Summer 2012 Intern Project- Lindsay Shurick

SIDE CHAIN MODIFICATIONS IN ORGANIC SEMICONDUCTORS FOR EVIRONMENTALLY FRIENDLY PROCESSING

Lindsay Shurick
CCS Chemistry
UC Santa Barbara

Mentor: Zac Henson
Faculty Advisor: Guillermo Bazan
Departments: Chemistry and Biochemistry, and Materials

Where would we be without semiconductors? Semiconductors are found in a wide variety of applications including many commercial products like computers and cell phones. Traditionally semiconductors have been made with inorganic materials such as silicon; however, organic semiconductors can perform the same tasks while providing multiple advantages. Most commonly, polymers have been used for organic semiconductor applications but small molecules offer even more advantages such as higher solubility, less batch to batch variation, and easier purification and characterization. Organic semiconductors can be processed via solution deposition on lightweight, flexible substrates. This enables high throughput, lowers cost, and reduces the use of raw materials. Additionally, the optical, electronic, and physical properties can be modified for each specific application using simple organic chemistry. Current processing techniques for organic semiconductors use chlorobenzene and chloroform, which requires toxic and harmful preparation and clean up procedures. This project focuses on modifying the solubility of organic semiconducting molecules while maintaining the semiconducting behavior. Our approach is to modify the side chains of the molecule while keeping the π-conjugated core (for charge transport) consistent with well known, high performing organic semiconductors. Using triethylene glycol as a solubilizing group, we’ve obtained a solubility in ethyl acetate between 38-42 mg/mL, which is suitable for facile thin film deposition (>10 mg/mL necessary). Future work will involve further modifications to the side chains to balance the desirable solubility properties with favorable self-assembly and charge transport characteristics.

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