Transient and steady state lateral charge transport in polymeric semiconductors

Abstract

This is a synopsis of the thesis entitled Transient and Steady State Lateral Charge Transport in Polymeric Semiconductors” delivered by Abhay K. Tiwari of the Chemistry and Physics of Materials Unit, Jawa- harlal Nehru Centre for Advanced Scientific Research, Bangalore, India. This thesis is divided into five chapters and three appendices. (A)The first chapter is an overview of field of organic semiconductors. In this chapter I have discussed some of the basic properties of organic semi- conductors, charge carriers in organic semiconductor devices and few models which have been used earlier by other groups to understand mechanism of the charge transport in organic semiconductors. (B)The second chapter of this thesis is based on the spreading impedance model proposed earlier in our group[18,47]. In this thesis, the model has been solved in the time domain, and thus has helped us in carrying out the transient analysis and modulation frequency dependence. Through the sim- ulations various aspects of transient analysis, effect of incident photocurrent, trapping and metal-semiconductor surface have been analyzed. Apart from the agreement with the existing experimental data and previous simulations, we have made a few new predictions, which await experimental confirmation. iv (C) The third chapter is related to the analytical treatment of the spread- ing impedance model. This work describes the effect of different time-scales involved in the transients. A detailed analysis of the dependence of the lat- eral photovoltage on the different device parameters has been done. Using this analysis, we propose ways of optimizing the performance of organic de- vices. (D) The fourth chapter has been devoted to the study of the mobilities of charge carriers in disordered organic semiconductors with the help of Kinetic Monte Carlo technique. (E) In the fifth chapter the salient features of findings of the thesis has been summarized and some of the future plans have been discussed.