Semiconductor device physics of conjugated polymers

Conjugated polymers form an important class of organic semiconductors, combining both desirable electronic properties together with the possibility of processing to obtain the material in the form desired in various electronic or optoelectronic devices structures. Much of the fundamental interest in these materials from the point of view of the semiconductor properties is related to the nonlinear electronic excitations of the polymer chain. This is best modelled for the case of polyacetylene, where the effect of introducing a charge onto the chain is to cause the π-bonding along the chain to reorganise so that the regular pattern of bond dimerisation is interrupted by kinks, which have the character of solitary waves or solitons. The author discusses some of the work carried out in Cambridge on the device physics of two polymers, covering the properties of MIS and MISFET devices based on Durham-route polyacetylene, and the properties of light-emitting p-i-n diodes based on PPV, poly(phenylene vinylene)