Ultrafast laser spectroscopic techniques have been used as powerful tools to probe the molecular dynamics in various material systems. In photovoltaic research, the light triggered processes at donor/acceptor interfaces such as exciton dissociation and charge transfer are effectively imaged using femtosecond transient absorption, fluorescence and terahertz spectroscopies. Solving various photophysics puzzles is highly demanded for a better understanding and potential guidance for further solar cell efficiency improvements.

The seminar includes a glance at important ultrafast processes at organic/organic semiconductor interfaces for photovoltaic applications, together with the research methodology and future visions. The photophysics of non-fullerenes, a novel class of organic electron acceptors, which recently pulled off the cell efficiencies to ~ 20%, is discussed. This will also introduce the next step of research; single component organic/organic interfaces (where the donor and acceptor moieties are covalently linked into a single material to achieve high morphological stability as well as efficient exciton dissociation and charge transfer) whose photophysics is nearly unexplored.