Spatio-Temporal Dynamics of Free and Bound Carriers in Photovoltaic Materials

Photoinduced charge separation into free carriers and subsequent charge transfer are key processes that govern the efficiencies of third generation solar cell technologies based on donor-acceptor heterojunctions. As these processes typically occur on picosecond to femtosecond timescales, it is necessary to employ ultrafast spectroscopic methods to enhance our understanding and provide vital information that can aide in furthering material design. Within the framework of the National Centre of Competence in Research “Molecular Ultrafast Science and Technology” (NCCR MUST), we have developed and utilized a suite of different ultrafast optical, infrared and terahertz techniques to study charge generation, separation, and transport in a variety of small molecule based organic and lead halide perovskite solar cells. Here, we provide an overview of the main techniques used in our laboratory and examples of recent results obtained using these experimental tools.