Influence of Film Morphology on Transient Photocurrent Pulse Shape in Organic Thin Films: A Monte Carlo Study

Abstract

The influence of film morphology on the broadening of the time-of-flighttransient photo-current pulse is investigated using Monte Carlo simulation.Simulation of the time-of-flight transient photo-current pulse shape is carriedout for homogeneous and inhomogeneous organic thin films by varying theoverall energetic disorder. In homogeneous system, the value of the tailbroadening parameter (W) of the photocurrent pulse is found to decrease upondecreasing the energetic disorder, which can be attributed to the variation inthe non-thermal field assisted diffusion. Interestingly, in the case of inhomo-geneous system, upon decreasing the overall energetic disorder of the systemthe value of W initially attains a maximum value before it starts decreasing.This observation is explained in terms of the morphology dependent carrierdiffusion. This study asserts the importance of the influence of the morphologydependent carrier diffusion on the charge transport in disordered systems andthe related experimental measurements.