Scientists from Ferdinand-Braun-Institut (FBH) and its spin-off UVphotonics plan to report on their advances related to UV LED efficiency and reliability at ICULTA-2018 in MELIÃ. They reportedly found a degradation mechanism that indicates that the first hours of operation induce an electromigration of hydrogen in the UV-B LED structure. This migration of hydrogen is followed by a drop in the device’s optical output.
Researchers at FBH said that they made design adjustments that resulted in UV-B LEDs that could demonstrate L50 lifetimes of 8,000 hours. According to the researchers, further optimization of the UV-B LEDs has led to additional enhancements to the reliability of the LEDs, which the researchers expect to have significantly longer L50 lifetimes. In addition, the researchers expect that the output power at 350 mA could be raised to 30 mW.
FBH has also investigated methods of improving internal quantum efficiency and for increasing the efficient light extraction.
At the conference, FBH scientists also intend to present a compact diode laser-based light source that emits in the deep UV spectral range a wavelength of 222 nm and therefore in a region difficult to access with LEDs. The device utilizes single-pass frequency doubling to convert the light of a GaN-based high-power diode laser into the UV spectral range. FBH says the diode laser light source offers the potential for miniaturization. Also, the narrow-band and wavelength-stabilized light source is particularly suited for spectroscopy applications, including Raman spectroscopy and absorption used in medical diagnostics and in substance analysis.
Lab Developments Range from Customized Housings to Ready-to-use Modules
FBH says that its Prototype Engineering Lab has helped develop the optimum package for each application. The lab tailors even complete modules to precisely to fit the range of use. For one of its research partners, for example, the lab designed and constructed several illumination systems that use LED lights to irradiate plants with specific wavelengths. These wavelengths and wavelength combinations are applied systematically to increase the proportion of health-promoting secondary plant metabolites.
Noteably, UV LEDs for use in greenhouses have to be protected with special packages against the warm and humid conditions. FBH will showcase one of these plant illumination modules along with a compact water disinfection system at its exhibition booth.
FBH Entwined with ICULTA-2018 Conference
The ICULTA-2018 conference is jointly organized by ‘International Ultraviolet Association’ and ‘Advanced UV for Life’. The Advanced UV for Life consortium, which is managed by Ferdinand-Braun-Institut (FBH), brings together 50 partners from academia and industry. Moreover, FBH scientists play a prominent role in the conference. For example, Prof. Michael Kneissl serves as co-chair of the conference and serves as the head of the Joint GaN Optoelctronics that FBH and TU (Berlin) jointly operate. Additionally, Professor Markus Weyers, who is head of the Materials Technology Department at Ferdinand-Braun-Institut, serves as chair of the program committee for the ICULTA-2018 conference.