Keynote Speaker
Professor Sam Zhang Shanyong, School of Mechanical & Aerospace Engineering, Nanyang Technological University, Singapore
Speech title: Towards high efficiency thin film solar cells
Abstract:
As an alternative to single crystal silicon photovoltaics, thin film solar cells have been extensively explored for miniaturized cost-effective photovoltaic systems. Though the fight to gain efficiency has been severely engaged over the years, the battle is not yet over. In this review, we comb the fields to elucidate the strategies towards high efficiency thin films solar cells and provide pointers for further development. Starting from the photoelectron generation, we look into the fundamental issues in photoelectric conversion processes, including light harvesting and charge handling (separations, transportations and collections). The emerging organic-inorganic halide perovskite systems, as well as the rapidly developed polycrystalline inorganic systems, organic photovoltaics and amorphous silicon cells are discussed in details. The biggest bottleneck for the cost-effective polycrystalline inorganic cells is the composition sensitivity and deep defects; for amorphous silicon cells, it is the quantum of the dangling bonds; for organic cells, it is the low charge carrier mobility and high exciton binding energy; and for perovskite cells, it is the environmental degradation and the controversial mechanisms of generation of I-V hysteresis. Strategies of light harvesting and charge handling as well as directions to break the bottlenecks are pointed out.
Chair Professor K. M. Liew, City University of Hong Kong
Speech title: Nanocomposites: Properties and Applications
Abstract:
Nanocomposites are advanced materials possessing high strength and stiffness as well as high aspect ratio and low density. In recent years, many researches have been focused on carbon nanotube (CNT) reinforced composites. Research findings have reported the remarkable physical and mechanical properties of CNTs, making them a strong candidate for the reinforcements in polymer composites. The axial Young's modulus of single-walled carbon nanotube arrays with diameters ranging from nanometer to meter scales. The mechanical properties of CNTs are superior to those of carbon fibers. In recent studies, CNTs have been designed to be uniaxially aligned in an axial direction following the functionally graded pattern, leading to a new class of composite material - that is, the CNT-reinforced functionally graded composite material. This CNT-reinforced composite can be used in the form of beam, plate or shell structural components. Because of their usage in a variety of structures, studies of their mechanical behavior, in terms of bending, buckling, vibration, large deformation, postbuckling and large amplitude vibration have received considerable attention. In this talk, the effects of various geometric and material parameters on the mechanical behavior of CNT-reinforced composite structures will be presented.
Mohini M. Sain, Director, Centre for Biocomposites and Biomaterials Processing ，University of Toronto,
Speech title: Biocarbon and Nano-structured Lightweight sustainable Materials for Devices and Transportation sector
Klaus Doelle, Ph.D. Associate Professor State University of New York College,
Speech title: Nanomaterials in the context of the STEAM (Science, Technology) Engineering, Art and Math) Education Challenge - Getting our Students Ready for Employment
Abstract:
Applications of nanotechnology can be found today in a wide range of industrial, municipal, and domestic products, processes and applications. The work force needed to research and develop new products as well as work on improvements and enhancements of existing products requires substantial knowledge in the Science, Technology Engineering Arts and Math (STEAM) field.
To develop the educational tools needed, and early on attract, train and educate teachers, students, policy makers and the general public into the STEAM field represents a challenge.
The presented educational approach represents one example how a STEAM learning network and interaction between project partners from industry, education and governmental can be established. It show how fun in science learning can be created by using hands-on experiences and activities that are designed to increase students interest from the elementary to high school, undergraduate to graduate level, and from the general public in the STEAM field of learning.
Professor Xiaorong Luo, University of Electronic Science and Technology of China
,
Speech title: Novel Ultralow Specific On-Resistance Power MOSFETS
Abstract:
The Power MOSFET plays an important role both in the discrete Power device and integrated Power device. Its main design target is to realize High the off-state breakdown voltage (BV) and Low specific on-resistance (Ron,sp). However, there is a “Silicon limit” relationship of Ron,sp∝BV2.5. There are three types of ways to optimize the trade-off relationship. Super Junction (SJ) devices and high permittivity dielectric are one type method by enhancing the depletion effect and thus increasing the doping concentration. Dielectric trench is the another method. Dielectric trench not only can sustain the high BV, but also reduce the Ron,sp by folding drift region. The current transports in the neutral region for both the methods nevertheless. The accumulation mode LDMOS is to generate electron accumulation layers and form ultra-low resistance path, thus significantly decrease the Ron,sp . Eventually, it greatly improves the tradeoff and leads the Ron,sp less sensitive to the Nd. This speech demonstrates several kinds of LDMOSFETs by using the three types of methods mentioned above. The mechanisms of these devices and the improvement in the electrical performance are also analyzed.
Professor ChunleiWan, School of Materials Science and Engineering, Tsinghua University, Beijing, China
Speech title: Flexible inorganic/organic superlattices for wearable thermoelectric energy harvesting
Abstract:
Two dimensional transitional metal dichalcogenides (2D-TMDCs) have been acttracting rapidly growing interest in a wide range of applications. Here we develop hybrid inorgainc/organic superlattice by intercalation of organic moleclues into the wan der Waals gap of layered 2D-TMDC TiS2, which shows very high thermoelectric performance together with excellent mechanical flexibility. An electrical conductivity of 790 S cm-1 and a power factor of 0.45mWm-1K-2 were obtained for a hybrid superlattice of TiS2/[(hexylammonium)x(H2O)y(DMSO)z], with an in-plane thermal conductivity of 0.12±0.03Wm-1K-1, which is two orders of magnitude smaller than the thermal conductivities of the bulk TiS2.(Fig. 1a) [1] It was also found that the polar molecules coexisting with organic cations in the van der Waals gap between TiS2 monolayers have dielectric screening effects to suppress the electrostatic attractive force between organic cations present in the gap and carrier electrons present in the TiS2 monolayers, and hence carrier mobility is enhanced by increasing dielectric constant of polar molecules, which leads to enhanced ZT.[2] We also developed an exfoliation-reassembly process to fabricate an n-type TiS2/organic hybrid film which is mechanically flexible. (Fig. 1b) [3] In addition, flexible device/module made of n-type hybrid element and p-type organic element has been fabricated, which would be beneficial for a variety of wearable energy-harvesting applications. [4]
Figure 1 (a) HRTEM image of TiS2(HA)x(H2O)y(DMSO)z, (b)flexible thermoelectric paper
JinganLi, Ph.D.,Associate Professor School of Materials Science and Engineering, Zhengzhou University, China
Speech title: New strategies for developing cardiovascular biomaterials surfaces: potential application of TiO2 micro/nano structures and Cu-doped TiO2 films
Abstract:
Cardiovascular disease is generally accepted as the leading cause of morbidity and mortality worldwide, and lots of people suffer from atherosclerosis and thrombosis every year. To treat these disorders and prolong the patients’ life, several cardiovascular devices have been developed and applied clinically. Nevertheless, late thrombosis and hyperplasia after devices implantation are recognized as long-term problems in the practice of interventional cardiology. Recent researches show that endowing a biocompatible surface to the devices can significantly reduce the late thrombosis and hyperplasia. Therefore, topic how to enhance the biomaterials’ surface biocompatibility, such as hemocompatibility, anti-inflammation property, ability on inhibiting vascular smooth muscle cells (SMC) migration/proliferation, and improving vascular endothelial cells (EC) migration/proliferation, attracts the keen attention of the majority of researchers.
Invited Speakers
Danhong Han, PhD Candidate, Key Lab. for the Physics and Chemistry of NanoDevices Department of Electronics Peking University
Speech title: Performance Optimization of Thermoelectric Measurement Based on Wearable Materials
Abstract:
Along with the development of nanotechnology, wearable devices and "Internet of Things", substrate materials using for wearables include PET, parylene, PDMS and less conventional substrates, such as papers [1, 2]. Polyethylene terephthalate (PET) has been broadly used as the substrate for fabrication of flexible electronics owing to that its optimal thermostability is beneficial to slow down the device performance degradation. Parylene has not only the well electrical properties, protective performance, but also the bio-compatibility, which is listed as a long-term implantable biological medical materials in the body. We can measure changes on physiological state like the surface and internal micro-scale temperature changes in living organisms through this flexible material. How to optimize the performance of a thin-film thermocouple array using for monitoring the body temperature at times on the flexible material is our concern.
Jingjing Xu, PhD Candidate, Key Lab. for the Physics and Chemistry of NanoDevices Department of Electronics Peking University
Speech title: A kind of biocompatible substrate material used for flexible, three-dimensional, implantable devices with sensors for the measurement of thermal and electrical signals in vivo
Abstract:
With the rapid development of micro-nano processing technologies, an increasing number of implantable sensors and actuators were made to measure the variety of signals in vivo, in which the bio-compatible materials are of great importance. Until now there has been several common materials for implantable devices such as PET, PDMS and Parylene.
Here, we designed a kind of three-dimensional implantable devices fabricated on the substrate named Parylene – C, which is with biological compatibility and thickness of a few microns, as well as flexible enough to have a good contact with the biological tissue or organs.
The device was completed through standard MEMS, after which it would be tailored into specific branched structure to fit the objectives in different positions. Thermocouples and electrodes had been integrated on every branches to measure the temperature, electrical and electromagnetic signals of the targets in real time, as seen in Figure 1.
Beining Du, PhD Candidate, Shenzhen Institute, Peking University
Speech title: The Crystal Structure, Precipitation and Evolution of the Grain Boundary Borides in a Ni-based Cast Superalloy
Abstract:
As a grain boundary strengthening element, B is widely applied in most Ni-based superalloys. The additive amount of B in superalloy is usually 0.01%-0.025% (wt. %), While the solid solubility of B in Ni matrix is only dozens of ppm, which is far below its additive amount. Therefore most of the B would segregate at the grain boundary and exist as solid solution form or boride. Studies have found that in superalloy, B would interact with other atoms near the grain boundary, like Cr and Mo, and form boride during aging treatment. The boride would influence the mechanical properties of superalloy. Since the superalloy needs to serve at high temperature for long time, the evolution of grain boundary microstructure during service could influence the mechanical properties and service life. Therefore, the investigation on the stability and evolution of grain boundary boride under high temperature and stress is very important. In the present research, a nickel-based cast IN792 superalloy with trace B addition was fabricated, the crystal structure and elemental composition of grain boundary boride were investigated firstly; then the alloy was preheated and thermal exposed at different temperatures and times to study the thermal stability of grain boundary boride; finally, the high-cycle fatigue (HCF) behavior of IN792 superalloy at different temperatures was tested and the evolution of grain boundary boride during HCF was analyzed to study the influence of high temperature and cyclic stress on the boride.
Jie Chen, Research Professor, School of Physics Science and Engineering in Tongji University
Speech title: Thermal Transport in Graphene-Based Two-Dimensional Materials
Abstract:
The increasing power density and the decreasing dimensions of transistors present severe thermal challenges to the design of modern microprocessors. The ultrahigh thermal conductivity of graphene makes it a promising candidate to address such problem, thus has attracted intensive interest. In this talk, I will present our recent progress on developing graphene based material for novel heat management applications. We show that by replacing the inter-layer van der Waals interaction with the covalent sp2 bond with the CNT, the graphene-CNT (G-CNT) hybrid outperforms graphene by more than 2 orders of magnitude for the c-axis heat transfer, while its thermal resistance is 3 orders of magnitude lower than the state-of-the-art thermal interface materials. When immersed in water, the G-CNT hybrid can provide sustainable cooling of high temperature and high heat flux hot surfaces via the solid-liquid interaction. The strategies to regulate the heat transfer across solid-liquid interface are discussed. Furthermore, we find the size and temperature dependence of thermal conductivity in graphene can be controlled by the defect/doping concentration and the substrate, which have a significant impact on the phonons with long mean free path. Such control of thermal conductivity opens doors for novel heat management applications, such as thermal dioade, phonon nanocapacitor and thermal cloaking.