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Mark D. Watson

Bio: Mark D. Watson is an academic researcher from Max Planck Society. The author has contributed to research in topics: Discotic liquid crystal & Hexabenzocoronene. The author has an hindex of 31, co-authored 52 publications receiving 4567 citations.

Papers published on a yearly basis

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TL;DR: In this paper, the authors describe the preparation of large, yet well-defined, nanoscale polycyclic aromatic hydrocarbons (PBAHs), which then self-assemble to highly ordered, supramolecular arrays with advantageous electronic properties.
Abstract: Recent advances in the field of organic molecular electronics include an increasingly significant role of discotic structures based on all-benzenoid polycyclic aromatic hydrocarbons (PBAHs), reflected by the growing research activities in this field. Progress has profited largely from an iterative approach based on cooperation between synthetic organic chemists and physicists, both in academia and industry. The current paper deals with this class of compounds, describing the preparation of large, yet well-defined, nanoscale PBAH moieties, which then self-assemble to highly ordered, supramolecular arrays with advantageous electronic properties. Progressive miniaturisation leads from thin films as one-dimensional charge-transport layers, to single columns as potential nanowires or data storage elements, to single molecules and nanoscale (opto)electronically active components. The use of ‘large’ (diameter ≥1 nm) disks ensures a columnar arrangement, which can be further modified by peripheral substitution to encode bulk 3-dimensional packing, orientation at interfaces, thermal properties, and processability. Adaptation of processing techniques from solution, melt or the vapour phase plays a crucial role for the (supra)molecular arrangement, which can be controlled from the macroscopic down to the nanometre scale. Finally, the characteristics of each new material can be evaluated in terms of supramolecular order, electronic device performance, single molecule properties, etc. This paper gives a brief overview of synthetic methods and molecular design, followed by evaluation of their columnar structures over various length scales down to nanoscale, processing techniques, and device performance/electrical characterisation.

273 citations

Journal ArticleDOI
TL;DR: Atomic force microscopy together with X-ray diffraction reveals single-crystalline-like order over several square centimeters, far exceeding the requirements for application of thin films of a discotic columnar thermotropic liquid crystalline material in organic molecular electronic devices such as field-effect transistors.
Abstract: Uniaxially aligned, thin films of a discotic columnar thermotropic liquid crystalline material can be prepared by a simple solution zone-casting method, without the need for modified surfaces or traditional alignment techniques. Atomic force microscopy together with X-ray diffraction reveals single-crystalline-like order over several square centimeters, far exceeding the requirements for application of such films in organic molecular electronic devices such as field-effect transistors.

243 citations

Journal ArticleDOI
Jishan Wu1, Mark D. Watson1, Li Zhang1, Zhaohui Wang1, Klaus Müllen1 
TL;DR: Compared to the normal alkyl-subsituted hexabenzocoronenes (HBCs), 14a-c exhibit more highly ordered columnar mesophases, including three-dimensionally ordered superstructures (helical columnar Mesophase) that could arise from additional intracolumnar pi-pi interactions between, and space-filling requirements introduced by, the rigid-rod side groups.
Abstract: Hexakis (4-iodophenyl)-peri-hexabenzocoronene (5), a novel functionalizable mesogenic building block, was prepared by rational multistep synthesis. Although sparingly soluble in common solvents, it can be obtained in pure form and then functionalized via Hagihara−Sonogashira coupling to give a series of highly ordered columnar liquid crystalline molecules 14a−c. The total synthesis involves five 6-fold transformations, all in excellent to near quantitative isolated yields. Their thermotropic liquid crystalline behavior was studied by differential scanning calorimetry (DSC), polarized optical microscopy (POM) and wide-angle X-ray diffraction (WAXD). Compared to the normal alkyl-subsituted hexabenzocoronenes (HBCs), 14a−c exhibit more highly ordered columnar mesophases, including three-dimensionally ordered superstructures (helical columnar mesophase). These could arise from additional intracolumnar π−π interactions between, and space-filling requirements introduced by, the rigid-rod side groups. Atomic for...

176 citations


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TL;DR: This review gives a general introduction to the materials, production techniques, working principles, critical parameters, and stability of the organic solar cells, and discusses the alternative approaches such as polymer/polymer solar cells and organic/inorganic hybrid solar cells.
Abstract: The need to develop inexpensive renewable energy sources stimulates scientific research for efficient, low-cost photovoltaic devices.1 The organic, polymer-based photovoltaic elements have introduced at least the potential of obtaining cheap and easy methods to produce energy from light.2 The possibility of chemically manipulating the material properties of polymers (plastics) combined with a variety of easy and cheap processing techniques has made polymer-based materials present in almost every aspect of modern society.3 Organic semiconductors have several advantages: (a) lowcost synthesis, and (b) easy manufacture of thin film devices by vacuum evaporation/sublimation or solution cast or printing technologies. Furthermore, organic semiconductor thin films may show high absorption coefficients4 exceeding 105 cm-1, which makes them good chromophores for optoelectronic applications. The electronic band gap of organic semiconductors can be engineered by chemical synthesis for simple color changing of light emitting diodes (LEDs).5 Charge carrier mobilities as high as 10 cm2/V‚s6 made them competitive with amorphous silicon.7 This review is organized as follows. In the first part, we will give a general introduction to the materials, production techniques, working principles, critical parameters, and stability of the organic solar cells. In the second part, we will focus on conjugated polymer/fullerene bulk heterojunction solar cells, mainly on polyphenylenevinylene (PPV) derivatives/(1-(3-methoxycarbonyl) propyl-1-phenyl[6,6]C61) (PCBM) fullerene derivatives and poly(3-hexylthiophene) (P3HT)/PCBM systems. In the third part, we will discuss the alternative approaches such as polymer/polymer solar cells and organic/inorganic hybrid solar cells. In the fourth part, we will suggest possible routes for further improvements and finish with some conclusions. The different papers mentioned in the text have been chosen for didactical purposes and cannot reflect the chronology of the research field nor have a claim of completeness. The further interested reader is referred to the vast amount of quality papers published in this field during the past decade.

6,059 citations

Journal ArticleDOI
29 Apr 2004-Nature
TL;DR: The future holds even greater promise for this technology, with an entirely new generation of ultralow-cost, lightweight and even flexible electronic devices in the offing, which will perform functions traditionally accomplished using much more expensive components based on conventional semiconductor materials such as silicon.
Abstract: Organic electronics are beginning to make significant inroads into the commercial world, and if the field continues to progress at its current, rapid pace, electronics based on organic thin-film materials will soon become a mainstay of our technological existence. Already products based on active thin-film organic devices are in the market place, most notably the displays of several mobile electronic appliances. Yet the future holds even greater promise for this technology, with an entirely new generation of ultralow-cost, lightweight and even flexible electronic devices in the offing, which will perform functions traditionally accomplished using much more expensive components based on conventional semiconductor materials such as silicon.

4,967 citations

Journal ArticleDOI
Chengliang Wang1, Huanli Dong1, Wenping Hu1, Yunqi Liu1, Daoben Zhu1 
TL;DR: The focus of this review will be on the performance analysis of π-conjugated systems in OFETs, a kind of device consisting of an organic semiconducting layer, a gate insulator layer, and three terminals that provide an important insight into the charge transport of ρconjugate systems.
Abstract: Since the discovery of highly conducting polyacetylene by Shirakawa, MacDiarmid, and Heeger in 1977, π-conjugated systems have attracted much attention as futuristic materials for the development and production of the next generation of electronics, that is, organic electronics. Conceptually, organic electronics are quite different from conventional inorganic solid state electronics because the structural versatility of organic semiconductors allows for the incorporation of functionality by molecular design. This versatility leads to a new era in the design of electronic devices. To date, the great number of π-conjugated semiconducting materials that have either been discovered or synthesized generate an exciting library of π-conjugated systems for use in organic electronics. 11 However, some key challenges for further advancement remain: the low mobility and stability of organic semiconductors, the lack of knowledge regarding structure property relationships for understanding the fundamental chemical aspects behind the structural design, and realization of desired properties. Organic field-effect transistors (OFETs) are a kind of device consisting of an organic semiconducting layer, a gate insulator layer, and three terminals (drain, source, and gate electrodes). OFETs are not only essential building blocks for the next generation of cheap and flexible organic circuits, but they also provide an important insight into the charge transport of πconjugated systems. Therefore, they act as strong tools for the exploration of the structure property relationships of πconjugated systems, such as parameters of field-effect mobility (μ, the drift velocity of carriers under unit electric field), current on/off ratio (the ratio of the maximum on-state current to the minimum off-state current), and threshold voltage (the minimum gate voltage that is required to turn on the transistor). 17 Since the discovery of OFETs in the 1980s, they have attracted much attention. Research onOFETs includes the discovery, design, and synthesis of π-conjugated systems for OFETs, device optimization, development of applications in radio frequency identification (RFID) tags, flexible displays, electronic papers, sensors, and so forth. It is beyond the scope of this review to cover all aspects of π-conjugated systems; hence, our focus will be on the performance analysis of π-conjugated systems in OFETs. This should make it possible to extract information regarding the fundamental merit of semiconducting π-conjugated materials and capture what is needed for newmaterials and what is the synthesis orientation of newπ-conjugated systems. In fact, for a new science with many practical applications, the field of organic electronics is progressing extremely rapidly. For example, using “organic field effect transistor” or “organic field effect transistors” as the query keywords to search the Web of Science citation database, it is possible to show the distribution of papers over recent years as shown in Figure 1A. It is very clear

2,942 citations