Color mixing is a fundamental process involving the combination of various colors to create different hues, serving as the foundation for advancements in solid-state lighting. The Department of Energy (DOE) has set energy efficiency goals for 2035, and while current lighting methods rely on phosphor down-conversion in LEDs to achieve white light, the potential of color mixing holds a higher theoretical maximum efficiency crucial for meeting future targets. The primary hurdle in color-mixed LED technologies is the "green gap," where existing green LEDs made from hexagonal III-nitride fall significantly short of the DOE's 2035 efficiency goals. Researchers at the University of Illinois Urbana-Champaign have presented a potential solution by introducing a green-emitting cubic III-nitride active layer, demonstrating an internal quantum efficiency (IQE) of 32%, which surpasses conventional cubic layers by over six times, aiming to triple the efficiency of current white LEDs.
The research, led by electrical and computer engineering professor Can Bayram and graduate student Jaekwon Lee, focuses on innovation in cubic nitrides as a material to enhance LED efficiency. Published in Applied Physics Letters, the study explores an alternative approach using cubic III-nitride to achieve highly efficient and droop-free green LEDs. The researchers employ aspect ratio phase trapping, confining defects and undesirable phases within grooves to produce a high-quality cubic-phase material. This cubic III-nitride system, with a 32% IQE and only 16% indium content, represents a substantial efficiency improvement compared to traditional hexagonal wells, showcasing the potential of cubic III-nitride to address the challenges posed by the green gap in solid-state lighting technologies. The research builds upon the University of Illinois's legacy in LED technologies, pioneered by Professor Nick Holonyak, Jr., the inventor of the LED in 1962.


