Ryan Hayward: Then and Now / 2011 Early Career Award Winner

Organic materials that conduct electricity can be used to make low cost electronic devices. These include light emitting diodes, redox flow batteries, radio frequency ID tags, and flexible solar panels. Since we know the materials perform better when they form well-ordered structures, we wanted to understand how to control their ordering. It turns out that the way that these molecules pack into crystalline structures (that span nanometer to micrometer length scales) determines their performance; yet the packing can be difficult to precisely control. 

Thanks to the DOE Early Career Award, we made several important breakthroughs. In one case, we developed a completely new type of organic conducting material. This material conducts electricity in a very different way along one spatial direction than it does along the perpendicular direction. Using this new material, we made logic devices similar to those in a computer. By controlling the ordering of the material, we could make them in a very simple process. This approach avoids the expensive patterning steps normally required. We also used it to make inexpensive sensor materials that can distinguish between many different harmful chemicals.

In a second example, we prepared electrically conducting wires 1000 times thinner than a human hair. We discovered a new strategy to make these wires resist degradation by temperature and solvents. Previously, processing these wires required harmful solvents. We found a way to process them using environmentally friendly solvents containing water and alcohol.

ABOUT:

Ryan Hayward is the James and Catherine Patten endowed professor of Chemical and Biological Engineering at the University of Colorado Boulder. 

SUPPORTING THE DOE SC MISSION:

The Early Career Research Program provides financial support that is foundational to early career investigators, enabling them to define and direct independent research in areas important to DOE missions. The development of outstanding scientists and research leaders is of paramount importance to the Department of Energy Office of Science. By investing in the next generation of researchers, the Office of Science champions lifelong careers in discovery science.

For more information, please go to the Early Career Research Program.

THE 2011 PROJECT ABSTRACT:

Crystallization‐Driven Assembly of Conjugated‐Polymer‐Based Nanostructures

The goal of this project is to use crystallization of electronically conducting (conjugated) polymers to fabricate well‐defined crystalline building blocks of nanometer‐scale dimensions. These materials will then be assembled into photovoltaic devices with optimized structures, and therefore improved efficiencies, in a cost‐effective manner.  

It is well known that conjugated polymers often crystallize into nanowires or fibrils, i.e., one‐dimensionally extended crystals with micrometer‐scale lengths and nanometer‐scale widths and thicknesses. The project will employ crystallization of a model conducting polymer, poly(3‐hexyl thiophene), as a driving force for the organization of several types of materials including inorganic semiconductor nanoparticles, diblock copolymers, and segmented polymer nanowires. 

Research will examine how these nanoscale structures organize themselves into superstructures on larger length scales and how organization of material on each length scale influences the photophysical properties of the resulting devices. 

The proposed work will open new routes to simultaneously controlling the organization and electronic properties of matter on three different length scales: the molecular scale, the nanoscale, and the colloidal scale. 

It will also contribute to the critically important mission of improving efficiencies of low‐cost, polymer‐based photovoltaic devices.

RESOURCES:

Bu, E. Pentzer, F.A. Bokel, T. Emrick, R.C. Hayward, “Growth of Polythiophene/Perylene Tetracarboxydiimide Donor/Acceptor Shish-Kebab Nanostructures by Coupled Crystal Modification.” ACS Nano, 6,10924 (2012). [DOI: 10.1021/nn3043836]

Bu, T.J. Dawson, R.C. Hayward, “Tailoring Ultrasound-Induced Growth of Perylene Diimide Nanowire Crystals from Solution by Modification with Poly(3-hexyl thiophene).” ACS Nano, 9, 1878 (2015). [DOI: 10.1021/nn506795q]

D.E. Acevedo-Cartagena, J. Zhu, E. Trabanino, E. Pentzer, T. Emrick, S.S. Nonnenmann, A.L. Briseno, R.C. Hayward, “Selective Nucleation of Poly(3-hexyl thiophene) Nanofibers on Multilayer Graphene Substrates.” ACS Macro Letters, 4, 483 (2015). [DOI: 10.1021/acsmacrolett.5b00038]

Additional profiles of the Early Career Research Program award recipients can be found at https://www.energy.gov/science/listings/early-career-program. 

Boilerplate: The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit www.energy.gov/science.

Author Credit: Sandra Allen McLean is a Communications Specialist in the Office of Science, Office of Communications and Public Affairs [email protected].