AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Plasma-Produced Silicon Nanocrystals for Light-Emitting Devices
REBECCA J. ANTHONY, Kai-Yuan Cheng, Zachary C. Holman, Russell J. Holmes, Uwe R. Kortshagen, University of Minnesota
Abstract Number: 532 Working Group: Synthesis of Functional Materials using Flames, Plasmas and other Aerosol Methods
Abstract Silicon nanocrystals (SiNCs) produced in a nonthermal plasma can exhibit efficient and tunable luminescence, making them attractive for use in opto-electronic devices such as light-emitting devices (LEDs). By adjusting the gases used, gas flowrates, and power supplied to the plasma reactor, we can exert control over the size, structure, and surface coverage of the SiNCs, which are also linked to luminescence characteristics. Here we demonstrate two routes to making LEDs using plasma-produced SiNCs.
First, we present a hybrid organic / SiNC LED structure, fabricated using solution-phase techniques. The SiNCs are surface-functionalized in a liquid-phase thermal reaction and then spin-cast onto device substrates incorporating polymer and small-molecule charge-transport layers. These devices exhibit exceptional performance (>8% external quantum efficiency) for a nanocrystal-based LED.
Second, we introduce a gas-phase-only method for fabricating devices. Using exclusively aerosol techniques, SiNCs can be synthesized, surface-passivated, and deposited as dense films suitable for LED construction. We demonstrate the viability of this method by depositing the SiNCs directly from the reactor onto device substrates and completing the device structure with a thermally-evaporated top electrode. These LEDs demonstrate >0.02% external quantum efficiency, which is a promising performance for this as-yet unoptimized device. This streamlined and versatile process opens the door to using nanomaterials in a manner that is compatible with traditional cleanroom techniques.