Optical imaging Organic substrate

Figure 10 Scheme of prepatterned substrate and PEDOT PSS drop deposition (A). AFM image of the source and drain electrodes (B). Scheme of UP organic FET (C). Optical Image under crossed polarizers showing the uniaxial aligned domain of F8T2 (D). Reprinted figures with permission from H. Sirringhaus, T. Kawase, R.H. Friend, T. Shimoda, M. Inbasekaran, W. Wu, E.P. Woo, Science 290, 2123 (2000), Figure 1. Copyright 2000 AAAS.

Transmission electron microscopy (TEM) is a powerful and mature microstructural characterization technique. The principles and applications of TEM have been described in many books [16 20]. The image formation in TEM is similar to that in optical microscopy, but the resolution of TEM is far superior to that of an optical microscope due to the enormous differences in the wavelengths of the sources used in these two microscopes. Today, most TEMs can be routinely operated at a resolution better than 0.2 nm, which provides the desired microstructural information about ultrathin layers and their interfaces in OLEDs. Electron beams can be focused to nanometer size, so nanochemical analysis of materials can be performed [21]. These unique abilities to provide structural and chemical information down to atomic-nanometer dimensions make it an indispensable technique in OLED development. However, TEM specimens need to be very thin to make them transparent to electrons. This is one of the most formidable obstacles in using TEM in this field. Current versions of OLEDs are composed of hard glass substrates, soft organic materials, and metal layers. Conventional TEM sample preparation techniques are no longer suitable for these samples [22-24], Recently, these difficulties have been overcome by using the advanced dual beam (DB) microscopy technique, which will be discussed later. 

Figure 5.7. Optical microscope image of a thin film (thickness 2 p.m) of a-p-NPNN grown on a glass substrate (1.6 x 1.0 mm, crossed polarizers). Reprinted from Journal of Crystal Growth, Vol. 209, J. Caro, J. Fraxedas and A. Figueras, Thickness-dependent spherulitic growth observed in thin films of the molecular organic radical p-nitrophenyl nitronyl nitroxide, 146-158, Copyright (2000), with permission from Elsevier.

As the temperature dependence of the CTL spectrum has information about the type of vapor, the present authors and coworkers [17] reported a method to recognize organic vapors by means of spectrum-temperature imaging. For this purpose, a system to simultaneously measure the CTL spectra at various temperatures was developed (Fig. 27). The sintered layer of the CTL catalyst is laid on a ceramic heater substrate of 5 x 60 mm2, which has a temperature distribution ranging from 440 to 530 °C along the stream of a sample gas in a quartz tube. A mask with an optical slit of 0.3 mm width is placed on a quartz tube. The CTL emission passing through the slit is focused on... 

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