Improved Light Extraction from GaN LEDs

Statement of the Problem or Situation that is being addressed: Effective light extraction remains one of the largest obstacles in realizing LED performance targets of efficiency and lifetime, and also plays into the brightness and cost of LEDs. Addressing this challenge with a cost effective solution represents one of the biggest opportunities towards broader commercialization of LEDs. Statement of how this Problem or Situation is being Addressed: To address the challenge of improving light extraction in the GaN LEDs, Triton proposes to develop a novel block copolymer system that has already demonstrated a refractive index of 1.8 with a potential to go higher than 2.0. In Phase I, we will modify and optimize the block copolymer chemistry for application specific performance improvements, which include high temperature stability, controlled curing, LED component compatibility, and optical clarity over the device lifetime. What is to be done in Phase I? Properties of this versatile block copolymer system will be modified by manipulating and controlling functional groups in branched structures. Fundamental chemistry and synthesis routes will also be optimized to improve purity and yield of the reaction byproducts. Further, we will investigate the additive chemistry to establish a user-friendly procedure of resin curing without compromising physical and chemical properties of the block copolymer system and existing LED components such as down-conversion phosphors. Commercial Applications and Other Benefits: A high refractive index solution, processable polymeric material with high temperature stability can be used to enhance light extraction efficiency of all solid state light generating devices such as LEDs and OLEDS. This material also can be used to improve light absorption efficiency for solar cells. Therefore easy-of-use and affordable optical coatings and encapsulants will have great and immediate commercial potentials for effective light managements. Keywords: High refractive index, Polymeric resins, Index matching, Light extraction efficiency, Temperature stability, High transmittance, LED encapsulation Summary for Members of Congress: Affordable and ease-of-use high refractive index polymeric resins are critically required technology for effective light management in all solid state lighting devices and solar cells. Availability of this material may increase light generation efficacy of these devices by 10% which equivalents to reducing 40Mt of CO2 emission worldwide.