This research stream focuses on the photophysics of novel semiconductors and devices, particularly the interactions between electrons/excitons and phonons/vibrational modes after the absorption of a photon. We study these concepts through the use of ultrafast spectroscopy, an advanced laser characterisation technique. Ultrafast spectroscopy can be likened to old fashioned strobe photography, albeit at a billion-fold better time resolution, wherein very fast processes/events are monitored by freezing in time a series of frames which when reconstructed give a picture of the electronic dynamics triggered by optical absorption. This family of techniques uses sequential ultrashort light pulses, usually in the femtosecond regime, to study/monitor photoinduced dynamical processes. These dynamical processes can be studied at femtosecond time scales via the “pump-probe” technique: first, an excitation or “pump” pulse creates a photoinduced change in the system of interest, and then the effect on a delayed and synchronized “probe” pulse is monitored, often via transmission or reflection. The temporal dynamics arise by adjusting the time delay between the pump/probe pulses. The major differences between different ultrafast optical spectroscopy techniques arises from variations in the pumping/probing approaches, including changes to the photon energies and detection strategy. While transmission based measurements are suited to understanding bulk properties, it is reflection based measurements that are sensitive to interfacial phenomena, including carrier dynamics such surface recombination velocity and carrier diffusion, interfacial electric fields, and the presence of intermediate states.