Optoelectronic device applications

The variation of nanostructures in conjugated rod-coil block copolymers holds considerable promise as the active layer in volatile organic compound (VOC) chemresistor sensors. It was reported that poly thiophene rod-coil block copolymers could vary their electrical conductivity by changing rod-coil ratios when they were exposed to a variety of VOC vapors 

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As mentioned in this review, AMPLEDs are especially attractive for motion picture applications. The Pay-Per-View effect in OLED displays reduces power consumption and extends operation lifetime. Motion picture applications also minimize image retention and optimize display homogeneity. AMOLED has been widely viewed as a promising display technology in competing with AMLCD and plasma displays. The dream of using organic semiconductor films for optoelectronic device applications has become a reality. 

There are four main classes of conjugated polymers that have been studied for optoelectronic device applications [44], They are classified according to the structure of the conjugated backbone and are the poly(/w<7-phenylene)s (PPPs), poly(para-phenylene vinylenejs (PPVs), polythiophenes (PTs), and polyfluorenes (PFs). Their structures are shown in Fig. 8.9. Of these four classes, the most widely studied and commercially significant have been the PPVs and PFs [45], although the PTs have... 

In this chapter, we discuss a number of optical and optoelectronic device applications such as hght-emitting diodes (LEDs), photovoltaic and photoconductive devices, field-effect optical modulator devices and all-optical modulator devices made from thiophenes. Following an introduction to the basic operating principles of each device, we will assess progress in the development of each type of device and focus on the underlying semiconductor physics issues. 

It is perhaps worth emphasising from the beginning, that the trends observed in dilute solution are in marked contrast with those in the solid state, relevant to optoelectronic device applications. We therefore decided to discuss this topic after consideration of purely intramolecular and intermolecular decay mechanisms. While planarity may favour higher PL efficiencies in isolated molecules or dilute, well-dispersed blends, planarity also favours aggregation and hence lower PL efficiencies in the solid state. 

Semiconductors in nano-crystallized form exhibit markedly different electrical, optical and structural properties as compared to those in the bulk form [1-10]. Out of these, the ones suited as phosphor host material show considerable size dependent luminescence properties when an impurity is doped in a quantum-confined structure. The impurity incorporation transfers the dominant recombination route from the surface states to impurity states. If the impurity-induced transition can be localized as in the case of the transition metals or the rare earth elements, the radiative efficiency of the impurity- induced emission increases significantly. The emission and decay characteristics of the phosphors are, therefore, modified in nanocrystallized form. Also, the continuous shift of the absorption edge to higher energy due to quantum confinement effect, imparts these materials a degree of tailorability. Obviously, all these attributes of a doped nanocrystalline phosphor material are very attractive for optoelectronic device applications. 

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