Regular Configuration

PEDOT PSS is the most commonly used p-type material, but different formulations are used. To process on top of ZnO, the PEDOT PSS solution needs to have neutral pH to prevent dissolution of the ZnO. This can been achieved by neutralizing the commercial PEDOTrPSS (PH500) dispersion in water with 2-dimethylaminoethanol (DMAE), or by using a commercial pH-neutral PEDOT PSS (Orgacon N-1005). The pH-neutral PEDOTrPSS, however, has a lower work function than the commonly used highly acidic PEDOTrPSS dispersion. The work function decreases from 5.05 eV (at pH 1.75) to 4.65 eV (at pH 7). This can cause a voltage loss when combined with photoactive layers that have a deep HOMO level. In practice it difficult to achieve a Poc 0.7 V with pH-neutral PEDOT. The problem can be alleviated, however, by depositing a thin layer of Nafion on the pH-neutral PEDOT PSS to modify the workfunction.  

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In stereoregular polymers, each monomer segment is in regular configuration, it gives a structural regularity to the polymer molecule as a whole. 

The cited relationship for all classes of regular configuration are just the simplest. The subject is discussed comprehensively by Nye (1962), and practically by Yushkin (1971). Some authors recommend Su, the hardness constant, and some Sik, the elasticity constant. 

Usually phase transition in a gas-solid system is described by the topochemical models [44,194]. Such models assuming chaotic or regular configurations of the islands or nuclei of the new phase - disks or squares for the two-dimensional and sphere for the three-dimensional reaction systems. The reaction rate depends on the duration of aggregation (on the initial distribution and configuration of the islands) and that of the reaction itself. Its value is much lower than that taking place in the chaotic distribution of the adspecies. 

Borates are far more complex in their structural chemistry than carbonates and nitrates, and for that reason are discussed separately later ( 11.02, 11.03). Here, however, we may remark that many orthoborates of composition JB03 contain discrete B033 ions with the same regular configuration as the C032 and N03 ions and with a B-0 distance of 1 37 A. 

The case studies presented in this chapter illnstrate the great variety of domains in which the concept of multipole, with its variations of structnre, is pertinent for modeling different systems. The choice to take irregular multipoles in some domains and regular ones in other domains is arbitrary, or merely dictated by the exemplarity of the system. Every multipole presented as irregnlar could have been studied in the regular configuration and conversely. 

The process of solification proceeds with the formation (when possible) of crystalline material in which chains pack in a lattice with tri-dimensional periodicity. The conditions for perfect packing are that chains possess chemical regularity, configurational periodicity, and conformational regularity. 

The surface of a carbon fiber (or of diamond, graphite, and any other crystalline solid) has been described as an extreme case of lattice defect. " The regular configuration of carbon atoms ends abruptly and the surface atoms have a different coordination with dangling bonds which are able to react with any atom or molecule present on the surface. The result is the formation of compounds such as basic or acidic surface oxides, COj, and... 

Not all polymer chains can be crystallized only those with stereoregularity can. For example, polyethylene can be crystallized because there is a regular configuration inherent in the monomer. Polypropylene, on the other hand, can be crystallized only under certain conditions. The crystal structures of these two polymers are also quite different. The former is packed in a zigzag form, whereas the latter has helical content (not, of course, 100%). We select these two polymers to illustrate the crystal structure, if any, of synthetic polymers. 

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