“Bottom-up” and “Top-down” Approaches to Functional Structures with Inorganic Materials

A central theme of micro- and nanotechnology is discovering and developing methods of tailoring materials into micro- or nanoscale objects for various desired functions. “Bottom-up” and “top-down” represent two different approaches for the manufacture of materials, from their constituent atoms or bulk wafers, respectively. In this presentation, I will demonstrate both approaches to functional structures with inorganic materials. The first part of this talk will highlight the “bottom-up” approach, with a focus on the shape-controlled synthesis of metallic nanocrystals. The universal methodology that has been developed in the past years will be discussed to show how a material chemist assembles atoms into well-defined shapes. The shape control of metallic nanocrystals not only enables us to finely tune their functionality for different applications, but also provides reliable sources of nanomaterials for investigating the human health and environmental implications. In the second part, I will discuss some new developments in “top-down” technology and demonstrate how highly ordered structures can be created from bulk wafers and integrated into complex functional systems. The developed techniques have allowed fabricating optoelectronic devices with extreme mechanical deformability at low material cost. Specifically I will elaborate on the invention of flexible and stretchable displays by fabricating and transfer-printing ultrathin, microscale inorganic light-emitting diodes (iLEDs).