Polymer Processing and Device Fabrication

This will require the development of innovative approaches to polymer processing and device fabrication, as discussed in Sections 7 and 8 below. 

All of the above applications of ICPs have significant commercial potential. However, in most cases, this has not been exploited due to the lack of convenient polymer processing and device fabrication protocols. For example, while polypyrroles exhibit the desirable properties mentioned above, polymerisation usually results in the formation of an insoluble, infusible material not amenable to subsequent fabrication. Conducting polyaniline and polythiophene salts are similarly intractable. Several approaches have recently been employed to overcome this problem of intractability. 

An important theme of this volume is the interrelationships among materials chemistry, photonic and optoelectronic properties, and device performance. The design and synthesis of novel polymer compositions and architectures aimed at enhanced properties are emphasized in some chapters. Other contributions feature the development of novel approaches to processing and fabrication of photonic and optoelectronic polymers into thin films, multilayers, fibers, waveguides, gratings, and device structures. These approaches, which emphasize polymer synthesis, processing, and device fabrication, are complementary and synergistic. 

The OPV device performance of all the isoindigo-based small molecules discussed in this section has been summarized (Table 5.2). While in general the solar cell performance is low compared to other small molecule systems, we have highlighted isoindigo small molecules, because their polymer-based counterparts have been shown to exhibit excellent PCE values >7% when incorporated into BHJ solar cell devices. Therefore, these results reinforce the need for further development of isoindigo-based small molecules as an organic functional material and improvements in materials processing and device fabrication. 

The science and technology of conducting polymers are inherently interdisciplinary they fall at the intersection of three established disciplines chemistry, physics and engineering hence the name for this volume. These macromolccular materials are synthesized by the methods of organic chemistry. Their electronic structure and electronic properties fall within the domain of condensed matter physics. Efficient processing of conjugated polymer materials into useful forms and the fabrication of electronic and opto-electronic devices require input from engineering i. e. materials science (more specifically, polymer science) and device physics. 

Polyethylene is the least costly of the major synthetic polymers. It has excellent chemical resistance and can be processed in a variety of ways (blown film, pipe extrusion, blow molding, injection molding, etc.) into myriad shapes and devices. Fabrication methods will be briefly discussed in Chapter 8. 

Transparent amorphous polymers such as poly(methyl methacrylate) (PMMA) have been found to be useful materials for polymer optical fibers (POFs) (1,2), waveguides (3), lenses (4), optical disks (5), and other optical components because of their excellent mechanical properties and easy processing. Many recently developed optical applications utilizing polarization techniques need optical polymers for maintaining more accurate polarization. However, applications of optical polymers are limited by birefringence which occurs in the process of device fabrication. 

Red-emissive complex used in PLEDs. Has achieved an external quantum efficiency of 10.3 % and a power efficiency of 8.0 % Im W" at 100 cd m" [103]. Originally, it was hoped that Ir(piq)3 could be directly applied as dopant into the polymer host for red emission. Unfortunately its use in LH) technology is limited by its solubility which hinders cheap solution processing for device fabrication. 

Sensitivity impacts upon the limit of detection and resolution of the device, making it a key performance parameter. Recently, several strategies have been developed in order to provide sensitivity enhancements for optical sensor platforms based on both optical absorption and fluorescence phenomena. These strategies are the result of rigorous theoretical analyses of the relevant systems and, combined with polymer processing technology and planar fabrication protocols, provide a viable route for the development of low-cost, efficient optical sensor platforms. 

Recently, Jen s group synthesized a series of high Tg fluorinated polymers with a hole transporting TPA group covalently attached as side chains (55) (Scheme 3.21) [99]. This type of polymer can be processed into thin films by simple thermal cyclopolymerization without introducing any by-products [100]. The polymers (56, 57) are insoluble in most organic solvents and can be conveniently streamlined into a multilayer device fabrication process [101,102]. The... 

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