Ninety percent of the world's energy is derived from non-renewable carbon resources, resulting in 32 billion metric tons of carbon dioxide emissions every year. The objective of this project is to investigate the morphology within novel polymeric materials for use in plastic (or organic) solar cells that convert clean and abundant solar energy to usable electricity. Organic solar cells are particularly attractive due to their low cost compared to the conventional silicon-based solar cell devices. However, their low efficiency has been a key impediment in their broad deployment. Precise control over material structure between the different semiconducting functional components of plastic solar cells is critical for efficient conversion of solar energy to electricity. The novel polymers in this work will be processed in the form of nanofibers, which will not only allow us to better control and tailor these structures at the nanometer length scale for enhanced device efficiency, but will also enable light and breathable smart fabrics with integrated solar cells. This project will provide one graduate and several undergraduate students with an interdisciplinary educational experience in nanomaterials and renewable energy.
The specific objective of this project is to combine experiments and simulations to investigate self-assembly of conjugated rod-rod block copolymers within electrospun nanofibers (diameter = 50-500 nanometers). Owing to the rapid solvent evaporation and short residence time during electrospinning (on the order of milliseconds), the microstructure in the initial solution is likely to have a significant influence on the final assembly in as-made nanofibers. Therefore, the role of each of the three stages of nanofiber fabrication (solution phase, drying/solvent evaporation and the post fabrication annealing) in defining the final hierarchical self-assembly structures will be investigated. Multi-scale simulations will be conducted to understand the thermodynamic and kinetic principles that direct self-assembly in confined systems. Optical property and performance characterizations of the materials will be conducted in plastic solar cells in the final stage of the project. This work will serve as the first ever study on self-assembly of conjugated block copolymers in nanofibers, with the potential to develop wearable smart fabrics.
