Charge injection influencing factors

The analytic theory outlined above provides valuable insight into the factors that determine the efficiency of OI.EDs. However, there is no completely analytical solution that includes diffusive transport of carriers, field-dependent mobilities, and specific injection mechanisms. Therefore, numerical simulations have been undertaken in order to provide quantitative solutions to the general case of the bipolar current problem for typical parameters of OLED materials [144—1481. Emphasis was given to the influence of charge injection and transport on OLED performance. 1. Campbell et at. [I47 found that, for Richardson-Dushman thermionic emission from a barrier height lower than 0.4 eV, the contact is able to supply... 

As pointed out before, interfaee stmeture in OFETs is important for both charge injection (metal-semiconductor interface) and charge transport (semi-conductor-dielectric interface). The discussion of the previous section demonstrates that even for the small number of model systems considered here a large variety of sfructures is observed. Because many factors influence the interface and film sfructures, it is difficult to establish general mles. Flowever, a few important observations regarding the stmcture-forming factors can be kept hold of ... 

In electroluminescence devices (LEDs) ionized traps form space charges, which govern the charge carrier injection from metal electrodes into the active material [21]. The same states that trap charge carriers may also act as a recombination center for the non-radiative decay of excitons. Therefore, the luminescence efficiency as well as charge earner transport in LEDs are influenced by traps. Both factors determine the quantum efficiency of LEDs. 

The above cited factors influencing the hole injection kinetics have important consequences on the dark open-circuit etching behavior of GaP single crystals in alkaline Fe(CN) solutions. At the (lll)-face, the open-circuit etching rate is always found to be controlled by the rate of the charge transfer reaction (so-called kinetic control). At the (lll)-face, on the other hand, the etching rate is always found to be limited by ion diffusion towards the semiconductor surface, either of Fe(CN) (for Fe(CN) concentrations lower than 0.3 mol -1 or of OH (for Fe(CN) concentrations higher than 0.3 mol 1 ). This difference between the two polar... 

Time, temperature, and pressure are the primary factors influencing the surface flnish of the molded part. Time factors include rate of injection, duration of ram pressure, time of cooling, cross-linking time, and rotation of the screw (RPM). Pressure factors are applied pressure (high or low), back pressure on the extruder screw, and pressure loss before the charge enters the cavity, which can be caused by a variety of restrictions in the mold cavity. Temperature factors are mold (cavity and core), barrel, and nozzle temperatures, as well as the melt temperature because of back pressure, screw speed, and frictional heat. 

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