NSF Award
2420040
Non-Technical Summary:<br/>Electronic devices rely heavily on semiconductors, materials that act as electronic switches, allowing the movement negative and positive charges (electrons and holes) only under certain conditions. Inorganic semiconductors like silicon and gallium nitride, which do not contain carbon, face some important disadvantages: they are rigid, heavy, and unsuitable for large area-production. They also have limited adjustability in their properties. In response to the challenges that these materials face, organic semiconductors" have achieved commercial success, particularly in OLED televisions and displays. Despite these advances, chemists and materials scientists still struggle with designing molecules with improved properties. This challenge is caused by the difficulty in predicting how organic molecules will arrange themselves into a crystal lattice because of the large number of weak interactions (non-covalent interactions) between the molecules. Prof. Samuel Thomas at Tufts University and Prof. Mu-Ping Nieh at the University of Connecticut are collaborating to address this challenge through this project, supported through the Solid-State and Materials Chemistry Program in the Division of Materials Research. The investigation deepens understanding of how strategically designed non-covalent interactions between organic semiconductor molecules can influence their arrangements in crystal lattices, and the properties that result from these arrangements. Furthermore, their research seeks to enhance control over the properties of organic semiconductor materials by combining different types of interactions between molecules. Beyond addressing a fundamental hurdle in the design of organic semiconducting materials, the project also broadens participation in STEM through by supporting undergraduate research students each summer the Visiting and Early Research Scholars Experience (VERSE) program at Tufts. <br/><br/>Technical Summary:<br/>The basis for this research, supported through the Solid State and Materials Chemistry Program in the Division of Materials Research, is the hypothesis by Prof. Samuel Thomas at Tufts University and Prof. Mu-Ping Nieh at the University of Connecticut that the electrostatic force between fluorinated and non-fluorinated groups in these molecules plays a critical role in determining these arrangements. The first part of this project focuses on improving fundamental understanding of how chemical structure can influence the likelihood of observing cofacial interactions between fused heterocyclic ring systems, which are common in high performance organic conjugated materials, and fluorinated arene pendants. The PIs are testing the hypothesis that that cofacial electrostatic complementarity determines whether ArF-ArH interactions occur in crystal structures of a series of arylene-ethynylene molecules with fluorinated benzyl ester pendants, even while dispersion interactions comprise most of the interaction energies. The second phase of this project focuses on determining the extent to which adding different discrete non-covalent interactions, such as hydrogen bonds or chalcogen bonds, can reinforce or preclude these stacking interactions. To accomplish this interdisciplinary project, the PIs combine their expertise in organic synthesis and design, X-ray crystallography, powder X-ray diffraction, optical spectroscopy, and computational chemistry. By advancing fundamental knowledge in this area, this research develops new strategies for designing next-generation organic optoelectronic materials. Additionally, the project broadens participation in scientific research by supporting two visiting undergraduate students from a diverse applicant pool in their initial research projects each summer. This includes comprehensive support with professional development modules, social events, and housing accommodations to create a supportive and inclusive research environment.<br/><br/>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.
