UC Santa Barbara

The properties of organic semiconductors make them well-suited for certain applications in electronic devices or energy conversion. Because of their low inherent conductivity, organic semiconductors need to be doped to be used in many of these applications. The limited set of small molecules commonly used for organic semiconductor doping do not always have the desired combination of properties for some applications, such as high ionization energy or air stability. In addition to removing or adding charges, these small molecule dopants can significantly alter the semiconducting film structure through Coulombic interactions. These challenges suggest a need to explore new dopants and doping mechanisms and to better understand the effects of doping on the electronic structure and morphology of organic semiconductors. We used a combination of experimental methods and DFT calculations to explore new doping mechanisms based on Lewis acid-base pair chemistry. Combining UV-Vis-NIR spectroscopy, electrical transport measurements, and grazing incidence wide-angle X-ray scattering, we connected changes in the electronic structure to changes in morphology and transport in both amorphous and semicrystalline semiconductor systems. Our results suggest ways to control the electronic structure and morphology of organic semiconductors, as well as providing a starting point to further apply Lewis pair chemistry to doping.