The Effect of the Wavelength of the LED used to Pump Phosphor Produced from Curcuminoids Dye Extracted from Turmeric (Curcuma longa L.) to Produce White Light

Previous studies have investigated the use of curcuminoids dye extracted from turmeric (Curcuma longa L.) for light down-conversion of UV light (390 nm) for application as white light emitting diode (WLED) as well as the three methods used to extract curcuminoids dye (the normal method, use of Soxhlet apparatus and by combining the normal method with the Soxhlet extraction). This paper goes a step further to analyze the effect of the wavelengths of LED sources (365, 390 and 445nm) used to pump phosphor in the conversion of white light. The chromaticity coordinates (CIE), color rendering index (CRI) and color temperature (CCT) were measured for different applied currents (20, 60 and 100mA) and weights of curcuminoids (5, 10, 15, 20, 25, 30, 35, 40, 45, 50 and 55mg). With optimum CRI, CIE and CCT values of 73.9, 0.3304;0.3501, and 5579K, respectively, the samples pumped with LED source of 365 nm wavelength produced better white light compared to 390 and 445 nm, in terms of the amount of phosphor used. Thus, the wavelength of the LED source used to pump phosphor is inversely related to the amount of yellow light produced into the blue light when the concentration of phosphor is constant. The stress test showed that the degradation time of the dye could be improved by reducing the wavelength used to pump the sample or selecting a weak thermal conductivity material

Investigation Of Arabic Gum Optical Properties As Uv-Blue Light Down Conversion For Light Emitting Diode Application

LED’s as energy-efficient lighting is the best way to reduce the cost besides give good brightness. The use of Arabic gum as a remote phosphor for light down conversion. In this study, two experiments were conducted using Gum Arabic Malaysia and Gum Arabic Sudan in different annealing temperature (150°C and 200°C) and different time 20, 40, 60, 80 and 100 minutes and using different mass, 100mg and 150mg. The gum power encapsulated in 0.7ml silicone gel and dried to do remote phosphor using for light conversion. The Gum Arabic from Sudan and Malaysia were measured using HPC-2 light source colorimeter. The measured result show that the gum Arabic has high value in rendering index, CRI if the gum annealed at longer time and at the optimal temperature. The CCT value that show the best result or positive values are below 2500. The gum Arabic with melting process also show improvement in result. The mass of the powder used give high concentration thus the CRI value is nearest to the 80 as references value

Chromaticity Properties Of Curcuminoids Dye Nanofibers Prepared By Electrospinning For White Light Downconversion

In this study, the chromaticity properties of curcuminoids dye were studied when it be in nanometer scale, where curcuminoids were loaded in nanofibers using the electrospinning technique. Poly(methyl methacrylate) PMMA was used in three types of viscosity (5, 10 and 15wt%) which were mixed with (curcuma longa L.) powder to produce curcuminoids solution by using the centrifuge to separate the curcuminoids solution from the impurities. Different amounts of polymer solution mixed with curcuminoids (1 to 5 ml) were spun by electrospinning to study its properties. The effect of annealing on samples was studied. The chromatic study of the samples and the effect of the amount and viscosity of the solution were studied by pumping the samples in three different LED wavelengths (365, 390 and 445 nm). The white light chromaticity coordinates (CIE), color temperature (CCT) and color rendering index (CRI) were measured. The optimum CIE, CRI and CCT values of (X = 0.3051; Y = 0.3370), 64 and 6809K, respectively were obtained. By using field emission scanning electron microscope (FESEM) device, the curcuminoids nanofibers diameter was measured, where the values obtained ranged between 191 to 234 nm. After the annealing process, 15 nm nanoparticles were obtained

Optical and structural properties of curcuminoids extracted from Curcuma longa L. for hybrid white light diode

In this study, curcuminoids were extracted from turmeric (Curcuma longa L.) by means of three methods, comprising the normal method, use of Soxhlet apparatus and by combining the normal method with the Soxhlet extraction approach. The limitation of stickiness in the use of curcuminoids was resolved by mixing it with silica gel. The curcuminoids used light down-conversion of UV light (390 nm) for the white light-emitting diode (WLED). The characteristics of the white light chromaticity were controlled by changing the current and concentration of the curcuminoids. The chromaticity coordinates (CIE) and correlated color temperature (CCT) were measured for different applied currents (20, 60 and 100 mA) and weights (25, 35 and 50 mg) of curcuminoids. It was observed from the concentration of phosphor that the combination of the normal and Soxhlet apparatus methods is most effective extraction approach. The results showed that increasing the concentration of phosphor significantly and remarkably increased the value of CCT when different values of current were applied. The stress test showed that the prolongation of dye degradation can be improved using air gap and glass slid, with air gap being more effective. An optimum color rendering index (CRI) value of 61.2 is obtained. The white phosphor exhibited CIE values of 0.333, 0.3151 and color temperature (CCT) of 5405 K