Charge Carrier Dynamics in Photoelectrodes for Artificial Photosynthesis
Steph received a Masters in Chemistry from the University of Edinburgh in 2008, and did her PhD with the Durrent group on Charge Carrier Dynamics in Hematite Photoanodes for Solar Water Oxidation (2008-2012). Her PhD research focussed on correlating charge carrier dynamics with efficiency of hematite (α-Fe2O3) photoanodes for water oxidation, using microsecond-second transient absorption spectroscopy (TAS) in conjunction with photoelectrochemical (PEC) techniques.
Steph's post-doctoral research area expanded to include other semiconductor materials for solar fuels, including BiVO4, TiO2, ZnO and GaN:ZnO. Ultrafast (picosecond-nanosecond) TAS is was used to monitor rapid electron/hole recombination. This provided greater insights into the factors limiting the efficiency of different photoanode materials.
The effects of doping, film thickness, morphology, surface treatment and heterostructures on charge carrier dynamics in photoelectrodes both in isolation and in complete working photoelectrochemical (PEC) cells were studied. Transient absorption spectroscopy (TAS) on picosecond-nanosecond and microsecond-second timescales were used to directly monitor photogenerated electrons and holes. Photoelectrochemical (PEC) techniques utilised include current/voltage measurements, IPCE/APCE (external/internal quantum efficiency) and fast (nanosecond-second timescale) transient photocurrent (TPC) and transient photovoltage (TPV). TAS in conjunction with TPC & TPV allow elucidation of the relative rates of charge carrier recombination, electron extraction and hole transfer (water oxidation). Understanding the effects of electrical bias (applied voltage) and light intensity on the rates of charge carrier recombination, electron extraction and water oxidation provide insights into the factors limiting solar-to-hydrogen efficiency of photoelectrode materials.