Advanced UV for Life
UV LEDs
Ultraviolet light-emitting diodes (UV LEDs) represent a highly advanced development in UV technology and offer a compact alternative to some other UV sources.
As solid-state components, UV LEDs emit radiation in the ultraviolet spectral range. UV LEDs can typically cover the main ranges UV-A (315–400 nm), UV-B (280–315 nm), UV-C (approx. 220–280 nm) and Far-UVC (below 235 nm). The so-called Near-UV or blue light LED at 405 nm is also considered on this page due to its spectral proximity to the UV range and its partially comparable fields of application.
UV LEDs differ fundamentally from classic LEDs for visible light – both in terms of structure and the semiconductor materials used. Visible LEDs usually consist of semiconductor materials and fluorescent substances that are optimized for the visible spectral range. In contrast, UV LEDs require specially adapted semiconductor materials and semiconductor structures.
UV LEDs should therefore not be simply viewed as a variant of visible LEDs, but as an independent technology with specific challenges and characteristics.
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How UV LEDs work
Like LEDs in the visible range, UV LEDs are based on the principle of electroluminescence: When an electric current is applied, electrons and holes recombine in the semiconductor material, emitting photons. The targeted material changes allow the emission wavelengths to be adapted to specific application requirements.
Materials from the so-called group of III-N semiconductors are often used. These include primarily aluminum nitride (AlN), aluminum gallium nitride (AlGaN), aluminum gallium indium nitride (AlGaInN) or indium gallium nitride (InGaN) in the border area to the blue spectrum. The differences in material and layer structure affect electrical and optical properties, influence efficiency and place special demands on manufacturing. The high-energy UV radiation also places high demands on all materials used, as many conventional LED components (e.g. substrates, contacts or housing materials) can absorb UV radiation or be damaged by it.
Properties of UV LEDs
UV LEDs generate ultraviolet radiation through the recombination of electrons and holes in semiconductor materials. They emit photons in a narrow, partially tunable wavelength range and are designed as compact semiconductor components suitable for mass production.
They operate on low-voltage direct current and reach their full light output immediately after switching on.
The luminous efficacy of UV LEDs is temperature-dependent, with high temperatures reducing efficiency. Over time, the light output can decrease continuously.
UV LEDs do not contain any volatile or toxic metals and are considered recyclable.
Challenges and development of UV LEDs
UV-A LEDs have made significant progress in recent years and are established in numerous applications. Their efficiency and lifetime are significantly higher than those of UV-C LEDs. They are used, among other things, in the curing of plastics, printing inks, and adhesives, in medical technology, as well as in analytics and forensics. The current focus is on increasing efficiency, light extraction, and reducing costs.
UV-B LEDs are well on their way to development and already offer sufficient performance for applications such as phototherapy, sensing, and certain disinfection tasks. Key challenges lie in improving material quality and external quantum efficiency. Continuous progress suggests increasing adoption in the coming years.
UV-C LEDs are already commercially available and are in a dynamic development phase. Currently, research and industry are working intensively on increasing radiation output, improving lifespan, and achieving higher chip packing densities, among other things. Advances in semiconductor and packaging technology are leading to steady improvements in efficiency, lifespan, and cost-effectiveness. Powerful UV-C LEDs are thus coming within reach for a multitude of applications.
Far-UVC LEDs refer to ultraviolet LEDs with emissions in the range below 240 nm. This technology is still facing significant development steps: Emission in the Far-UVC range requires semiconductor materials with a high aluminum content, which presents particular challenges. Although the quantum efficiency is currently still lower than that of conventional UV-C LEDs, new approaches promise steady improvements. The service life is also developing positively thanks to advanced designs. Far-UVC LEDs are considered particularly promising for use indoors for continuous disinfection and infection prevention.
Near-UV or blue light LEDs (e.g. 405 nm), also known as “antimicrobial blue light” or “High-Intensity Narrow Spectrum” (HINS), emit in the transition range between visible light and UV-A. They can have a disinfecting effect on various bacteria and viruses – albeit to a lesser extent than UV-C. This technology is subject to a different risk assessment with regard to health protection and material compatibility. Compliance with relevant standards is often less complex than with classic UV systems. Nevertheless, photobiological risks, especially for the eyes, must also be observed here at high intensities or longer exposure. 405-nm LEDs offer potential advantages in terms of safety and material compatibility and are also commercially readily available with high intensity and comparatively inexpensive.
