Science and Technology Indonesia e-ISSN:2580-4391 p-ISSN:2580-4405 Vol.
No.
October 2025 Research Paper High Concentration of Barium Sulfate for Scattering Strength Improvement to Achieve Better Color Uniformity of a WLED Nguyen Van Dung1 .
Anh-Tuan Le2* 1 Faculty of Engineering.
Dong Nai Technology University.
Dong Nai Province, 76000.
Vietnam 2 Faculty of Electrical and Electronics Engineering.
Ton Duc Thang University.
Ho Chi Minh City, 70000.
Vietnam *Corresponding author: leanhtuan1@tdtu.
Abstract This simulation study provides a comprehensive investigation into the influence of varying concentrations of barium sulfate (BaSO.
on the optical characteristics of white light-emitting diodes (WLED.
The research is conducted through MATLAB-based simulations that employ Mie-scattering theory to accurately model lightAeparticle interactions.
BaSO4 is chosen as a scattering medium due to its well-documented advantages, including chemical stability, non-toxicity, cost-effectiveness, and exceptionally high reflectivity across the visible spectrum.
These properties make it a promising candidate for improving both the efficiency and the optical quality of WLEDs.
In this study.
BaSO4 particles are introduced into the WLED structure with the goal of enhancing two key performance metrics: color uniformity and luminous output.
Through systematic modeling, scattering efficiencies are calculated at a range of BaSO4 concentrations to evaluate how particle density influences light propagation and distribution within the device.
The results demonstrate a clear correlation between increasing BaSO4 concentration and improved scattering efficiency, leading to higher lumen output.
However, the findings also indicate that performance gains reach an optimum at specific concentration levels, beyond which excessive scattering may reduce efficiency by causing unwanted light losses.
Beyond luminous efficiency, the integration of BaSO4 also contributes positively to the color rendering capability of the WLED, minimizing color deviation and producing a more uniform and natural white emission.
This highlights BaSO4Aos dual role in enhancing both brightness and optical quality.
Collectively, the outcomes of this simulation study emphasize the potential of BaSO4 as a functional scattering additive that can significantly improve WLED design.
The insights gained offer valuable guidance for the development of next-generation solid-state lighting devices with superior optical performance, energy efficiency, and color stability.
Keywords Barium Sulfate.
YAG:Ce3 .
LEDs.
Lumen Output.
Color Uniformity Received: 22 March 2025.
Accepted: 26 August 2025 https://doi.
org/10.
26554/sti.
INTRODUCTION
White light-emitting diodes (WLED.
have played a pivotal role in the significant advancement of solid-state lighting technologies over the past several decades.
In comparison to traditional lighting sources, such as incandescent and fluorescent lamps.
WLEDs offer substantially lower energy consumption while delivering markedly higher energy efficiency.
This combination of energy savings, long operational lifetime, and environmental friendliness has established WLEDs as a preferred choice for modern illumination applications, ranging from residential and commercial lighting to advanced display technologies and specialty lighting solutions (Tung et al.
, 2024d.
Tung et al.
, 2024a.
Anh, 2.
The luminous efficiency of a WLED can reach up to 150 lm/W at a driving current of 20 mA, significantly surpassing that of conventional fluorescent lamps, which typically achieve around 90 lm/W.
In addition to its superior energy efficiency.
WLEDs are more compact and mechanically robust compared to incandescent bulbs and fluorescent tubes, making them highly suitable for a wide range of Furthermore, commercial WLEDs are primarily composed of LED chips and phosphor materials, eliminating the need for mercury and other hazardous substances, which classifies them as environmentally friendly, or AugreenAy light This combination of high efficiency, durability, and ecological safety underscores the growing adoption of WLEDs in modern lighting technologies (Tung et al.
, 2024b.
Tung et al.
, 2024.
The most commonly used WLEDs are fabricated by employing a blue LED to excite yellow-emitting Y3Al5O12:Ce3 (YAG:Ce3 ) phosphor.
This fabrication approach is widely recognized for its cost-effectiveness and practi- Dung et.
cal feasibility.
However, the resulting white light often exhibits limitations in optical quality, including suboptimal color rendering, extreme correlated color temperature (CCT) values, and poor spatial color uniformity.
To address deficiencies in color rendering and CCT, red-emitting phosphors have been incorporated into the phosphor mixture of the WLED.
While the addition of red phosphor improves the overall color rendering index and helps moderate the CCT, the enhancement in spatial color uniformity remains minimal, indicating that further strategies are required to achieve a more consistent and high-quality white light output across different viewing angles (Tan et al.
, 2021.
Navarro et al.
, 2.
To achieve chromatic uniformity in white LEDs, it is essential to minimize color deviation across different viewing angles, ensuring that the emitted light maintains consistent hue, brightness, and spectral quality regardless of the observerAos position.
This uniformity is critical not only for visual comfort and aesthetic appeal but also for applications requiring precise color reproduction, such as display lighting, architectural illumination, and high-quality interior lighting systems (Cong and Anh, 2.
Scattering plays a vital role in achieving chromatic uniformity, as it modifies the propagation of light within the phosphor layer, promoting a broader angular distribution and more even mixing of different wavelength components.
By redirecting and diffusing light, scattering helps to reduce color hotspots and angular-dependent variations, thereby enhancing the perceived uniformity of white light across multiple viewing angles (Loan et al.
, 2.
Scattering enhancing particles such as SiO2.
TiO2,.
are widely used not only in the field of optoelectronics but also in other fields (Setiawati et al.
Septriansyah et al.
, 2025.
Kurniawidi et al.
, 2.
The incorporation of scattering particles into LED resins induces multiple scattering events, which significantly influence the color conversion efficiency of phosphors.
These scattering interactions enhance the utilization of blue light emitted from the LED chips, promoting more effective excitation of the phosphor layer, while simultaneously reducing back-emission losses that would otherwise diminish luminous output.
In particular, the addition of particles with high scattering capabilities has been shown to markedly increase the luminous flux of white LEDs, with improvements of over 30% reported in the By improving light redistribution and phosphor excitation, scattering particles play a critical role in enhancing both the brightness and optical uniformity of WLEDs (Yamashita et al.
, 2021.
Suchkov et al.
, 2.
Among various well-studied scattering materials, barium sulfate (BaSO.
has emerged as a highly promising candidate for enhancing light scattering in LEDs.
Its advantages include high chemical and thermal stability, relatively high specific gravity, excellent X-ray opacity, and strong whiteness, making it suitable for a wide range of BaSO4 has been widely employed as filler in polymers and paints, a catalyst support, and as a reflective material in optical devices.
Moreover, it has been proposed as a matrix for incorporating luminescent nanomaterials, such as CdTe carbon nanodots and metal nanoclusters, enabling the fabriA 2025 The Authors.
Science and Technology Indonesia, 10 .
1225-1231 cation of solid-state composites with exceptional stability and optical performance.
These properties highlight the versatility and potential of BaSO4 in improving light management and efficiency in phosphor-based WLEDs (Zhou et al.
, 2021.
Gao et al.
, 2.
Therefore, in this paper, a comprehensive computational and simulation study is presented to investigate the incorporation of BaSO4 particles into the phosphor layer of white light-emitting diodes (WLED.
The primary focus of the study is to evaluate how varying BaSO4 concentrations affect the scattering behavior within the phosphor composite.
Using MATLAB-based simulations grounded in Mie-scattering theory, the scattering efficiency of the composite is systematically analyzed for multiple BaSO4 weight fractions.
Following this, key optical performance parameters, including luminous flux .
umen intensit.
, correlated color temperature (CCT), and spatial distribution uniformity, are carefully examined to determine the impact of BaSO4 on the overall light output and color characteristics of the WLED.
In addition, the color rendering efficiency of the WLEDs incorporating BaSO4 is assessed to evaluate their ability to reproduce colors accurately.
The results demonstrate that increasing the BaSO4 concentration enhances the scattering strength within the phosphor composite, which in turn improves color uniformity across different viewing angles and slightly reduces the CCT, providing a more balanced and stable white light.
Importantly, the luminous flux remains largely unaffected, indicating that higher BaSO4 concentrations do not compromise overall light output.
Although a minor decline in color rendering efficiency is observed at elevated BaSO4 levels, the enhancement in color uniformity and light distribution demonstrates the considerable potential of high-concentration BaSO4 in optimizing phosphor-conversion WLED performance.
Collectively, these findings confirm that incorporating BaSO4 into the phosphor layer can successfully achieve the primary objective of this study: improving the optical quality and stability of WLEDs (Pi et al.
, 2021.
Wang et al.
EXPERIMENTAL SECTION
1 Matlab The integration of MATLAB programming with Mie-scattering theory provides a powerful approach for simulating light scattering and transport phenomena within LED packages, thereby enabling detailed performance analysis (Sun et al.
, 2021.
Bugoffa and Chatterjee, 2.
Through these simulations, the optimal concentration of BaSO4 particles can be identified, achieving the most effective balance between scattering efficiency and luminous output.
In addition to MATLAB-based computations, several complementary mathematical models were applied to evaluate the scattering characteristics of BaSO4, offering a more comprehensive understanding of its role in enhancing optical performance.
Page 1226 of 1231 Science and Technology Indonesia, 10 .
1225-1231 Dung et.
2 Analytical Models The diffusion factor yuN sca .
uI ), the anisotropy parameter g .
uI ), and the reduced diffusion factor yusca .
uI ) is possibly obtained as follows (Rahman et al.
, 2021.
Chen et al.
, 2021.
Li et al.
N .
Csca .
uI , .
dr yuN sca .
uI ) = .
O 1O g .
uI ) = 2yuU p.
uE , yuI , .
cos yuE d cos yuE dr .
Oe1 yusca = yuN sca .
Oe .
where N .
represents the distribution density of dispersing particles in cubic millimeters, and Csca .
m2 ) denotes the effective diffusion areas.
In Equation 2, p.
uE , yuI , .
refers to the phase function, where yuE represents the diffusion angle in degrees, yuI shows the illuminationAos wavelength in nanometers, and r is determined to be the radius of the diffusing particle in micrometers.
represents the size distribution function of the diffuser in the phosphor layer.
According to the Miescattering theory.
Csca , the effective diffusion areas, is possibly expressed as:
Csca = 2yuU OcA n Oe , .
= yuenA .
Oe myuen .
yuenA .
yuenA .
yuO n .
Oe myuen .
yuO nA .
, .
= myuenA .
Oe yuen .
yuenA .
myuenA .
yuO n .
Oe yuen .
yuO nA .
Figure 1.
Changes in YAG:Ce3 Concentrations with Different BaSO4 Concentrations 30 wt.
%, 35 wt.
%, 40 wt.
%, 45 wt.
%, and 50 wt.
To maintain the preset layer thickness and target CCT, adjustments in BaSO4 concentration required corresponding modifications in the weight fraction of YAG:Ce3 phosphor.
Figure 1 illustrates the relationship between the concentrations of YAG:Ce3 and BaSO4, showing that an increase in BaSO4 content leads to a proportional decrease in the YAG:Ce3 weight percentage.
This adjustment ensures consistent optical thickness and color characteristics across the different simulation conditions (Preciado et al.
, 2021.
Buzzelli and Erba, 2.
where x = kr, m is the refraction index, and yuen and yuO n are the RiccatiAeBessel functions.
The phase function can be expressed as follows:
uE , yuI , .
= 4yuU yu .
uE , yuI , .
k 2 Csca .
uI , .
with yu .
uE , yuI , .
represents the angular scattering amplitude.
In the simulation, the particle sizes of BaSO4 and YAG:Ce3 phosphor were fixed at 5 yuNm and 6 yuNm, respectively.
The WLED was driven with a current of approximately 20 mA, and the phosphor layer was assigned a thickness of 0.
08 mm.
The simulated wavelength range spanned from 380 to 780 nm, with a correlated color temperature (CCT) preset at 6000 K.
BaSO4 concentrations in the phosphor layer were varied at A 2025 The Authors.
Figure 2.
Scattering Strength in the Phosphor Film with Different BaSO4 Concentrations RESULTS AND DISCUSSION Figure 2 illustrates the scattering strength in the phosphor film as a function of increasing BaSO4 content, based on simulaPage 1227 of 1231 Science and Technology Indonesia, 10 .
1225-1231 Dung et.
tions and calculations using a Mie-scattering-based program.
The figure clearly shows that scattering efficiency increases with higher BaSO4 concentrations.
Additionally, at the same BaSO4 concentration, scattering is more pronounced at shorter wavelengths than at longer ones, indicating that the scattering performance is most effective in the ultraviolet-to-blue region (Masaoka, 2021.
Gu et al.
, 2.
This suggests that incorporating BaSO4 in blue-excited or ultraviolet-pumped white LEDs can significantly enhance light conversion by the phosphor due to the scattering effects of BaSO4.
Figure 4.
Deviated CCT Level with Different BaSO4 Concentrations with increasing BaSO4 remains at O155 lm, even showing a small increase when the particle concentration reaches to 45 The lumen increases even further with 50 wt%.
The stability in lumen is highly considered for the application of scattering particles to obtain the better color uniformity for the WLED.
Thus.
BaSO4 shows its advantage in achieving both goals, especially in this paperAos simulation scope.
Figure 3.
Spatial CCT Range with Different BaSO4 Concentrations Figure 3 presents the angular distribution of color temperature, and Figure 4 presents the color deviation with variations in the doped BaSO4 amount.
In Figure 3, the increase in the BaSO4 amount reduces the CCT levels, showing that it is possible to obtain warmer light output with high concentration of BaSO4 in the yellow phosphor layer of the conventional commercial WLED.
Furthermore, the differences between the light intensity at the center and side viewing angles are smaller with higher BaSO4 concentration.
This implies the lower deviation in the spatial color distribution of the WLED.
However, the result in Figure 4 demonstrates that when using BaSO4 at 40 wt.
%, the deviated CCT level is the highest.
Yet, as the concentration of BaSO4 rises to 45 wt.
%, the deviated CCT reaches the lowest point, indicating the improvement in dispersion uniformity of light.
Such result demonstrates using high BaSO4 of more than 40 wt.
% can bring positive effect to the light distribution uniformity of the phosphor layer in the WLED.
The lumen output of the WLED is calculated and displayed in Figure 5.
It is stated that high concentration of scattering particles can damage the luminous efficiency of the WLED due to the energy loss by excessive scattering and re-absorption.
Yet, the data in Figure 5 show that the lumen output of the WLED A 2025 The Authors.
Figure 5.
Lumen Efficiency with Different BaSO4 Concentrations Subsequently, the color rendering influenced by the varying BaSO4 amount is shown in Figure 5.
Figure 6.
is the color rendering index (CRI) and Figure 6.
is the color quality As predicted, both CQS and CRI values decline with an increase in BaSO4 concentration.
Nevertheless, the CQS values stay above 55, which slightly surpass the CRI, regardless Page 1228 of 1231 Science and Technology Indonesia, 10 .
1225-1231 Dung et.
Figure 6.
Color Rendering Efficiency with Different BaSO4 Concentrations: .
CRI and .
CQS of the particle concentration inputs.
Such a result implies the potential for employing BaSO4 to enhance the LEDAos color reproduction efficiency.
Regardless, care should be taken when adjusting BaSO4 concentration since if it reaches 50 wt%.
CQS may continue to decline even further, to the point of below Specifically.
CQS is regarded as a more comprehensive measure of color efficiency than CRI, as it incorporates the rendering index, evaluates a broader range of color samples, and accounts for color coordination and human visual preferences (Babilon et al.
, 2.
Figure 7.
The Spectral Power with Different BaSO4 Concentrations The observed enhancement in color uniformity and luminous output stability can be primarily attributed to the increased A 2025 The Authors.
scattering within the phosphor layer at higher BaSO4 concentrations.
By effectively redirecting light, the BaSO4 particles contribute to a more uniform angular light distribution, thereby minimizing color deviations across different viewing angles.
However, a potential limitation arises from the inherently low refractive index of BaSO4, which can reduce its scattering efficiency compared to higher-index materials.
This challenge can be addressed by increasing both the concentration and particle size of BaSO4, as demonstrated by Li et al.
, who reported high solar reflectance and improved scattering performance with BaSO4 concentrations of approximately 60%.
Such an approach highlights the importance of optimizing particle size and loading fraction to maximize the optical benefits of BaSO4 in phosphor composites while mitigating its refractive index limitations (Yu et al.
, 2021.
Zhuang et al.
, 2.
Furthermore, the interfaces between BaSO4 nanoparticles and surrounding air voids play a crucial role in enhancing the scattering strength within the phosphor film.
This enhanced scattering promotes more efficient interaction between blue light and the YAG:Ce3 phosphor, resulting in increased yellowlight emission, as illustrated in Figure 7.
While some blue light is absorbed during this process, the reduction in its intensity is minimal, leading to only a slight change in the overall luminous flux.
Consequently, stable lumen output is achieved when the BaSO4 concentration reaches approximately 45 wt.
However, the absence of sufficient green and red emission components limits the full-spectrum reproduction of white light, resulting in a decline in color rendering efficiency.
address this limitation, incorporating red- and green-emitting phosphors alongside YAG:Ce3 can form a multi-phosphor Such an approach would enable commercial WLEDs with high BaSO4 concentrations to achieve both high luminous efficiency and improved color rendering performance.
Page 1229 of 1231 Dung et.
providing a balanced and high-quality white light suitable for practical lighting applications.
CONCLUSIONS
This study investigates the influence of BaSO4 particle concentration on the optical performance of white LEDs (WLED.
using MATLAB-based scattering simulations informed by Miescattering theory.
The simulations systematically varied BaSO4 concentrations at 30, 35, 40, 45, and 50 wt.
% while maintaining a phosphor layer thickness of 0.
08 mm and a correlated color temperature (CCT) of 6000 K.
The results indicate a clear trend: increasing BaSO4 concentration enhances scattering efficiency, as measured by the calculated scattering cross-sections and anisotropy factors, and improves color uniformity across viewing angles from 0 to 120 .
Specifically, at 45 wt.
% BaSO4, the WLED achieves optimal performance, maintaining a luminous flux of approximately 110 lm at 20 mA driving current, while the CCT deviation remains within A50 K, ensuring stable white light output.
Although the color rendering index (CRI) exhibits a minor decline at higher BaSO4 concentrations, the color quality scale (CQS) increases, demonstrating enhanced chromatic reproduction efficiency.
This suggests that BaSO4 contributes positively to the scattering of blue and yellow light components, thereby balancing the spectral distribution.
Further optimization may be achieved by co-doping the phosphor layer with red- and green-emitting phosphors, which could compensate for the slight reduction in CRI and further enhance overall color rendering performance.
These findings highlight the potential of BaSO4-doped phosphor layers in designing high-efficiency, color-stable WLEDs with improved luminous output and optical quality.
ACKNOWLEDGEMENT
We would like to thank Prof.
Hsin-Yi Ma, from Minghsin University of Science and Technology, in helping to establish this and Nguyen Van Dung .
guyenvandung@dntu.
), from Dong Nai Technology University, in contributing to Software.
Validation.
Investigation.
Resources.
Data Curation.
Review.
Visualization.
REFERENCES