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All Journal International Journal of Advances in Applied Sciences Science and Technology Indonesia Indonesian Journal of Electrical Engineering and Computer Science
Cong, Pham Hong
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Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Earth & Planetary Sciences Environmental Science Materials Science & Nanotechnology Mathematics Physics

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Application of KBaYSi2O7:Bi3+,Eu3+ Phosphor for White Light-Emitting Diodes with Excellent Color Quality Loan, Nguyen Thi Phuong; Thuy, Le Xuan; Thai, Nguyen Le; Lee, Hsiao Yi; Cong, Pham Hong
Science and Technology Indonesia Vol. 9 No. 3 (2024): July
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2024.9.3.756-765

Abstract

This paper examines the properties of two phosphor materials synthesized via utilizing the sol gel method: KBaYSi2O7:Bi3+ (KBYS:Bi) phosphor providing cyan/deep-blue emission and KBaYSi2O7:Bi3+,Eu3+ (KBYS:Bi,Eu) phosphor exhibiting tunable emission from near-UV to red. The optimal doping concentrations for Bi3+ and Eu3+ are 0.2% and 3.5%, respectively. It is found that the ability to give discrepant emission peaks under different excitation sources of the KBYS:Bi phosphor is attributed to the occupancy of Bi3+ in different cation hosts. Meanwhile, co doping the Eu3+ and Bi3+ into the KBYS host leads to red and cyan emission regions, enabling the emission tunability of the KBYS:Bi,Eu phosphor. KBYS:Bi,Eu phosphor was then used in combination with YAG:Ce3+ and blue chips to fabricate a white light emitting diode (LED) model. The particle sizes of KBYS:Bi,Eu phosphor are adjusted to examine its influences on the LED properties. With increasing particle sizes (≥12 µm), the KBYS:Bi,Eu phosphor can improve the scatter efficacy, transmission power, lumen output, and color performance (rendition and uniformity). Both KBYS:Bi and KBYS:Bi,Eu phosphors are promising luminescent phosphors that can be combined with other phosphor with different emission colors to obtain the full-spectrum or tunable white light for LEDs.
Effects of TiO2 in graphene-quantum-dot film on lighting color uniformity of a white light-emitting diodes Le, Phan Xuan; Cong, Pham Hong
Indonesian Journal of Electrical Engineering and Computer Science Vol 36, No 2: November 2024
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v36.i2.pp800-807

Abstract

Improvement in color uniformity of white light-emitting diodes (WLED) is one of the imperative goals for high-quality solid-state illumination. The conventional WLED model with a single yellow phosphor YAG:Ce3+ (TiO2@GD) is proposed to fulfill this goal. The TiO2@GD composites prove to possess excellent biocompatibility, low toxicity, and thermal and chemical stability, holding great potential in high-power WLED production. By maintaining a constant GDs content of 10 wt%, the research explores the impact of varying TiO2 doping concentrations on the lighting performance of the WLEDs via the mean of light scattering. The TiO2@GD layer also induces a red-shift in the emitted light spectrum, contributing to a reduction in color variation. While a decline in luminosity and color rendering performance becomes evident with excessive TiO2 content, the study underscores the potential of TiO2@GD as a viable diffusing layer for LEDs to obtain improved angular uniformity of color distribution.
Impacts of Eu2+ -doped K3LuSi2O7 phosphor and a scattering particle on conventional white light emitting diodes Duy, Le Doan; Thai, Nguyen Le; Cong, Pham Hong; Tran, Thinh Cong
Indonesian Journal of Electrical Engineering and Computer Science Vol 35, No 2: August 2024
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v35.i2.pp743-750

Abstract

The K3LuSi2O7 phosphor doping Eu2+ rare-earth ions (KLS:Eu) was reported to possess broad emission band from near-ultraviolet to nearinfrared. Additionally, this phosphor showed a wide absorption band of 250-600 nm, allowing it to be excited by blue-light chip of 460 nm, making it one of the suitable phosphor materials for a light emitting diode (LED). Besides, the scattering particle material CaCO3 is incorporated into the yellow phosphor layer to serve the scattering-enhancement purpose. The combination of both materials aims at accomplishing improvements in performance of commercial LED package. The concentration of KLS:Eu is constant while that of CaCO3 is modified. As a result, the scattering factor is regulated and become the key factor influencing the optical outputs of the simulated LED. The increasing CaCO3 concentration enhances the phosphor scattering efficiency of light, helping to improve the lumen output and color-temperature consistency of the LED. However, the color rendering performance declines as a function of the CaCO3 growing amount, despite the presence of a KLS:Eu phosphor layer. Further works should be done to optimize the application of KLS:Eu in cooperation with scattering particles for a higher-quality LED device.
Research on the using of ZnO nanostructures to increase the white light-emitting diodes optics effectiveness Le, Phan Xuan; Cong, Pham Hong
Indonesian Journal of Electrical Engineering and Computer Science Vol 36, No 2: November 2024
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v36.i2.pp793-799

Abstract

In conventional white light-emitting diodes (WLEDs), the combination of blue-LED chips with a yellow-phosphor type is the commonly employed method of production. However, this approach often results in low angular correlated color temperature (CCT) homogeneity. To address this issue, this research proposes the incorporation of ZnO nanostructures into WLED packages to enhance color homogeneity. The impacts of varying concentrations of ZnO nanoparticles on the morphologies, scattered energy, and CCT deviations in WLED packages are studied utilizing the Mie-scattering theory and MATLAB measurement techniques to analyze the scattering effects of ZnO nanoparticles. The scattering analysis reveals that the presence of ZnO nanoparticles significantly increases the scattered strength of WLEDs, especially with larger particles’ radii, due to their strong scattering influence. Then, 1 µm is the selected size of the ZnO used in further tests. With different ZnO concentrations (2-50 wt.%) in the phosphor layer, the CCT deviation holds an inverse proportion to the luminous efficiency. Particularly, higher concentrations of ZnO nanoparticles reduce the CCT deviation, leading to improved color homogeneity, but a decline in lumen efficiency. The findings provide the basis of ZnO scattering performance, which can be utilized to explore potential ways for enhancing WLED’s color uniformity and overall performance.
Augmenting Chroma Performance for WLED Employing Sr8ZnSc(PO4 )7:Eu2+@SiO2 as a Scattering-Enhancing Substance Cong, Pham Hong; Anh, Nguyen Doan Quoc
Science and Technology Indonesia Vol. 10 No. 2 (2025): April
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2025.10.2.467-472

Abstract

Featuring the B-Ca3(PO4)2 phosphor system, Sr8ZnSc(PO4)7:Eu2+ (SZSPOE) phosphor can be used as an alternative to YAG:Ce3+ yellow phosphor for the advancement of the white light-emitting diode (WLED). Its potentials are demonstrated in this paper, including the expected emission power and wavelength based on the previous studies and its impacts on WLED illumination properties employing Mie-theory-based scattering simulation and calculation and MATLAB software. SZSPOE phosphor can display a wide yellow discharge peaking at 511 and 571 nm and a redshift upon the increase in doped Eu2+ dosage. A phosphor layer comprised of SZSPOE phosphor, SiO2 particles, and silicone gel is simulated for making a WLED. The WLED performance is observed with varying SiO2 amount. Changes in simulation results of the WLED’s lighting properties can be attributed to the scattering within the phosphor layer in response to different SiO2 concentrations. Results demonstrate that increasing SiO2 amount can lead to the better spatial color distribution uniformity and luminous output of the WLED. Meanwhile, the lower color rendering index is observed owing to the insufficient red light power. However, the improvement in color uniformity and luminosity alongside the emission tunability of the SZSPO host, SZSPOE phosphor can be a promising candidate for substituting the original YAG:Ce3+ for advanced WLEDs.
Computer simulation and software engineering in optical analysis of phosphor-converted white light-emitting diodes utilizing barium sulfate Trang, Le Thi; Loan, Nguyen Thi Phuong; Cong, Pham Hong; Anh, Nguyen Doan Quoc; Lee, Hsiao-Yi
International Journal of Advances in Applied Sciences Vol 14, No 4: December 2025
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijaas.v14.i4.pp1384-1392

Abstract

Achieving uniform nanoparticle dispersion in electrospun polymer nanofibers remains a critical challenge, as conventional electrospinning often leads to particle agglomeration and nozzle clogging, reducing fiber uniformity and functional efficiency. This study explicitly addresses this problem by developing poly (vinyl alcohol) (PVA)/BaSO4 composite nanofibers through both conventional and ultrasonic-assisted electrospinning. Scanning electron microscopy (SEM) revealed that ultrasonication effectively disrupted nanoparticle agglomerates, yielding smoother and more uniform fiber morphologies. X-ray diffraction (XRD) analysis further confirmed that ultrasonic processing reduced the crystalline intensity of PVA and BaSO4, indicating enhanced polymer–filler interaction and finer BaSO4 distribution. Quantitatively, the agglomeration slope decreased from 0.039 (conventional) to 0.006, and the mean crystallite size was reduced from approximately 470 to 300 nm. These results are consistent with recent advances showing that ultrasonic electrospinning improves nanoparticle dispersion and stability in polymer matrices, thereby enhancing optical and mechanical properties. Ultimately, this work demonstrates that ultrasonic-assisted electrospinning provides a robust and scalable strategy to fabricate lightweight, flexible, and multifunctional PVA-based radiation shielding materials with superior nanoparticle dispersion and structural homogeneity.
Influence of potassium bromide phosphor on optical properties of white light-emitting diodes Cong, Pham Hong; Loan, Nguyen Thi Phuong; Anh, Nguyen Doan Quoc; Lee, Hsiao-Yi
International Journal of Advances in Applied Sciences Vol 14, No 4: December 2025
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijaas.v14.i4.pp1359-1366

Abstract

Conventional phosphor-converted light-emitting diodes (LEDs) using silicone binders often suffer from yellowing, moisture degradation, and limited spectral tunability, restricting their performance in high-power street lighting. To overcome these limitations, this study aims to develop an advanced LED illumination system integrating a KBr-doped sol-gel/silica phosphor with total internal reflection (TIR) lenses and a reflective housing, encapsulated by an atomic layer deposition (ALD)-coated minilens panel. The sol-gel matrix, synthesized from MTEOS, TEOS, and silica granules, was engineered to achieve uniform KBr particle dispersion, reduced thermal quenching, and improved chromatic stability. The ALD laminate provides an additional moisture and heat barrier, sealing micro-defects and minimizing stress-induced cracking. Optical performance was quantitatively assessed using Monte Carlo beam-tracking simulations under various street configurations, including focal, zigzag, and single-plane pole layouts. Results demonstrated enhanced luminous efficacy, precise glare control, and high uniformity in street illumination. Overall, this integrated sol-gel/ALD LED design effectively addresses the durability and color instability problems of traditional silicone systems, offering a scalable and energy efficient solution for next-generation street lighting.
Enhancing Scattering Strength Improvement and Color Uniformity in White Light-Emitting Diodes Using High Concentration of Yttrium Oxide Cong, Pham Hong; Loan, Nguyen Thi Phuong; Tung, Ha Thanh
Science and Technology Indonesia Vol. 11 No. 1 (2026): January
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2026.11.1.174-181

Abstract

This study investigates the effect of yttrium oxide (Y2O3) doping on the phase evolution of barium titanate (BaTiO3), a key dielectric material used in multilayer ceramic capacitors (MSCCs). Two types of starting powders were examined: pure BaTiO3 and a commercial X7R composition containing 1 wt% Y2O3. Using the solid-state method under high temperature, Y2O3 was added in varying amounts, and the powders were processed under controlled sintering conditions to evaluate its influence on phase formation. The resulting ceramics were characterized to determine formational alterations as well as the potential generation of secondary phases. Increasing Y2O3 content led to a transmutation from the tetragon structure to a merger between tetragon as well as cubic phases. The commercial X7R powder exhibited greater densificating process, surpassing pure BaTiO3 and formed a cuboid formation under greater Y2O3 concentrations. Notably, the sample doped with 20 wt% Y2O3 produced the Ba6Ti17O40 phase, augmenting scattering capacity and color uniformity. These findings clarify the role of Y2O3 in phase evolution and highlight its implications for optimizing BaTiO3-based MSCC materials.
Co-Authors Anh, Nguyen Doan Quoc Duy, Le Doan Le, Phan Xuan Lee, Hsiao Yi Lee, Hsiao-Yi Loan, Nguyen Thi Phuong Thai, Nguyen Le Thuy, Le Xuan Tran, Thinh Cong Trang, Le Thi Tung, Ha Thanh