Most LEDs emit visible light, but RIKEN physicists have created an LED that emits in narrow areas of far ultraviolet light that are safe for humans but deadly to viruses and bacteria. Image source: Silver Image/Science Photo Library
An efficient LED that is fatal to microorganisms and viruses but safe for humans was designed by three RIKEN physicists. One day, it could help countries get rid of the shadow of the pandemic by killing pathogens in a room full of people.
UV sterilization lamp is very effective in eliminating bacteria and viruses, and they are often used in hospitals to disinfect surfaces and medical devices.
This kind of lamp can be made of LED to make it energy-saving. However, these LEDs use ultraviolet rays in the range of destroying DNA, so they cannot be used around people. People have begun to develop efficient LEDs that emit light in a narrow far-ultraviolet light band, which seems to be both good at disinfecting and safe for the human body.
Bactericidal LED lamps that work without humans are usually made of aluminum, gallium and nitrogen. By increasing the amount of aluminum they contain, these LEDs can be modified to operate in areas of wavelengths that are safe for humans. But traditionally, this greatly reduced their power.
To solve this problem, Jo Masayoshi, Itaokazu Yuri and Heiyama Hideki both created a more complex LED at the RIKEN Quantum Optoelectronics Experimental Institute. They are sandwiched in multiple layers, each containing slightly different proportions of aluminum, and in some layers they also add trace amounts of silicon or magnesium.
This effectively creates a barrier process for electrons, hindering their movement on the material and capturing them in certain areas for longer periods of time. This in turn increases the amount of light emitted by the device and reduces the amount it absorbs.
To help determine the best design, the team used computer simulations to model all possible impacts. “Then we plant the sample and see if it works,” Joe said. The biggest experimental challenge is precisely controlling the thickness of each layer. They created an LED that works under far UV light, with output power almost ten times the best it used to be.
COVID-19 pandemic has re-aware of the importance of being able to destroy viruses and microorganisms on the surface. “We believe that our discoveries and technology will be very useful in protecting society from this and future pandemics,” Jo said.
Jo added that the three will work hard to further improve their LED performance. “There is still a lot of room for improvement in output power and power efficiency,” he noted.
Their research was published in "Applied Physics Express" .
More information: Masafumi Jo et al., milliwatt power far-ultraviolet aldehyde LED on sapphire substrate , Application Physical Express (2022). DOI: 10.1063/5.0088454
Journal information: Application Physics Express
