Investigating the Effects of Molecular Aggregation in Copper Phthalocyanine Thin Films
Organic photovoltaics (OPV) can be used to supplement the areas in which conventional solar panels cannot such as on windows or backs of phones. Certain organic molecules such as copper phthalocyanine (CuPc) have become areas of interest due to their photostability, accessibility, and inexpensiveness for uses in OPVs. Previous work determined the electronic excited states and the lifetimes in CuPc thin films using transient absorption spectroscopy, there is now interest in studying how molecular aggregation of CuPc will influence Forster and Dexter energy transfer and the intersystem crossing (ISC) time. To determine how aggregation affects these processes, a series of solutions of varying ratios of CuPc and polymethyl methacrylate (PMMA) were made and used to create thin films. UV-Vis Spectra was taken of the series of films to ensure that films of varying concentrations were created and to characterize the degree of aggregation. Transient absorption spectroscopy was used to determine that there was a significant difference in the ISC time between the most and least concentrated films. Long time spectroscopy was used to determine that there was no significant difference in the triplet lifetime between the films. Future work includes determining the diffusion length of the energy in the films.