Electronic Structure and Excited-State Dynamics of Strongly-Coupled Cyanine-Based Aggregates Templated Using DNA

Supramolecular assemblies of dye molecules, known as dye aggregates, are of great interest for applications in light harvesting, nanoscale computing, and energy conversion, among others. This broad interest in dye aggregates stems from the unique and tunable electronic and optical properties they exhibit, which are sensitive to structural parameters including inter-dye separation and orientation. An emerging strategy for controlling dye aggregate properties is to assemble them using DNA nanostructures as a template. In recent years, DNA templating has facilitated systematic investigations of the relationship between aggregate structural parameters and properties. Here we elucidate electronic structure and excited state-dynamics in a broad survey of DNA-templated cyanine aggregates. We show that, in general, strongly coupled cyanine-based aggregates templated using DNA exhibit drastically reduced excited-state lifetimes relative to their respective monomers. We find that the reduced excited-state lifetimes result from enhanced nonradiative decay. We discuss potential mechanisms to explain the enhanced nonradiative decay and ways that it might be suppressed or further enhanced in accordance with the demands of various applications.