Efficiency Improvement of UVC LEDs by Epoxy Molding Compound With Metallized Reflector

Wan, Chuiming; Zeng, Zhaoming; Xiao, Guowei; Lan, Yian; Li, Chencheng; Lin, Hongwei; Wang, Hong

doi:10.1109/lpt.2023.3325394

Cited by 2 publications

(1 citation statement)

References 18 publications

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“…Recently, Shih et al proposed the use of Al-Co-Zn-Ni high-entropy alloy films as UVC reflectors, which exhibit an average reflectance of 70% across the UVC wavelength range [ 9 ]. Wang et al proposed enhancing the light extraction of UVC LEDs using an epoxy molding compound with a metallized reflector [ 10 ]. Therefore, enhancing the reflectance of the UVC LED lead frame will increase the LOP of UVC LEDs.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of Light Efficiency of Deep-Ultraviolet Light-Emitting Diodes by Encapsulation with a 3D Photonic Crystal Reflecting Layer

Lai,

Lin,

Lee

2024

Nanomaterials

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Recently, UVC LEDs, which emit deep ultraviolet light, have found extensive applications across various fields. This study demonstrates the design and implementation of thin films of three-dimensional photonic crystals (3D PhCs) as reflectors to enhance the light output power (LOP) of UVC LEDs. The 3D PhC reflectors were prepared using the self-assembly of silica nanospheres on a UVC LED lead frame substrate via the evaporation-induced method (side) and the gravitational sedimentation method (bottom), respectively. These PhCs with the (111) crystallographic plane were deposited on the side wall and bottom of the UVC LED lead frame, acting as functional materials to reflect UVC light. The LOP of UVC LEDs with 3D PhC reflectors at a driving current of 100 mA reached 19.6 mW. This represented a 30% enhancement compared to commercial UVC LEDs with Au-plated reflectors, due to the UVC light reflection by the photonic band gaps of 3D PhCs in the (111) crystallographic plane. Furthermore, after aging tests at 60 °C and 60% relative humidity for 1000 h, the relative LOP of UVC LEDs with 3D PhC reflectors decreased by 7%, which is better than that of commercial UVC LEDs. Thus, this study offers potential methods for enhancing the light output efficiency of commercial UVC light-emitting devices.

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Section: Introductionmentioning

confidence: 99%

Enhancement of Light Efficiency of Deep-Ultraviolet Light-Emitting Diodes by Encapsulation with a 3D Photonic Crystal Reflecting Layer

Lai,

Lin,

Lee

2024

Nanomaterials

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Investigation of optical polarization characteristics of ultraviolet-C AlGaN multiple quantum wells by angle-resolved cathodoluminescence

Gong,

Zhu,

Cai

et al. 2024

Opt. Express

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AlGaN-based ultraviolet-C (UV-C) light-emitting diodes (LEDs) face challenges related to their extremely low external quantum efficiency, which is predominantly attributed to the remarkably inadequate transverse magnetic (TM) light extraction efficiency (LEE). In this study, we employ angle-resolved cathodoluminescence (ARCL) spectroscopy to assess the optical polarization of (0001)-oriented AlGaN multiple quantum well (MQW) structures in UV-C LEDs, in conjunction with a focused ion beam and scanning electron microscopy (FIB/SEM) system to etch samples with various inclination angles (θ) of sidewall. This technique effectively distinguishes the spatial distribution of TM- and transverse electric (TE)-polarized photons contributing to the luminescence of the MQW structure. CL spectroscopy confirms that UV-C LEDs with a θ of 35° exhibit the highest CL signal compared to samples with other θ. Furthermore, we establish a model using finite difference time domain (FDTD) simulation to validate the mechanism of the outcomes. The complementary contribution of TM and TE photons at different specific angles are distinguished by ARCL and confirmed by simulation. At angles near the sidewall, the CL is dominated by the TM photons, which mainly contribute to the increased LEE and the decreased degree of polarization (DOP) to make the spatial distribution of CL more uniform. Additionally, this method allows us to analyze the polarization of light without the need for polarizers, enabling the differentiation of TE and TM modes. This distinction provides flexibility for selecting different emission mode based on various application requirements. The presented approach not only opens up new opportunities for enhanced UV-C light extraction but also provides valuable insights for future endeavors in device fabrication and epitaxial film growth.

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Efficiency Improvement of UVC LEDs by Epoxy Molding Compound With Metallized Reflector

Cited by 2 publications

References 18 publications

Enhancement of Light Efficiency of Deep-Ultraviolet Light-Emitting Diodes by Encapsulation with a 3D Photonic Crystal Reflecting Layer

Enhancement of Light Efficiency of Deep-Ultraviolet Light-Emitting Diodes by Encapsulation with a 3D Photonic Crystal Reflecting Layer

Investigation of optical polarization characteristics of ultraviolet-C AlGaN multiple quantum wells by angle-resolved cathodoluminescence

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