Sheng-Hsiung Yang

Bio: Sheng-Hsiung Yang is an academic researcher from National Chiao Tung University. The author has contributed to research in topics: Perovskite (structure) & Materials science. The author has an hindex of 19, co-authored 63 publications receiving 4346 citations.

Synthesis of Conjugated Polymers for Organic Solar Cell Applications

Abstract: -phenylenevinylene)s L4. Fluorene-Based Conjugated Polymers L4.1. Fluorene-Based Copolymers ContainingElectron-Rich MoietiesM4.2. Fluorene-Based Copolymers ContainingElectron-Deficient MoietiesN4.3. Fluorene-Based Copolymers ContainingPhosphorescent ComplexesQ5. Carbazole-Based Conjugated Polymers R5.1. Poly(2,7-carbazole)-Based Polymers R5.2. Indolo[3,2-

Liquid crystalline conjugated polymers and their applications in organic electronics

Abstract: This article de- scribes the syntheses and electro- optical applications of liquid crys- talline (LC) conjugated polymers, for example, poly(p-phenylene vinylene), polyfluorene, polythio- phene, and other conjugated poly- mers. The polymerization involves several mechanisms: the Gilch route, Heck coupling, or Knoeve- nagel condensation for poly(p- phenylenevinylene)s, the Suzuki- or Yamamoto-coupling reaction for polyfluorenes, and miscella- neous coupling reactions for other conjugated polymers. These LC conjugated polymers are classified into two types: conjugated main chain polymers with long alkyl side chains, namely main-chain type LC polymers, and conjugated polymers grafting with mesogenic side groups, namely side-chain type LC conjugated polymers. In general, the former shows higher transition temperature and only nematic phase; the latter possesses lower transition temperature and more mesophases, for example, smectic and nematic phases, depending on the structure of mesogenic side chains. The fully conjugated main chain promises them as good candidates for polar- ized electroluminescent or field- effect devices. The polarized emission can be obtained by sur- face rubbing or thermal annealing in liquid crystalline phase, with maximum dichroic ratio more

Nano approach investigation of the conduction mechanism in polyaniline nanofibers.

Abstract: A nanotechnological approach is applied to measurements of the electric field dependence of resistance under a high electric field while in low voltage. With this technique, the conduction mechanism on a mesoscopic scale is explored in a single, nonagglomerated nanofiber. Polyaniline nanofibers are prepared by vigorous mixing of aniline and oxidation agent ammonium persulfate in acid solution. They exhibit a uniform nanoscale morphology rather than agglomeration as that produced via conventional chemical oxidation. The as-synthesized polyaniline nanofibers are doped (dedoped) with a HCl acid (NH3 base), and their temperature behaviors of resistances follow an exponential function with an exponent of T−1/2. To measure the conduction mechanism in a single nanofiber, the dielectrophoresis technique is implemented to position nanofibers on top of two electrodes with a nanogap of 100−600 nm, patterned by electron-beam lithography. After the devices are irradiated by electron beam to reduce contact resistances,...

Optical and electrical properties of PPV/SiO2 and PPV/TiO2 composite materials

Abstract: Composites made by incorporation of SiO2 or TiO2 nanoparticles into poly(p-phenylene vinylene) (PPV) have been fabricated and their optical and electrical properties have been investigated. The UV–vis absorption band of the composite films showed a large blue-shift with SiO2 nanoparticles, but only little difference with TiO2 nanoparticles. Photoluminescence (PL) spectra showed the same blue-shift trend for SiO2 composites, and in addition, an increase in intensity of the high energy shoulder (515 nm) when the concentration of nanoparticles increased. Raman spectra showed a reduction of the 1547/1625 cm−1 band ratio in SiO2 composites but not in TiO2 ones. These results suggest that SiO2 nanoparticles reduced the PPV conjugation length, while TiO2 nanoparticles did not. For SiO2 particles, the reduction of conjugation lengths is more pronounced on increasing the oxide concentration or on decreasing the particle size. Fourier-transform Infrared (FT-IR) spectra showed that both types of nanoparticles reduced the formation of carbonyl groups in PPV main chains. Current-voltage characteristics measured in ITO–composite–MgAg diodes exhibit different electrical behavior of the composites depending on the particle size and the nature of the oxide. The composite-electrode contact morphology, the polymer–dielectric particle contact and the change in the polymer chain length are the possible explanations for these changes in behavior of the diodes.

Phd by thesis

Abstract: Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Polymer solar cells

Abstract: This Review summarizes recent progress in the development of polymer solar cells. It covers the scientific origins and basic properties of polymer solar cell technology, material requirements and device operation mechanisms, while also providing a synopsis of major achievements in the field over the past few years. Potential future developments and the applications of this technology are also briefly discussed.

Molecular design of photovoltaic materials for polymer solar cells: toward suitable electronic energy levels and broad absorption.

Abstract: Bulk heterojunction (BHJ) polymer solar cells (PSCs) sandwich a blend layer of conjugated polymer donor and fullerene derivative acceptor between a transparent ITO positive electrode and a low work function metal negative electrode. In comparison with traditional inorganic semiconductor solar cells, PSCs offer a simpler device structure, easier fabrication, lower cost, and lighter weight, and these structures can be fabricated into flexible devices. But currently the power conversion efficiency (PCE) of the PSCs is not sufficient for future commercialization. The polymer donors and fullerene derivative acceptors are the key photovoltaic materials that will need to be optimized for high-performance PSCs.In this Account, I discuss the basic requirements and scientific issues in the molecular design of high efficiency photovoltaic molecules. I also summarize recent progress in electronic energy level engineering and absorption spectral broadening of the donor and acceptor photovoltaic materials by my researc...

Synthesis of Light-Emitting Conjugated Polymers for Applications in Electroluminescent Devices

Abstract: A review was presented to demonstrate a historical description of the synthesis of light-emitting conjugated polymers for applications in electroluminescent devices. Electroluminescence (EL) was first reported in poly(para-phenylene vinylene) (PPV) in 1990 and researchers continued to make significant efforts to develop conjugated materials as the active units in light-emitting devices (LED) to be used in display applications. Conjugated oligomers were used as luminescent materials and as models for conjugated polymers in the review. Oligomers were used to demonstrate a structure and property relationship to determine a key polymer property or to demonstrate a technique that was to be applied to polymers. The review focused on demonstrating the way polymer structures were made and the way their properties were controlled by intelligent and rational and synthetic design.

Organic and solution-processed tandem solar cells with 17.3% efficiency

Abstract: Although organic photovoltaic (OPV) cells have many advantages, their performance still lags far behind that of other photovoltaic platforms. A fundamental reason for their low performance is the low charge mobility of organic materials, leading to a limit on the active-layer thickness and efficient light absorption. In this work, guided by a semi-empirical model analysis and using the tandem cell strategy to overcome such issues, and taking advantage of the high diversity and easily tunable band structure of organic materials, a record and certified 17.29% power conversion efficiency for a two-terminal monolithic solution-processed tandem OPV is achieved.