A high efficiency driver for high-brightness white LED lamp

2010 ◽  
Author(s):  
Yu-Jen Chen ◽  
Wen-Ching Yang ◽  
Chin-Sien Moo ◽  
Yao-Ching Hsieh
Keyword(s):  
High Efficiency ◽  
White Led ◽  
High Brightness

A New Prediction Model on the Luminance of OLEDs Subjected to Different Reverse Biases for Alleviating Degradation in AMOLED Displays

2014 ◽  
Author(s):  
Paul C.-P. Chao ◽  
Yen-Ping Hsu ◽  
Yung-Hua Kao ◽  
Kuei-Yu Lee
Keyword(s):  
Reverse Bias ◽  
High Efficiency ◽  
Life Time ◽  
Density Currents ◽  
High Brightness ◽  
Light Emitting ◽  
Wide Viewing Angle ◽  
Time Operation ◽  
Long Time ◽  
History Of

Organic light-emitting diodes (OLEDs) have drawn much attention in areas of displays and varied illumination devices due to multiple advantages, such as high brightness, high efficiency, wide viewing angle, and simple structure. However, the long-time degradation of OLED emission is a serious drawback. This degradation was investigated by past works, which pointed out that the degradation was induced by high-density currents through OLED component under the long-time operation [1][2]. Proposed by a past work [3], different reverse biases was imposed on OLED components in display frames to alleviate the long-time degradation on OLEDs. Most recently, along with the reverse bias, new pixel circuits [4][5] for AMOLED displays are designed to alleviate OLED degradation, thus successfully extending OLED life time. However, since emission luminances in different frame times during AMOLED displaying differs significantly for displaying varied images, the OLED degradation evolves in a highly unpredictable fashion. In this study, based on valid theories, the voltage across the OLED is first used as indicator for OLED degradation. Then the relation between the level of OLED degradation, in terms of OLED’s cross voltage, and the history of imposing reverse biases are precisely modeled. With the model, the degradation of the OLED under reverse bias to extend lifetime can be successfully predicted. Based on this model, engineers can then optimize the applied reverse bias on OLEDs to maximize the OLED lifetime for varied display requirement.

Moisture-resistant Nb-based fluoride K2NbF7:Mn4+ and oxyfluoride phosphor K3(NbOF5)(HF2):Mn4+: synthesis, improved luminescence performance and application in warm white LED

2021 ◽  
Author(s):  
Ge Pang ◽  
Feng Hong ◽  
Xiaoyi Liu ◽  
Yunxiao Zhang ◽  
Chunyan Zhang ◽  
...  
Keyword(s):  
Acid Solution ◽  
High Efficiency ◽  
Precipitation Method ◽  
White Led ◽  
Co Precipitation ◽  
Moisture Resistant ◽  
Luminescence Performance

Herein, high-efficiency Nb-based oxyfluoride K3(NbOF5)(HF2):Mn4+ and fluoride K2NbF7:Mn4+ phosphors were successfully synthesized using different amounts of HF acid solution by simple co-precipitation method. XRD, SEM and EDS were used to...

Dopant preferential site occupation and high efficiency white emission in K2BaCa(PO4)2:Eu2+,Mn2+ phosphors for high quality white LED applications

2019 ◽  
Vol 6 (5) ◽  
pp. 1289-1298 ◽  
Author(s):  
Xinguo Zhang ◽  
Zhenpeng Zhu ◽  
Ziying Guo ◽  
Zishan Sun ◽  
Zichao Yang ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
External Quantum Efficiency ◽  
High Efficiency ◽  
White Led ◽  
High Quality ◽  
White Emission ◽  
Site Occupation ◽  
Preferential Site ◽  
Color Tunable

Novel color-tunable and white-emitting K2BaCa(PO4)2:Eu2+,Mn2+ phosphors with external quantum efficiency of 70% were developed for NUV LED.

Improvement of efficiency and its roll-off at high brightness in white organic light-emitting diodes by strategically managing triplet excitons in the emission layer

2018 ◽  
Vol 6 (40) ◽  
pp. 10793-10803 ◽  
Author(s):  
Shian Ying ◽  
Dezhi Yang ◽  
Xianfeng Qiao ◽  
Yanfeng Dai ◽  
Qian Sun ◽  
...  
Keyword(s):  
High Performance ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Emission Layer ◽  
High Brightness ◽  
Light Emitting ◽  
Organic Light ◽  
Low Efficiency ◽  
Triplet Excitons

High-performance WOLEDs realizing high efficiency and low efficiency roll-off simultaneously were achieved by strategically managing triplet excitons in the emission layer.

Highly efficient dual-core derivatives with EQEs as high as 8.38% at high brightness for OLED blue emitters

2019 ◽  
Vol 7 (46) ◽  
pp. 14709-14716 ◽  
Author(s):  
Seokwoo Kang ◽  
Hyocheol Jung ◽  
Hayoon Lee ◽  
Sunwoo Park ◽  
Joonghan Kim ◽  
...  
Keyword(s):  
High Efficiency ◽  
High Luminance ◽  
High Brightness ◽  
Highly Efficient ◽  
Fluorescent Materials ◽  
Blue Emitters ◽  
Dual Core ◽  
Very High

Three blue fluorescent materials were newly synthesized. A device doped with p-TPA-AP-TPA displayed a very high efficiency of 9.14 cd A−1 and an EQE of 8.38% at a high luminance of 5000 cd m−2.

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