Bulk Heterojunction Photovoltaic Cells Prepared by Evaporative Spray Deposition using Ultradilute Solution Technique

The evaporative spray deposition using ultradilute solution (ESDUS) technique enables layer-by-layer deposition of polymer semiconductors. In this study we prepared bulk heterojunction type photovoltaic cells composed of blend film of a polythiophene and a fullerene derivative by ESDUS. The bilayer structure of a polythiophene film without fullerene and the blend film brought about significant improvement in the device performance probably due to the electron blocking at the polythiophene film. Though the device performance of the cells prepared by ESDUS were lower than that prepared by spin-coating, it can be understood in terms of the larger polymer domain observed in the blend film prepared by ESDUS than the spin-coat film.