Delineating photothermal and photoexcitation effects in the photoelectrodeposition of cuprous oxide.

by Lowe, James; Mehrabi, Hamed; Coridan, Robert

Cuprous oxide (Cu2O) is an earth-abundant, p-type semiconductor of interest to photovoltaic and photoelectrochem. applications. Cu2O can be synthesized directly into its semiconducting phase by electrodeposition, rather than requiring a high-temp. calcining step as is necessary for most other electrodeposited metal oxides. As a result, Cu2O electrodeposition rates can be enhanced by illumination during growth. In recent work, we showed that photoelectrodeposition forms a composite of Cu2O doped by Cu nanocrystals throughout, resulting in a black film with high absorptivity across the visible spectrum. Continued growth is enhanced even for illumination with energies smaller than the band gap of Cu2O due to the sensitivity of the Cu2O electrodeposition to local temps. at the electrode-electrolyte interface. Here, we describe expts. to discriminate the local photothermal and photoelectrochem. effects in the photoelectrodeposition of Cu2O. Identifying the role of each effect will lead to more robust control over the compn. and structure of Cu2O-based interfacial heterostructures. In addn. to std. spectroscopic and electrochem. characterization, we will describe novel expts. that use in situ high-speed microscopy to unveil the complex interplay between light and heat on the electrodeposition of Cu2O.