Warm White Light-emitting Diodes Research Articles

Optical analysis of Dy3+/Sm3+ co-doped NaY(MoO4)2 phosphors for warm white LED

A series of NaY(MoO4)2: RE3+(RE=Dy3+, Sm3+) materials were synthesized by high temperature solid phase method and coated on UV chip to prepare white light LED devices. XRD and SEM scans showed that the material was small spherical particles, and the crystal form was consistent with the standard NaY(MoO4)2. The fluorescence spectrum analysis shows that under the excitation of 400 nm near-ultraviolet light, NaY(MoO4)2: Dy3+, Sm3+ materials show 482 nm blue light and 570 nm green-yellow light corresponding to the characteristic transitions of 4F9/2→6H15/2 and 4F9/2→6H13/2 of Dy3+, while yellow light at 600 nm and red light at 646 nm, on the other hand, correspond to characteristic transitions of 4G5/2→6H7/2 and 4G5/2→6H9/2 for Sm3+. Under the excitation of near ultraviolet light, the superposition of three colors can form a good white light emission. According to Dexter 's theory of energy transfer method, it is calculated that the mechanism of energy transfer is galvanic dipole-galvanic dipole interaction. The white light LED device can realize warm white light emission (3705 K) alone, and greatly reduce the cost under the premise of reducing the harm of blue light to the human eye. It suggests that this material is an excellent single substrate white phosphor material that can be applied to near-UV excited white LEDs.

Up and down-conversion photoluminescence energy demonstration of Ho3+/Yb3+ co-doped double perovskites microcrystals

Recently, lanthanide-doped fluorescence materials with perovskite structures have attracted great attention due to their abundant 4f energy levels, of which up- and down-conversion photoluminescence (PL) usually can be achieved by energy-level transition of single or multiple rare-earth ions (REI). Here, we synthesized for the first time a series of holmium (Ho) and ytterbium (Yb) co-doped Cs2Ag0.4Na0.6In0.9Bi0.1Cl6 (CANIBC) microcrystals (MCs) by hydrothermal method and realized the synergistic effect of efficient dual-mode PL of host and REI. The CANIBC MCs show yellow-white light emission stimulated by a 405 nm laser, of which the down-conversion (DC) PL is superimposed by the self-trapped excitons (STEs) emission of [AgCl6]5- octahedral and the energy level leap emission of REI. While the green emission of Ho3+ can be observed on the up-conversion (UC) PL stimulated by a 980 nm laser. We systematically analyzed the effect of CANIBC MCs in the dual-mode PL by time-resolved spectroscopy and found the existence of energy transfer between the STEs to REI in the DC PL process. Whereas in UC PL there is only energy transfer between REI. The variable-temperature dual-mode PL, reflects good temperature measurement performance. Simultaneously, it is effectively processed into a powder and mixed with 415 nm chips to create warm white light-emitting diodes with a CIE of (0.34, 0.36).

A 3-Fluoropyridine Manipulating the Aggregation and Fibril Network of Donor Polymers for Eco-Friendly Solution-Processed Versatile Organic Solar Cells.

The development of eco-friendly solvent-processed organic solar cells (OSCs) suitable for industrial-scale production should be now considered the imperative research. Herein, asymmetric 3-fluoropyridine (FPy) unit is used to control the aggregation and fibril network of polymer blends. Notably, terpolymer PM6(FPy = 0.2) incorporating 20% FPy in a well-known donor polymer poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione)] (PM6) can reduce the regioregularity of the polymer backbone and endow them with much-enhanced solubility in eco-friendly solvents. Accordingly, the excellent adaptability for fabricating versatile devices based on PM6(FPy = 0.2) by toluene processing is demonstrated. The resulting OSCs exhibit a high power conversion efficiency (PCE) of 16.1% (17.0% by processed with chloroform) and low batch-to-batch variation. Moreover, by controlling the donor-to-acceptor weight ratio at 0.5:1.0 and 0.25:1.0, semi-transparent OSCs (ST-OSCs) yield significant light utilization efficiencies of 3.61% and 3.67%, respectively. For large-area (1.0cm2 ) indoor OSC (I-OSC), a high PCE of 20.6% is achieved with an appropriate energy loss of 0.61eV under a warm white light-emitting diode (3,000K) with the illumination of 958lux. Finally, the long-term stability of the devices is evaluated by investigating their structure-performance-stability relationship. This work provides an effective approach to realizing eco-friendly, efficient, and stable OSCs/ST-OSCs/I-OSCs.

Structure and photoluminescence studies of Rb3GdSi2O7: Eu2+ phosphor used for NUV converted white LEDs

In pursuit of healthy lighting, the exploitation of high-quality Eu2+-activated phosphors available for near-ultraviolet light-emitting diode (NUV-LED) chip-based white LED (WLED) has fetched growing interest. Herein, a novel NUV-light excitable Rb3GdSi2O7: Eu2+ phosphor is successfully synthesized via a high-temperature solid-state reaction method. The crystal structure of Rb3GdSi2O7 is found to be hexagonal, belonging to space group P63/mmc. The Rb3GdSi2O7: Eu2+ phosphor exhibits a broad excitation band in the 300–450 nm wavelength range, and it emits strong yellow-green light with peak at 543 nm upon 365 nm excitation. Benefitting from the high structure rigidity of host matrix, Rb3GdSi2O7: Eu2+ also possesses a desired luminescence thermal stability (423 K, 85.6%). The WLED device fabricated using a 365 nm chip and a blend of the as-prepared Rb3GdSi2O7: Eu2+ yellow-green phosphor and commercial BaMgAl10O17: Eu2+ blue phosphor displays an excellent color-rendering index of 95.9 at a low correlated color temperature of 4373 K. This work confirms the applicative potential of Rb3GdSi2O7: Eu2+ in NUV-converted warm WLEDs, which may promote the development of high-color-quality healthy lighting.

Spectral Light Treatment Influenced Morpho-Physiological Properties and Carvacrol Accumulation in Indian Borage.

The online version contains supplementary material available at 10.1007/s00344-023-11028-6.

Highly thermostable mixed lanthanide organic frameworks with high quantum yield for warm white light-emitting diodes.

A mixed lanthanide organic framework was prepared via hydrothermal methods using m-phthalic acid (m-H2BDC), 1,10-phenanthroline (1,10-Phen), and Ln3+ ions, formulated as [HNMe2][Eu0.095Tb1.905(m-BDC)3(phen)2] (ZTU-6). The structure and stability of ZTU-6 were characterised by X-ray diffraction (XRD) and thermogravimetric analysis (TGA), which revealed a three-dimensional pcu topology with high thermal stability. Fluorescence tests showed that ZTU-6 emitted orange light with a high quantum yield of 79.15%, and it can be effectively encapsulated in a light-emitting diode (LED) device emitting orange light. In addition, ZTU-6 was found to be compatible with BaMgAl10O17:Eu2+ (BAM) blue powder and [(Sr,Ba)2SiO4:Eu2+] silicate yellow and green powder to create a warm white LED with a high colour rendering index (CRI) of 93.4, a correlated colour temperature (CCT) of 3908K, and CIE coordinates of (0.38, 036).

Recycling the Energy of Indoor Light: Highly Efficient Organic Photovoltaics via a Ternary Strategy

A ternary approach in organic photovoltaics (OPVs) is simple and reliable to effectively tune the optical, electrical, and morphological properties of the photoactive layer for high efficiency as well as long-term stability under 1 sun. However, there have been few papers reporting the benefits of ternary systems for recycling the energy of indoor light, which has narrow emission spectra and weak illumination compared to outdoor light. In this study, by using two compatible donor polymers (PM7 and PM7 D1) with slightly different band gaps and similar chemical structures, we demonstrate a simultaneous modulation of light absorption and molecular packing under ambient conditions, which resulted in efficient indoor OPVs exhibiting power conversion efficiency (PCE) over 20% under 1000 lx of warm white light-emitting diode (2900 K). From morphological analysis, we infer that PM7 serves to seed the nucleation of PM7 D1 in the ternary blend, templating its crystallization and alignment along the PM7 backbone. Such templating effect leads to increased domain spacing and relative degree of crystallinity (rDoC) compared to those of each binary system. We further show that higher rDoC helps suppress both bimolecular and trap-assisted recombination of photogenerated charges in the ternary devices. As a result, the complementary absorption and synergistic molecular assembly of the two donor polymers enhance the short-circuit current density as to increase the average PCEs from 9.6 to 10.3% under 1 sun and from 18.7 to 20.0% under 1000 lx. We envision that our strategy of incorporating both a planar and a flexible donor polymer with similar chemical structures can be generally applicable to attain a high-performance ternary OPV under both 1 sun and indoor light.

Designing multicolor luminescence in Tb3+/Eu3+-codoped KGd2F7 nanoparticles through energy transfer engineering for warm white light-emitting diode

By a facile precipitation method at room temperature, series of Tb3+-doped and Tb3+/Eu3+-codoped KGd2F7 nanoparticles (NPs) were synthesized. Upon 377 nm excitation, Tb3+-doped KGd2F7 NPs possess intense green emissions and their strongest intensities are obtained when Tb3+ ion is 30 mol%, where the corresponding concentration quenching mechanism is electric dipole-quadrupole interaction. As for Tb3+/Eu3+-codoped KGd2F7 NPs, dazzling multi-color emissions are achieved, excited by 377 nm, triggered by the energy transfer (ET) from Tb3+ to Eu3+. Specially, the emitting color is changed from green to yellow and finally to red as Eu3+ content increases. Through systematical discussion based on the emission spectra and decay time, the ET mechanism is decided by dipole-dipole interaction. Moreover, Tb3+/Eu3+-codoped KGd2F7 NPs do not only have high thermal stability but also exhibit admirable quantum efficiency of 65.7% excited by 377 nm. Furthermore, through utilizing the resultant NPs as yellow-emitting components, a warm white light-emitting diode with high color rendering index (85.5) and low correlated color temperature (4323 K) is fabricated, which are insensitive to injection current. Our findings may provide promising luminescence materials with multicolor emissions to meet the requirement of phosphor-converted solid-state lighting.

Highly luminescent and thermostable R6G@DUT-52 composite for sensing Fe3+ ion and white light emitting diode

Introduction of the yellow rhodamine 6G (R6G) fluorescent dyes into the nanopores of DUT-52 has been successfully achieved the R6G@DUT-52 composite by the one-pot hydrothermal method. Its structure, stability and morphology are well characterized by the XRD, TGA and SEM, whose fluorescent properties are also studied in detail. The obtained R6G@DUT-52 exhibits the highly thermostability with the blue emission of the DUT-52 at 435 nm, the characteristic emission of R6G dyes at 568 nm and the highly quantum yields (QY) of 77.8%, which shows the potential application prospects as the probes for high selectivity and sensitivity of detecting Fe3+ ion from 12 kinds of metals ions. In addition, R6G@DUT-52 is cooperated with the commercial green phosphor powder (GGA) that is further encapsulated on the 455 nm blue LED chip to achieve the warm white light emitting diode (WLED) device with the CIE coordinates of (0.373, 0.364), correlated color temperature (CCT) of 4107 K and luminous efficiency (LE) of 113.08 lm/w.

Green synthesis strategy to construct strong zero-phonon line red emission phosphor Na2SiF6:Mn4+: Photoluminescence properties, thermal stability and application in warm white LEDs

Green synthesis strategy to construct strong zero-phonon line red emission phosphor Na2SiF6:Mn4+: Photoluminescence properties, thermal stability and application in warm white LEDs

Highly efficient and water-resistant K3ZrF7:Mn4+ red-emitting phosphors

Mn4+ activated fluorides are promising red phosphors to be used in warm white light emitting diodes and liquid crystal display (LCD) backlighting due to their unique narrow-band red emission and broad band absorption in blue wavelength region. However, the instability in humid environment of these phosphors limited their practical application. In this work, we developed a facile co-precipitate method to prepare Mn4+ doped K3ZrF7 phosphors with good water-resistant properties. The crystal structure of K3ZrF7 was analyzed by XRD Rietveld refinement. The photoluminescence intensity was maintained at 95% after being immersed in water for 40 min in comparison with only 39.8% for Mn4+ doped K2TiF6 phosphors. The intrinsic seven coordination environment of Mn4+ in K3ZrF7 crystal was proposed as the main reason contributing to the good water resistance of the sample. The internal quantum efficiency and external quantum efficiency of optimized K3ZrF7:Mn4+ was measured to be 70.8% and 19.5% respectively. The thermal stability of the obtained phosphors was studied. A warm white light LED device with color temperature of 4074 K and color rendering index of 76.5 was fabricated by combining a mixture of K3ZrF7:Mn4+ and Y3Al5O12:Ce3+ with a blue InGaN chip.

P3HT vs Spiro-OMeTAD as a hole transport layer for halide perovskite indoor photovoltaics and self-powering of motion sensors

Recent years have witnessed the emergence of indoor photovoltaic (PV) devices with the rapid development of the Internet of things technology field. Among the candidates for indoor PVs, halide perovskites are attracting enormous attention due to their outstanding optoelectronic properties suitable for indoor light harvesting. Here we investigated the indoor PV properties of CH3NH3PbI3-based devices using Spiro-OMeTAD and P3HT as the hole transport layers. The Spiro-OMeTAD-based devices show a consistently higher power conversion efficiency under indoor illumination and 1 sun, with the champion devices showing a power conversion efficiency of 21.0% and 30.1% for the forward and reverse scan under 1000 lux warm white LED illumination. Fewer trap states and higher carrier lifetime were revealed for Spiro-OMeTAD based devices compared to P3HT. The best-performed Spiro-OMeTAD-based devices are used to self-power a wearable motion sensor, which could detect human motion in real-time, to create a primary sensor system with independent power management. By attaching the Spiro-OMeTAD indoor PV device to the strain sensor, the sensor exhibits an accurate and sensitive response with finger bending movements with good repeatability and negligible degradation of mechanical stability, which indicates the success of sensor powering with the indoor PV device.

Strategic Tuning of Photophysical Response in the Polyhedral Framework of the Garnet Structure toward White Light-Emitting Devices with Enhanced Color Rendering.

Designing a single-phase phosphor with high quantum efficiency and full spectrum emission is inevitable for today's scientific world. Herein, an optimal strategy for realizing white emission in a single component matrix is envisaged based on the structure-property-design-device policy. Cationic substitution corresponding to polyhedral expansion and contraction in A2A'B2V3O12 confirms the existence of strong and intricate linkage in the garnet structure. The dodecahedral expansion causes compression of VO4 tetrahedra and a blue shift. The direct correlation of V-O bond distance with red shift validates the distortion of the VO4 tetrahedra. The interdependence of photophysical properties via cationic substitution and subsequent correlation of the V-O bond distance with emission bands enabled the tailoring of phosphor-CaSrNaMg2V3O12 with a high quantum efficiency of 52% and excellent thermal stability of 0.39 eV. Bright warm white light-emitting diode (WLED) devices are fabricated based on Eu3+ and Sm3+-activators. A high quantum efficiency-74% is obtained for the designed Eu3+ phosphor. CIE coordinates near the achromatic point (0.329, 0.366), low CCT-5623 K, and high color rendering index (CRI)-87 are obtained for the single-phase WLED device. This work puts forth a new direction for designing and engineering promising WLEDs with enhanced color rendering based on single-phase phosphors with full spectrum emission.

Remarkable solution and solid-state color-tunable luminescence of diethylamino-coumarin derivatives and application in warm-white LEDs

Organic materials with solution and solid dual efficient, color-tunable luminescence are potentially useful for sensors and optical devices. Herein, a series of donor-π-acceptor luminophores, named BMs, with different phenyl substituents at the 3-positions of 7-diethylamino-coumarin was developed. All four compounds with slightly twisted structure rendering BMs have bright emission in solution and solid state. BMs not only possess solvatochromic properties in solution but also realize color tuning from cyan (480 nm) to deep red (661 nm) in solid states. Among them, the fluorescence quantum yield of compound BM1 in solid state reached 98.2%, and the fluorescence quantum yield in solution was 77.1%. Time dependent density functional theory calculation and single crystal analysis show that with the increase in the electron-withdrawing ability of 4-phenyl moiety at the 3-position of coumarin, the charge transfer effect was strengthened gradually, and the photoluminescence mechanism changed from intramolecular charge transfer (ICT) to twisted ICT on account of the electron acceptor changed accordingly. Moreover, the cyan phosphor BM1 and the deep-red phosphor BM4 were laminated to fabricate an impressive warm-white light-emitting diode device with a maximum brightness of 52,090 cd/m2 at an operating voltage of 4.0 V.

Ultrahighly Efficient Narrowband Red Luminescence of Uniquely Distorted Mn4+ Octahedron in the Feldspar‐Type LED Phosphor

AbstractThe mineral structure‐inspired discovery of red phosphors has become a research hotspot that can help compensate for the missing red components in cold white light‐emitting diodes (WLEDs). Herein, first the feldspar‐type structure is utilized to develop narrowband red‐emitting CaAl2Si2O8:Mn4+/Mn4+, Mg2+ phosphors. Rietveld refinement results confirm the Mn4+ occupation of the distorted [Ca1O6] octahedron, resulting in a strong nephelauxetic effect, and thus exhibits bright red luminescence with a narrow full width at half maximum (43 nm). Compared with CaAl2Si2O8:Mn4+, the fluorescence intensity of CaAl2Si2O8:Mn4+, Mg2+ is further enhanced by up to 210% owing to the decreasing nonradiative decay rate from 2Eg excited state, which weakens the concentration quenching effect resulting from energy migration along the adjacently aggregated Mn4+. CaAl2Si2O8:Mn4+, Mg2+ shows preferable thermal stability with an ultrahigh quantum efficiency (90.3%), surpassing other current Mn4+‐doped oxide phosphors and UCr4C4‐type nitride phosphors. A fabricated prototype WLED obtains ideal warm white light with a low correlated color temperature (3081 K) and a wide color gamut covering 112% of the National Television System Committee standard. Guided by natural mineral‐type structural prototypes, this study demonstrates the possibility of designing a uniquely distorted local structure to achieve a superior luminescence performance of Mn4+ for warm WLEDs.

Excitation‐dependent energy transfer and color tunability in Dy3+/Eu3+ co‐doped multi‐component borophosphate glasses

AbstractUsing the melt‐quench technique, potassium zinc borophosphate (KZnBP) glasses incorporated with Dy3+, Eu3+, and Dy3+/Eu3+ ions individually and combinedly were prepared, and their photoluminescence (PL)‐related features were investigated. The KZnBP glass containing an optimized content of Dy3+ (0.5 mol%) is co‐doped with Eu3+ in various contents, and the energy transfer (ET) process between them was studied at λexci = 349, 364, 387 (Dy3+), and 394 nm (Eu3+). The Dy3+/Eu3+ co‐doped system, when excited with Dy3+ excitations has resulted in a significant decrease in the intensity of Dy3+ peaks observed at 480 nm (4F9/2→6H15/2, blue) and 574 nm (4F9/2→6H13/2, yellow), with simultaneous enhancement of the intensity of Eu3+ peaks at 591 nm (5D0→7F1, orange) and 617 nm (5D0→7F2, red). This trend is due to the efficient energy transfer from Dy3+ to Eu3+, indicating that Eu3+ ions were sensitized by Dy3+ ions. Dexter's theory and the Inokuti–Hirayama (I–H) model revealed that the dipole–dipole interaction is accountable for the energy transfer from Dy3+ to Eu3+ through energy‐transfer channels [4F9/2(Dy3+)+7F1,2(Eu3+)→6H15/2(Dy3+)+5D2(Eu3+)] and [4F9/2(Dy3+)+7F0(Eu3+)→6H13/2(Dy3+)+5D0(Eu3+)]. The color coordinates of the Dy3+/Eu3+ co‐doped glasses under various excitations fall within the white light emission spectrum, indicating their potential application in warm white LEDs.

Ce,Tb,Gd:YAG-Al2O3 eutectic crystal phosphor plates for high-power warm white LED applications

Ce,Tb,Gd:YAG-Al2O3 eutectic crystal phosphor plates (ECPPs) were grown by the micro-pulling-down (μ-PD) method to adjust correlated color temperature (CCT) and color rendering index (Ra) for high-power warm white LED applications. Tb3+ and Gd3+ ions in Ce:YAG-Al2O3 play a positive role in spectra adjustment based on the structural and luminescent properties investigations. Tb3+ ions enhance the fluorescence lifetime of Ce3+ ions from 61.1 to 63.8 ns and improve the luminescence efficiency, and the highest optical-optical conversion efficiency (OCE) is 270.56 lm/W. Corresponding luminescence shift from cold white to greenish yellow. Gd3+ ions increase the peak wavelength from 554 to 564 nm and improve the Ra value, and the maximum Ra is 75.5. Corresponding luminescence is shifted from cold white to reddish violet. In addition, the luminescence of Ce,Tb,Gd:YAG-Al2O3 ECPPs is adjusted to warm white with CIE coordinate (0.374, 0.364) and CCT of 4102 K, and Ra of 73.0, which is of great significance for realizing the high-power warm white LED lighting.

Performance Comparison of Tungsten-Halogen Light and Phosphor-Converted NIR LED in Soluble Solid Content Estimation of Apple.

A Tungsten-Halogen (TH) lamp is the most popular light source in NIR spectroscopy and hyperspectral imaging, which requires a warm-up to reach very high temperatures of up to 250 °C and take a long time for radiation stabilization. Consequently, it has a large enough volume to enable heat dissipation to prevent the thermal runaway of the electric circuit and turn out its power efficiency very low. These are major barriers for miniaturizing spectral systems and hyperspectral imaging devices. However, TH lamps can be replaced by pc-NIR LEDs in order to avoid high temperature and large volume. We compared the spectral emission of the available commercial pc-NIR LEDs under the same condition. As a replacement for the TH lamp, the VIS + NIR LED module was developed to combine a warm-white LED and pc-NIR LEDs. In order to feature out the availability of the VIS + NIR LED module against the TH lamp, they were used as the light source for evaluating the Soluble Solid Content (SSC) of an apple through VIS-NIR spectroscopy. The results show a remarkable feasibility in the performance of the partial least square (PLS) model using the VIS + NIR LED module; during PLS calibration, the correlation coefficient (R) values are 0.664 and 0.701, and the Mean Square Error (MSE) values are 0.681 and 0.602 for the TH lamp and VIS + NIR LED module, respectively. In VIS-NIR spectroscopy, this study indicates that the TH lamp could be replaceable with a warm-white LED and pc-NIR LEDs.

Quantitative Calculation of the Most Efficient LED Light Combinations at Specific Growth Stages for Basil Indoor Horticulture: Modeling through Design of Experiments

Indoor farms are a promising way to obtain vegetables in standard quantity and quality. As opposed to previous studies, this study attempts to calculate optimized LED light conditions for different growth stages (five-days time step) of basil (Ocimum basilicum) to enhance its indoor growth through a statistical approach. Design of Experiments (DoE) was used to plan a limited number of experiments (20) and to calculate quantitatively the effect of different light recipes on four responses: the number of plants, their height, the Leaf Area Index, and the amount of water used. Different proportions (from 25% to 77%) of Hyper Red (660 nm) and Deep Blue (451 nm), intensities in terms of LEDs–plant distance (60, 70 and 80 cm), and the addition of Warm White (3000 K) LEDs were considered as independent variables. The obtained models suggest that a light recipe tailored for every growth step in the plant’s life is beneficial. Appropriate LEDs must be carefully chosen at the beginning of growth, whereas distance becomes relevant at the end. This is confirmed by the results analysis carried out at the end of an additional growth test where the optimal light recipe extracted from the DoE’s results were used.

Hydrothermal synthesis of orange fluorescent carbon dots and their application in fabrication of warm WLEDs and fluorescent ink

Herein, we are reporting the synthesis of orange fluorescent carbon quantum dots (OFCDs) using o-phenylenediamine and semicarbazide by hydrothermal method and the synthesized OFCDs were applied for warm white light emitting diodes (WLEDs) and fluorescent ink applications. The fluorescence emission spectrum of OFCDs shows the emission maximum at 625 nm with an excitation wavelength of 540 nm. The quantum yield of OFCDs was calculated to be 23%. We have prepared warm WLED device by coating PVA-OFCDs polymer matrix on near UV LED light (λem: 420 nm). The OFCDs based warm WLED device exhibits chromaticity coordinate (0.42, 0.48), Colour Correlated Temperature (CCT) 2500 K and Color Rendering Index (CRI) value 82. We also prepared the highly stable fluorescent ink using the same PVA-OFCDs for security information encryption and anti-counterfeiting applications. This OFCDs and their WLEDs device would be an efficient one in optoelectronics and forensic fields.