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Proceedings Paper

Integration of 3D printed lens with InGaN light-emitting diodes with enhanced light extraction efficiency
Author(s): Yu Kee Ooi; Christopher Ugras; Cheng Liu; Matthew Hartensveld; Shaunak Gandhi; Denis Cormier; Jing Zhang
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Paper Abstract

III-nitride based light-emitting diodes (LEDs) have great potential in various applications due to their higher efficiency and longer lifetime. However, conventional planar structure InGaN LED suffers from total internal reflection due to large refractive index contrast between GaN (nGaN = 2.5) and air (nair = 1), which results in low light extraction efficiency (ηextraction). Accordingly, various approaches have been proposed previously to enhance the ηextraction. Nevertheless, most of the proposed methods involve elaborated fabrication processes. Therefore, in this work, we proposed the integration of three-dimensional (3D) printing with LED fabrication as a straightforward and highlyreproducible method to improve the ηextraction. Specifically, 500-μm diameter dome-shaped lens of optically transparent acrylate-based photopolymer is 3D-printed on planar structure 500 × 500 μm2 blue-emitting LEDs. Light output power measurement shows that up to 9% enhancement at injection current 4 mA can be obtained from the LEDs with 3D printed lens on top as compared to LEDs without the lens. Angle-dependent electroluminescence measurement also exhibits significant light output enhancement between angles 0 and 30° due to the larger photon escape cone introduced by the higher refractive index of the 3D printed lens (nlens = 1.5) than the air medium as well as the enhanced light scattering effect attributed to the curvature surface of the 3D printed lens. Our simulation results based on 3D finitedifference time-domain method also show that up to 1.61-times enhancement in ηextraction can be achieved by the use of 3D-printed lens of various dimensions as compared to conventional structure without the lens.

Paper Details

Date Published: 20 February 2017
PDF: 7 pages
Proc. SPIE 10115, Advanced Fabrication Technologies for Micro/Nano Optics and Photonics X, 1011508 (20 February 2017); doi: 10.1117/12.2252734
Show Author Affiliations
Yu Kee Ooi, Rochester Institute of Technology (United States)
Christopher Ugras, Rochester Institute of Technology (United States)
Cheng Liu, Rochester Institute of Technology (United States)
Matthew Hartensveld, Rochester Institute of Technology (United States)
Shaunak Gandhi, Rochester Institute of Technology (United States)
Denis Cormier, Rochester Institute of Technology (United States)
Jing Zhang, Rochester Institute of Technology (United States)

Published in SPIE Proceedings Vol. 10115:
Advanced Fabrication Technologies for Micro/Nano Optics and Photonics X
Georg von Freymann; Winston V. Schoenfeld; Raymond C. Rumpf, Editor(s)

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