Ultra high performance light sources based on organic field activated devices (FADs)

Wake Forest University, Winston Salem NC

Investigators

Abstract

Abstract title: Development of Ultra-High Efficiency Lighting Using AC-driven Organic Devices Abstract: Non-technical: If the efficiency of lighting in US homes and offices could be increased by 50%, it would save $115 Billion nationally by 2025, alleviate the need for 133 new power stations, eliminate 258 million metric tons of carbon and save 273TWh/year in energy. And this is just for room lighting! But, if that increase was larger: 100% or 200%, the impact to the world economy, with all of its applications, could be staggering! How could this be done? In this program an exciting new approach to using organic materials in making light is examined-one that can be far more efficient than the methods used today. The approach uses a newly introduced, nanoengineered, organic thin film lamp architecture and drives the lamp with a resonant AC-electric field which not only stimulates light emission, but introduces internal magnetic fields that allow control over internal quantum efficiencies. So, losses typically associated with the direct flow of current into and out of the structure are managed through reactive power coupling and the proper choice of materials that insulate the emitter of the lamp from the electrical contacts, and internal losses are managed by the magnetic field. Preliminary results from these devices are intriguing, suggesting extraordinary efficiencies combined with high brightness. But exactly how far the efficiency and performance of the principle can be pushed is still unknown. This program will set the foundations of that understanding and potentially drive a revolution in ultra-high performance lighting that is cheap, efficient, and long lived, challenging even the inorganic light emitting diode (LED) for supremacy in the marketplace. Technical: The proposed research will establish a framework for understanding the fundamental mechanisms of light emission in the AC-coupled, organic, field-induced electroluminescent devices. The focus of the work will be an examination of the basic physics of AC field-induced exciton formation required to push forward performance. Specifically, exciton creation rates will be tied to the properties of internal "charge generators"such as nanoparticles (ie. single walled carbon nanotubes, nanoplatelettes, and quantum dots) or small molecules placed proximate to the emitters. Triplet harvesting will be demonstrated in field-induced light generation. This will be tied to modifications of resonant energy transfer efficiency through nanoantennae effects mediated through nanoparticle additives. Finally, a direct correlation between internal magnetic fields and the modification of de-excitation routes that alter single to triplet population dynamics will be shown. The outcome of this work will establish the principles necessary to balance dopants, magnetic interactions and internal energy transfer rates in these types of devices generally, pushing the very limits of their power efficiency and brightness. However, the program also has the potential to set new directions in high performance magneto-optic devices based in organics, based on control over excitation lifetimes using internal magnet fields. This would open opportunities in optical switching, displays, organic lasers, and a host of other such applications.