8.2 Future Work

Using the advances as the foundation for further study, we finally consider some possibilities for future work. Of course, there is initial work on device models [136,137,138], which, however, did not take into account the disorder in organic semiconductors or the hopping transport effect on device characteristics. So the first extension would implement the mobility models and injection models into device simulators.

Another extension would be to consider the role of the limiting effect of the space charge on the injection current. This can be incorporated into our injection model, either diffusion model or master equation model through solving the Poisson equation.

Further, it may be important to consider the effect of Coulomb forces on the doping and trapping model. It has been pointed out that doping in organic semiconductors produces a random distribution of dopant ions [139], which electrostatically interact with carriers localized in intrinsic hopping sites. This interaction further increases the energy disorder and broadens the deep tail of the DOS distribution.

Finally, an improvement of Arkhipov's transport [140] energy model may be developed. This model should consider the effect of both downward and upward hops on transport. It can be used to explain the electric field dependence of the mobility in organic semiconductors.

The framework provided by this thesis can be a starting point for these, and possibly other, further investigations. By continuing to successively remove some of the more restrictive assumptions of our work, significant progress may continue towards a better understanding of these organic semiconductors materials and devices.