Dual Function OLED Transparent Electrode and Light Extraction Layer

Organic light emitting diode (OLED) based lighting technology currently suffers from low light extraction efficiency and high production cost- The Department of Energy’s Solid State Lighting Program under the Office of Energy Efficiency & Renewable Energy has set aggressive targets for improved efficiency and cost reduction for OLEDs which will require new materials and manufacturing technologies- Two specific areas of interest for the Solid State Lighting program, and the associated research and manufacturing communities, are: 1) new scalable technologies that efficiently extract light that would otherwise be lost to guided or surface plasmon modes, and 2) new lower cost, high performance technologies to replace physical vapor deposited indium tin oxide transparent conductive electrodes- This project aims to develop a dual function transparent electrode and light extraction enhancement layer for OLED based solid state lighting- The layer will simplify and lower the cost of OLED manufacturing by combining light extraction and transparent electrode functionality, typically requiring two separate material layers, into a single layer- The dual function layer will be based on ZnO and will be deposited using a green chemistry, aqueous solution deposition process- Compared to physical vapor deposition of indium tin oxide, solution deposited ZnO will provide lower raw material, capital equipment, and operating costs- The light extraction functionality in the layer will be enabled by the creation of nano/micro scale porosity within the ZnO crystals- Depending on their size, density, and other characteristics, the pores may be used to vary the effective refractive index and or act as light scattering centers in the ZnO layer, both of which can be used to enhance light extraction- In Phase I of the project, there will be four major tasks/objectives to demonstrate technical feasibility: modelling/simulation to identify target materials properties and device structures and predict their performance, develop processes for achieving target properties in the ZnO layer, develop a OLED structure and scalable fabrication process incorporating the ZnO layer, and demonstrate an OLED incorporating the ZnO layer with at least 2-5 times greater light extraction than a reference OLED design using indium tin oxide-