Preparation and Luminescence Properties of Polymeric 2,5-Bis[2´-(8´´-alkoxyquinolin-2´´-yl)ethenyl]hydroquinone Derivatives

2002 ◽  
Vol 55 (8) ◽  
pp. 499 ◽  
Author(s):  
M.-A. Hsu ◽  
T. J. Chow
Keyword(s):  
Reduction Potential ◽  
Light Emitting Diode ◽  
Monomer Unit ◽  
Green Light ◽  
Emission Spectra ◽  
Coupling Reaction ◽  
Hydroxyl Groups ◽  
High Solubility ◽  
Light Emitting ◽  
Coumarin 6

A PPV-type polymer (1) incorporating 5,5�-diquinolinyl moieties is prepared by a Yamamoto homo-coupling reaction from the dibromide (2). Since all the hydroxyl groups were alkylated, this polymer showed high solubility in most organic solvents. It can be spin-coated readily to form a thin layer in the fabrication of light emitting diode (LED) devices. The adjacent quinoline rings are twisted to form a dihedral angle due to steric hindrance, so that π-conjugation is confined within each monomer unit. The emission spectra of (1) and (2) are nearly identical. The reduction potential of (1) was estimated to be –1.10 V (onset), with a band gap of 2.53 eV (490 nm). A single hetero-junction LED device fabricated by combining the films of poly(vinylkarbazol) (PVK) and (1) yielded promising results. The device ITO/PVK/(1)/Ca/Al exhibited a turn-on voltage at 6 V and reached a maximal brightness of 250 cd/m2 at 15 V. An alternate potential usage of (1) as an electron-injecting material was also explored on a green-light device using coumarin-6 as an emitter.

n-type GaN surface etched green light-emitting diode to reduce non-radiative recombination centers

2021 ◽  
Vol 118 (2) ◽  
pp. 021102
Author(s):  
Dong-Pyo Han ◽  
Ryoto Fujiki ◽  
Ryo Takahashi ◽  
Yusuke Ueshima ◽  
Shintaro Ueda ◽  
...  
Keyword(s):  
Radiative Recombination ◽  
Light Emitting Diode ◽  
Green Light ◽  
Light Emitting ◽  
Recombination Centers

scholarly journals Operando direct observation of spin-states and charge-trappings of blue light-emitting-diode materials in thin-film devices

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Fumiya Osawa ◽  
Kazuhiro Marumoto
Keyword(s):  
Blue Light ◽  
High Performance ◽  
Density Functional ◽  
Light Emitting Diode ◽  
Green Light ◽  
Spin States ◽  
Light Emitting ◽  
Full Color ◽  
Color Displays ◽  
Materials Used

Abstract Spin-states and charge-trappings in blue organic light-emitting diodes (OLEDs) are important issues for developing high-device-performance application such as full-color displays and white illumination. However, they have not yet been completely clarified because of the lack of a study from a microscopic viewpoint. Here, we report operando electron spin resonance (ESR) spectroscopy to investigate the spin-states and charge-trappings in organic semiconductor materials used for blue OLEDs such as a blue light-emitting material 1-bis(2-naphthyl)anthracene (ADN) using metal–insulator–semiconductor (MIS) diodes, hole or electron only devices, and blue OLEDs from the microscopic viewpoint. We have clarified spin-states of electrically accumulated holes and electrons and their charge-trappings in the MIS diodes at the molecular level by directly observing their electrically-induced ESR signals; the spin-states are well reproduced by density functional theory. In contrast to a green light-emitting material, the ADN radical anions largely accumulate in the film, which will cause the large degradation of the molecule and devices. The result will give deeper understanding of blue OLEDs and be useful for developing high-performance and durable devices.

Green Light Emitting Diode Irradiation Enhances Fibroblast Growth Impaired by High Glucose Level

2005 ◽  
Vol 23 (2) ◽  
pp. 167-171 ◽  
Author(s):  
Elke M. Vinck ◽  
Barbara J. Cagnie ◽  
Maria J. Cornelissen ◽  
Heidi A. Declercq ◽  
Dirk C. Cambier
Keyword(s):  
Glucose Level ◽  
High Glucose ◽  
Light Emitting Diode ◽  
Green Light ◽  
Fibroblast Growth ◽  
Light Emitting ◽  
High Glucose Level

Promotion of neural sprouting using low-level green light-emitting diode phototherapy

2015 ◽  
Vol 20 (2) ◽  
pp. 020502 ◽  
Author(s):  
Noa Alon ◽  
Hamootal Duadi ◽  
Ortal Cohen ◽  
Tamar Samet ◽  
Neta Zilony ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Green Light ◽  
Light Emitting ◽  
Low Level

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.

Highly Flexible Green Light-emitting Diode Based on CsPbBr3 Perovskite Quantum Dots

2020 ◽  
Vol 41 (3) ◽  
pp. 233-240
Author(s):  
郭 洁 GUO Jie ◽  
陆 敏 LU Min ◽  
孙思琪 SUN Si-qi ◽  
胡 强 HU Qiang ◽  
张 佳 ZHANG Jia ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Light Emitting Diode ◽  
Green Light ◽  
Light Emitting ◽  
Perovskite Quantum Dots

Electrically driven nanopyramid green light emitting diode

2012 ◽  
Vol 100 (6) ◽  
pp. 061106 ◽  
Author(s):  
S.-P. Chang ◽  
Y.-C. Chen ◽  
J.-K. Huang ◽  
Y.-J. Cheng ◽  
J.-R. Chang ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Green Light ◽  
Light Emitting

Electrostatic Discharge Characteristics of InGaN/GaN Light-Emitting Diodes with Si-Doped Graded Superlattice

2015 ◽  
Vol 15 (10) ◽  
pp. 7733-7737 ◽  
Author(s):  
Kwanjae Lee ◽  
Cheul-Ro Lee ◽  
Jin Soo Kim ◽  
Jin Hong Lee ◽  
Kee Young Lim ◽  
...  
Keyword(s):  
Light Emission ◽  
Electrostatic Discharge ◽  
Light Emitting Diode ◽  
Emission Spectra ◽  
Small Variation ◽  
Injection Current ◽  
Light Emitting ◽  
Current Voltage ◽  
Gan Led ◽  
Si Doped

We report the influences of a Si-doped graded superlattice (SiGSL) on the electrostatic discharge (ESD) characteristics of an InGaN/GaN light-emitting diode (LED). For comparison, a conventional InGaN/GaN LED (C-LED) was also investigated. The luminous efficacy for the SiGSL-LED was 2.68 times stronger than that for the C-LED at the injection current of 20 mA. The resistances estimated from current–voltage (I–V) characteristic curves were 16.5 and 8.8 Ω for the C-LED and SiGSL-LED, respectively. After the ESD treatment at the voltages of 4000 and 6000 V, there was no significant change in the I–V curves for the SiGSL-LED. Also, there was small variation in the I–V characteristics for the SiGSL-LED at the ESD voltage of 8000 V. However, the I–V curves for the C-LED were drastically degraded with increasing ESD voltage. While the light emission was not observed at the injection current of 20 mA from the C-LED sample after the ESD treatment, the emission spectra for the SiGSL-LED sample were clearly measured with the output powers of 10.47, 9.66, and 7.27 mW for the ESD voltages of 4000, 6000, and 8000 V respectively.

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