Plasticizer hole transporting

Numerous photoconductive plasticizers are used to lower the glass transition temperature to below 20°C and act as hole transporting plasticizers. " These include N-meth-ylcaibazole, N-ethylcaibazole, N-butylcarbazole, N-hexylcaibazole, N-phenylcarbazole,... 

Figure 10.26 shows the efficiency of the LED, as a function of the current density. The emission efficiency reaches a peak of 14.5 Cd/A at about 34 mA/cm2 with 5000 Cd/m2 luminance. The corresponding external quantum efficiency is 3.86%. The inset of Fig. 10.26 shows the luminous efficiency as a function of the current density. The peak value is 2.26 lm/W at 17 mA/cm2 with 2400 Cd/m2 luminance. He and Kanicki later reported higher efficiencies (56.2 Cd/A and 9.0 lm/W) for LEDs using the same emitting and hole-transport layers for an LED fabricated on a flexible, plastic substrate.61 The turn-on voltage of the LEDs was measured to be 6 V. 

The basic structure of a typical OLED is shown in Fig. 3.1 [35]. It consists of a transparent conducting anode, typically indium tin oxide (ITO) coated on a glass or plastic mechanical support, the organic layers, and a metal cathode. The thickness of OLEDs (excluding the mechanical support) is typically <0.5 j,m. Under forward bias electrons are injected from the low-workfunction cathode into the electron-transport layer (ETL). Similarly, holes are injected from the high-workfunction ITO into the hole-transport layer (HTL). Due to the applied bias, the electrons and holes drift toward each other, and typically recombine in a recombination zone near, or at, the ETL/HTL interface. A fraction of the recombination events forms radiative excited states. The radiative decay of these states provides the electroluminescence (EL) of the device. 

Poly(siloxane)s. An alternative to PVK is the hole-transporting polymer poly(methyl-bis-(3-methox5 henyl)-(4-propylphenyl)amine)siloxane. It has been doped with the photorefractive chromophore 4-di(2-methoxy-ethyl) aminobenzylidene malononitrile. The low intrinsic glass transition temperature of the siloxane pol5mier allows the preparation of samples without additional plasticizers. The composites exhibit good chromophore orientational mobility and exhibit photorefractive response times in the millisecond range. ... 

The general structure of the bilayer solar cells is similar to the light-emitting diodes (LEDs). The devices are fabricated in sandwich geometry (Fig. 11.9). The active layer is sandwiched between two contacts an indium-tin-oxide electrode (ITO) (cathode) coated with a hole transport layer/glass or plastic foil. The blend polymer/PCBM solution was doctor-bladed on top of the hole conductor PEDOT PSS [poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonic acid]. It improves the surface quality of ITO electrode. On the top of this polymer, about 100-nm aluminum layer is placed as an electrode (anode). 

In general terms, as has already been mentioned, plastic deformation is a transport process analogous with electrical and thermal conductivity. These involve an entity to be transported, a carrier that does the transporting, and a rate of transport. In the case of electrical conductivity, charge is the transport entity, electrons (or holes) are the carriers, and the electron net velocities determine the rate. In the case of plastic deformation, displacement, b (cm) is the transport entity, dislocations are the carriers, N ( /cm2), and their velocities, v (cm/sec) determine the shear deformation rate, d8/dt. In two dimensions, the latter is given by the Orowan Equation ... 

The dual-mode model has also been applied with some success to the sorption and transport behavior of small- and intermediate-size organic molecules in glasses (75). Above some size, however, the penetrant may be too large to be accommodated solely within individual holes, and two truly distinct environments may not actually exist for these penetrants. Even in this case, however, the concept of unrelaxed free volume remains valid, and observations of sorption and dilation behavior that apply to gases also apply qualitatively to larger penetrants up to the point of extreme plasticization where an actual glass transition occurs. 

Final stage coarse screening machines must handle high trash content On the other hand low fiber loss and high cleanUness efficiency are required. The machine in Fig. 4.18 is not pressurized and operates at a consistency of about 1-4% in the accept Screen hole sizes are about 2 to 4 mm. Rotors fitted with vanes keep the screen clear and transport the debris such as plastics to the outlet During the pass through the machine water sprays support the separation of fibers and debris resulting in a low fiber content in the reject Another type of tail screen (Fig. 4.19)... 

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