Polymer, lifetime

Ionic Liquid Used in Long-Lifetime Polymer Light-Emitting Electrochemical Cells... 

Long-lifetime polymer light-emitting electrochemical cells with ionic liquid... 

The importance of polymer composites arises largely from the fact that such low density materials can have unusually high elastic modulus and tensile strength. Polymers have extensive applications in various fields of industry and agriculture. They are used as constructional materials or protective coatings. Exploitation of polymers is of special importance for products that may be exposed to the radiation or temperature, since the use of polymers make it possible to decrease the consumption of expensive (and, sometimes, deficient) metals and alloys, and to extent the lifetime of the whole product. 

If we multiply the time elapsed per monomer added to a radical by the number of monomers in the average chain, then we obtain the time during which the radical exists. This is the definition of the radical lifetime. The number of monomers in a polymer chain is, of course, the degree of polymerization. Therefore we write... 

The lifetime of polystyrene radicals at 50 C was measuredt by the rotating sector method as a function of the extent of conversion to polymer. The following results were obtained ... 

However, not all excitons have sufficiently long lifetimes to reach the interface before recombining. To circumvent this problem and increase device efficiency, heterostmcture devices have been fabricated. In these devices, donors and acceptors are mixed together to create a network that provides many internal interfaces where charge separation can occur. Heterostmcture devices made from the donor polymer... 

Quantum well interface roughness Carrier or doping density Electron temperature Rotational relaxation times Viscosity Relative quantity Molecular weight Polymer conformation Radiative efficiency Surface damage Excited state lifetime Impurity or defect concentration... 

Thus, in order to reproduce the effect of an experimentally existing activation barrier for the scission/recombination process, one may introduce into the MC simulation the notion of frequency , lo, with which, every so many MC steps, an attempt for scission and/or recombination is undertaken. Clearly, as uj is reduced to zero, the average lifetime of the chains, which is proportional by detailed balance to Tbreak) will grow to infinity until the limit of conventional dead polymers is reached. In a computer experiment Lo can be easily controlled and various transport properties such as mean-square displacements (MSQ) and diffusion constants, which essentially depend on Tbreak) can be studied. 

Consider normal Rouse dynamics of a polymer of length A chosen such that, during its lifetime, the chain MSQ is equal to its gyration radius Rg. Within a time interval Tbreak = cf. Eq. (24), where = o exp(-7) is... 

Despite the scientific progress and the demonstration of novel device concepts, there was considerable skepticism that semiconducting polymers would ever reach the levels of purity required for long-lifetime commercial devices. In the context of the last 50 years of semiconductor physics, conjugated polymers were often... 

PM spectra and their decays in DOO-PPV films and dilute solutions, we conclude that the primary excitations in DOO-PPV films are also singlet excitons [26]. The long excitonic lifetime and a corresponding high PL quantum efficiency [27] indicates that DOO-PPV is a high quality polymer material, which is very suitable for electrooptics and laser action applications [28],... 

The utility and importance of multi-layer device structures was demonstrated in the first report of oiganic molecular LEDs [7]. Since then, their use has been widespread in both organic molecular and polymer LEDs [45, 46], The details of the operating principles of many multi-layer structures continue to be investigated [47—49], The relative importance of charge carrier blocking versus improved carrier transport of the additional, non-luminescent layers is often unclear. The dramatic improvements in diode performance and, in many cases, device lifetime make a detailed understanding of multi-layer device physics essential. 

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