EAPSI: Investigating Intermolecular Interactions in the Formation of Polymer-Based Nanowires

Acevedo Daniel E, Amherst MA

Investigators

Abstract

Semiconducting polymers promise to deliver low cost electronic devices such as solar cells and transistors due to their easy processabililty. Fabrication conditions have been identified that allows poly(3-hexyl thiophenes) (P3HT), an extensively studied semiconducting polymer, to crystallize into nanowires (NWs), which can improve a solar cell?s efficiency. This project aims to understand the assembly of P3HT into NWs. Both the NW alignment and the orientation of the polymer chains with respect to the substrate are crucial parameters to control for ensuring efficient transport of charges in solar cells. In order to characterize the structural features of the NWs, near edge X-ray absorption fine structure (NEXAFS), a highly specialized technique capable of proving the molecular orientation of thin films down to monolayers of the material will be used. Dr. Kilwon Cho, an expert in surface and electronic device characterization at Pohang University of Science and Technology, will be the host for this research, providing a U.S. graduate student vital access and expertize for NEXAFS analysis. This project will focus on the surface crystallization of P3HT from graphene deposited on supporting substrates. Utilizing a metastable solution of P3HT, with a strong driving force for crystallization that is not sufficient to induce homogenous crystallization, NWs of P3HT will be formed selectively on graphene. During the crystallization, the polymer chains in solution interact with graphene and the underlying substrate. A systematic study of the NW growth from graphene deposited on modified substrates employing surface characterization techniques such as NEXAFS will unveil the surface properties and the morphology evolution of P3HT. This will help us determine the effects of intermolecular forces on the P3HT crystallization. Ultimately, the beneficial effects of the NWs will be assessed by the fabrication and characterization of solar cells. This NSF EAPSI award is funded in collaboration with the National Research Foundation of Korea. This award is jointly funded by NSF and the National Research Foundation of Korea.