Research Projects

Photoinduced symmetry-breaking charge separation (SB-CS) and singlet fission (SF) are two exciting-state processes that have gained attention in recent years. Molecular dimers and trimers are ideal models for studying these processes, as they illustrate the photophysical processes occurring in nature. The efficiency of SB-CS is determined by the interplay of electronic coupling, reorganization energy, and free energy change between the chromophores within the PDI dimer and trimer systems. Singlet fission (SF) is another interesting photophysical phenomenon observed in molecular dimers, trimers, and aggregates. SF materials are commercially more demanding as they generate more charge carriers, increasing the overall photoconversion efficiency of OSCs. To understand the role of interchromophoric coupling in regulating SB-CS vs. SF, researchers plan to investigate ultrafast excited state dynamics of a series of covalently bonded linear, bent, and non-parallel PDI dimers and trimers connected via bay and imide positions. The study will use UV-Visible femtosecond/nanosecond transient absorption, time-resolved IR techniques, and theoretical/computational tools to explore the ultrafast excited state dynamics of the proposed systems. The transient redox species formed during SB-CS will be characterized through chemical redox titration and steady-state UV-Vis-NIR absorption spectroscopy. The rational design of chromophoric dimers and trimers can be exploited for the development and fabrication of robust and proficient SB-CS/SF materials, potentially revolutionizing artificial light harvesting and photovoltaics.