PERIODIC TRENDS IN STRUCTURE FUNCTION RELATIONSHIP OF ORGANIC HETEROACENES

• Main Author: Grimminger, Marsha Loth
• Format: Others
• Published: UKnowledge 2011
• Subjects: Organic Semiconductors; Acenes; Organic Thin Film Transistors; HOMO Energy Levels; Solution Processing; Chemistry
• Online Access: http://uknowledge.uky.edu/gradschool_diss/850; http://uknowledge.uky.edu/cgi/viewcontent.cgi?article=1853&context=gradschool_diss

Our group has previously shown that small changes to molecular structure result in large changes to device properties and stability in organic electronic applications. By functionalizing aromatic heteroacenes with group 14 and group 16 elements, it is possible to control morphology and improve stability for a variety of applications such as thin film transistors and solar cells. Functionalization within the heteroacene core led to changes in electronic structure as observed by electrochemistry and light absorption. By substituting down the periodic table, the carbon heteroatom bond length increased, leading to subtle changes in crystal packing. Absorption maxima were red-­‐shifted and stability to light decreased. Substitution of group 14 elements to the solubilizing ethynyl groups attached to the heteroacene also had an effect on crystallization and stability. Substitution of silicon with carbon decreased solubility as well as stability to light. Substitution with germanium also decreased stability to light, but close contacts within the crystal structure and solubility in nonpolar organic solvents increased.