2D photonic crystal layer assisted thiosilicate ceramic plate with red‐emitting film for high quality w‐LEDs

Abstract

In this work, we have succeeded in obtaining high quality warm w-light-emittingdiodes (LEDs) by adopting hybrid two-dimensional (2D) structure of SiN x photonic crystal layer (PCL) assisted cyan-emitting ceramic-plate thiosilicate SrLa 2-Si 2 S 8 :Ce 3+ with red-emitting film SrLiAl 3 N 4 :Eu 2+ phosphor on a 430 nm blue LED chip at 350 mA. 2D SiN x PCL was capped with thiosilicate is because it can enhance the luminous efficacy and maintain the low correlated color temperature (CCT) and high color-rendering index (CRI). High luminous efficacy (82.3 lm/W), high special CRI (R 9 =75) as well as the low CCT (5431 K) of the optimal w-LED was obtained due to the assistances of 2D SiN x PCL and narrowband red-emitting phosphor with the doping percentage at 10 wt%. The synthesis processes, structural analysis, optical properties and LED device performances were detailed investigated to find out the relationship between the optimum composition and good optical properties. Based on intriguing luminescence properties by the 2D SiN x PCL and red-emitting film phosphor introducing, we proclaim this method could also have high potential application in other phosphorconverted w-LEDs. K E Y W O R D SCe 3+ , Eu 2+ , nitride, optical properties, thiosilicate, w-LEDs

Synthesis and photoluminescence properties of Eu3+-activated LiCa3ZnV3O12white-emitting phosphors

“…Such so-called phosphor-converted WLEDs are generally fabricated through three approaches: (1) combining a blue LED chip with a yellow phosphor (e.g., YAG:Ce 3+ ) or a blend of green and red phosphors, (2) combining an ultraviolet (UV) LED chip with a blend of tricolor (blue, green, and red) phosphors, and (3) combining an UV LED chip with a single-phased white-emitting phosphor. [11][12][13][14] Nowadays, the widely used WLEDs are fabricated by coating YAG:Ce 3+ yellow phosphors on InGaN blue LED chips, however these WLEDs commonly suffer from high correlated color temperature (CCT) and low color rendering index (CRI) owing to the lack of a red component, limiting their applications in indoor lighting. [15][16][17][18][19][20][21] On the other hand, the WLEDs made by multiple-emitting phosphors also have some drawbacks, such as intrinsic color balance, device complication and high cost.…”

Design of photonic crystals for light‐emitting diodes

“…WLEDs with high CRI and low CCT have been created as a consequence of research conducted and published by Dai et al who examined and reported a hybrid structure of SiN x PCL-aided phosphorescence. 100 The structure is shown schematically in Figure 27A, and as seen in Figure 27B-D, the electroluminescence (EL) spectrograms for different phosphor concentrations (0-15 wt%) had the best performance for the red phosphor LED with 10 wt%. In contrast, the LED with the SiN x PCL structure had a higher luminous efficiency and CCT than the LED without the SiN x PCL.…”

Structure and luminescence properties of single-component melilite Sr2MgSi2O7:Ce/Tb/Sm for n-UV wLEDs

“…Till now, there are three mainstream modes for the construction of pc-wLEDs (Scheme S1, ESI †), (i) blue InGaN LED chip + yellow phosphor YAG:Ce, (ii) n-UV chip + red, green, and blue phosphors, and (iii) n-UV chip + single-phase phosphor (co)doped with rareearth (RE) and/or transition metal (TM) ions via energy transfer (ET). [7][8][9][10] Mode (iii) is now the focus of research as the others have obvious drawbacks. For mode (i), only 'cool' white light could be gained with a low color rendering index (CRI) and high coordinated color temperature (CCT) because of the innate lack of red emission.…”