(241f) Structure-Property Relations for the Design of Organic Glasses for Organic Electronics and Nanolithography

In the last decade, there has been an increasing interest in the use of small molecule organic glasses instead of polymers for a wide variety of high technology applications, especially organic electronics and as photoresist materials for next generation high volume integrated circuit fabrication. These small molecule organic glasses are attractive compared to polymers for a variety of reasons. They can have unique electronic and photoactive properties for use as electrically conducting materials, photovoltaic devices, electroluminescent devices, and a variety of other applications. In photoresist applications, they are favorable because they provide molecules that are much smaller than polymers, effectively reducing the molecular pixel size of the resist. One major advantage that molecular glass materials have over polymers is that they can easily and repeatably be made as completely monodisperse materials. Polymers can have significant variations in chain-to-chain molecular weight (polydispersity) and variations in chain compositional uniformity both along an individual chain and from chain-to-chain, especially in complex ter- and tetra-polymers that are commonly used in high technology applications. Since molecular glasses have a well-defined structure compared to these polymers, it is possible to generate accurate structure-property relations for a number of important material properties based purely on the chemical structure of the small molecules.

We have developed bond and group additivity models that accurately predict the glass transition temperature (Tg) of both organic electronic and molecular photoresist materials. The correlation between glass transition and conventionally predicted properties such as boiling and melting point have been examined to extend glass transition predictions to new material classes. Another important material property, especially in molecular photoresists, is solubility and dissolution rate characteristics. To that end, we have extended the conventionally calculated partition coefficient (log P) and distribution coefficient (log D) to predict a priori molecular resist solubility. We have determined that that dissolution rate can be broken down into a kinetically controlled and a thermodynamically controlled regime. Application of log D and another structure-predictor that can be extracted from the log D calculation allows accurate prediction of dissolution rate across both regimes. These and other new areas of property prediction for the design of organic molecular glass materials will be discussed.