Ti:Saphire regenerative amplifier, frequency doubling and tripling, two non-collinear optical parametric amplifiers with pulse compression. Transient absorption measurement using either whitelight or singl-wavelength sources.
The efficiency of solar cell panels is determined by photoinduced dynamics. For example, in organic solar cells, the optical absorption of the electron “donor” and the injection of electrons from the “donor” into the “acceptor”, which generate the charge separation, must be accelerated. The back electron transfer and recombination, which destroy the charge separation, must be suppressed. Ultrafast laser spectroscopy provides a powerful tool to quantitatively measure and hence understand these procedures, potentially improving the conversion efficiency, and even the invention of new types of solar cells. In our ultrafast spectroscopy lab, an experimental system for transient absorption spectroscopy has been set up to study the dynamics that contribute to the energy transfer and charge separation in solar cells. A laser pulse with ultrashort time duration (~30 fs) is used to pump the system, while a second ultrashort laser pulse with either a continuous wavelength distribution (so-called “white light”) or a narrow wavelength range is used to “probe” the photoinduced dynamics. Our investigations include transient absorption spectroscopy of both dye-sensitized solar cells based on nanoparticles and nanowires, and organic solar cells.