Solid-state Far-UVC Roadmapping Workshop Report
Light in the 200-235 nm range, or far-UVC, is one of the most promising tools for dramatically reducing airborne transmission from day one of almost any pandemic caused by airborne pathogens. If adopted widely, it could also have a dramatic impact on seasonal flu, colds, and endemic COVID-19.
Unfortunately, progress on development and adoption has been much slower than one would have hoped. One bottleneck is the high cost and low efficiency of the only commercially available source at this wavelength range, 222 nm krypton chloride excimer lamps. For example, by our calculations, equipping a classroom with far-UVC would cost >$10k/classroom/year in lamps alone.
Last year, our roadmapping analysts Jasper Götting and Vivian Belenky set out to understand what it would take to get to decrease the cost by two orders of magnitude. On June 12 and 13, 2023, they convened a workshop with top experts on solid-state UV emitters to scope out the most promising approaches in emitter development, forecast timelines with respect to relevant milestones, and list priorities for R&D and broader ecosystem support. The results are summarized in the workshop report.
The brief technical punchline: Participants were most optimistic about AlGaN LEDs and second-harmonic generation (SHG) with blue lasers. AlGaN LEDs benefit from an established materials platform and large research community, while SHG device developments are more uncertain but potentially faster. Cathodoluminescent devices already perform well today but are unlikely to reach the ultimate performance goals.
Another key take-away from the workshop is that while directly supporting solid-state far-UVC R&D to accelerate availability is important, growing the far-UVC market in general and enabling greater private investment is even more critical. Comprehensive safety studies, real-world effectiveness trials, infrastructure technology development, public outreach and education, and support for clear, comprehensive, and sensible far-UVC standards are all needed to make ubiquitous air disinfection a reality.
Report Executive Summary
Far ultraviolet-C (far-UVC) is a promising emerging technology for air and surface disinfection as well as in vivo inactivation of multi-drug-resistant pathogens. Currently, the only widely available far-UVC emitters are krypton-chloride excimer lamps, which lack many desired performance characteristics and scale poorly in cost. In theory, the performance and scalability of solid-state sources, like LEDs, make them ideal for all lighting applications, but uncertainties around solid-state far-UVC emission remain.
To analyze the prospect for next-generation far-UVC sources, Convergent Research gathered representatives from academia, industry, and philanthropy to discuss development goals, approaches, and bottlenecks for solid-state far-UVC.
Aluminum gallium nitride (AlGaN) devices—primarily, but not exclusively, LEDs—and sec- ond-harmonic generation (SHG) blue laser devices were considered the most promising approaches and were regarded as having the greatest potential to achieve the relevant target metrics. A third viable approach, cathodoluminescent devices, was ultimately determined to be less promising and more analogous to excimer lamps than to LEDs: a transition technology that could perform well in the short and perhaps medium term but would ultimately not be competitive with either AlGaN or SHG devices. Based on these discussions, we recommend:
Research and development priorities: A universal priority across all approaches is in the development of far-UVC-transparent materials for p-side alloys, device encapsulants, filters, and other balance-of-system components. Another approach-agnostic priority is the development of aluminum nitride as a material platform. For any AlGaN-based approach— whether LEDs, laser diodes, or any other solid-state design—the priority is in understanding point defects, and in improving light extraction efficiency and doping. SHG device improvements—including refining blue laser diodes and their integration with nonlinear optical elements—lie along a different development path but are, in general, an R&D priority due to the greater uncertainty associated with their potential.
Funding strategies: While allocating resources to the identified R&D priorities is important, of potentially even greater importance is the funding of projects that will grow the far-UVC market and enable greater private investment into solid-state R&D. These projects include comprehensive safety studies, real-world effectiveness trials, infrastructure technology development, public outreach and education, and support for clear, comprehensive, and sensible standards for far-UVC air disinfection. Identifying potential beachhead markets and considering the role of advance market commitments and prizes can stimulate demand and further R&D investment.
