Inexpensive sources of clean, renewable energy to expand the US energy portfolio are among the most urgent needs of today's society. Substituting conventional silicon with solution-processed organic semiconductors promises to drive down manufacturing costs and significantly increase the production capacity of solar panels. This Faculty Early Career Development (CAREER) Program grant will support fundamental research addressing the continuous manufacturing of organic semiconductor crystal arrays optimized for maximum sunlight absorption and electricity generation. Thin scaffolds that can guide organic semiconductor crystal formation and growth during deposition from solution will be incorporated directly into solar panels. As a generalizable strategy to control solution-phase crystallization, the findings from this research will promote the progress of science and advance the national prosperity in a broad range of scientific disciplines, from disposable sensors to pharmaceutical manufacturing. By engaging students in emerging renewable energy technologies, this project will serve as a platform to promote long-term retention of K-12 students and women in science and engineering.
Confinement of crystals within nanoporous scaffolds is a powerful strategy to select for specific crystal orientations and polymorphs and has contributed to a fundamental understanding of critical nucleus sizes and crystal growth mechanisms. This research project endeavors to restrict nucleation events to nanoscale environments but allow subsequent crystal growth to proceed unconfined above the scaffolds. In doing so, control over the crystal orientation and structure will be retained while significantly increasing the accessible crystal surface area. By systematically varying solute-solvent interactions, solute-substrate interactions, and processing conditions, relationships between molecular parameters and the orientation, density and structure of nuclei will be uncovered. Such knowledge will be used to establish design principles to achieve desired crystallization outcomes. For example, control over the orientation of nuclei will enable the first realization of vertical organic semiconductor crystal arrays in which the stack direction is aligned with the charge transport direction in solution-processed organic solar cells. This research strategy will be compatible with continuous processing methods that will drive down manufacturing costs compared to conventional batch spin coating used to deposit active layers in the majority of the state-of-the-art organic solar cells.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
