Dr. Kenneth Graham, an assistant professor of chemistry at the University of Kentucky, has been selected as a recipient of a CAREER Award from the Department of Energy. This award supports the development of individual research programs of outstanding scientists early in their careers and stimulates research programs in the disciplines supported by the DOE Office of Science.
Dr. Graham’s research funded under this award focuses on a promising set of emerging solution-processed semiconductors, organometal halide perovskites (OMHPs). These low-cost semiconductors can be printed from solution to make solar cells with power conversion efficiencies equal to current state-of-the-art commercial solar cell materials, which require slower and more expensive processing methods. Furthermore, these OMHPs can be used in light emitting diodes for energy efficient solid-state lighting applications, solid-state lasers, and transistors. Ultimately, with further development these OMHPs may lead to lower cost and more efficient solar cells, light emitting diodes, and other electronic devices. However, there are still multiple challenges to developing these materials for use in practical electronic devices, including creating more stable materials and devices and replacing lead with a less toxic element, such as tin.
One essential need for developing higher performing, stable, and less toxic OMHPs and their applications in electronic devices is a better understanding and utilization of surface chemistries and interfacial processes. The chemistry at organic-inorganic interfaces plays a major role in determining the performance of almost all electronic and optoelectronic devices and materials, with OMHPs being no exception. Understanding, developing, and using surface chemistry in these OMHPs is thus the primary theme of the award.
The Graham group has developed advanced photoelectron spectroscopies to probe chemistry and energetics at interfaces, and these tools will be applied to investigate OMHPs and interfaces between OMHPs and organic semiconductors. As organic semiconductors can be solution-processed, are mechanically flexible, and potentially low cost, they are an ideal material for combining with OMHPs in electronic and optoelectronic devices. The proposed research will uncover necessary fundamental knowledge to enable the OMHP surface chemistry to be tuned to create more stable and higher performing materials and devices, while also discovering broadly applicable strategies for manipulating charge-transfer processes and energetics at organic-inorganic interfaces.
Specifically, the research will focus on uncovering how perovskite surface ligands influence photoluminescence properties, energetics, charge transfer processes, and stability, as well as developing strategies and surface ligands to systematically manipulate all of these aspects.
The $750,000 award titled “Surface Ligand Effects on Energetics, Charge Transfer, and Stability at Interfaces Between Metal Halide Perovskites and Organic Semiconductors” will establish key information that can be widely applied in both academics and industry to facilitate the development of this exciting material class.