JCAP Special Seminar
Recent advances in inorganic semiconducting and dye-sensitized photoelectrochemical synthesis materials for water splitting and CO2 reduction are pushing research toward new strategies to integrate organic and inorganic materials to realize efficient, stable and robust device designs. Our research focuses on fundamentals and applications of vapor-phase atomic layer deposition (ALD). ALD can create highly uniform and conformal inorganic and organic thin films on 3D structures, and we explore several ways that it can be used to influence performance of silicon photocathodes and dye-sensitized mesoporous oxide photoanodes in photoelectrochemical water-splitting systems. For silicon, we have examined oxide coatings as a means to stabilize photocathodes in the dark. For photoanodes, we produced in collaboration with Duke, core/shell TCO/TiO2 structures that yield 0.58 mA/cm2 for AM 1.5G in 1 M KOH. We also work with the Meyer group at UNC-Chapel Hill to show that ALD can substantially stabilize molecular chromophore and catalyst binding, including phosphonate or carboxylate linkers, over a wide pH range (1-12) on oxide semiconductors. Using in-situ IR analysis during ALD, we observe half-reaction steps associated with transitions from mono-dentate to bi-dentate carboxylate binding upon ALD precursor exposure. We also translated this stabilization strategy to dye sensitized photovoltaic cells and showed improved long-term performance. This new ALD strategy for improved chromophore and catalyst activity and stability opens new possibilities to engineer advanced visible-light dye-sensitized water splitting systems.