Current challenges in energy research motivate the development of new material assembly techniques and also raise fundamental questions about the mechanisms of charge transfer/ storage in molecular materials.  Layer-by-layer assembly and Langmuir-Blodgett deposition have been used to grow multilayer films of wide bandgap semiconductor nanosheets interleaved with redox polymers.  These assemblies act as electrochemical current rectifiers that can mimic energy- and electron-transfer cascade processes in photosynthesis.  In a multi-step electron transfer cascade, a photosensitizer molecule absorbs light and electrons transfer through progressively more positive band edge potentials and molecular LUMO levels. Modeling current rectification and photovoltaic energy conversion in these systems is challenging because the underlying physics is different from that of conventional semiconductor p-n junctions. A fundamental study of the diode characteristics, as well as the multi-layer molecular transfer kinetics, will facilitate the design and characterization of multilayer molecular photodiodes. This presentation discusses the results of experiments probing current-voltage characteristics and molecular electron transfer kinetics in multilayer diodes consisting of alternating layers of redox polymers and oxide semiconductor nanosheets.

Current rectification in multilayer assemblies of oxide nanosheets

244th National Meeting (2012)

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