| 1. |
- Cui, Xiaolei, et al.
(författare)
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Temperature-dependent electronic properties of inorganic-organic hybrid halide perovskite (CH3NH3PbBr3) single crystal
- 2017
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Ingår i: Applied Physics Letters. - : AMER INST PHYSICS. - 0003-6951 .- 1077-3118. ; 111:23
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the temperature-dependent electronic properties of inorganic-organic hybrid halide perovskite (CH3NH3PbBr3) single crystals are investigated. The dynamic current-time measurement results at different temperatures directly demonstrate that the electrical properties of the perovskite single crystal are dependent on the work temperature. We find that the Poole-Frankel conduction mechanism fits the current-voltage curves at small bias voltage (0-1 V) under darkness, which is mainly attributed to the surface defect states. The capability of carriers de-trapping from defects varies with different work temperatures, resulting in an increased current as the temperature increases under both darkness and illumination. In addition, the different transient photocurrent responses of incident light at two wavelengths (470 nm, 550 nm) further confirm the existence of defect states on the single crystal surface. Published by AIP Publishing.
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| 2. |
- Ling, Li, et al.
(författare)
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Precisely Controlled Hydration Water for Performance Improvement of Organic-Inorganic Perovskite Solar Cells
- 2016
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Ingår i: Advanced Functional Materials. - : Wiley-VCH Verlagsgesellschaft. - 1616-301X .- 1616-3028. ; 26:28, s. 5028-5034
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Tidskriftsartikel (refereegranskat)abstract
- Recently, intensive studies on the role of water molecule in the formation of organic-inorganic perovskite film have been reported. However, not only the contradictive phenomena but also the complex processing technique has hindered the widespread use of water molecule in perovskite preparation. Here the hydration water is introduced into the precursors instead of water. By precisely controlling the content of hydration water, a smoother and more uniform perovskite film is obtained through a simple one-step spin coating method. The improvement of perovskite film quality leads to highly efficient planar perovskite solar cells. Summing up the device studies and the investigation of morphology, crystallization, and optical properties, the impact of water molecule in the formation of perovskite crystal and consequences of device performance is understood. Due to its universal adaptability and simplified process, precise control of hydration water is therefore of great utility to high quality perovskite films fabrication and large-scale production of this upcoming photovoltaic technology.
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| 3. |
- Tu, Li, et al.
(författare)
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A wide-range operating synaptic device based on organic ferroelectricity with low energy consumption
- 2018
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Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 8:47, s. 26549-26553
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Tidskriftsartikel (refereegranskat)abstract
- In thiswork, a wide-range operating synaptic device based on organic ferroelectricity has been demonstrated. The device possesses a simple two-terminal structure by using a ferroelectric phase-separated polymer blend as the active layer and gold/indium tin oxide (ITO) as the top/bottom electrodes, and exhibits a distinctive history-dependent resistive switching behavior at room temperature. And the device with low energy consumption (similar to 50 fJ mu m(-2) per synaptic event) can provide a reliable synaptic function of potentiation, depression and the complex memory behavior simulation of differential responses to diverse stimulations. In addition, using simulations, the accuracy of 32 x 32 pixel image recognition is improved from 76.21% to 85.06% in the classical model Cifar-10 with 1024 levels of the device, which is an important step towards the higher performance goal in image recognition based on memristive neuromorphic networks.
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| 4. |
- Tu, Li, et al.
(författare)
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Aerosol jet printed silver nanowire transparent electrode for flexible electronic application
- 2018
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Ingår i: Journal of Applied Physics. - : AMER INST PHYSICS. - 0021-8979 .- 1089-7550. ; 123:17
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Tidskriftsartikel (refereegranskat)abstract
- Aerosol jet printing technology enables fine feature deposition of electronic materials onto low-temperature, non-planar substrates without masks. In this work, silver nanowires (AgNWs) are proposed to be printed into transparent flexible electrodes using a Maskless Mesoscale Material Deposition Aerosol Jet VR printing system on a glass substrate. The influence of the most significant process parameters, including printing cycles, printing speed, and nozzle size, on the performance of AgNW electrodes was systematically studied. The morphologies of printed patterns were characterized by scanning electron microscopy, and the transmittance was evaluated using an ultraviolet-visible spectrophotometer. Under optimum conditions, high transparent AgNW electrodes with a sheet resistance of 57.68 X/sq and a linewidth of 50.9 mu m were obtained, which is an important step towards a higher performance goal for flexible electronic applications.
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| 5. |
- Wang, Pengfei, et al.
(författare)
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Boosting the performance of perovskite solar cells through a novel active passivation method
- 2018
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 6:32, s. 15853-15858
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Tidskriftsartikel (refereegranskat)abstract
- Potassium halides have recently garnered much attention, due to their improvement of perovskite solar cell performance. A small amount of potassium halide incorporated in a perovskite absorber is able to provide advantages in terms of crystallinity, light absorption and trap state reduction. Here, we present a potassium chloride (KCl) pretreatment process to fabricate high-efficiency perovskite solar cells (PSCs). A KCl layer was inserted at the SnO2/MAPbI(3-x)Cl(x) interface via a simple spin coating method. It is observed that potassium cations (K+) and chloride anions (Cl-) diffused into the perovskite film during the thermal annealing process. The diffusion of K+ and Cl- will stop when they reach a bulk defect, resulting in an active passivation effect. It is verified that the incorporation of KCl enhances the crystal perfection and light absorption of the perovskite film. The average power conversion efficiency (PCE) of PSCs increases from 16.62% to 17.81%, with a leading PCE of 19.44%.
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| 6. |
- Yang, Kunlong, et al.
(författare)
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A flexible artificial synapse for neuromorphic system
- 2018
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Ingår i: 2018 IEEE International Conference on Electron Devices and Solid State Circuits (EDSSC). - : IEEE conference proceedings.
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Konferensbidrag (refereegranskat)abstract
- Neuromorphic computing, as a new paradigm, highlighted for its highly parallel, energy efficient features, has attracted a lot of attention. The hardware implementation for a neuromorphic system proposes the strong desire for suitable building blocks. The synaptic device is a very promising solution because of its stimulation-history-related response, which fits the nature of a neural network. In this work, an artificial synapse based on a memristive transistor fabricated by a simple process is realized. The device not only shows multi-level states which is the main feature of a memristor and is essential to hardware implementation neuromorphic system, but also exhibits physical flexibility, a feature that supports wearable and portable electronics. On this basis, a proof-of-feasibility simulation using the experimental data is performed to realize the pattern classification.
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| 7. |
- Yang, Kunlong, et al.
(författare)
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A photoelectrical artificial synapse for novel neuromorphic network
- 2018
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Ingår i: 2018 IEEE 18th International Conference on Nanotechnology (IEEE-NANO). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781538653364
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Konferensbidrag (refereegranskat)abstract
- The requirement of information acquisition and processing is growing rapidly. However, existing systems either suffering from inadequate processing ability or from architecture limitations being restricted by the data sensing and transmission process. In this work, a novel photoelectrical artificial synapse is developed to settle down these issues by proposing a new possibility of having a photoelectrical neuromorphic network. The photoelectrical artificial synapse has both light sensing and non-volatile multilevel states making it a suitable candidate as building block in a sensing-processing merged and photoelectrical- enabled neuromorphic system. The device also has physical flexibility to adapt to flexible and wearable systems. This work initiates a new area of novel artificial synapses and neuromorphic networks.
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| 8. |
- Yang, Kunlong, et al.
(författare)
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Humidity effect on photoelectrical response in photosensitive field effect transistors
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Environmental influences on photoelectrical devices are critical for a reliable working condition. Among all the factors, the effect of relative humidity received less attention. Up to date, reported humidity effects were mostly about the electrical properties. The relationship of humidity and photoelectrical response has rarely been investigated. In this work, we first reported the novel dependency of photocurrent on the relative humidity in photosensitive field effect transistors. Both the amplitude and the decay time of the photocurrent were related to the humidity. To further clarify the mechanism, experiments were carefully designed to distinguish possible influence factors, and simulations were also performed to provide theoretical supports. The observed phenomenon indicated that the trapping of carriers and the polarization of dielectric both existed in the device, and were involved in the photoelectrical responses. Since the water molecules in the atmosphere had effect on both processes, the observed change in photoelectrical properties could be explained. This work clarified the origin of the novel relationship between the humidity and the photoelectrical response, thus pushed forward the photoelectrical devices to real application.
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| 9. |
- Yang, Kunlong, et al.
(författare)
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Merged acquisition-processing system based on a photoelectrical neural network
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In brain-inspired computing, one of the most attractive fields of study currently, new issues are emerging despite its booming development. From the systems perspective, the performances of the existing systems are hindered by inadequate hardware support, particularly the unavoidable data acquisition and transmission between the sensor module and the data processing module. In this work, we break this bottleneck by proposing a photoelectrical neural network (PNN) that merges the new sensing function into the processing network. Benefitting from its high-parallel structure and minimized hardware consumption, a novel merged acquisition-processing (MAP) system with very high efficiency and very low cost has been developed. As the key component of the MAP system, a dual-mode photoelectrical synapse (DMPS) is carefully designed and developed. It has advantages in terms of both function and performance as compared to the existing artificial synapses, which make it the best candidate for the proposed system. This work will initiate an entirely new field of unconventional neuromorphic systems.
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| 10. |
- Yang, Kunlong, et al.
(författare)
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Tunable flexible artificial synapses : a new path toward a wearable electronic system
- 2018
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Ingår i: npj Flexible Electronics. - : Springer Science and Business Media LLC. - 2397-4621. ; 2:20
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Tidskriftsartikel (refereegranskat)abstract
- The flexible electronics has been deemed to be a promising approach to the wearable electronic systems. However, the mismatching between the existing flexible devices and the conventional computing paradigm results an impasse in this field. In this work, a new way to access to this goal is proposed by combining flexible devices and the neuromorphic architecture together. To achieve that, a high-performance flexible artificial synapse is created based on a carefully designed and optimized memristive transistor. The device exhibits high-performance which has near-linear non-volatile resistance change under 10,000 identical pulse signals within the 515% dynamic range, and has the energy consumption as low as 45 fJ per pulse. It also displays multiple synaptic plasticity features, which demonstrates its potential for real-time online learning. Besides, the adaptability by virtue of its three-terminal structure specifically contributes its improved uniformity, repeatability, and reduced power consumption. This work offers a very viable solution for the future wearable computing.
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