Advances in potential-modulated attenuated total reflectance (PM-ATM) spectroscopy for characterization of transparent metal oxide/semiconductor interfaces relevant to solar energy conversion

The atomic- and molecular-level behavior of materials at transparent metal oxide/semiconductor interfaces significantly affects the overall photoconversion efficiency of photovoltaics. However, it is often difficult to isolate and characterize this critical interface. This talk will describe recent advances in the application of potential-modulated attenuated total reflectance (PM-ATR) spectroscopy to probe indium tin oxide (ITO)/CdSe nanocrystal interfaces. The ITO/CdSe interface serves as a chemically modified working electrode in a traditional 3-electrode electrochemical cell. Potential-dependant absorbance changes in the nanocrystals are monitored as the electrode potential is modulated at a range of frequencies. The phase shift of the optical change relative to the potential modulation frequency reflects interfacial properties that may be relevant to charge transfer dynamics. Waveguide geometry affords the sensitivity to examine sub-monolayer coverages of nanocrystals. By combining optical and electrochemical data, PM-ATR gives insight into the fundamental chemical properties governing the behavior of this interface while also enabling more strategic design of future energy conversion platforms.