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The use of CaO:Eu3+ and Zn2SiO4:Mn2+ phosphors to increase the color quality and illumination intensity of WLEDs Thanh Tung, Ha; An Nguyen Thi, Dieu; Xuan Le, Phan
Bulletin of Electrical Engineering and Informatics Vol 12, No 6: December 2023
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v12i6.4754

Abstract

The lumen efficacy in remote phosphor structure displayed remarkable enhancements, which is notable for the development of white light-emitting diodes (WLEDs). Nevertheless, its quality of colour is deemed not as good as that of the conformal or in-cup phosphor structure. Therefore, the goal of this research is to achieve a better quality of colour and significant luminous flux value for remote phosphor configuration by using extra phosphor layers. In particular, the two-layer and three-layer structures with the implementation of green and red phosphors are proposed. Comparing these two structures can help pinpoint the best suited for the WLED production. The assessment of each structure’s effect on the WLEDs’ optical parameters was determined under various correlated temperatures of colour (5,600-8,500 K). The outcomes indicated that the three-layer structure enhanced the quality of colour with greater efficiency compared to the two-layer structure due to the increased color rendering index (CRI), color quality scale (CQS), and photoluminescence (PL), and reduced colour deviation. The scattering improvement of the three-layer structure is a key factor of these accomplishments, proven by the scattering theory of Mie. Therefore, the three-layer structure is potential for developing WLED production.
The effects of Ca14Mg2(SiO4)8:Eu2+ phosphor on white light emission quality of LED-phosphor packages Thanh Tung, Ha; An Nguyen Thi, Dieu; Doan Quoc Anh, Nguyen
Bulletin of Electrical Engineering and Informatics Vol 12, No 6: December 2023
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v12i6.4792

Abstract

Ca14Mg2(SiO4)8: Eu2+ (CMS:Eu2+) green phosphor is used for creating the white-light emitting diode (W-LED) packages with conversion phosphor materials. The phosphor shows the broadband green emission that peaks at 505 nm in the blue wavelength. The phosphor introduces the improvement in the blue and green emission spectra, which helps to heighten the luminous flux. Moreover, that the concentration of CMS:Eu2+ increases, the scattering events are enhanced to benefits the color blending for lower color variations or better color uniformity. The color renditions reduce with the rising green-phosphor concentration. The green-light amount becomes surplus and redundant for balancing color elements of white light emission. Thus, it should adjust and keep the concentration of CMS:Eu2+ in the range of ~2–8 wt%, to get the average number of color rendering index (CRI) (73–75), and color quality scale (CQS) (60–64). The CMS: Eu2+, hence, is suitable for white light realization, and the W-LED aiming at high-luminescence white light emission with improved color uniformity, and average rendering performances.
Performance of ZnS and ZnSe Doped on Cu2+ for Photovoltaic Devices Thuy, Le Xuan; Thanh Tung, Ha; Dat, Le Tien; Le Minh Nhan
Science and Technology Indonesia Vol. 10 No. 3 (2025): 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.2025.10.3.952-957

Abstract

This study utilizes passive ZnS@Cu2+ and ZnSe@Cu2+ layers deposited on the CdS and CdSe quantum dots to reduce dark current and enhance photon absorption. The films were fabricated utilizing the successive ionic layer adsorption and reaction technique with an optimized and suitable Cu/Zn doping ratio. Ultraviolet–visible spectroscopy, X-ray diffraction, and field emission scanning electron microscopy analyses indicate a change in the absorption edge within the visible light region when ZnS and ZnSe are doped with Cu2+ ions. Power conversion efficiency measurements reveal that the ZnSe@Cu2+ photoelectrode increases the current density (JSC ~23 mA.cm-2) compared to ZnS@Cu2+ The photoelectrode exhibits a short-circuit current density (JSC ≈ 22 mA · cm−2), leading to improved conversion efficiency. It also shows the lowest charge transfer resistance (Rct2 = 33 − Ω), indicating efficient interfacial kinetics in the photoelectrode suggests more efficient electron transport and reduced recombination.