scholarly journals Observation of Highly Durable Silicone Resin for Encapsulating AlGaN-Based UVB Light-Emitting Diodes

2021 ◽  
Vol 11 (19) ◽  
pp. 9278
Author(s):  
Mu-Jen Lai ◽  
Rui-Sen Liu ◽  
Tsung-Yen Liu ◽  
Shih-Ming Huang ◽  
Ray-Ming Lin ◽  
...  
Keyword(s):  
Quartz Glass ◽  
Light Emitting Diode ◽  
Light Output ◽  
Ultraviolet B ◽  
Silicone Resin ◽  
Light Emitting ◽  
Term Operation ◽  
Degradation Rates ◽  
Packaging Structure

In this paper, we report an AlN-based ceramic lead frame (LF) with encapsulating silicone between the surface of an AlGaN-based ultraviolet-B light-emitting diode (UVB-LED) chip and a quartz glass cover; the light output power (LOP) of this structure was 13.8% greater than that of the corresponding packaging structure without encapsulating silicone. Another packaging structure in which the silicone fully filled the cavity of the AlN-based ceramic LF included covering with quartz glass; in this case, the enhancement of the LOP was 11.7%. Reliability tests performed over a period of 3500 h at a forward current (If) of 100 mA revealed that the LOPs of these two silicone-containing packaging types decreased to 45.3 and 48.6%, respectively, of their initial values. The different degradation rates of these UVB-LEDs were not, however, correlated with the appearance of cracks in the encapsulating silicone during long-term operation. Excluding any possible mechanisms responsible for degradation within the UVB-LED chips, we suggest that the hermetic cover should be removed to avoid the appearance of cracks. Moreover, the main mechanism responsible for the slow degradation rates of LOPs in these proposed packaging structures involves the encapsulated silicone, after cracks have appeared, undergoing further deterioration by the UVB irradiation.

scholarly journals Long-Term Reliability Characteristics of OLED Panel and Luminaires for General Lighting Applications

2020 ◽  
Vol 11 (1) ◽  
pp. 74
Author(s):  
Jeungmo Kang ◽  
Yoonhee Cho ◽  
Woojin Jang
Keyword(s):  
Light Emitting Diode ◽  
Light Output ◽  
Color Temperature ◽  
Light Sources ◽  
Operating Voltage ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Reliability Characteristics ◽  
Color Rendering

Organic light-emitting diode is one of the future-proof solid-state-based lighting sources. OLED shows great aesthetic advantages and good color quality without glare. Moreover OLED is a kind of surface light sources naturally. There are some studies on the long-term reliability characteristics of OLED light source. However, these studies focused on the light output degradation of OLED light sources mainly. In this paper, we have investigated the long-term reliability characteristics of OLED panel and luminaires in terms of lumen maintenance, correlated color temperature, color rendering index, and operating voltage. Total twelve OLED panels with four different kinds and six OLED luminaires with two different kinds were analyzed up to six thousand hours and analyzed for the general lighting applications.

scholarly journals Photocatalytic Degradation of Sulfolane Using a LED-Based Photocatalytic Treatment System

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 624
Author(s):  
Sripriya Dharwadkar ◽  
Linlong Yu ◽  
Gopal Achari
Keyword(s):  
Photocatalytic Degradation ◽  
Oil And Gas ◽  
Light Emitting Diode ◽  
Tap Water ◽  
Aqueous Media ◽  
Ultrapure Water ◽  
Light Emitting ◽  
Degradation Rates ◽  
Reduced Graphene ◽  
The Impact

Sulfolane is an emerging industrial pollutant detected in the environments near many oil and gas plants in North America. So far, numerous advanced oxidation processes have been investigated to treat sulfolane in aqueous media. However, there is only a few papers that discuss the degradation of sulfolane using photocatalysis. In this study, photocatalytic degradation of sulfolane using titanium dioxide (TiO2) and reduced graphene oxide TiO2 composite (RGO-TiO2) in a light-emitting diode (LED) photoreactor was investigated. The impact of different waters (ultrapure water, tap water, and groundwater) and type of irradiation (UVA-LED and mercury lamp) on photocatalytic degradation of sulfolane were also studied. In addition, a reusability test was conducted for the photocatalyst to examine the degradation of sulfolane in three consecutive cycles with new batches of sulfolane-contaminated water. The results show that LED-based photocatalysis was effective in degrading sulfolane in waters even after three photocatalytic cycles. UVA-LEDs displayed more efficient use of photon energy when compared with the mercury lamps as they have a narrow emission spectrum coinciding with the absorption of TiO2. The combination of UVA-LED and TiO2 yielded better performance than UVA-LED and RGO-TiO2 for the degradation of sulfolane. Much lower sulfolane degradation rates were observed in tap water and groundwater than ultrapure water.

scholarly journals A 3 W High-Voltage Single-Chip Green Light-Emitting Diode with Multiple-Cells Network

2015 ◽  
Vol 2015 ◽  
pp. 1-4 ◽  
Author(s):  
W. Wang ◽  
Y. Cai ◽  
Y. B. Zhang ◽  
H. J. Huang ◽  
W. Huang ◽  
...  
Keyword(s):  
High Voltage ◽  
Light Emitting Diode ◽  
Light Output ◽  
Green Light ◽  
Current Crowding ◽  
Single Chip ◽  
Light Output Power ◽  
Large Area ◽  
Light Emitting ◽  
Multiple Cells

A parallel and series network structure was introduced into the design of the high-voltage single-chip (HV-SC) light-emitting diode to inhibit the effect of current crowding and to improve the yield. Using such a design, a6.6×5 mm2large area LED chip of 24 parallel stages was demonstrated with 3 W light output power (LOP) at the current of 500 mA. The forward voltage was measured to be 83 V with the same current injection, corresponding to 3.5 V for a single stage. The LED chip’s average thermal resistance was identified to be 0.28 K/W by using infrared thermography analysis.

scholarly journals Reflectance-Based Organic Pulse Meter Sensor for Wireless Monitoring of Photoplethysmogram Signal

Biosensors ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 87 ◽  
Author(s):  
Fahed Elsamnah ◽  
Anubha Bilgaiyan ◽  
Muhamad Affiq ◽  
Chang-Hoon Shim ◽  
Hiroshi Ishidai ◽  
...  
Keyword(s):  
Power Consumption ◽  
Structural Design ◽  
Signal To Noise Ratio ◽  
Light Emitting Diode ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Wireless Monitoring ◽  
Organic Light ◽  
Reduced Power Consumption

This paper compares the structural design of two organic biosensors that minimize power consumption in wireless photoplethysmogram (PPG) waveform monitoring. Both devices were fabricated on the same substrate with a red organic light-emitting diode (OLED) and an organic photodiode (OPD). Both were designed with a circular OLED at the center of the device surrounded by OPD. One device had an OLED area of 0.06 cm2, while the other device had half the area. The gap distance between the OLED and OPD was 1.65 mm for the first device and 2 mm for the second. Both devices had an OPD area of 0.16 cm2. We compared the power consumption and signal-to-noise ratio (SNR) of both devices and evaluated the PPG signal, which was successfully collected from a fingertip. The reflectance-based organic pulse meter operated successfully and at a low power consumption of 8 µW at 18 dB SNR. The device sent the PPG waveforms, via Bluetooth low energy (BLE), to a PC host at a maximum rate of 256 kbps data throughput. In the end, the proposed reflectance-based organic pulse meter reduced power consumption and improved long-term PPG wireless monitoring.

Enhanced Emission from a Light-Emitting Diode Modified by a Photonic Crystal

2000 ◽  
Vol 637 ◽  
Author(s):  
Alexei A. Erchak ◽  
Daniel J. Ripin ◽  
Shanhui Fan ◽  
John D. Joannopoulos ◽  
Erich P. Ippen ◽  
...  
Keyword(s):  
Photonic Crystal ◽  
Planar Waveguide ◽  
Optical Pumping ◽  
Extraction Efficiency ◽  
Light Emitting Diode ◽  
Active Material ◽  
Light Output ◽  
Vertical Direction ◽  
Light Emitting ◽  
Spectrally Resolved

AbstractEnhanced light output is observed from a light-emitting diode (LED) structure containing a two-dimensional (2D) photonic crystal. The capture of emitted light into planar waveguide modes reduces the extraction efficiency of LEDs. Here, 2D photonic crystals are utilized to: 1) enhance the extraction of light in the vertical direction from an LED and 2) enhance optical pumping by directly coupling light from a pump laser into the LED structure. Spatially and spectrally-resolved photoluminescence (PL) is used to characterize the enhancements. A 100-fold enhancement in extraction for a single wavelength into the vertical direction is obtained without the photonic crystal penetrating the active material.

scholarly journals Emission Characteristics and Effect of Battery Drain in “Budget” Curing Lights

2016 ◽  
Vol 41 (4) ◽  
pp. 397-408 ◽  
Author(s):  
MM AlShaafi ◽  
JE Harlow ◽  
HL Price ◽  
FA Rueggeberg ◽  
D Labrie ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Medical Instrument ◽  
Light Output ◽  
The Internet ◽  
Spectral Emission ◽  
Light Emitting ◽  
Power Spectral ◽  
Radiant Power ◽  
And Performance ◽  
Emission Ratios

SUMMARY Recently, “budget” dental light-emitting diode (LED)–based light-curing units (LCUs) have become available over the Internet. These LCUs claim equal features and performance compared to LCUs from major manufacturers, but at a lower cost. This study examined radiant power, spectral emission, beam irradiance profiles, effective emission ratios, and the ability of LCUs to provide sustained output values during the lifetime of a single, fully charged battery. Three examples of each budget LCU were purchased over the Internet (KY-L029A and KY-L036A, Foshan Keyuan Medical Equipment Co, and the Woodpecker LED.B, Guilin Woodpecker Medical Instrument Co). Major dental manufacturers provided three models: Elipar S10 and Paradigm (3M ESPE) and the Bluephase G2 (Ivoclar Vivadent). Radiant power emissions were measured using a laboratory-grade thermopile system, and the spectral emission was captured using a spectroradiometer system. Irradiance profiles at the tip end were measured using a modified laser beam profiler, and the proportion of optical tip area that delivered in excess of 400 mW/cm2 (termed the effective emission ratio) was displayed using calibrated beam profile images. Emitted power was monitored over sequential exposures from each LCU starting at a fully charged battery state. The results indicated that there was less than a 100-mW/cm2 difference between manufacturer-stated average tip end irradiance and the measured output. All the budget lights had smaller optical tip areas, and two demonstrated lower effective emission ratios than did the units from the major manufacturers. The budget lights showed discontinuous values of irradiance over their tip ends. One unit delivered extremely high output levels near the center of the light tip. Two of the budget lights were unable to maintain sustained and stable light output as the battery charge decreased with use, whereas those lights from the major manufacturers all provided a sustained light output for at least 100 exposures as well as visual and audible indications that the units required recharging.

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