Silver nanowires (AgNWs) have attracted considerable attention as the material for emerging flexible, high conductive, and transparent wearable healthcare monitoring. However, due to the high ...possibility of AgNWs being oxidized in air and the discomfort caused by direct contact between silver nanowires and human skin, there are still some concerns to be taken into account in the direct application of AgNWs to ECG electrodes. Here, we combined AgNWs with graphene oxide (GO), and adopted the screen-printing technology for the fabrication of AgNWs/GO hybrid transparent conductive electrodes. Using the screen-printing technology throughout the whole fabrication process gives the ability to fabricate patterned films easily, and has the advantages of simple control and low cost, which makes it superior in mass production compared to previous studies. By encapsulating the AgNW with the GO layer, the electrodes obtained exhibit excellent optical and electrical properties (transmittance of 83.5% at 550 nm and sheet resistance of 11.9 Ohm/sq). Apart from optical and electrical properties, with GO as a protective layer, the reliability, bio-friendliness and long-term stability of AgNWs/GO hybrid electrodes have been greatly improved. In addition, AgNWs/GO electrodes fabricated on PET substrate also show excellent mechanical flexibility. We anticipate that AgNWs/GO electrodes will be promising materials for the implementation of emerging portable healthcare electronics such as wearable ECG monitoring.
2D/3D perovskite heterostructure can combine the advantages of 2D perovskite with well stability and 3D perovskite with high efficiency. 2D BA2PbI4/3D MAPbI3 heterostructures are constructed to study ...the interfacial electrical properties and charge transfer characteristics by first-principle calculations. 3D MAPbI3 perovskite have two kinds of contacting interface, i.e., PbI interface and I interface. The 2D/3D interface heterostructures are van der Waals contacting, and their light absorption can be enhanced as compared to pure 2D or 3D perovskite, mainly resulting from 3D perovskite part in the heterostructure. In 2D/I interface heterostructure, the band gap is 1.15 eV, and the charge recombination center is at 2D BA2PbI4 interface, which favor to improve the power conversion efficiency (PCE). While in 2D/PbI heterostructure, the band gap is as small as 0.53 eV, and the charge recombination center is at PbI interface, leading to a large number of recombination and low PCE. The work function difference of 2D BA2PbI4 and 3D MAPbI3 perovskite is the nature of energy level shifting and interface charge oriented movement. These results demonstrate that the construction of 2D BA2PbI4 and 3D I interface heterostructure by interfacial engineering is a potential strategy to enhance the performance of the 2D/3D heterostructured PSCs.
The charge recombination center is at the 2D BA2PbI4 interface in 2D/I interface heterostructure. Display omitted
•2D/3D perovskite heterostructures are constructed with BA2PbI4 and MAPbI3.•The charge recombination center is at the 3D PbI interface in 2D/PbI interface heterostructure.•The charge recombination center is at the 2D BA2PbI4 interface in 2D/I interface heterostructure.•The 2D BA2PbI4 and 3D I interface heterostructure could enhance the performance of 2D/3D heterostructured solar cells.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Thin-film transistors (TFTs) have experienced tremendous development during the past decades and show great promising applications in flat displays, sensors, radio frequency identification tags, ...logic circuit, and so on. The printed TFTs are the key components for rapid development and commercialization of printed electronics. The researchers in China play important roles to accelerate the development and commercialization of printed TFTs. In this review, we comprehensively summarize the research progress of printed TFTs on rigid and flexible substrates from China. The review will focus on printing techniques of TFTs, printed TFT components including semiconductors, dielectrics and electrodes, as well as fully printed TFTs and printed flexible TFTs. Furthermore, perspectives on the remaining challenges and future developments are proposed.
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IJS, KILJ, NUK, PNG, UL, UM
The stability of CH3NH3PbI3 was investigated by observing the degradation in a coevaporated film irradiated by a blue laser in ultrahigh vacuum. X-ray photoelectron spectroscopy (XPS) and scanning ...electron microscopy (SEM) were employed to investigate the effects of irradiation on the surface. The core levels of CH3NH3PbI3 were observed to shift toward a higher binding energy (BE) during the irradiation, suggesting that the surface became more n-type. A new metallic Pb component in the XPS spectrum appeared after 120 min of irradiation, indicating that the film had started to decompose. The decomposition saturated after about 480 min of irradiation when the ratio of metallic Pb to total Pb was about 33%. Furthermore, the film was no longer continuous after irradiation, as the elements gold and oxygen from the substrate were detected by XPS. SEM images also show a roughened surface after irradiation. The results strongly indicate that CH3NH3PbI3 is sensitive to the laser irradiation and that the light induced decomposition is a self-limiting process.
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IJS, KILJ, NUK, PNG, UL, UM
Optoelectronic‐neuromorphic transistors are vital for next‐generation nanoscale brain‐like computational systems. However, the hardware implementation of optoelectronic‐neuromorphic devices, which ...are based on conventional transistor architecture, faces serious challenges with respect to the synchronous processing of photoelectric information. This is because mono‐semiconductor material cannot absorb adequate light to ensure efficient light–matter interactions. In this work, a novel neuromorphic‐photoelectric device of vertical van der Waals heterojunction phototransistors based on a colloidal 0D‐CsPbBr3‐quantum‐dots/2D‐MoS2 heterojunction channel is proposed using a polymer ion gel electrolyte as the gate dielectric. A highly efficient photocarrier transport interface is established by introducing colloidal perovskite quantum dots with excellent light absorption capabilities on the 2D‐layered MoS2 semiconductor with strong carrier transport abilities. The device exhibits not only high photoresponsivity but also fundamental synaptic characteristics, such as excitatory postsynaptic current, paired‐pulse facilitation, dynamic temporal filter, and light‐tunable synaptic plasticity. More importantly, efficiency‐adjustable photoelectronic Pavlovian conditioning and photoelectronic hybrid neuronal coding behaviors can be successfully implemented using the optical and electrical synergy approach. The results suggest that the proposed device has potential for applications associated with next‐generation brain‐like photoelectronic human–computer interactions and cognitive systems.
A novel neuromorphic photoelectric device of vertical van der Waals heterojunction phototransistor based on colloidal 0D‐CsPbBr3‐quantum‐dots/2D‐MoS2 heterojunction channel is proposed using a polymer ion‐gel electrolyte as the gate dielectric. Efficiency‐adjustable photoelectronic classical Pavlovian conditioning and photoelectronic‐hybrid neural coding behaviors can be successfully achieved by utilizing the spatiotemporal and photoelectronic 4D synergy approach.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Combining transition metal oxide catalysts with conductive carbonaceous material is a feasible way to improve the conductivity. However, the electrocatalytic performance is usually not distinctly ...improved because the interfacial resistance between metal oxides and carbon is still large and thereby hinders the charge transport in catalysis. Herein, the conductive interface between poorly conductive NiO nanoparticles and semi‐conductive carbon nitride (CN) is constructed. The NiO/CN exhibits much‐enhanced oxygen evolution reaction (OER) performance than corresponding NiO and CN in electrolytes of KOH solution and phosphate buffer saline, which is also remarkably superior over NiO/C, commercial RuO2, and mostly reported NiO‐based catalysts. X‐ray photoelectron spectroscopy and extended X‐ray absorption fine structure spectrum reveal that a metallic Ni–N bond is formed between NiO and CN. Density functional theory calculations suggest that NiO and CN linked by a Ni–N bond possess a low Gibbs energy for OER intermediate adsorptions, which not only improves the transfer of charge but also promotes the transmission of mass in OER. The metal–nitrogen bonded conductive and highly active interface pervasively exists between CN and other transition metal oxides including Co3O4, CuO, and Fe2O3, making it promising as an inexpensive catalyst for efficient water splitting.
The conductive interface between nickel oxide nanocrystals and polymer carbon nitride is produced by a Ni–N bond, which exhibits highly efficient performance in electrocatalytic oxygen evolution reaction.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The fabrication of organic semiconductor thin films is extremely important in organic electronic devices. This tutorial review--which should particularly appeal to chemists and physicists interested ...in organic thin-film growth, organic electronic devices and organic semiconductor materials--summarizes the method of weak epitaxy growth (WEG) and its application in the fabrication of high quality organic semiconductor thin films. WEG achieves the thin-film fabrication of disk-like organic semiconductor molecules with highly structural order, molecular level smoothness and large size domains on amorphous substrate. The organic field-effect transistor devices based on these thin films exhibit a high charge mobility that is comparable with their corresponding single-crystal devices. Moreover, it provides a way to produce organic superlattices.
Electrocardiogram (ECG) signals are crucial for determining the health status of the human heart. A clean ECG signal is critical in analysis and diagnosis of heart diseases. However, ECG signals are ...often contaminated by motion artifact noise in the non-contact ECG monitoring systems. In this paper, an ECG motion artifact removal approach based on empirical wavelet transform (EWT) and wavelet thresholding (WT) is proposed. This method consists of five steps, namely, spectrum preprocessing, spectrum segmentation, EWT decomposition, wavelet threshold denoising, and EWT reconstruction. The proposed approach was used to process real ECG signals collected by the non-contact ECG monitoring equipment. The results of quantitative study and analysis indicate that this approach produces a better performance in terms of restorage of QRS complexes of the original ECG with reduced distortion, retaining useful information in ECG signals, and improvement of the signal to noise ratio (
) value of the signal. The output results of the practical ECG signal test show that motion artifact in the real recorded ECG is effectively filtered out. The proposed method is feasible for reducing motion artifacts from ECG signals, whether from simulation ECG signals or practical non-contact ECG monitoring systems.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Flexible perovskite solar cells (f‐PSCs) have attracted great attention due to their promising commercial prospects. However, the performance of f‐PSCs is generally worse than that of their rigid ...counterparts. Herein, it is found that the unsatisfactory performance of planar heterojunction (PHJ) f‐PSCs can be attributed to the undesirable morphology of electron transport layer (ETL), which results from the rough surface of the flexible substrate. Precise control over the thickness and morphology of ETL tin dioxide (SnO2) not only reduces the reflectance of the indium tin oxide (ITO) on polyethylene 2,6‐naphthalate (PEN) substrate and enhances photon collection, but also decreases the trap‐state densities of perovskite films and the charge transfer resistance, leading to a great enhancement of device performance. Consequently, the f‐PSCs, with a structure of PEN/ITO/SnO2/perovskite/Spiro‐OMeTAD/Ag, exhibit a power conversion efficiency (PCE) up to 19.51% and a steady output of 19.01%. Furthermore, the f‐PSCs show a robust bending resistance and maintain about 95% of initial PCE after 6000 bending cycles at a bending radius of 8 mm, and they present an outstanding long‐term stability and retain about 90% of the initial performance after >1000 h storage in air (10% relative humidity) without encapsulation.
By precisely controlling the film properties of electron transport layer SnO2, flexible perovskite solar cells with a structure of indium tin oxide/SnO2/FA0.945MA0.025Cs0.03Pb(I0.975Br0.025)3/Spiro‐OMeTAD/Ag gives a power conversion efficiency of 19.51% and a steady output of 19.01%. The flexible devices present excellent bending resistance and long‐term stability.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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