Luminous Power Research Articles

ABOUT THE CREATION OF AN LED LIGHT SOURCE WITH VARIABLE COLOR TEMPERATURE

The article is devoted to the development and research of an LED lamp of the A65 form factor and the type of E27 base with a choice of color temperature when the lamp is alternately connected to the supply network. The description of LEDs, driver, radiator, housing, base is given. Analysis of the results of measurements of lighting characteristics showed that the luminous flux and power consumption of the LED lamp amounted to 1004.1 lm and 12.5 W at a measured color temperature of 3056 K and 1059.8 lm and 12.37 W at 4120 K. Change in the color temperature of the lamp from 3056 K to 4120 K is characterized by an increase in the spectral density in the region of short-wave radiation with an increase in the proportion of blue, blue and violet colors. The shape of the lamp luminous intensity curve is close to the diffuse distribution. The change in color temperature is carried out by turning off and then turning on the lamp in the mains for no more than 5 seconds.

Experimental Validation of Inverse M-PPM Modulation for Dimming Control and Data Transmission in Visible Light Communications

A hybrid-coding scheme based on Multi-Pulse Position Modulation (M-PPM) and Pulse Width Modulation (PWM) is proposed and experimentally validated for simultaneous control of illumination and data transmission in a visible light communication system VLC (Visible Light Communications). The implemented VLC system complies with the dual functionality of indoor lighting and data transmission using low cost components. The codification implemented allows data transmission at a constant speed despite the lighting levels supported by the VLC system. The proposed and experimentally validated coding solves the problem of the interdependence between the data transmission rate and the variation of the lighting levels. Such interdependence is caused by the variation of the useful cycle available for data transmission after the lighting control performed by PWM.In this work, the feasibility of the implementation of the proposed scheme is demonstrated using low cost elements and commercial photodetectors. A constant transmission speed of 30 kbit/s was obtained with two 10W RGB LEDs at 0.9 meters from the OPT101 photodetector from Texas Instruments, with a range of illumination ranging from 25\% to 85\% of the possible luminous power of the LED sources.

Numerical investigation of traps and optical response in III-V nitride quantum LED

The impact of trapping on the optical properties of Gallium Nitride (GaN) Light Emitting Diodes (LED) has been analyzed in this work. The analysis is carried out by using Technology Computer Aided Design (TCAD) physical simulator. GaN LED with four quantum Wells have been considered with donor trap density ranging from 5 × 1015 cm−3 to 1 × 1019 cm−3. Polarization, radiative recombination and Auger recombination models were used in the simulation. The TCAD simulation results indicate that luminous power and quantum efficiency of GaN LEDs decreases with increase of trap density.

Red Phosphorescent Platinum(II) Complexes with Tetradentate Pyridine-Containing Ligands for Organic Light Emitting Diodes.

Here, red phosphorescent platinum(II) complexes based on tetradentate pyridine-containing lig-ands are studied. To investigate their electroluminescent properties, multilayer devices were fabricated in the following sequence; ITO (180 nm)/4,4',4″-Tris[2-naphthyl(phenyl)amino]triphenylamine (2-TNATA) (30 nm)/N, N'-di(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl)4,4'-diamine (NPB) (20 nm)/ Tris(4-carbazoyl-9-ylphenyl)amine (TCTA) (10 nm)/4,4'-Bis(N-carbazolyl)-1,1'-biphenyl (CBP) (20 nm)/Platinum(II) complex (20 nm)/1,3,5-Tris(1-Phenyl-1H-benzimidazol-2-yl)benzene) (TPBi) (40 nm)/Liq (2 nm)/Al (100 nm). In particularly, a device using platinum(II) complex based on N-(3,5-di-tert-butylphenyl)-3-(pyridin-2-yl)-N-(3-(pyridin-2-yl)phenyl)benzenamineligand showed the efficient red emission, with a luminous efficiency, power efficiency, and external quantum efficiency of, and the Commission International de LEclairge (CIE) coordinates of 27.26 cd/A, 10.54 lm/W, 8.50% at 20 mA/cm², and (0.65, 0.33) at 11.0 V, respectively.

Deep Blue Organic Light-Emitting Diodes Based on [7,7-Dimethyl-9-(10-phenylanthracen-9-yl)-7H-Indeno[1,2-f] Isoquinoline] Derivatives.

In this study, we synthesized and characterized two novel deep blue emitting materials based on indenoquinoline-substituted phenylanthracene derivatives. Multilayer organic light-emitting diodes were fabricated with the following sequence: indium-tin-oxide (ITO)/4,4',4″-tris[2-naphthyl(phenyl)amino (2-TNATA)/4,4'-bis(N-N-naphthyl)-N-phenylamino) biphenyl (NPB)/Blue emitting material (1 or 2)/Bathophenanthroline (Bphen)/lithium quinolate (Liq)/Al. A device B using '7,7-dimethyl-9-(10-phenylanthracen-9-yl)-7H-indeno[1,2-f] isoquinoline (2)' as an emitter showed the efficient emission with the luminous efficiency, power efficiency, and external quantum efficiency of 2.30 cd/A, 1.02 lm/W, 2.94% at 20 mA/cm², respectively. This device exhibited deep-blue emission with the Commission Internationale De LÉnclairage (CIE) coordinates of (0.16, 0.08) and λmax = 436 nm at 8.0 V.

Platinum (II) Complexes Based on Tetradentate Pyridine-Containing Ligands for Phosphorescent Organic Light-Emitting Diodes.

In this study, we designed and synthesized two phosphorescent emitting materials based on tetradentate pyridine-containing ligands. Their photophysical properties were examined for OLEDs and multilayer devices using these materials were fabricated in the following sequence; ITO (180 nm)/4,4',4″-Tris[2-naphthyl(phenyl)amino]triphenylamine (2-TNATA) (30 nm)/N,N'-di(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl)4,4'-diamine (NPB) (20 nm)/Tris(4-carbazoyl-9-ylphenyl)amine (TCTA) (10 nm)/4,4'-Bis(N-carbazolyl)-1,1'-biphenyl(CBP): 5, 8, 15% Platinum (II) complexes (20 nm)/1,3,5-Tris(1-Phenyl-1H-benzimidazol-2-yl)benzene) (TPBi) (40 nm)/Liq (2 nm)/Al (100 nm). In particularly, a device using Platinum (II) complex based on A/-(3,5-di-tert-butylphenyl)-6-phenyl-N-(6-phenylpyridin-2-yl)pyridin-2-amine ligand showed the efficient emission, with luminous efficiency, power efficiency, and external quantum efficiency, and the Commission International de LEclairge (CIE) coordinates of 29.29 cd/A, 9.37 lm/W, 8.66% at 20 mA/cm2, and (0.32, 0.62) at 8.0 V, respectively.

The dual-injection Ge-on-Si photodetectors with high saturation power by optimizing light field distribution

In this work, we put forward the length design principle of the dual-injection integrated Ge-on-Si photodetectors based on the characteristics of the light field distribution. When the length of the absorption layer makes the maximum intensity of the incident light from both ends are alternately distributed, the light field distribution is more uniform. Based on this principle, the shorter photodetector could get better saturation performance. Two dual-injection photodetectors with the length of 6μm and 10μm have been investigated, the experimental results show that the saturation current of 6μm length device is 18.33% higher, and the bandwidth is 138.60% higher at 10 mW incident power comparing with the 10μm length device. The 6μm length photodetector realized a responsivity of 1.07 A/W, a bandwidth of 37.3 GHz at 50 μW luminous power @1550 nm.

Luminous power improvement in InGaN V-Shaped Quantum Well LED using CSG on SiC Substrate

This paper presents the design and simulation of Silicon Carbide (SiC) based technology, Indium Gallium Nitride (InGaN) Multiple Quantum Well (MQW) Light-Emitting Diode (LED) with a Compositionally Step Graded (CSG) InGaN barrier and V-Shaped well in the active region. The simulations are obtained in Silvaco Computer Aided Design simulator and parameters such as Internal Quantum Efficiency (IQE) with respect to input current, spontaneous emission in regard to wavelength and power versus current in the device are theoretically studied. The CSG InGaN barrier LED with V-shaped quantum well shows substantial growth in output power when compared to the CSG GaN barrier structure with conventional MQW. The high carrier confinement in the V-shape well causes, transportation/injection of hole and change in band bending due to polarization effect. Moreover, lattice-matched SiC substrate over GaN material increases the InGaN V-shaped MQW LEDs radiative recombination rate which in turn leads to high output power. The optical luminous power of 160mW and 82% of peak IQE, emitting wavelength at 460 nm and 200mA of injection current is obtained for the proposed LED. The enactment of the V shape MQW CSG-InGaN device technology is a good alternative choice for commercial and industrial lighting applications.

Blue Fluorescent Organic Light-Emitting Diodes Using 11,11-Dimethyl-3-(10-phenylanthracen-9-yl)-11H-Indeno[1,2-b]Quinoline Derivatives.

In this study, we designed and synthesized two blue fluorescence materials using phenylanthracenesubstituted-indenoquinoline derivatives by Suzuki coupling reaction for organic light-emitting diodes (OLEDs). In order to study their electroluminescent properties, we fabricated the OLED devices using these two materials as emissive layer (EML) with the following sequence: indium-tin-oxide (ITO, 180 nm)/4,4',4″-tris[2-naphthyl(phenyl)-amino]triphenylamine (2-TNATA, 30 nm)/N,N'-diphenyl-N,N'-(2-napthyl)-(1,1'-phenyl)-4,4'-diamine (NPB, 20 nm)/Blue emitting materials (20 nm)/4,7-Diphenyl-1,10-phenanthroline (Bphen, 30 nm)/lithium quinolate (Liq, 2 nm)/Al (100 nm). In particular, a device using 11,11-dimethyl-3-(10-phenylanthracen-9-yl)-11H-Indeno[1,2-b]quinoline in emitting layer showed luminous efficiency, power efficiency, and external quantum efficiency of 2.18 cd/A, 1.10 lm/W, 2.20% at 20 mA/cm², respectively, with Commission Internationale d'Énclairage (CIE) coordinates of (0.15, 0.11) at 8.0 V.

The Structural, Electronic, and Optical Properties of Ge/Si Quantum Wells: Lasing at a Wavelength of 1550 nm.

The realization of a fully integrated group IV electrically driven laser at room temperature is an essential issue to be solved. We introduced a novel group IV side-emitting laser at a wavelength of 1550 nm based on a 3-layer Ge/Si quantum well (QW). By designing this scheme, we showed that the structural, electronic, and optical properties are excited for lasing at 1550 nm. The preliminary results show that the device can produce a good light spot shape convenient for direct coupling with the waveguide and single-mode light emission. The laser luminous power can reach up to 2.32 mW at a wavelength of 1550 nm with a 300-mA current. Moreover, at room temperature (300 K), the laser can maintain maximum light power and an ideal wavelength (1550 nm). Thus, this study provides a novel approach to reliable, efficient electrically pumped silicon-based lasers.

Three series π-extended fluorescent compounds based on dehydroabietic acid triarylamine moiety: Syhthesis, photophysical properties and hole transporting properties

Fluorescent compounds based on a dehydroabietic acid skeleton with favorable photophysical properties show promise for use as the hole-transporting layer in organic light-emitting diodes (OLEDs). In this work, we report the synthesis of three series of compounds (15 in total), series 1 (1a–1e), series 2 (2a–2e), and series 3 (3a–3e), by linking polycyclic aromatic hydrocarbons (PAHs) to dehydroabietic acid-based triaryamine moiety through C-C coupling reactions. The three series of compounds exhibited ultraviolet absorption, fluorescence emission, electrochemical, and thermal properties, as well as highest occupied molecular orbital levels and energy gaps that made them suitable for use as hole-transporting materials. OLEDs with 1a, 2a, or 3d as a hole-transporting layer showed better performance in terms of maximum brightness, turn-on voltage, maximum of external quantum efficiency, maximum luminous efficiency and power efficiency than that of a comparable device based on a conventional hole-transporting material. In particular, the device with 1a exhibited the most promising performance, with a high maximum brightness of 21445 cd/m2, low turn-on voltage of 2.8 V, maximum of external quantum efficiency of 1.62%, maximum luminance efficiency of 4.9 cd/A, and maximum power efficiency 3.7lm/W. The present work highlights the potential of π-extended compounds based on dehydroabietic acid for use in luminescent material applications.

Efficient and Long Lived Green Light‐Emitting Electrochemical Cells

AbstractThe combination of high efficiencies and long lifetime in a single light‐emitting electrochemical cell (LEC) device remain a major problem in LEC technology, preventing its application in commercial lighting devices. Three green light‐emitting cationic iridium‐based complexes of the general composition [Ir(C^N)2(N^N)][PF6] with 4‐Fppy (2‐(4‐fluorophenyl)pyridinato) as the cyclometalating C^N ligand and 1,10‐phenanthroline (1), 4,7‐diphenyl‐1,10‐phenanthroline (bathophenanthroline, bphen, 2), and 2,9‐dimethyl‐4,7‐diphenyl‐1,10‐phenanthroline (bathocuprione, dmbphen, 3) as ancillary N^N ligands are synthesized and characterized. Computational studies are carried out in order to compare the electronic structure of the three ionic transition metal complexes (iTMCs) and provide insights into their potential as LEC emitter materials. LECs are then fabricated with complexes 1–3. Driven under a pulsed current, they display a high luminance and current and power efficiencies. As the LEC based on complex 2 displays the overall best device performance, including the longest lifetime of 474 h, it is selected for subsequent driving conditions optimization. An extraordinary power efficiency of 25 lm W−1 and current efficiency of 30 cd A−1 are achieved under optimized operation conditions with reduced current density, resulting in a long device lifetime of 720 h. Altogether, ligand design in iTMCs and optimization of the device driving conditions leads to a significant improvement in LEC performance.

Improvement in efficiency and luminous power of AlGaN-based D-UV LEDs by using partially graded quantum barriers

In this article, we have demonstrated a new AlGaN-based D-UV LED (Deep-Ultraviolet Light Emitting Diode) structure and investigated improved electrical output characteristics theoretically. In the new structure, we have used partially graded quantum barriers (PQBs) rather than stepped quantum barrier (SQBs) as setup in conventional LEDs. The simulation results confirm that the usage of PQBs in new D-UV LED structure notably enhances the internal quantum efficiency (IQE), light output power (LOP) or luminous power and enhances power spectral density in the D-UV region. The reason behind this improvement is higher potential barrier for carriers in the active region which helps in improving the carrier's confinement in the quantum wells and favors significant increment in radiative recombination. • Design of new heterostructure for AlGaN-based D-UV LED. • Usage of partially graded quantum barriers (PQBs). • Simulation using SRH (Shockley-Read-Hall) recombination and k. p model. • Significant improvement in efficiency and luminous power. • Significant improvement in spectral power density in D-UV region.

IR femtosecond laser micro-filaments in diamond visualized by inter-band UV photoluminescence.

Single microscale filaments were produced in monocrystalline Ia-type diamond by 1030 nm, 300 fs laser pulses tightly focused at NA = 0.3 and different peak powers, visualized by transverse imaging and spectrally characterized by longitudinal micro-spectroscopy, using intrinsic UV A-band photoluminescence (PL) with its peak at about 430 nm. Power-dependent scaling relationships for the local PL yield and diameters of the accompanying luminous micro-channels of recombining electron-hole plasma indicate a transition from three-photon absorption to free-carrier plasma absorption, as the consequent energy deposition mechanisms at increasing peak laser power. Power-dependent elongation of the luminous micro-channels versus peak laser power fitted by a Marburger formula yields, on average a diffraction-based estimate of 0.6 MW critical power for self-focusing within the diamond at the pump laser wavelength of 1030 nm.

Avaliação integrada do desempenho visual e eficiência energética pelo DIALux evo 8 para projetos de iluminação artificial

O comportamento ambiental dos edifícios vem sendo discutido visando integrar aspectos quantitativos e qualitativos do desempenho energético ao processo de elaboração de projetos de iluminação artificial. O objetivo deste artigo é examinar a capacidade do software DIALux evo 8 em avaliar, de forma integrada, o desempenho visual e a eficiência energética de modelos virtuais durante a elaboração de projetos de iluminação artificial residencial. O delineamento do estudo consistiu na: (i) definição de indicadores de desempenho visual e eficiência da iluminação artificial; (ii) verificação do potencial de elaboração destes indicadores pelo software; (iii) aplicação da simulação em ambiente residencial. Os indicadores relativos ao conforto visual avaliados foram: iluminância mantida, uniformidade, índice limite de ofuscamento unificado, índice reprodução de cor e temperatura de cor. Os indicadores concernentes à eficiência energética avaliados foram: eficiência luminosa, densidade de potência da iluminação, densidade de potência limite da iluminação e densidade de potência relativa. A simulação objetivou fomentar a discussão da capacidade de análise por meio das métricas determinadas pelo software e dos aspectos relacionados à interface com o usuário durante as análises de desempenho visual e energético. Verificou-se que todos dos indicadores propostos são calculados pelo DIALux evo 8, porém a análise integrada propiciada pela interface gráfica do software prioriza as análises das iluminâncias. O índice limite de ofuscamento e as densidades de potência da iluminação são apresentados somente na documentação, demandando análises comparativas realizadas externamente ao programa. Observou-se limitações referente às normas utilizadas pelo software, exclusiva à EN 12464-1, consequentemente não incluindo tipologias residenciais. A contribuição deste trabalho consiste em discutir os recursos oferecidos pelo software e suas repercussões na gestão de projetos luminotécnicos.

Efficient Organic Light-Emitting Diodes Based on Indeno-Type Polyaromatic Hydrocarbons.

To develop the efficient emitters for organic light-emitting diode (OLED), three indeno-type polyaromatic hydrocarbons materials were designed and synthesized through Buchwald-Hartwig amination. OLED devices using these materials were fabricated in the following sequence: indium-tin-oxide (ITO) (180 nm)/N,N'-diphenyl-N,N'-(2-napthyl)-(1,1'-phenyl)-4,4'-diamine (NPB) (50 nm)/Emitting materials (1-3) (30 nm)/4,7-diphenyl-1,10-phenanthroline (BPhen) (30 nm)/lithium quinolate (Liq) (2 nm)/Al (100 nm). All devices showed the efficient emissions. In particular, a device using 8,8-dimethyl-N,N-diphenyl-8H-indeno[2,1-b]fluoranthen-6-amine (2) as efficient emitter showed luminous efficiency, power efficiency, and external quantum efficiency of 8.35 cd/A, 5.70 lm/W, 2.37% at 20 mA/cm², respectively, with Commission Internationale d'Énclairage (CIE) coordinates of (0.37, 0.59) at 6.0 V.

Studies on Organic Light Emitting Diodes Using Phenanthroline Derivatives as Emitters.

In this study, we designed and synthesized blue emitting materials based on 1, 10-phenanthroline derivatives. OLED devices using these materials were fabricated in the following sequence; indium-tin-oxide (ITO) (180 nm)/N,N'-diphenyl-N,N'-(2-napthyl)-(1,1'-phenyl)-4,4'-diamine (NPB) (50 nm)/Tris(4-carbazoyl-9-ylphenyl)amine (TCTA) (10 nm)/Blue materials (20 nm)/2,2',2″-(1,3, 5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi) (30 nm)/lithium quinolate (Liq) (2 nm)/Al (100 nm). Particularly, a device using 2-(4-(9,9-dimethylacridin-10(9H)-yl)phenyl)-1-phenyl-1Himidazo[ 4,5-f][1,10] phenanthroline as a blue emitter showed the maximum values of luminous efficiency, power efficiency, and external quantum efficiency of 1.45 cd/A, 1.52 lm/W, 0.99%, respectively with the Commission Internationale d'Énclairage (CIE) (x,y) coordinates of (0.16, 0.14) at 8.0 V.

LED-based opto-wetting and fluidic transport for droplet mixing

Light energy is utilized as an extensive tool for actuation of fluid flow in microfluidic devices. We report a novel method of droplet actuation using LED (light-emitting diode) that can be utilized for microfluidic mixing applications. This low power LED which emits light of peak wavelength 395 nm delivering luminous power of less than 300 millicandela (mcd) was used to create an interfacial tension gradient on solid–liquid interface containing photoresponsive molecule of azobenzene (C12H10N2). LED-induced photoisomerization of azobenzene creates a spatial gradient in interfacial energy on the solid–liquid interface, which enhances the droplet movement. The concept of LED-enhanced fluidic actuation was demonstrated using droplets of water, urine, blood serum over photoresponsive substrate. The substrates were prepared by coating the surface of silicon substrate with azobenzene dissolved in silicone resin solution. Detailed experimental characterization of LED-actuated droplet velocity was performed, where the effect of parameters such as frequency of light actuation, droplet volume, concentration of azobenzene was evaluated. Droplet transport of DI water (de-ionized) of volume 60 µL was achieved at a velocity of 160 µm/s corresponding to LED actuation frequency of 1 Hz. In vitro quantification of blood calcium and urine pH was performed using fabricated chip scale opto-wetting platforms. The proposed work could be useful in the development of droplet microfluidic chips, where combinatorial mixing can be achieved using an array of LEDs.

Indenophenanthrene Derivatives for Highly Efficient Blue Organic Light-Emitting Diodes.

In this study, we designed and synthesized three fluorescent blue emitting materials based on indenophenanthrene derivatives. These derivatives were synthesized by Suzuki coupling reaction. Particularly, a device C using 9,10-bis(9,9-dimethyl-9H-indeno[2,1-l]phenanthren-11-yl)anthracene as blue emitter showed maximum values of luminous efficiency, power efficiency, and external quantum efficiency of 7.58 cd/A, 5.87 lm/W, 4.20%, respectively.

Blue electroluminescent materials based on indeno[1,2-a]arene derivatives for Organic Light-Emitting Diodes

In this study, as a continuous effort for searching efficient blue-emitting materials, we designed and synthesized materials based on indeno[1,2-a]arene. OLED devices using these materials were fabricated in the following sequence; ITO (180 nm)/N,N'-diphenyl-N,N'-(2-napthyl)-(1,1'-phenyl)-4,4'-diamine (NPB) (50 nm)/emitting materials (30 nm)/4,7-diphenyl-1,10-phenanthroline (Bphen) (30 nm)/Liq/Al (2/100 nm). Particularly, a device using 7,7-dimethyl-7H-indeno[1,2-a]pyrene as emitter showed maximum values of luminous efficiency, power efficiency, and external quantum efficiency of 1.10 cd/A, 0.49 lm/W, 1.47% at 20 mA/cm2, respectively with CIE (x,y) coordinates of (0.15, 0.08) at 6.0V.