Filling the Gap: Synthesis and Monolayer Formation with an n-Type Organic Semiconductor

Abstract

Organic electronics is an increasingly popular field, but device fabrication is severely limited by the scarcity of n-type organic compounds. The compound C6-NTCDI-PA was synthesized and characterized with this problem in mind; the NTCDA core is a known n-type semiconductor, the phosphonic acid group allows for binding to oxide surfaces, and the hexyl chain increases surface energy, promotes alignment, and increases solubility. T-BAG deposition experiments were carried out with C6-NTCDI-PA on indium tin oxide and silicon oxide surfaces. A marked increase in contact angle on both surfaces confirms a change in surface energy due to T-BAG. However XPS data show no evidence of nitrogen or phosphorus on silicon oxide, which would deny the presence any compound. XPS data of indium tin oxide surfaces, though, verify the presence of C6-NTCDI-PA with new phosphorus and nitrogen peaks, as well as changes in the carbon and oxygen signals. AFM images confirm this result and add that the compound formed in a monolayer, albeit a holed one.