Cheaper, high performing LED developed

Scientists have developed a new type of light-emitting diode (LED) using an organic-inorganic hybrid that could lead to cheaper, brighter and mass produced lights and displays in the future.
The researchers used a class of materials called organometal halide perovskites to build a highly functioning LED.
"Early work suggested perovskites could be a promising material to build LEDs. But, the performance was not up to their potential," said Hanwei Gao, Assistant Professor of Physics at the Florida State University in US.
Perovskites are any materials with the same type of crystal structure as calcium titanium oxide.
"We came up with our novel approach to solve some critical problems and get a high-performance LED," said Biwu Ma, Associate Professor of Chemical Engineering at the Florida State University.

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 glowed exceptionally bright. It is measured at about 10,000 candelas per square metre at a driving voltage of 12V. Candela is the unit of measurement for luminescence.
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," Gao said.
Researchers 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 remarkable 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.
The research is crucial to the advance of LED technology, which is fast becoming an avenue to reduce the country's electric consumption.
LED lighting is already sold in stores, but widespread adoption has been slow because of the costs associated with the material and the quality.

"If you can get a low cost, high performing LED, everyone will go for it," Ma said.
"For industry, our approach has a big advantage in that earth abundant materials can be processed in an economic way to make the products," Ma said.
The study was published in the journal Advanced Materials.