NSF Award
2403957
In this NSF-DFG MISSION project, researchers at the University of Massachusetts Amherst and the Technical University of Munich will collaborate to study polymer materials at so-called "buried interfaces," referring to a material located well below the surface of another material. Understanding the molecular structure and orientation of materials at such interfaces is both challenging and critically important to emerging technologies. The amount of material at an interface is small relative to the overall structure. Therefore, specialized "in situ" and "operando" techniques such as advanced x-ray and neutron scattering are required to probe material structures at buried interfaces. The ability to identify interfacial structure and orientation using these methods could translate to advances in electronic materials where energy flow and power conversion are crucial. For example, solar cell design efforts would benefit from this knowledge, given the functional importance of the interface of soft (polymer) and hard (metal electrode) materials. From an educational standpoint, the NSF-DFG MISSION program will propel the UMass-Munich team to build a new, in-depth international collaboration from which the participating students gain a unique foundation in professional development as they grow scientifically through this cross-continental collaborative project. <br/><br/>This U.S. and German team will systematically investigate interlayer materials in polymer-based systems and the soft-hard interfaces involving polymers and conducting or semiconducting substrates. Deep, fundamental understanding of such interfaces is critically important in numerous contexts, e.g., electronic materials interfaces where charge transport processes dictate the efficiency, durability, and sustainability of devices, such as solar cells. The study combines the team's expertise in using neutrons to probe polymer-based interfaces (Müller-Buschbaum - Technical University of Munich), polymer synthesis innovations (Emrick - UMass Amherst), and implementing soft and hard x-ray synchrotron sources (Russell - UMass Amherst) to precisely focus on interfaces comprising only ~10^-3 of the total material volume. Through in situ and operando methods, the team will study the impacts of interfacial interactions and the electronic effects of disparate materials interfaces in contact with one another (i.e., polymer-metal, polymer-semiconductor, and polymer-polymer interfaces). A detailed understanding of such interfaces, while crucial for improving electronic device performance, is presently lacking and will be enabled by using in situ and operando techniques. The team will develop patterned-enhanced scattering methods to detail interface evolution over time by merging materials chemistry with transmission and grazing incidence resonance soft x-ray and neutron scattering techniques. For example, interfacial contact between polymer zwitterions and metal electrodes offers simultaneous modulation of 1) work function of an electrode and 2) charge transport with an adjacent polymer layer. The orientation and spatial location of zwitterionic dipoles will strongly influence surface interactions, and in situ studies will allow probing of interfaces as orientation evolves over time. Concurrent with the research, the project's design is uniquely suited to build a diverse, collaborative, international research effort that will bolster the participants' professional development and contribute insights into research designs and strategies that cross geographic boundaries and scientific disciplines.<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.
