Production Device Geometry

Indium-doped tin oxide (ITO) glasses are commonly used as semitransparent substrates with a transmission of around 90% in the visible range and a conductivity of around 20 ohm/square. The glass substrates 

In the following, we discuss strategies for optimizing the power efficiency of polymeric solar cells based upon bulk heterojunctions. 

Short-Circuit Current. Key parameters for efficient charge collection by plastic solar cells are the hole and electron mobilities of the interpenetrating networks and the lifetime of the carriers within this network. While the lifetime of the carriers in the bulk heterojunction blends has already been discussed as a peculiarity of the interpenetrating network, the mobility of the individual components is a true material parameter. The interplay between network quality and mobility and their impact on the short-circuit current will be discussed by means of a simple model in this section. 

The experimentally observed Voc of PSC cannot be explained by the MIM picture alone. For typical devices, based on ITO/conjugated polymer fullerene/Al, values of Voc can be observed in a range of 800 mV and higher for several polymer/fullerene mixtures, in contrast to the 400 mV expected from the MIM picture. The origin of the open-circuit voltage in plastic solar cells will be discussed and explained in Sect. 5.3.4. 

Fill Factor. The fill factor of solar cells is determined by 

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Erosion is typically characterized by either occurring on the surface or in the bulk. Surface erosion is controlled by the chemical reaction and/or dissolution kinetics, while bulk erosion is controlled by diffusion and transport processes such as polymer swelling, diffusion of water through the polymer matrix, and the diffusion of degradation products from the swollen polymer matrix. The processes of surface and bulk erosion are compared schematically in Fig. 1. These two processes are idealized descriptions. In real systems, the tendency towards surface versus bulk erosion behavior is a function of the particular chemistry and device geometry (Tamada and Langer, 1993). Surface erosion may permit the... 

While the metal (primarily Fe, iron) contamination of W CMP does not directly lead to any functionality or yield loss in the manufacturing of products of the current 0.35- m or larger technologies, it is questionable that the Fe contamination can be acceptable for the products with device geometries 0.25 fim and smaller. As the speed of the transistor increases to a certain crossover point, the speed of the integrated circuit as a whole becomes predominately dictated by the back-end processes [21]. 

The detection of chemical reaction products in device geometries has largely been limited to the observation of indirect effects. Electrochemical instability has been used to explain the differences in the lifetimes of OLEDs based on compounds of a homologous series when the expected correlation with the glass transition temperature (Tg) or the ionization potential was not observed.19 The oxidative... 

For detectors with photogain, an additional figure of merit, the gain-bandwidth MB) product is defined. It is simply the product of the 3-dB bandwidth and the DC gain. In many cases, the MB product is closely related to device geometry and device parameters. 

The radiation and temperature dependent mechanical properties of viscoelastic materials (modulus and loss) are of great interest throughout the plastics, polymer, and rubber from initial design to routine production. There are a number of laboratory research instruments are available to determine these properties. All these hardness tests conducted on polymeric materials involve the penetration of the sample under consideration by loaded spheres or other geometric shapes [1]. Most of these tests are to some extent arbitrary because the penetration of an indenter into viscoelastic material increases with time. For example, standard durometer test (the "Shore A") is widely used to measure the static "hardness" or resistance to indentation. However, it does not measure basic material properties, and its results depend on the specimen geometry (it is difficult to make available the identity of the initial position of the devices on cylinder or spherical surfaces while measuring) and test conditions, and some arbitrary time must be selected to compare different materials. 

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