Charge generating and transporting

The performance characteristics of ceramic sensors are defined by one or more of the foUowing material properties bulk, grain boundary, interface, or surface. Sensor response arises from the nonelectrical input because the environmental variable effects charge generation and transport in the sensor material. 

Charge generating and transporting behavior of irradiated m.etallotetrapyr-role layers is exploited in the function of colour copiers [281-284]. Suited and practically used electrophotographic photoreceptors in the copiers comprise TiPc, TiOPc, VOPc, MnPc as parts of the layers. 

In order to study the physics of charge generation and transport in devices, it is helpful to define an internal measure. The internal quantum efficiency (IQE) or quantum yield can be obtained from the external quantum efficiency by considering only the light absorbed in the device. The sum of total absorp-tance A, transmittance T and reflectance R must be unity A + T + R = 1. In the case of thick devices, the transmittance is zero. Therefore the internal quantum efficiency is... 

Latent image fonnation involves the creation of free electron-hole pairs by the absorption of an image exposure and the displacement of these carriers by a field. Experimental techniques for characterizing these phenomena are of considerable importance to xerography. This section reviews experimental methods for measuring parameters that describe charge generation and transport phenomena. 

H. J. Snaith and R. H. Friend. Morphological dependence of charge generation and transport in blended polyfluorene photovoltaic devices. Thin Solid Films, 451-52 567-571, 2004. 

On the basis of these findings, it was suggested that PyF forms self-assembled coordination complexes at the interface between the top blend layer and underlying ZnPc film and these complexes mediate efficiently charge generation and transport at the interface. The power conversion efficiency of the first multicomponent cells was around 2.0%. 

The spectral response of photodiodes of this type provides detailed information about the device operation. Fig. 29.22 shows the spectral dependence of the short-circuit current for devices made with the polymer blend and with the individual polymers. Halls and coworkers find that the spectral response of the blend device matches the absorption (also shown in the figure) very closely and consider that this is excellent evidence of efficient charge generation and transport to the device electrodes. In contrast, the devices made with the individual polymers show more complicated spectral responses. For example, the peak in response for the MEH-PPV at the absorption edge is attributed to electron trapping in the photogeneration region [105]. 

Harvey T J, Wood R J K, Denuault G, Powrie H E G, Effect of oil quality on electrostatic charge generation and transport. Journal of Electrostatic,... 

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