Typical state-of-the-art research on organic photovoltaics relies on the spin-coating of thin films in an inert atmosphere. In order to prepare materials for large-scale industrial processing (roll-to-roll in air), we are blade coating (doctor blade) organic thin-films under ambient conditions. By coupling the blade coater with in-situ UV-vis/reflectance spectroscopy, we can understand the effects of various processing conditions on device film formation as the film dries1. These in-situ studies will teach us how the final film morphology forms and can be controlled.
Schematic of in-situ blade coating UV-vis spectroscopy.
The bulk-heterojunction morphology of the active layer in organic solar cells is pivotal to the performance of the device. Using in-situ UV-vis/reflectance we probe how morphology evolves when processing from solution to film using blade coating.
Left: AFM profiles of blade-coated P3HT films. Right: GIWAXS data for P(T3-TPD) polymer
To further investigate how various processing parameters impact thin film morphology we couple in-situ UV-vis/reflectance with Atomic Force Microscopy (AFM) and synchrotron measurements, such as Grazing Incidence Wide Angle X-ray Scattering (GIWAXS). Using these techniques, we can probe thin film microstructure and develop an understanding of how processing conditions impact film morphology development and solar cell
1. Hernandez, J. L.; Reichmanis, E.; Reynolds, J. R. Org. Elec. 2015, 25, 57-65.