Organometal halide perovskites create cheaper, high performing LEDs
Assistant Professor of Physics Hanwei Gao and Associate Professor of Chemical Engineering Biwu Ma are using a class of materials called organometal halide perovskites to build a highly functioning LED. The team has reported its findings in the journal Advanced Materials.
“Early work suggested perovskites could be a promising material to build LEDs,” said Gao. “But, the performance was not up to their potential. We believed there was significant room for improvement.”
Perovskites are any materials with the same type of crystal structure as calcium titanium oxide. Other researchers experimented with perovskites to build LEDs in the past but could not build particularly effective ones. Gao and Ma believed this organic-inorganic hybrid could perform better, if the formula could be appropriately tweaked.
“When we thought about this class of material, we knew it should perform better than this,” said Ma. “We came up with our novel approach to solve some critical problems and get a high-performance LED.”
After months of experiments using synthetic chemistry to fine-tune the material properties and device engineering to control the device architectures, they ultimately created an LED that performed even better than expected.
The material is measured at about 10,000 candelas per square meter at a driving voltage of 12 V. As a benchmark, LEDs glowing at about 400 candelas per square meter are sufficiently bright for computer screens.
“Such exceptional brightness is, to a large extent, owing to the inherent high luminescent efficiency of this surface-treated, highly crystalline nanomaterial,” explained Gao.
Gao and Ma claim they can produce the material in about an hour in the lab and have a full device created and tested in about half a day.
Additionally, while bare hybrid perovskites tend to be unstable in humid air, the nanostructured perovskites exhibit good stability in ambient environment because of the purposely designed surface chemistry. Such chemical stability largely reduces the requirement of sophisticated infrastructure to produce this new type of LEDs and could be of huge benefit for cost-effective manufacturing in the future.
“If you can get a low cost, high performing LED, everyone will go for it,” suggested Ma. “For industry, our approach has a big advantage in that earth abundant materials can be processed in an economic way to make the products.”
Gao and Ma came to FSU as part of the Energy and Materials Strategic Initiative with the mission of producing high tech materials for new generation, energy sustainable technology. By chance, they wound up with offices next to each other and began collaborating.
They also work with Assistant Professor of Industrial and Manufacturing Engineering Zhibin Yu, who also focuses on LED technology research, as well as Assistant Professor of Chemistry Kenneth Hanson, who is a co-author on this current paper.
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