Haley Guthrie, Graduate Student, Cahill Lab, GW Department of Chemistry

The Department of Chemistry Presents:  Haley Guthrie, Graduate Student, Cahill Lab, GW Department of Chemistry.  

Hybrid perovskites are an emerging class of materials valued for their structural flexibility and tunable electronic properties. While widely studied for applications in solar cells and light-emitting devices, these materials are also gaining attention in nuclear chemistry for their potential use in radiation detection, waste encapsulation, and isotope separation. Our work reports the synthesis and characterization of a new family of hybrid metal halides made from isolated ruthenium-halide octahedra ([RuX6]2-, where X = Cl or Br) charge balanced with halopyridinium organic cations. These materials serve as model systems to better understand how small changes in structure – particularly non-covalent “second-sphere” interactions – influence light absorption and electronic behavior. Using diffuse reflectance spectroscopy, we found that bromide-containing compounds exhibited lower energy bandgaps (1.05-1.08 eV) than their chloride counterparts (1.22-1.43 eV). Computational studies using density functional theory (DFT), natural bond orbital analysis (NBO), and other quantum chemical methods help quantify non-covalent interaction strengths and provide insight into orbital behavior and assembly mechanisms. The quantum chemical methods revealed that weak second-sphere interactions influence assembly but do not significantly influence electronic structure.  This work highlights how subtle molecular-level features can be used to evaluate optoelectronic properties of hybrid materials. Understanding these relationships is critical not only for developing efficient solar energy materials but also for designing new functional solids for nuclear applications, where fine-tuned control over electronic structure, stability, and radiation response is essential. Our findings offer a path forward in the rational design of low-dimensional hybrid materials for energy and nuclear science.

BIO

Haley earned her B.S. in Biology at Purdue University in Indiana and completed her M.S. in Biology at East Carolina University in North Carolina where she studied salinity tolerance and parasite diversity in native crustaceans. Since joining the Cahill Research Group in Spring of 2024, she has been working on using a combined experimental and computational approach to study structure-property relationships in hybrid materials.