Contactive charge transport

The efficient formation of singlet excitons from the positive and negative charge carriers, which are injected via the metallic contacts and transported as positive and negative polarons (P+ and P ) in the layer, and the efficient radiative recombination of these singlet excitons formed are crucial processes for the function of efficient electroluminescence devices. 

In coulometry these exchange membranes are often used to prevent the electrolyte around the counter electrode from entering the titration compartment (see coulometry, Section 3.5). However, with membrane electrodes the ion-exchange activity is confined to the membrane surfaces in direct contact with the solutions on both sides, whilst the internal region must remain impermeable to the solution and its ions, which excludes a diffusion potential nevertheless, the material must facilitate some ionic charge transport internally in order to permit measurement of the total potential across the membrane. The specific way in which all these requirements are fulfilled in practice depends on the type of membrane electrode under consideration. 

Kushmerick JG, Holt DB, Yang JC, Naciri J, Moore MH, Shashidhar R (2002) Metal-molecule contacts and charge transport across monomolecular layers measurement and theory. Phys Rev Lett 89 86802... 

The discrepancies in the reported conductance data of Au-alkanedithiol-Au junctions attracted our attention, and we decided to carry out an in-depth experimental study of the charge transport properties of Au-a,oo-alkanedithiol-Au molecule junctions in a non-conducting solvent. The combination with quantum chemistry ab initio simulations yielded a detailed view of this archetype of molecular junctions, and helped to resolve the puzzle on the role of microscopic geometries at the contacts and in the molecular conformation. 

To facilitate good charge transport in an OLED, the organic materials must satisfy three key requirements they must have a high mobility for either electrons or holes, a good injection efficiency from the contact electrode, and suitable band offsets with other organic layers within the device. These processes are discussed in detail by, for example, Kalinowski [73] and Greenham and Friend [74],... 

In the case of redox sites covalently bound to a polymer backbone, when only Dg contributes to charge transport. Equation 2.12 has systematically failed to explain the dependence of D pp with the concentration of redox sites. Blauch and Saveant have shown that for completely immobile centers, charge transport is basically a percolation process random distribution of isolated clusters of electrochemically coimected sites [33,40]. Only by dynamic rearrangements can these clusters become in contact and charge transport occur, giving rise to the concept of bound diffusion where each... 

In principle a STM should be adequate to measure the electrical resistance of a single molecule since it suffices to measure I-V curves of the metal (tip)-molecule-metal (substrate) system. However, published results in the literature concerning this subject have to be considered cautiously because of the generally unknown nature of the molecule-metal contacts. An illustrative experiment demonstrates the relevance of the interface (Kushmerick et al, 2002). This experimental work studies charge transport using the cross-wire tunnel junction technique, where two... 

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