ORCID Profile
0000-0002-5397-0129
Current Organisation
Hong Kong University of Science and Technology
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Publisher: American Chemical Society (ACS)
Date: 24-01-2020
Abstract: In complex environments, there are often toxic and harmful conditions, and so self-powered sensors that use wireless access have a huge advantage. However, there is still a risk of short circuit for self-powered sensors in harsh environments. A single-electrode self-powered sensor was designed, which can be used to monitor body movements such as walking and running, as well as monitoring the motion of some mechanical devices, such as peristaltic pumps, door, and window switches. By using a threshold delay algorithm, this self-powered sensor can be connected to the phone to warn the phone user to check for theft or illegal intrusion when the door and window are opened. Further research shows that the single-electrode configuration can avoid the short-circuit behavior caused by device damage so that the self-powered sensor can still work even if it is pierced. Therefore, the wireless single-electrode self-powered sensor system has better reliability and is more applicable to harsh environments.
Publisher: American Chemical Society (ACS)
Date: 09-03-2023
Publisher: American Chemical Society (ACS)
Date: 14-03-2018
DOI: 10.1021/ACS.LANGMUIR.7B02786
Abstract: We demonstrate for the first time the application of p-NiFe
Publisher: Elsevier BV
Date: 2015
Publisher: American Chemical Society (ACS)
Date: 07-03-2012
DOI: 10.1021/NN204848R
Abstract: High-performance flexible electronics has attracted much attention in recent years due to potential applications in flexible displays, artificial skin, radio frequency identification, sensor tapes, etc. Various materials such as organic and inorganic semiconductor nanowires, carbon nanotubes, graphene, etc. have been explored as the active semiconductor components for flexible devices. Among them, inorganic semiconductor nanowires are considered as highly promising materials due to their relatively high carrier mobility, reliable control on geometry and electronic properties, and cost-effective synthesis processes. In this review, recent progress on the assembly of high-performance inorganic semiconductor nanowires and their applications for large-scale flexible electronics will be summarized. In particular, nanowire-based integrated circuitry and high-frequency electronics will be highlighted.
Publisher: American Chemical Society (ACS)
Date: 11-03-2014
DOI: 10.1021/NL500359E
Abstract: Photoelectrochemical (PEC) solar water splitting represents a clean and sustainable approach for hydrogen (H2) production and substantial research are being performed to improve the conversion efficiency. Hematite (α-Fe2O3) is considered as a promising candidate for PEC water splitting due to its chemical stability, appropriate band structure, and abundance. However, PEC performance based on hematite is hindered by the short hole diffusion length that put a constraint on the active layer thickness and its light absorption capability. In this work, we have designed and fabricated novel PEC device structure with ultrathin hematite film deposited on three-dimensional nanophotonic structure. In this fashion, the nanophotonic structures can largely improve the light absorption in the ultrathin active materials. In addition, they also provide large surface area to accommodate the slow surface water oxidation process. As the result, high current density of 3.05 mA cm(-2) at 1.23 V with respect to the reversible hydrogen electrode (RHE) has been achieved on such nanophotonic structure, which is about three times of that for a planar photoelectrode. More importantly, our systematic analysis with experiments and modeling revealed that the design of high performance PEC devices needs to consider not only total optical absorption, but also the absorption profile in the active material, in addition to electrode surface area and carrier collection.
Publisher: IEEE
Date: 06-2015
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5TA01960E
Abstract: An ultra-thin freestanding Au NSP film is fabricated by simple wet etching. Supercapacitors fabricated based on such structure show notable electrochemical improvements.
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4EE01850H
Abstract: Optimized nanospiked solar cell achieved efficiency of 7.92 % which is among the highest on a flexible substrate.
Publisher: American Chemical Society (ACS)
Date: 04-09-2013
DOI: 10.1021/NN4040074
Abstract: Much greater surface-to-volume ratio of hierarchical nanostructures renders them with promising potential for high performance chemical sensing. In this work, crystalline nanocombs were synthesized via chemical vapor deposition and fabricated into resistive gas sensors. Particularly, NO2 sensing performance of these devices has been systematically characterized, showing higher sensitivity as compared to their nanobelt counterparts. Through device simulation, it was discovered that the teeth part of a nanocomb could serve as a "negative-potential gate" after accumulating electrons captured by surface adsorbed NO2 molecules. This self-gating effect eventually results in a greater reduction of nanocomb device channel conductance upon NO2 exposure, as compared to a nanobelt device, leading to a much higher NO2 detection sensitivity. This study not only sheds light on the mechanism of performance enhancement with hierarchical nanostructures, but also proposes a rational approach and a simulation platform to design nanostructure based chemical sensors with desirable performance.
Publisher: Elsevier BV
Date: 2012
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8NR01968A
Abstract: In this work, a low-cost, scalable and highly repeatable approach was developed to prepare polystyrene films with three-dimensional nanopyramids on the surface for antibacterial applications.
Publisher: American Chemical Society (ACS)
Date: 18-09-2014
DOI: 10.1021/JP507800T
Publisher: Elsevier BV
Date: 2016
Publisher: Wiley
Date: 18-11-2013
Publisher: Wiley
Date: 25-02-2016
Abstract: Integrating devices with nanostructures is considered a promising strategy to improve the performance of solar energy harvesting devices such as photovoltaic (PV) devices and photo-electrochemical (PEC) solar water splitting devices. Extensive efforts have been exerted to improve the power conversion efficiencies (PCE) of such devices by utilizing novel nanostructures to revolutionize device structural designs. The thicknesses of light absorber and material consumption can be substantially reduced because of light trapping with nanostructures. Meanwhile, the utilization of nanostructures can also result in more effective carrier collection by shortening the photogenerated carrier collection path length. Nevertheless, performance optimization of nanostructured solar energy harvesting devices requires a rational design of various aspects of the nanostructures, such as their shape, aspect ratio, periodicity, etc. Without this, the utilization of nanostructures can lead to compromised device performance as the incorporation of these structures can result in defects and additional carrier recombination. The design guidelines of solar energy harvesting devices are summarized, including thin film non-uniformity on nanostructures, surface recombination, parasitic absorption, and the importance of uniform distribution of photo-generated carriers. A systematic view of the design concerns will assist better understanding of device physics and benefit the fabrication of high performance devices in the future.
Publisher: American Chemical Society (ACS)
Date: 18-08-2017
Publisher: Springer Science and Business Media LLC
Date: 07-03-2014
DOI: 10.1038/SREP04243
Publisher: American Chemical Society (ACS)
Date: 08-04-2014
DOI: 10.1021/JZ500306F
Abstract: Light management is of paramount importance to improve the performance of optoelectronic devices including photodetectors, solar cells, and light-emitting diodes. Extensive studies have shown that the efficiency of these optoelectronic devices largely depends on the device structural design. In the case of solar cells, three-dimensional (3-D) nanostructures can remarkably improve device energy conversion efficiency via various light-trapping mechanisms, and a number of nanostructures were fabricated and exhibited tremendous potential for highly efficient photovoltaics. Meanwhile, these optical absorption enhancement schemes can benefit photodetectors by achieving higher quantum efficiency and photon extraction efficiency. On the other hand, low extraction efficiency of a photon from the emissive layer to outside often puts a constraint on the external quantum efficiency (EQE) of LEDs. In this regard, different designs of device configuration based on nanostructured materials such as nanoparticles and nanotextures were developed to improve the out-coupling efficiency of photons in LEDs under various frameworks such as waveguides, plasmonic theory, and so forth. In this Perspective, we aim to provide a comprehensive review of the recent progress of research on various light management nanostructures and their potency to improve performance of optoelectronic devices including photodetectors, solar cells, and LEDs.
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1JM12240A
Publisher: American Chemical Society (ACS)
Date: 19-02-2013
DOI: 10.1021/NN400160N
Abstract: Efficient light absorption in thin-film photovoltaic (PV) devices is crucial for improving their efficiency and reducing cost. Here we have not only developed a low-cost and scalable method to fabricate a unique type of integrated-nanopillar-nanowell (i-NPW) structure by integrating nanopillar and nanowell arrays together vertically, but also demonstrated the attractive optical property of the i-NPW arrays by leveraging the advantages of "positive" and "negative" nanostructures for photon harvesting. Impressively, the 2 μm thick i-NPW arrays with only 40 nm a-Si coating obtained a day-integrated absorption of 89.27%, as opposed to only 33.45% for the planar control s le. These results suggest the feasibility and clear advantage of vertical integration of three-dimensional (3-D) nanophotonic structures, and meanwhile also pave a viable and convenient way toward a 3-D ultrathin film PV module with potency for high energy conversion efficiency.
Publisher: American Chemical Society (ACS)
Date: 17-01-2014
DOI: 10.1021/JP410279Z
Publisher: American Chemical Society (ACS)
Date: 06-09-2022
Publisher: American Chemical Society (ACS)
Date: 05-06-2014
DOI: 10.1021/NN5023878
Abstract: Thin film photovoltaic (PV) technologies are highly attractive for low-cost solar energy conversion and possess a wide range of potential applications from building-integrated PV generation to portable power sources. Inverted nanocones (i-cones) have been demonstrated as a promising structure for practical thin film PV devices/modules, owning to their antireflection effect, self-cleaning function, superior mechanical robustness, and so forth. In this work, we have demonstrated a low-cost and scalable approach to achieve perfectly ordered i-cone arrays. Thereafter, thin film amorphous silicon (a-Si:H) solar cells have been fabricated based on various i-cone substrates with different aspect ratios and pitches to investigate the impact of geometry of i-cone nanostructures on the performance of the as-obtained PV devices. Intriguingly, the optical property investigations and device performance characterizations demonstrated that the 0.5-aspect-ratio i-cone-based device performed the best on both light absorption capability and energy conversion efficiency, which is 34% higher than that of the flat counterpart. Moreover, the i-cone-based device enhanced the light absorption and device performance over the flat reference device omnidirectionally. These results demonstrate a viable and convenient route toward scalable fabrication of nanostructures for high-performance thin film PV devices based on a broad range of materials.
Publisher: IEEE
Date: 04-2014
Publisher: IEEE
Date: 11-2010
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3NR06675D
Abstract: 3D electrodes are critical to high-performance power sources. Now by combining imprint and soft-printing technologies, 3D nanocone arrays have been designed and fabricated for high performance pseudocapacitors.
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0TA08909E
Abstract: Herein, we report a non-toxic triboelectric nanogenerator for baby care applications.
Publisher: Springer Science and Business Media LLC
Date: 13-02-2019
DOI: 10.1038/S41467-019-08561-Y
Abstract: Metal halide perovskite has emerged as a promising material for light-emitting diodes. In the past, the performance of devices has been improved mainly by optimizing the active and charge injection layers. However, the large refractive index difference among different materials limits the overall light extraction. Herein, we fabricate efficient methylammonium lead bromide light-emitting diodes on nanophotonic substrates with an optimal device external quantum efficiency of 17.5% which is around twice of the record for the planar device based on this material system. Furthermore, optical modelling shows that a high light extraction efficiency of 73.6% can be achieved as a result of a two-step light extraction process involving nanodome light couplers and nanowire optical antennas on the nanophotonic substrate. These results suggest that utilization of nanophotonic structures can be an effective approach to achieve high performance perovskite light-emitting diodes.
Publisher: American Chemical Society (ACS)
Date: 02-12-2016
DOI: 10.1021/ACS.ANALCHEM.6B03170
Abstract: A facile single-cell patterning (ScP) method was developed and integrated with time-of-flight secondary ion mass spectrometry (TOF-SIMS) for the study of drug-induced cellular phenotypic alterations. Micropatterned poly(dimethylsiloxane) (PDMS) stencil film and centrifugation-assisted cell trapping were combined for the preparation of on-surface single-cell microarrays, which exhibited both high site occupancy (>90%) and single-cell resolution (>97%). TOF-SIMS is a surface-sensitive mass spectrometry and is increasingly utilized in biological studies. Here we demonstrated, for the first time, its successful application in high-throughput single-cell analysis. Drug-induced phenotypic alterations of HeLa cells in the early stage of apoptosis were investigated using TOF-SIMS. The major molecular sources of variations were analyzed by principle component analysis (PCA).
Publisher: American Chemical Society (ACS)
Date: 24-05-2018
Abstract: In this work, we present a high-performance smart electronic nose (E-nose) system consisting of a multiplexed tin oxide (SnO
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2CS15335A
Abstract: Semiconducting inorganic nanowires (NWs), nanotubes and nanofibers have been extensively explored in recent years as potential building blocks for nanoscale electronics, optoelectronics, chemical/biological/optical sensing, and energy harvesting, storage and conversion, etc. Besides the top-down approaches such as conventional lithography technologies, nanowires are commonly grown by the bottom-up approaches such as solution growth, template-guided synthesis, and vapor-liquid-solid process at a relatively low cost. Superior performance has been demonstrated using nanowires devices. However, most of the nanowire devices are limited to the demonstration of single devices, an initial step toward nanoelectronic circuits, not adequate for production on a large scale at low cost. Controlled and uniform assembly of nanowires with high scalability is still one of the major bottleneck challenges towards the materials and device integration for electronics. In this review, we aim to present recent progress toward nanowire device assembly technologies, including flow-assisted alignment, Langmuir-Blodgett assembly, bubble-blown technique, electric/magnetic- field-directed assembly, contact/roll printing, planar growth, bridging method, and electrospinning, etc. And their applications in high-performance, flexible electronics, sensors, photovoltaics, bioelectronic interfaces and nano-resonators are also presented.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3EE41139G
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5NR08836D
Abstract: Utilization of nanostructures on photovoltaic devices can significantly improve the device energy conversion efficiency by enhancing the device light harvesting capability as well as carrier collection efficiency. However, improvements in device mechanical robustness and reliability, particularly for flexible devices, have rarely been reported with in-depth understanding. In this work, we fabricated efficient, flexible and mechanically robust organometallic perovskite solar cells on plastic substrates with inverted nanocone (i-cone) structures. Compared with the reference cell that was fabricated on a flat substrate, it was shown that the device power conversion efficiency could be improved by 37%, and reached up to 11.29% on i-cone substrates. More interestingly, it was discovered that the performance of an i-cone device remained more than 90% of the initial value even after 200 mechanical bending cycles, which is remarkably better than for the flat reference device, which degraded down to only 60% in the same test. Our experiments, coupled with mechanical simulation, demonstrated that a nanostructured template can greatly help in relaxing stress and strain upon device bending, which suppresses crack nucleation in different layers of a perovskite solar cell. This essentially leads to much improved device reliability and robustness and will have significant impact on practical applications.
Publisher: Springer Science and Business Media LLC
Date: 05-06-2014
DOI: 10.1038/NCOMMS5007
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2NR30437F
Abstract: As the demand for renewable energy resource is growing rapidly worldwide, a variety of energy materials and technologies are being developed. In this review, we aim to summarize recent developments in the state-of-the-art research on energy harvesting technologies such as thin-film Si or Ge, CdTe, GaAs, organic, hybrid, and dye-sensitized solar cells (DSSCs) utilizing one-dimensional (1D) nanomaterials, mainly semiconductor nanowires, nanocones, nanotubes and nanofibers, which are prepared by vapor-liquid-solid method, colloidal lithography, template-guided growth, or electrospinning. Moreover, the future challenges (such as efficiency improvement and natural resource limitations) and prospects of nanostructured solar cells are proposed.
Publisher: Elsevier BV
Date: 10-2011
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1NR04769H
Abstract: A TENG with a grid structure verified that pressure can change the effective contact area and it can be used as a self-powered code lock.
Publisher: American Chemical Society (ACS)
Date: 13-08-2018
Abstract: Moravec's paradox shows that low-level sensorimotor skills are more difficult than high-level reasoning in artificial intelligence and robotics. So simplifying every sensing unit on electronic skin is critical for endowing intelligent robots with tactile and temperature sense. The human nervous system is characterized by efficient single-electrode signal transmission, ensuring the efficiency and reliability of information transmission under big data conditions. In this work, we report a sensor based on a single-electrode piezoelectric nanogenerator (SPENG) by electrospun polyvinylidene fluoride (PVDF) nanofibers that can realize steady-state sensing of pressure integrating cold/heat sensing on a single unit. Piezoelectric signals appear as square wave signals, and the thermal-sensing signals appear as pulse signals. Therefore, the two signals can be acquired by a single unit simultaneously. The SPENG overcomes the shortcoming of electronic skins based on a single-electrode triboelectric nanogenerator (STENG), which can sense only dynamic movement and cannot sense temperature variations. The new sensor configuration uses a capacitor instead of the STENG's ground wire as a potential reference, allowing it to be used for truly autonomous robots. At the same time, the traditional advantages of polymer piezoelectric materials, such as flexibility, transparency, and self-powered advantages, have also been preserved.
Publisher: Springer Science and Business Media LLC
Date: 07-06-2013
Abstract: Porous anodic alumina membranes (AAMs) have attracted great amount of attention due to their potential application as templates for nanoengineering. Template-guided fabrication and assembly of nanomaterials based on AAMs are cost-effective and scalable methods to program and engineer the shape and morphology of nanostructures and nanomaterials. In this work, perfectly ordered AAMs with the record large pitch up to 3 μm have been fabricated by properly controlling the anodization conditions and utilization of nanoimprint technique. Due to the capability of programmable structural design and fabrication, a variety of nanostructures, including nanopillar arrays, nanotower arrays, and nanocone arrays, have been successfully fabricated using nanoengineered AAM templates. Particularly, amorphous Si nanocones have been fabricated as three-dimensional nanophotonic structures with the characterization of their intriguing optical anti-reflection property. These results directly indicate the potential application of the reported approach for photonics and optoelectronics.
Publisher: IEEE
Date: 05-2012
Publisher: American Chemical Society (ACS)
Date: 16-09-2020
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2016
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7TA10175A
Abstract: A flexible hybrid piezoelectric–pyroelectric nanogenerator has been constructed using non-woven nanofiber membranes, which can in idually or simultaneously harvest mechanical and thermal energies.
Location: United States of America
No related grants have been discovered for Zhiyong Fan.