Date of Award

Fall 2015

Project Type


Program or Major


Degree Name

Master of Science

First Advisor

Glen P Miller

Second Advisor

Arthur Greenberg

Third Advisor

Erik Berda


Organic semiconductors have been of interest to scientists since the 1970s. However, while much attention was focused on p-type organic semiconductors, n-type organic semiconductors were seldom reported. In this thesis, a series of linearly extended tropylium salts (LETS) were synthesized as n-type organic semiconductors and characterized by 1H NMR, 13C NMR spectroscopy, MALDI-TOF-Mass spectrometry and UV-Vis spectroscopy. The proposed synthetic strategy has proven highly suitable to synthesize LETS compounds. UV-Vis spectra of LETS in solution have been studied as well as their stability. Linear extension of the backbones has been found to be an effective way to improve the optical properties. With each addition of one benzene ring to the backbone, the UV-Vis absorption can be red-shifted by about 170 nm and the HOMO-LUMO gap can be narrowed by approximate 0.7±0.2 eV. While linear extension of the LETS compounds improves their optical properties, it also reduces their stability, limiting their potential applications. LETS compounds with low HOMO-LUMO gaps are short-life species in solution. A detailed decomposition mechanism has not been studied, but nucleophilic attack by residual water in the solution appears to be involved. Fortunately, all LETS compounds were found to be stable in the solid state. In sealed vials stored in desiccators, they can be stored for years with very little decomposition. Their potential use in solid-state, sealed device is worth pursuing.