UNC-CH Physics and Astronomy Dissertation Defense

Rohan Isaac

“Electron-phonon coupling and excited-state absorption studies of binary charge-transfer complexes containing pyromellitic dianhydride”

Organic semiconductors are a class of materials that have considerable potential in the development of cheap and efficient solar cells and display technologies, however their electronic processes are not well understood. We investigate a range of binary organic semiconductor crystals to understand the impact of varying one of the constituent molecules on the electronic properties of these materials. Excited-state absorption experiments are conducted to measure the lifetime and energies of the excited species created by the absorption of light. Vibrational motion has a strong impact on the electronic properties, and we characterize this electron-phonon coupling using a time-dependent resonance Raman experiment. In addition, we characterize subtle changes in their structure with temperature, and corroborate all of these measurements with results from numerical simulations and theoretical calculations.