Interface Engineering and Electrode Engineering for Organic Solar Cells

Interface engineering and electrode engineering play important roles in the performance improvement for organic solar cells (OSCs). We here would investigate the effect of various cathode modifying layers and ITO-free electrodes on the device performance. First, for inverted organic solar cells (IOSCs) with a poly (3-hexylthiophene-2,5-diyl):[6,6]-phenyl C61 butyric acid methyl ester blend, an aqueous solution method using low temperatures is adopted to deposit a ZnO interlayer in IOSCs. When the ZnO annealing temperature is above 80°C, the corresponding IOSCs show senior PCEs over 3.5%. Meanwhile the flexible devices based on poly(ethylene terephthalate) substrate display a PCE of 3.26% and good flexibility. Second, the performance of IOSCs based on AZO cathode and Ca modifier are studied. The resulted IOSCs with an ultrathin Ca modifier (~1 nm) could achieve a senior PCE above 3%, and highly efficient electron transport at AZO/Ca/organic interface, which obviously weakens the light soaking issue. Third, by introducing a 2 nm MoO3 interlayer for Ag anode deposition, the obtained OSCs show an improved PCE of 2.71%, and the flexible device also achieves a comparable PCE of 2.50%. All these investigations may be instructive for further improvement of device performance and the possible commercialization in the future

Highly sensitive magnetite nano clusters for MR cell imaging

High sensitivity and suitable sizes are essential for magnetic iron oxide contrast agents for cell imaging. In this study, we have fabricated highly MR sensitive magnetite nanoclusters (MNCs) with tunable sizes. These clusters demonstrate high MR sensitivity. Especially, water suspensions of the MNCs with average size of 63 nm have transverse relaxivity as high as 630 s-1mM-1, which is among the most sensitive iron oxide contrast agents ever reported. Importantly, such MNCs have no adverse effects on cells (RAW 264.7). When used for cell imaging, they demonstrate much higher efficiency and sensitivity than those of SHU555A (Resovist), a commercially available contrast agent, both in vitro and in vivo, with detection limits of 3,000 and 10,000 labeled cells, respectively. The studied MNCs are sensitive for cell imaging and promising for MR cell tracking in clinics

Mechanism investigation and structure design of organic photovoltaic cells for improved energy conversion efficiency

Ph.DDOCTOR OF PHILOSOPH

Microstructure Engineering of Metal-Halide Perovskite Films for Efficient Solar Cells

Photovoltaic (PV) devices with metal-halide perovskite films, namely perovskite solar cells, have become a rapidly rising star due to low cost of raw materials, simple solution processability, and swiftly increased power conversion efficiency (PCE). The PCEs so far certified have gone beyond 22% for perovskite solar cells and 23.6% for tandem devices with single crystalline silicon solar cells, which offer a promising PV technology for practical applications. In principle, performance of perovskite solar cells are largely dominated by the optoelectronic properties and stability of metal-halide perovskite films, which are determined by the microstructure features of the films in turns. In this chapter, we will describe the recently developed strategies on microstructure engineering of metal-halide perovskite films for efficient perovskite solar cells

Organic Field-Effect Transistor: Device Physics, Materials, and Process

Organic field-effect transistors have received much attention in the area of low cost, large area, flexible, and printable electronic devices. Lots of efforts have been devoted to achieve comparable device performance with high charge carrier mobility and good air stability. Meanwhile, in order to reduce the fabrication costs, simple fabrication conditions such as the printing techniques have been frequently used. Apart from device optimization, developing novel organic semiconductor materials and using thin-film alignment techniques are other ways to achieve high-performance devices and functional device applications. It is expected that by combining proper organic semiconductor materials and appropriate fabrication techniques, high-performance devices for various applications could be obtained. In this chapter, the organic field-effect transistor in terms of device physics, organic materials, device process, and various thin-film alignment techniques will be discussed

Traffic congestion simulation and evaluation method for large passenger station region

The passenger station region is an important distribution channel which connects the large passenger station with the outside traffic of the region. Based on the actual situation of passenger station region and "point-line-area" thought, a "section (intersection)-road-network" traffic congestion evaluation index system was built for the passenger station region. Moreover, the combined method of "status division" and "integrated weighting" was adopted to evaluate the traffic congestion intensity of "point”, “line” and “area” layers. Further, a VISSIM simulation platform was established for the Beijing South Railway Station region to simulate and evaluate its traffic congestion intensity. The result shows that most of the “points” are in a state of mild congestion, parts of the “lines” are severe congested, and the whole network’s traffic congestion intensity is moderate congested. That means the congestion has a cumulative effect and a congested point may lead to the whole network congestion

Optimisation of Signal Timing at Intersections with Waiting Areas

Unconventional geometric designs such as continu-ous-flow intersections, U-turns, and contraflow left-turn lanes have been proposed to reduce left-turn conflicts and improve intersection efficiency. Having a waiting area at a signalised intersection is an unconventional de-sign that is used widely in China and Japan to improve traffic capacity. Many studies have shown that waiting areas improve traffic capacity greatly, but few have con-sidered how to improve the benefits of this design from the aspect of signal optimisation. Comparing the start-up process of intersections with and without waiting areas, this work explores how this geometric design influenc-es vehicle transit time, proposes two signal optimisation strategies, and establishes a unified capacity calculation model. Taking capacity maximisation as the optimisation function, a cycle optimisation model is derived for over-saturated intersections. Finally, the relationship among waiting-area storage capacity, cycle time, and traffic ca-pacity is discussed using field survey data. The results of two cases show that optimising the signal scheme helps reduce intersection delays by 10–15%

A Study on the Media Framework during Beijing Winter Olympic Games from a Comparative Perspective: Taking People’s Daily Online and CNN as Examples

Upon the conclusion of the 2022 Beijing Winter Olympic Games, the media coverage of this sports event of worldwide prestige has piled up as countless. However, the coverage of the Beijing Winter Olympics varies across countries, and it is up to different media to tailor and package the information to be delivered to the public according to their value standards, political tendencies, ideologies, etc. Based on a review of existing literature, this paper is devoted to the exploration of the underlying media framework of China and United States through a comparative study with a certain theoretical basis by taking their practices as examples to distinguish the choices made by these two countries on conducting both negative and positive reporting and their divergence in pursing either the “universal solidarity” or conflicts and divisions