Publication Date

12-2016

Date of Final Oral Examination (Defense)

9-30-2016

Type of Culminating Activity

Dissertation

Degree Title

Doctor of Philosophy in Materials Science and Engineering

Department

Materials Science and Engineering

Supervisory Committee Chair

Wan Kuang, Ph.D.

Supervisory Committee Co-Chair

William L. Hughes, Ph.D.

Supervisory Committee Member

Jeunghoon Lee, Ph.D.

Supervisory Committee Member

Bernard Yurke, Ph.D.

Supervisory Committee Member

Igor Medintz, Ph.D.

Abstract

Near-field energy transfer has great potential for use in nanoscale communications, biosensing, and light harvesting photonic devices. However, the light collecting and energy transferring efficiency of current devices is poor, resulting in few commercially available applications. Current human-made light harvesting devices lack the benefits of natural selection. Natural systems are typically highly optimized and highly efficient. For example, transfer efficiency in photosynthesis is greater than 90%.

In this work, two classes of optical devices were designed, synthesized, and characterized: Plasmonic waveguides and FRET-based photonic devices. In the case of plasmonic waveguides, a multi-scaffold DNA origami synthesis method was developed to fabricate linear waveguides with 10-nm diameter gold nanoparticles. Precise control over interparticle gaps and interchromophore distances was demonstrated. Using a similar approach, DNA labeled fluorophores were arranged in linear and branched geometries to form FRET-based photonic wires and light harvesting devices.

Recently, homogeneous FRET (homoFRET) has emerged as a potential way of increasing the transfer efficiency of photonic wires. However, little is known about the design principles needed to construct such devices. To address this knowledge gap, linear photonic wires, and three light harvesting devices were designed, synthesized, and characterized. All the devices contained a homoFRET region to extend the energy transfer distance. Over 50 different FRET-based photonic wires with different homogeneous FRET configurations were evaluated. Several configurations were found that resulted in a higher end-to-end efficiency despite possessing fewer dyes. A six-fold antenna gain was achieved in the case of the light-harvesting devices. The findings demonstrate that homoFRET can be used to increase the energy harvesting capability of photonic devices. In general, the work also showed that DNA nanotechnology can be used to self-assemble a variety of photonic devices. Additionally, the work has established some basic design rules that will enable the bottom-up assembly of more elaborate devices.

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