Combining vacuum deposited with solution processed layers in organic solar cell

Heterojunction cells are the subject of much current research. They can be differentiated by their production processes: solution processing and vacuum processing. Both production processes have advantages and disadvantages. Solution processed devices have the advantages of monodisperity and simple synthesis, but the use of solution processing is limited to soluble conjugated polymers due to their ability to form a smooth film on spin coated materials and the devices are characterised by lower mobilities due to their disordered structures. Vacuum processing can lead to relatively high throughput and sequential stacking of well-defined layers and extraction of exciton diffusion lengths can be performed. Vacuum processed devices, however, tend to suffer from lower efficiencies. Our approach is based on combining vacuum deposited active layers with solution processed layers in organic photovoltaic cells using pentacene and buckminsterfullerene.