Self-Assembly and Polymerization at Surfaces and Interfaces

Almost all new technologies are intrinsically linked to the application of new materials. The invention of Scan Probe Microscopy (SPM) enabled the imaging of materials down the scale of individual atoms, making it possible not only to investigate the structure of existing materials at the nanoscale but to develop entirely new kinds of materials, driving progress in areas such as solar energy, nanoelectronics, sensors, and molecular separation.

One of the key concepts in nanomaterials is self-assembly, the spontaneous organization of building blocks into larger patterns. We therefore study molecular interactions in self-assembly, to understand the organization of the building blocks of the biopolymer eumelanin, or to investigate new templates for host-guest systems that could control crystallization from 2D to 3D.

A related theme of our research is on-surface polymerization, where molecular building blocks on a surface are used to produce a two-dimensional polymer, which have highly intriguing properties as organic analogues of graphene such as high charge carrier mobilities. Notably, they do not have graphene’s limitation of a zero band gap, which causes it to conduct as a metal and has limited its application in electronics. We are currently investigating novel building block molecules and their subsequent transfer to device substrates to build and test prototype FETs, OLEDs, OFETS, or sensors.

A third area of our research focuses on novel materials for all-solid-state lithium batteries. Lithium ion batteries are a critical energy storage technology for the transition to renewable energy, electric cars, and personal electronics, but the existing materials based on liquid electrolytes are reaching their theoretical limits. Solid-state electrolytes would allow the graphite anode to be replaced with much-higher capacity lithium metal, resolve the risk of flammability of liquid electrolytes, and facilitate thinner cells that are flexible or have higher energy density. However, solid-state electrolytes are hampered by poor contact with the electrode or reaction to form non-conductive interfaces, which has limited their commercial development. To address these problems, we are applying the tools of surface science, including electrostatic force microscopy, to characterize new materials and study ionic transport within them.