Ionic electronic devices

The uncertainty principle is negligible for macroscopic objects. Electronic devices, however, are being manufactured on a smaller and smaller scale, and the properties of nanoparticles, particles with sizes that range from a few to several hundred nanometers, may be different from those of larger particles as a result of quantum mechanical phenomena, (a) Calculate the minimum uncertainty in the speed of an electron confined in a nanoparticle of diameter 200. nm and compare that uncertainty with the uncertainty in speed of an electron confined to a wire of length 1.00 mm. (b) Calculate the minimum uncertainty in the speed of a I.i+ ion confined in a nanoparticle that has a diameter of 200. nm and is composed of a lithium compound through which the lithium ions can move at elevated temperatures (ionic conductor), (c) Which could be measured more accurately in a nanoparticle, the speed of an electron or the speed of a Li+ ion ... 

Knowing the electrochemical properties of CNTs is important for the rational design of electronic devices however, the study of the electrochemical properties of carbon nanotubes as individual entities or individual molecules has encountered diverse problems. The extremely low solubility of CNT samples, the ionic strength... 

From the foregoing discussion of electric field effects In Ionic equlibria It Is clear that a solution of a weak electrolyte shows a non-linear behavior In conductance (or resistance) at high field strengths. With an Interdisciplinary look at the field of electronics we note that such nonlinearities are at the heart of all modern electronic circuits and devices. We therefore can use a solution of a weak electrolyte subjects to high electric fields as an electronic device, which Is the basic Idea of the Field Modulation Tecnnlque, the general principles we will discuss now. 

The formation of photonic, electronic, ionic switching devices from molecular components and their incorporation into well-defined organized assemblies represents the next step towards the development of circuitry and functional materials at... 

Chemical bonds and population analysis Most metals of interest in the context of polymer-based electronic devices form some kind of chemical bond to the polymer upon interaction with a polymer surface. Population analysis, based on the electronic structure, is used to determine the character of this bond. According to the commonly used chemical terminology, bonds are classified as ionic if the bonded atoms are oppositely charged and held together by the attractive Coulomb force, and covalent if the two atoms are neutral but share the same pair of electrons. In the latter case, much of the electron density is located between the bonded atoms whereas for the ionic bond the charge density is concentrated at the atomic sites. 

The degree of ionicity in the bond between a metal atom and a polymer, or molecule, is related to the ionization potential and electron affinities of the substituents. The metals we have studied are of interest as electron injecting contacts in electronic devices. These metals must have a low ionization potential (or work function), of the same order as the electron affinity of the polymer, in order for the charge transfer process to occur. If the ionization potential of the metal is lower than the polymery-electron affinity, spontaneous charge transfer occurs which is the signature of an ionic bond. Thus, the character of the charge distribution in the metal-polymer complexes we are studying is related to the situation in the electronic device. 

The range of possible applications of multiscale simulations methods to electrochemical systems is extensive. Electrochemical phenomena control the existence and movement of charged species in the bulk, and across interfaces between ionic, electronic, semiconductor, photonic and dielectric materials. The existing technology base of the electrochemical field is massive and of long-standing [15, 16]. The pervasive occurrence of these phenomena in technological devices and processes, and in natural systems, includes ... 

Solid-state electrochemistry is an important and rapidly developing scientific field that integrates many aspects of classical electrochemical science and engineering, materials science, solid-state chemistry and physics, heterogeneous catalysis, and other areas of physical chemistry. This field comprises - but is not limited to - the electrochemistry of solid materials, the thermodynamics and kinetics of electrochemical reactions involving at least one solid phase, and also the transport of ions and electrons in solids and interactions between solid, liquid and/or gaseous phases, whenever these processes are essentially determined by the properties of solids and are relevant to the electrochemical reactions. The range of applications includes many types of batteries and fuel cells, a variety of sensors and analytical appliances, electrochemical pumps and compressors, ceramic membranes with ionic or mixed ionic-electronic conductivity, solid-state electrolyzers and electrocatalytic reactors, the synthesis of new materials with improved properties and corrosion protection, supercapacitors, and electrochromic and memory devices. 

Typical transfer molding compositions for encapsulation of electronic devices are mixtures of an epoxy novolac resin, a phenolic resin hardener, a catalyst, large amounts of inorganic filler (e.g., Si02) flame-retardant ingredients, internal lubricants, carbon black, and sometimes other additives such as getters to trap ionic impurities (34,35), corrosion-protection materials, and stress-relief ingredients. 

The most desirable properties for electrically conductive polymeric materials are film-forming ability and thermal and electrical properties. These properties are conveniently attained by chemical modification of polymers such as polycation-7, 7,8, 8-tetracyanoqninodimethane (TCNQ) radical anion salt formation (1-3). However, a major drawback of such a system is the brittle nature of the films and their poor stability (4,5) resulting from the polymeric ionicity. In recent years, polymeric composites (6-8) comprising TCNQ salt dispersions in non-ionic polymer matrices have been found to have better properties. In addition, the range of conductivities desired can be controlled by adjusting the TCNQ salt concentration, and other physical properties can be modified by choosing an appropriate polymer matrix. Thus, the composite systems are expected to have important advantages for use in electronic devices. 

However, the use of these ionic and redox polymers was rather limited to applications, such as molecular electronic devices, or sensors and biosensors (using immobilized enzymes), where the need for fast electrochemical reactions was not essential, because of the limitation of the reaction rate by a slow charge transport process inside the polymer (see Section 2). This excludes large-scale applications, as in fuel cells or in organic electrosynthesis. 

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