Deposition of Microlens Arrays
In collaboration with Professor Nelson Tansu (ECE), we are developing a thin film microlens array for InGaN quantum well light emitting diodes (LEDs). Due to the GaN-air index of refraction mismatch, the brightness of LEDs is significantly limited by total internal reflection. We are developing a technique to partially embed a monolayer of microspheres in a polymer layer at this interface to enhance light extraction. Preliminary results demonstrate a peak intensity increase of ~230% and an order of magnitude increase in overall white-light brightness. Our process uses rapid convective deposition of a suspension that is low cost and can be scaled to industrial processes. We are investigating the coupling of various flow parameters to the resulting structure of the polycrystalline microlens array by directly visualizing the crystallization front using CLSM.
Monolayer coating resulting from rapid convective deposition
Measured intensity of LEDs with and without microlens array