaction CoO6 cluster model calculation. The early stages of growth are characterized by the formation of a CoO wetting layer at the CoO/HOPG interface. The electronic structure of the CoO wetting layer presents a clear 2D character, which is closer to the 2D HOPG substrate than to the 3D CoO bulk. This character of the wetting layer explains the posterior formation of CoO islands and excludes the alternative layer by layer growth mode. Further, the interaction between the CoO wetting layer and the outermost graphite layer favors the oxidation of the HOPG substrate which can be controlled by the thickness of the deposited CoO overlayer.
关键词： x-ray absorption spectroscopies,x-ray photoemission spectroscopies,wetting layers,CoO/HOPG interfaces,HOPG oxidation
更新于2025-09-16 10:30:52
-
[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Tailored Disorder for the Light Management in Photovoltaics
摘要： Light management in photovoltaics continues to be an important ingredient when working towards high efficiency devices. Various approaches have been perceived. Besides spectral modification, e.g. based on up- or down-conversion, the spatial and angular redistribution of light is important. For the latter aspect, on which we concentrate here, various supporting photonic structures were suggested, e.g. photonic crystals, metallic nanostructures, or textured interfaces. From a higher executive perspective we can categorize most structures as being either periodic or random. The emergence of such material classes is explained by the fabrication means. The Fourier spectrum, i.e. the angular distribution with which photonic modes can be excited from such structures beyond specific near-field effects is either discrete and wavelength sensitive or unspecific and spectrally flat. Both combinations are far from optimum when integrating them into photovoltaic devices. In this contribution we elaborate on the notion of a tailored disorder to improve the photon management. With tailored disorder we achieve hyperuniform interfaces. They are characterized by a suppressed variation in the feature density across the interface, like in a periodic structure, but at the same they offer the same properties when viewed from different directions. The hyperuniform interfaces we have in mind combine the benefits of the previously considered categories. Hyperuniform interfaces offer (a) a structured Fourier spectrum, (b) are rather wavelength insensitive, and (c) are subject to a deterministic design process.
关键词： light management,hyperuniform interfaces,photovoltaics,tailored disorder
更新于2025-09-16 10:30:52
-
Blocking exciton-quenching pathways in host and guest interfaces for high performance solution-processed TADF OLEDs with external quantum efficiency approaching 25%
摘要： Although doping system can effectively reduce the concentration quenching of thermally activated delayed fluorescence emitter, the inevitable collision between host and guest may be other energy leakage pathways, which are usually ignored in the previous studies. Here, a new encapsulated molecule Cz-4CzIPN with TADF emissive core and steric shield is conveniently synthesized and fully characterized. The TADF property ensures the efficient triplet exciton utilization, while the encapsulated feature endows the adjacent molecules a big steric bulk to reduce exciton quenching. By using the encapsulated TADF materials as both host and guest, solution-processed TADF OLEDs achieved the maximum external quantum efficiency (EQE) as high as 24.3%, which is among the best results for solution-processed TADF OLEDs reported so far. However, removing any protection of host or guest, the device efficiency will be accordingly reduced. Particularly, when the host and guest are both unencapsulated, the device can only exhibits the EQEmax of 8.0%, which indicates the existence of severe exciton quenching process. This research demonstrates the molecular interface engineering is a promising strategy for blocking the exciton quenching pathways of the solution-processed doping system by suppressing the intermolecular interaction.
关键词： TADF,host-guest interfaces,solution-process,organic light emitting diodes technology
更新于2025-09-16 10:30:52
-
Interface Engineering of Aira??Stable na??Doping Fullerenea??Modified TiO <sub/>2</sub> Electron Transport Layer for Highly Efficient and Stable Perovskite Solar Cells
摘要： As one common electron transport material for planar n-i-p perovskite solar cell, titanium dioxide (TiO2) compact layer has several challenging issues, such as surface hydroxyl groups, high defect density, and unmatched energy levels, causing severe energy loss and poor stability at contact. To solve these problems, the authors introduce a thin [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) interlayer doped with an air stable n-type dopant, 3-dimethyl-2-phenyl-2,3- dihydro-1H-benzoimidazole (DMBI) to modify the TiO2 surface. The state-of-the-art characterizations demonstrate such modification significantly improves charge transfer at MAPbI3/TiO2 interface together with smaller energy level offset, leading to suppressed charge recombination. High-quality perovskite film with larger crystal grain size grows on the n-doped PCBM/TiO2 attributed to the better surface affinity. As a result, the average power conversion efficiency of perovskite solar cell exhibits a prominent improvement from 17.46% to 20.14%, with an enhancement in all device photovoltaic parameters. In addition, the stability of the device with n-doped PCBM/TiO2 is much better than that of the control device with the bare TiO2 due to hydrophobicity nature of PCBM and low defect densities in the perovskite film and at the interface. This work indicates that many further device performance improvements should be conceivable by focusing on the perovskite interface.
关键词： stability,interfaces,perovskite solar cells,n-type doping,efficiency,electron transport layers
更新于2025-09-16 10:30:52
-
AIP Conference Proceedings [AIP Publishing PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS: ICAM 2019 - Kerala, India (12–14 June 2019)] PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS: ICAM 2019 - A review on computational modelling of individual device components and interfaces of perovskite solar cells using DFT
摘要： Perovskite structures with the same crystal structure as CaTiO3, are of importance in the field of Materials Science right from the discovery of ceramic high-temperature superconductors to the organic–inorganic semiconductors for high-efficiency photovoltaics. Owing to their unique crystal structure, perovskites display a variety of interesting properties like ferroelectricity, superconductivity, magnetoresistance, birefringence, piezoelectricity etc. Moreover, the efficiency of perovskite solar cells has increased from 3.1% in 2009 to 22.1% in 2017. Since a large number of elements can be combined to form perovskite structures, one can selectively design and optimize perovskite’s physical, optical and electrical characteristics. Through theoretical and computational modelling, it is possible to access the hitherto unknown atomistic properties, opto-electronic properties and operational mechanisms of these materials with high accuracy. This paper aims at explaining some of the potentialities of DFT hybrid functionals to analyze the electronic, structural and optical properties of compounds constituting various layers of a perovskite solar cell with the help of software packages like VASP, Wien 2k. Gaussian 09 etc. This paper also reviews the effect of doping on the electronic properties of various layers of perovskite solar cells including the band gap, visible light absorption, relaxation time of holes and electrons using DFT, which in turn determines the optimum charge separation. The effect of introduction of an Intermediate Band Gap in the perovskite structure using DFT methods based on G0W0+SOC approach is also discussed here. A study on the effect of various intrinsic defects present in perovskite structures using DFT calculations with VASP package is also discussed. The relevance of modelling the interfaces of various layers of perovskite solar cells with DFT packages is discussed with the help of selected examples of materials and representative interfaces.
关键词： optical properties,DFT,computational modelling,electronic properties,interfaces,Perovskite solar cells
更新于2025-09-12 10:27:22
-
Nonequilibrium site distribution governs charge-transfer electroluminescence at disordered organic heterointerfaces
摘要： The interface between electron-donating (D) and electron-accepting (A) materials in organic photovoltaic (OPV) devices is commonly probed by charge-transfer (CT) electroluminescence (EL) measurements to estimate the CT energy, which critically relates to device open-circuit voltage. It is generally assumed that during CT-EL injected charges recombine at close-to-equilibrium energies in their respective density of states (DOS). Here, we explicitly quantify that CT-EL instead originates from higher-energy DOS site distributions significantly above DOS equilibrium energies. To demonstrate this, we have developed a quantitative and experimentally calibrated model for CT-EL at organic D/A heterointerfaces, which simultaneously accounts for the charge transport physics in an energetically disordered DOS and the Franck–Condon broadening. The 0–0 CT-EL transition lineshape is numerically calculated using measured energetic disorder values as input to 3-dimensional kinetic Monte Carlo simulations. We account for vibrational CT-EL overtones by selectively measuring the dominant vibrational phonon-mode energy governing CT luminescence at the D/A interface using fluorescence line-narrowing spectroscopy. Our model numerically reproduces the measured CT-EL spectra and their bias dependence and reveals the higher-lying manifold of DOS sites responsible for CT-EL. Lowest-energy CT states are situated ～180 to 570 meV below the 0–0 CT-EL transition, enabling photogenerated carrier thermalization to these low-lying DOS sites when the OPV device is operated as a solar cell rather than as a light-emitting diode. Nonequilibrium site distribution rationalizes the experimentally observed weak current-density dependence of CT-EL and poses fundamental questions on reciprocity relations relating light emission to photovoltaic action and regarding minimal attainable photovoltaic energy conversion losses in OPV devices.
关键词： organic electronics,Franck–Condon vibronic progression,energetic disorder,electroluminescence at organic interfaces,3D kinetic Monte Carlo model
更新于2025-09-12 10:27:22