Controlled growth of dibenzotetraphenylperiflanthene thin films by varying substrate temperature for photovoltaic applications

We investigate the growth of a novel organic photovoltaic material, dibenzotetraphenylperiflanthene (DBP) thin film by ultra-high-vacuum evaporation. It is shown that the surface morphology and crystalline order of DBP thin films are greatly changed by growth temperature. Especially, at 90 degrees C, the DBP exhibits a unique orientated growth with long well-directional grain structures. The power conversion efficiency of the device using DBP grown at 90 degrees C is enhanced by a factor of 61% relative to that of the device using DBP grown at room temperature due to the improvements in photocurrent, open-circuit voltage and fill factor. The results indicate the feasibility of the controlled growth of DBP thin films, which plays a crucial role in improving the performances of photovoltaic devices. (C) 2011 Elsevier B.V. All rights reserved.