Collaborative Research: Hydrazone-Based Solid-State Light Emitters

Dartmouth College, Hanover NH

Investigators

Abstract

Non-Technical Abstract Replacing widely used and highly inefficient incandescent bulbs and compact fluorescent lamps with efficient solid-state light devices can drastically reduce our total domestic energy consumption and CO2 production. This project is developing two classes of solid-state light emitters to address multiple drawbacks associated with organic material-based solid-state light emitters. To accomplish this goal, the research team is advancing the molecular level understanding of hydrazone-based solid-state light emitters using experimental and computational techniques. The two lead investigators are actively involved in educational and outreach activities that provide meaningful learning opportunities for underprivileged pre-college students in NH and VT, retain students already in the chemistry pipeline at their institutions, and engage the general public through informal science education activities. These research and outreach activities are supported by the Solid State and Materials Chemistry program in the Division of Materials Research as well as the Marcromolecular, Supramolecular, and Nanochemistry program in the Division of Chemistry. Technical Abstract This collaborative research project employs the tools of organic and physical chemistry to advance fundamental understanding of two remarkable photophysical properties of hydrazone-based materials, namely, aggregation induced emission (AIE) and broad fluorescent bandwidths. BF2-hydrazone (BODIHY) dyes have brought about a paradigm shift in the field of solid-state light (SSL) emitters as these molecules exhibit AIE in the solid-state despite the presence of intermolecular pi-pi interactions that would seem to favor quenching. The other family of hydrazone-based materials investigated here, triazolopyridinium (TOP) salts, are blue light emitting materials with large Stokes shifts and broad fluorescent bandwidths, two properties of great potential value in advanced energy applications. The research team at Dartmouth College uses an efficient synthetic approach to prepare diverse libraries of BODIHY and TOP dyes for structure-property analyses. The photophysical properties of these BODIHY and TOP dyes are extensively characterized, both in solution and the solid-state, primarily using electronic absorption and fluorescence spectroscopies. In addition, the research team at the University of Vermont utilizes electronic structure calculations to elucidate the photophysical mechanisms of hydrazone-based dyes, and make a priori predictions regarding their fluorescent properties to expedite the discovery and development of new and efficient solid-state emitters that can be easily deployed and integrated into SSL applications. Ultimately, this project creates new, fundamental knowledge in the fields of organic and physical chemistry, which is of significant value to the materials and supramolecular chemistry communities.