PFI-TT: Synthesis of low-cost and environmentally sustainable organic phosphors for light emitting diode lighting fixtures

The broader impact/commercial potential of this Partnerships for Innovation - Technology Translation (PFI-TT) project is to eliminate dependence on rare-earth (REEs) in phosphors used in light emitting diode (LED) lighting applications while continuing to improve lighting quality and efficiency. Rare earth elements are essential for inorganic phosphors used in commercial LED products.

Even though the REEs are currently available; They are geographically unevenly distributed, so their availability is susceptible to various factors, such as social and political constraints, environmental regulations and economics, and thus, a high degree of uncertainty exists in their future availability. As a result, inorganic phosphors present an inherent risk to the long-term commercial viability and utility of LED lighting.

Moreover, there exists an opportunity to improve the efficiency and light quality performance of existing inorganic phosphors. Improvements could result in reduced electricity consumption, which could lead to significant reductions in greenhouse gas emissions considering the wide application of LEDs. In addition to direct impacts on visual performance, light quality affects human mood and behavior.

Improved light quality may lead to elevated mental states, sharpened alertness, and boosted productivity.

The proposed project develops an eco-friendly method to synthesize organic phosphors using an abundant natural product in place of rare earth elements, at a commercially competitive cost. The final product, a phosphor-imbed sheet, can be integrated into lighting products as the outer cover and achieve enhanced efficiency and color quality compared to rare earth element-derived inorganic phosphors.

The team is the first to report the syntheses of highly fluorescent organic phosphors from theobromine, a molecule derived from cacao beans, through direct arylation. Using an abundant, non-toxic natural product and advanced green chemistry allows the research group to produce the desired organic phosphors at both reduced cost and environmental impacts.

Moreover, introducing theobromine to organic phosphors enhances their ambient stability, which is essential for LEDs given their long lifetime. The synthetic and molecular design challenges the common conception that organic phosphors are expensive and unstable. Dr.

Luscombe and her students recently developed theobromine-derived phosphors offering efficiency and light quality performance that exceeds most commercial products. Their next steps will focus on further enhancing the stability of the theobromine-derived phosphors through molecular optimization and encapsulation designs, aiming to narrow or eliminate the gap between lab research and a commercial product.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.