Titanium oxide to significantly improve efficiency and photoluminescence
White LEDs may soon be supplanted as the world’s go-to light source by alternative light sources with much better sense of direction.
As a next-generation light control technology, photonic crystal Also nano antenna It is a two-dimensional structure in which nano-sized particles are periodically arranged on a substrate.When irradiated, the nano-antenna and phosphor plate Achieves the ideal mixture of blue and yellow light.
White LEDs have already been improved in the form of white laser diodes (LDs), which consist of a yellow phosphor and a blue LD. Blue LDs are highly directional, whereas yellow phosphors radiate in all directions, resulting in undesirable color mixing.
To address this issue, researchers have developed phosphor plates using metallic aluminum combined with nanoantennas. photoluminescenceAluminum nanoparticles effectively scatter light, improving light intensity and directionality. However, aluminum also absorbs light, which reduces the output. This is a major bottleneck, especially in high-brightness lighting applications.
Now, a team of Kyoto University researchers have succeeded in enhancing forward photoluminescence by a factor of 10 by replacing aluminum with a better material.
“We found that titanium dioxide, which has a higher refractive index and less light absorption, was a better choice,” says lead author Shunsuke Murai.
Initially, the light scattering intensity of titanium oxide seemed inferior to that of metallic aluminum, but the team used computer simulations to come up with an optimal nanoantenna design.
“The new nanoantenna phosphor can reduce the temperature rise during irradiation, which is advantageous for very bright and energy-saving solid-state lighting,” explains Murai.
“In the process of finding the optimal dimensions, we were surprised to find that the thinnest phosphors gave the brightest photoluminescence, showing how to improve forward emission intensity and overall performance.”
Original: Nano-antennas leading to a brighter future
Than: Kyoto University
