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