Session Index

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  Preview abstract

To accurately control the chromatic performance, a color mixing model for the printer inks has been successfully established and widely verified with the aids of their reflective spectra. First, the PCA analysis help set up the relation between their reflectivity spectra and the control gray levels of each single inks. Then, the color mixing model for multiple inks has been developed and verified.

 

We aims to study the night-time visibility for four types of LED traffic signs, including LED local backlight type, LED backlight type, LED external lighting type, and LED dot matrix type. We found that the visibility is an important factor that affects LED traffic sign reading.

  Preview abstract

Light is one of the factors that can restore the sleep cycle and improve the quality
life in people living with dementia (PWD). Exposure of appropriate light (healthy lighting) to
the dementia’s patient can restore their sleep cycle. We have developed an evaluation function
for a neural network to help in optimizing healthy lighting to improve the sleep quality of
PWDs.


 

Here we present a dual-gate transistor structure to suppress the dynamic on-resistance increase. The auxiliary gate under a proper fixed voltage is able to induce additional electrons to compensate the channel carrier loss during main gate switching, leading to a lower dynamic on resistance. In this work, we benchmarked the fundamental electrical properties of both single-gate and dual-gate HEMTs. We further extracted the dynamic behaviors by stressing the devices with short pulses. The results suggest a significant improvement of dynamic behaviors of a dual-gate HEMT under a proper bias applied on the auxiliary gate electrode.

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For nitride-based blue and green light-emitting diodes (LEDs), the forward voltages (Vf) are higher due to the large barriers to vertical carrier transport caused by the total polarization discontinuity at multiple quantum well (QW) and quantum barrier interfaces. As we know, the turn-on voltages for blue and green LED are both affected by random alloy fluctuation and V-defect density. In our model, we find that the Vf of the green LEDs is reduced significantly by V-defects, where the smaller polarization barrier at the V-defect sidewall is the major path for lateral carrier injection.

 

AlGaN-based UVC-LED structure has electrochemical (EC) treated porous AlGaN layer. The photoluminescence peak wavelength has a slightly blueshift phenomenon from non-treated LED (274.1nm) to EC-LED (272.4nm) due to the partial strain release in the active layer with embedded porous layer. In electroluminescence (EL) emission spectrum, the intensity for the AlGaN active layer (~270nm) was increased. By forming the conductive porous-AlGaN:Si layer, the EL emission intensity of the EC-LED has 20% enhancement compared to non-treated LED. High light extraction effect of the UVC-LED with porous-AlGaN layer has been studied for the high efficiency UVC-LED applications.

 

In this study, green quantum dot light-emitting diodes (QLEDs) comprised of inorganic/organic hybrid hole injection/transport layers with solution-process was reported. Molybdenum oxide (MoOx) was used as hole injection layer (HIL), Poly-TPD as hole transport layer (HTL) and magnesium doped zinc oxide nanoparticles (Mg0.1Zn0.9O NPs) served as electron transport layer (ETL) prepared by synthesis nanoparticles method were demonstrated. The maximum luminance (Lmax) of the fabricated QLEDs can be up to 138,612 cd/m2 with current efficiency of about 6.72 cd/A.

 

For nitride-based AlGaN LEDs, the potential fluctuations caused by alloy disorder may relax the compressive strain in the lower Al (higher Ga) composition sites. In this paper, the k·p method combined with 3D-DDCC solver is used to study the polarization ratio changes due to the random alloy fluctuation and different Al composition in the buffer layer. When the TM polarization ratio is higher, increasing the Al composition of the buffer layer from 60% to 100%, the polarization ratio decreases from 0.33 to -0.57 due to the increased compressive strain.

 

In order to achieve a better heat dissipation, diamond powder is added into the QDLED package. The results show that the maximum temperature and surface areal temperature can be reduced, but the optical performance will be impacted when mixed with diamond.

 

Our design goal is to pass the German Bicycle Entry Light Regulations. First, analyze the optical characteristics and cost of a variety of commercially available white light high-power LED, find the LED that meet the characteristics and cost, and pass this regulation with a direct TIR lens.

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The quality of sleep can affect the efficiency, concentration and mood of workers.In order to improve the quality of sleep, this study has previously proposed lamps with low blue light source LEDs and color temperature changes. In order to be closer to life, it is easy to carry and use as a starting point every day, so it is applied to smart mobile devices as a method to enhance sleep quality, and develop a mobile device assistant of Light App according to the needs of the experiment.

 

A high luminance white light source based on blue laser diode pumping single-crystal phosphor is proposed. The photon recycling method is used to minimize the Étendue and increase the luminance effectively. The final design can achieve the luminance value at 1200 cd/mm^2 in the 1.6×1.2 mm^2 emitting area.

 

In order to read text clearly, people often increased the brightness of desk lamp, which rose the incidence rate of photoretinitis. We found that the illuminance required for clear reading increased with diopters and it increased more when font size was reduced. In addition, we also found that under same font size, the illuminance required for reading with white light is higher than that of candlelight.

  Preview abstract

The effects of p-type last barrier on deep ultraviolet light emitting diodes (DUV LEDs) were investigated. The hole injection of DUV LEDs was improved by p-type last barrier, and the light output power of DUV LEDs with p-type last barrier was enhanced approximately 42% at injection current of 600 mA.

 

In this study, a white light lamp with adjustable axially symmetric colour non-uniform light pattern, which is composed a blue LED, a TIR lens, a moved double convex lens and a phosphor plate, is proposed. The optical performance of the lamp will be evaluated in below.

  Preview abstract

The use of LED array substrates is not limited to the packaging of a single LED. For the light source space, we have a greater degree and use chips in different positions to generate different light types to meet different needs or regulations.

  Preview abstract

The performance of DUV LED is optimized by employing a triangular EBL. Simulation results show that wall plug efficiency (WPE) has improved from 1.89% to 2.21% due to reduction of electron overflow. The WPE is further improved to 2.28% by optimizing Al composition of triangular EBL from 70% to 80%.

  Preview abstract

This research uses Graphene, which is the most popular in recent years, as a dopant. Graphene is doped into silver paste. With Graphene's high thermal conductivity, we can improve the optical-thermal characteristics and increase the life of the LED.

 

In this study, the replication of rose petal surface structure are patterned onto the top surface of phosphor-converted LEDs (pcLEDs) to reduce the angular variation of correlated color temperature (CCT) of pcLEDs. It is found that the replication of rose petal surface structure on the pcLED can redistribute the blue and yellow light from normal direction to large angle. Thus, the angular color uniformity of pcLEDs with the replication of rose petal surface can be improved.

  Preview abstract

The photochemical stability of the curcumin used in the phosphor-converted LEDs (pc-LEDs) is investigated in this study. The host materials of silicone and epoxy are used to encapsulate the curcumin, and then illuminated by a blue emitter LED to access the emission spectra measured at different illuminating times. The long-term photochemical stability of the curcumins film using silicone and epoxy is also conducted to verify the use of the curcumins in pcLEDs.

  Preview abstract

An atomic layer deposition (ALD) system was used to deposit SiO2 films with various thicknesses on the red CdSe/ZnS core-shell quantum dots (QDs) as the protective layer. According to the long-time aging testing results, SiO2 protective layer deposited by ALD could effectively prevent QDs being affected by the external environment.

 

Lighting spectra associated with different correlated color temperatures and different circadian stimulus values are designed to evaluate the influence on users’ concentration. The signal processing of acquired brainwaves involves the combination of Hilbert-Huang transform, probability density functions, and receiver operating characteristic curves with their areas under the curves.

 

To achieve high output power and high uniformity using the laser-driven assembled planar light sources, the scattering of light introduced with the SiO2 layer between two adjacent planar glasses are important. In this, study, the SiO2 concentration of the SiO2 layer between two adjacent planar glasses is investigated to contribute the light from the blue laser diodes (LDs) and re-emitting light from remote phosphor layer, and then determine the output luminace and uniformity.

  Preview abstract

The Red Pomegranate extract was used in the phosphor-converted LEDs (pcLEDs) to achieve the white light output with low correlated color temperature (CCT). By combining the yellow phosphor and Red Pomegranate extract with the blue LED chip, the white light emission with high output lumens and low CCT can be obtained.

  Preview abstract

We demonstrate converting into the illuminance by using the color camera to catch the projection of 2D image, which can be applied to judge if the projection pattern of a headlamp passes the K-mark or ECE R113 class B regulation.

  Preview abstract

This research focuses on enhancing the luminous efficiency of white phosphorescent organic light-emitting diodes (PHOLED) by optimizing the parameters of the blue and red light-emitting layers and the dual charge control layer (CCL). Optimized device structure is glass/ITO/MoO3/NPB/mCP/mCP:FIrpic/ mCP/TPBi/TPBi: Ir(piq)2(acac) /TPBi/LiF/Al.

 

A practical algorithm based on commercial specification of a purple light-emitting diode was proposed for seeking the optimal power parameters driven by pulse-width modulation (PWM) suitable for color-tunable application. Our preliminary result indicated that the brightness can be increased over 30% under constant-power mode.

  Preview abstract

Ultraviolet mercury lamp has been widely used in food, skin surface sterilization. However, traditional mercury lamps are heavy, short in life, and long in the warm-up period. This paper studies Ultraviolet-C light-emitting diodes (UVC-LED) light panel composed of 64 UVC-LED arrays with a wavelength of 274.5nm and uses high thermal conductivity inorganic material packaging which can increase service life and reduce warm-up time. Analyzes and measures its uniformity and radiant flux. The light emission angle is 140°, the uniformity is 93.14%. It can successfully replace the low-pressure mercury lamp as the next generation of disinfection and sterilization technology.