The remarkable efficiency gains achieved by LED lighting over the past few years has led some within the industry to doubt that improvements can continue much longer. A recently published paper in Applied Physics Letters, however, shows that the scientific understanding behind LED technology continues to improve at the same time that manufacturers continue to improve the efficiency of their LED modules.
In the paper, researchers from Rensselaer Polytechnic Institute identify the cause of a common LED challenge known as “efficiency droop,” where the efficiency of the light source decreases as a higher current is applied. Efficiency droop is especially troublesome for lighting applications, which compared to other uses for LEDs like signage or flat-screen monitors, requires higher-lumen outputs. While the new research does not immediately make available a commercially viable solution, it does indicate that efficiency gains won’t be slowing down anytime soon. The study shows that as current increases in an LED, an electric field develops that pushes electrons away from the region where those electrons would otherwise produce light. Now that researchers and engineers have a more accurate understanding of this effect, they will be better able to design systems to minimize it.
Announcements of ever-higher LED efficiencies seem to come out weekly. In a July 23 press release, Seoul Semiconductor announced its new 5630C as the world’s most efficient mid-power LED package at 180 lumens per watt (lm/W). On July 29, Shanghai-based Pozeen launched a retrofit kit for recessed lighting fixtures that can achieve an overall efficiency of 110 lm/W. These come on top of regular announcements by companies such as Cree and Philips that LED chips and packaged LED modules are reaching ever new heights. Cree announced in February that its R&D department had made a demonstration chip that achieved 276 lm/W. Philips announced in April that it had developed a prototype tube LED that delivers 200 lm/W.
None of those recent advancements were achieved with the benefit of the Rensselaer study, indicating that the steady drumbeat of product announcements will keep sounding for at least the next several years. Anyone doubting that science will keep pushing the envelope toward LEDs’ theoretical limits will be sorely disappointed.
Tags: Building Systems, Energy Efficiency, Industrial Innovations, LEDs, Smart Buildings Program, Smart Lighting
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