Carrier dynamics in photovoltaic structures and materials studied with time-resolved terahertz spectroscopy

Terahertz (THz) radiation, covering the frequency range from a few to about a hundred milli-electron volts (meV), is particularly sensitive to the response of charge motion in materials. Using a pump-probe scheme, time resolved terahertz spectroscopy (TRTS) allows, in a contact-free way, the study of charge carrier dynamics with ultrafast time resolution. In this chapter, we review how TRTS has been successfully employed for the characterization of photovoltaic materials and architectures. Particularly, we focus on TRTS studies that interrogate key processes occurring after photo-excitation in nano-structured semiconductor systems, including charge generation, separation and transport. Understanding the fundamental properties of charge carriers in these novel geometries is important for the development of future solar energy conversion technologies.