Investigation of ultrafast charge dynamics in aminoanthraquinone by transient absorption spectroscopy

Photoinduced intra and intermolecular charge transfer processes are vital in the solar energy conversion system. This research compared the photoinduced charge transfer processes of 1-aminoanthraquinone (AAQ) and 1,5-diaminoanthraquinone (DAAQ) molecules in ethanol using steady-state and transient absorption spectroscopic techniques, along with density functional theory (DFT) methods. The results revealed that AAQ shows greater intramolecular charge transfer (ICT) than the intermolecular charge transfer process. On the other hand, DAAQ, which has a lower solubility in ethanol and exhibits strong π-π stacking, displays higher intermolecular charge transfer processes than AAQ alongside its ICT process. The lifetimes for ICT and intersystem crossing (ISC) are shorter for DAAQ than AAQ molecules, representing their fast ICT and ISC processes. This work provides a comprehensive insight into the photoinduced intra- and intermolecular charge transfer processes of these two molecules, explaining their respective suitability as additives in photovoltaics and other optoelectronic devices due to their photoinduced charge transfer processes and structural planarity.