Organic Semiconductors: Technology and Environment

Abstract

The inherent limitations of inflexible semiconductor wafers prevent the application of inorganic microelectronics on flexible substrates. Thus, an alternative to inorganic semiconductor is needed i.e. organic materials. Organic materials such as plastic which are generally used to make toys or shopping bags are electrically insulator but a special family of organic materials known as conjugated polymers show semiconducting properties. In this modern era of microelectronics, the low cost flexible devices are produced by these organic semiconductors. These materials offer new possibilities for applications in different areas of organic light emitting diode (OLED), organic field effect transistor (OFET), photovoltaic, sensors. Organic semiconductors based organic light-emitting diode (OLED) displays are widely used in smart phones. Organic field effect transistors (OFETs) are extremely important as they are the main component of organic electronics. Organic materials present the possibility of devices like organic thin film transistor (OTFT) when used in human biological systems promises applications in health sector. The device that “uses specific biochemical reactions mediated by isolated enzymes, immunosystem, tissues, organelles or whole cells to detect chemical compounds usually by electrical, thermal or optical signal,” is said to be biosensor as defined by Kergoat et.al. Organic materials are too sensitive to environmental conditions and are environmental friendly too but their performance deteriorates with time. The organic semiconductors have relatively low charge mobility that is why not competed with Si (inorganic counterparts) in applications that require switching speed. OFETs are integral part of organic electronics. In this chapter detailed description of organic semiconductors, their applications, limitations, types, energy gap, localization of charge, optical characteristics, determination of energy levels, polaron, exciton and advancements in technology is given. This chapter reviews the basic mechanism of conduction in organic semi-conductors leading to the integral device organic thin film transistor (OTFT) and the challenges to be handled such that the technology can be viable for the human life.