Charge mobility measurement techniques in organic semiconductors

Organic electronics is currently experiencing a surge of activities worldwide prompted in part by recent advances in achieving high electronic mobility, light emission over a broad range of frequencies, demonstration of spin valve operation with giant magneto-resistance and other effects. Despite these encouraging promises, there are many roadblocks that hinder a broader proliferation of "plastic electronics" in contemporary technology. Such devices involve charge transport as a main process in their operation processes, and therefore, require high-performance charge-transporting materials. The charge-carrier mobility is the major determining factor for the speed of electronic devices. Arguably, the most significant of them is the challenge to achieve a comprehensive understanding of the fundamentals of charge injection and charge transport in organics. In spite of its simple definition, because of the difficulty of measuring velocity, accurate determination of the mobility of the carriers is not easy and indirect ways are used, each with its own advantages and disadvantages. The article discusses important mobility measurement techniques employed for organic optoelectronic devices.