CAREER: Synthetically Controlled Plasmon-Multiexciton Interaction in Semiconductor-Metal Hybrid Nanostructures

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The Macromolecular, Supramolecular, and Nanochemistry (MSN) Program in the Division of Chemistry at the NSF is funding Professor Jing Zhao of the University of Connecticut (UCONN) to develop synthetic methods to improve the emitting properties of nanostructures based on metallic and semi-conductor nanoparticles for applications in lasers. When excited by light, nanosized metal and semiconductor crystals exhibit unique optical properties. By combining these two types of particles in one hybrid structure, increased light emission is expected. The hybrid nanomaterials can potentially be used in nanolasers and as the photon source in communication systems. New courses are being developed for undergraduate and graduate students focusing on optical nanomaterials and their applications in many different technologies. The research is also being integrated into outreach activities for high school students participating in a UCONN chemistry summer workshop, where the synthesis and optical characterization of metal and semiconductor nanocrystals are being undertaken. In this research, a novel synthetic method is being developed to fabricate a one-to-one metal-semiconductor hybrid nanostructure with control of its spatial relationship. Geometric and optical factors that modulate the plasmon-exciton interaction in the hybrid nanostructures are identified so that the hybrid materials can be effectively designed and fabricated for desired applications. A correlated structure-property approach at the single particle level is used to understand how the geometry of the nanostructures determines their plasmon resonance and exciton/multiexciton emission efficiencies. This work focuses on the plasmonic effect on the multiexciton emission efficiency of single semiconductor nanocrystals and its dependence on interparticle distance, excitation conditions and geometry of the nanostructures. The research includes: (i) producing new synthetic strategies to fabricate one-to-one, metal-semiconductor hybrid nanostructures; (ii) revealing the relationship between the geometry of the hybrid nanoparticles and their optical properties at a single particle level; and (iii) elucidating the plasmon enhancement mechanism of the multiexciton emission efficiency of single semiconductor nanocrystals. The knowledge and nanomaterials obtained from the research is applied in the design and fabrication of optoelectronic devices to improve their performance. In collaboration with the UCONN Early College Experience program, short courses and laboratory demonstrations for high school teachers and students are also being developed. Moreover, female and underrepresented minorities are encouraged to participate in the research program.