![]() ![]() conclude that in polyfluorene copolymers hole transport is entirely dominated by disorder. In fact, in their recent work, Mensfoort et al. Copyright (2008) by the American Institute of Physics. The data are inferred from space-charge-limited current experiments and analyzed in terms of the extended Gaussian disorder model (see Sect. 8 Temperature dependence of the zero field hole mobility in the low carrier density limit in a polyfluorene copolymer. ![]() Woo, Transient and steady-state space-charge-limited currents in polyfluorene copolymer diode structures with ohmic hole injection contacts, Appl. (13.4), the monopolar SCLC current could be well approximated by. Muigatroyd was able to show that, for a mobility as in Eq. One result of the field-dependent mobility is that the space charge-limited current (SCLC, the maximum current that can How in the bulk of the sample) does no longer follow a simple V2H scaling on the voltage Land sample thickness L. A summary of the results for the hole mobility of PPV and PPV- related polymers is given in Table 11-1. Two main methods have been used to measure the charge carrier mobility in electroluminescent polymers time of flight (TOF) carrier transit time measurements and analysis of the current-voltage (1-V) characteristics of single carrier devices in the space charge-limited current (SCLC) regime. The charge density and potential are then given by In 1940, Mott and Gurney derived an exact solution in the particular case where 7 = 0, for a semi infinite material, and assuming that the electric field is zero at X = 00. ![]() This second order differential equation cannot be analytically solved in the general case. The electric field created by the injected charges generates a current density J, which is the sum of a drift and a diffusion current The resulting carrier profile can be calculated from Maxwell s equations, the more pertinent of which is Poisson s equation Į is the dielectric constant of the insulator, and o the permittivity of free space. When charges diffuse into an insulating material, they give rise to an electrostatic field that acts against the penetration of additional charges into the material. For information on how to file an appeal, see your Medicare & You handbook, or visit /appeals.Space-charge limited current (SCLC) occurs in materials with very low concentrations of free carriers (ideally, perfect insulators). If you disagree with a Medicare coverage or payment decision, you have the right to appeal. It’s important to ask questions so you understand why your doctor is recommending certain services and whether Medicare will pay for them. If this happens, you may have to pay some or all of the costs. Or, they may recommend services that Medicare doesn’t cover. Your doctor or other health care provider may recommend you get services more often than Medicare covers. When getting certain supplies and DME, Medicare will only pay for them from suppliers enrolled in Medicare, no matter who submits the claim (you or your supplier). The limiting charge applies only to certain services and doesn’t apply to some supplies and durable medical equipment (DME). However, there’s a limit called “the limiting charge,” which means the provider can’t charge more than 15% over the Medicare approved amount for non-participating providers. If your doctor doesn’t accept assignment, they may charge you more than the Medicare-approved amount for a service. If you choose to go to a physician or supplier that does not accept assignment, there are a few things you should know. When you visit a doctor or provider that accepts assignment, you know that they are contracted with Medicare to accept the Medicare-approved amount for a particular service as full payment. ![]()
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