Supported by the U.S. Office of Naval Research

Despite tremendous advances in controlling self-assembly of organic molecules, the impact on high-performance organic electronic materials has been limited.  The challenge lies in the stiff conformations and complex phase behavior of conjugated molecules and polymers, including liquid crystalline interactions and phases that complicate the control of domain sizes and interface structures.  As such, there is a tremendous opportunity to design materials that exploit these factors to control self-assembly in the active layer of electronic devices.  Recent advances by Center members in theoretical descriptions of interaction parameters, chain conformations and liquid crystallinity of stiff molecules uniquely position SOE to develop new ways to control the microstructure. SOE will demonstrate systematic control and full characterization of donor and acceptor interfaces of organic photovoltaic (OPV) materials composed of high-performance polymers and state-of-the-art non-fullerene acceptors. These will be used to train multi-scale tight-binding models that are coupled to universal descriptions of stiff polymers at interfaces to build predictive design rules about how molecular structure influences self-assembly and guide further development of high performance OPV devices.

Flexible and light-weight electronics and solar cells provide a promising solution for wearable electronics and light-weight power generation. SOE is focused on demonstrating key advances in self-assembly of conjugated molecules and polymers in the context of organic electronics, with a special emphasis on solar cells.  Specifically, a premise of SOE is that the synthetic and structural versatility of recently developed non-fullerene acceptors provides a pathway to ideal blend morphologies, for design of block copolymers and oligomers to control the mesoscale and interfacial structure, and for programmable hydrogen bonding units to tune self-assembly.  In addition to designing chemical structures that drive systems towards thermodynamically stable states, SOE will map the interplay between miscibility and crystallization through time-temperature-transformation diagrams, which represent the morphological evolution of complex mixtures used in organic solar cells. Thus, SOE is poised to demonstrate new opportunities in chemical design to enable robust processing of binary and multicomponent solar cells, by leveraging our recently developed flow-coating approaches, our universal descriptions of the dynamics of stiff polymers, and our high throughput characterization and spectroscopy methods that will guide machine learning approaches to identify predictive design rules.