ORONO — A University of Maine-led research team, in collaboration with the University of Alabama, will design a new class of materials capable of improving solar cells, lasers and other optoelectronic devices that convert light into energy with a $525,000 collaborative research award from the National Science Foundation.
Liping Yu, an assistant professor of physics at the University of Maine, will lead the project and collaborate with Robert Lad, a professor of physics at UMaine, and Feng Yan, an assistant professor with the Department of Metallurgical and Materials Engineering at the University of Alabama.

Perovskite halides exhibit strong potential for developing more efficient optoelectronic devices because they possess “desired light absorption, long carrier lifetimes and remarkable defect tolerance,” Yu says. Despite their optimal properties, these materials have multiple limitations for industrial applications. For instance, they typically contain lead that is toxic to the environment and they become unstable when exposed to the real-world environment, particularly natural heat, humidity, ultraviolet light and oxygen levels.

The team plans to predict, synthesize and characterize a new group of lead-free, high entropy perovskite halide materials that can remain stable and withstand realistic temperatures and other challenging environmental conditions. One distinctive attribute of these materials is that they contain five or more principal metal elements in almost equal concentration, and the mixing of these elements can generate a considerable entropy effect that enhances the stability.

“These new optoelectronic materials can be integrated into many applications including solar cells, light-emitting devices, photoelectrochemical catalysts, photodetectors and lasers, radiation detectors, and sensors,” Lad says. “This research effort enables Maine to build capacity in this important technology area.”

The team’s investigation will involve three interlinked tasks, each one led by a different researcher, featuring a closed feedback loop between theory, simulation and experiment synthesis and characterization.  

Yu will lead the group’s efforts to theoretically predict which combinations of metal elements can be used to create the new class of perovskite halides through first-principles calculations and modeling. Using the results, Yan will spearhead the synthesis of new materials through solid-state solution, hydrothermal and solvent precipitation techniques. The team will then, under Lad’s leadership, investigate and explore new ways to enhance the stability of each material under various environmental conditions.

Three Ph.D. students and six undergraduate students will participate in the three-year project, during which they will obtain extensive training in computational materials science, materials synthesis and characterization, and data analysis. Much of the experimental work will be carried out using facilities within UMaine’s Frontier Institute for Research Sensor Technologies (FIRST).

Researchers will share the data generated from their investigation with various publicly available databases. They also plan to incorporate some of their findings into course materials for undergraduate and graduate level classes.

“This project allows students to become immersed in cutting-edge investigations of new optoelectronic materials,” Yu says, “and the combined theoretical and experimental approach is an efficient way to pursue the development of these new materials.”