Photonic Crystal Phosphors Integrated on a Blue LED Chip for Efficient White Light Generation

Lee, Jong-Ho; Min, Kyungtaek; Park, Yeonsang; Cho, Kyung‐Sang; Jeon, Heonsu

doi:10.1002/adma.201703506

Cited by 54 publications

(37 citation statements)

References 29 publications

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“…[48] The composition of PQDs and S-AIMs is further confirmed by the elemental maps of AeroPQDs, as shown in Figure 3e-h. [54,55] The PL intensity comparison plot (integrated from 480 to 580 nm) of the green AeroPQDs and green PQDs in solution confirms this explanation ( Figure S8, Supporting Information). Additionally, the strong adsorption of PQDs within the S-AIMs was confirmed by mixing green and red AeroPQDs together in silicone and then by packaging them onto a blue LED to achieve white light, the green and red emission peaks are clearly observed without undergoing anion exchange, as shown in Figure S6 (Supporting Information).…”

Section: Resultssupporting

confidence: 64%

Highly Efficient and Water‐Stable Lead Halide Perovskite Quantum Dots Using Superhydrophobic Aerogel Inorganic Matrix for White Light‐Emitting Diodes

Song

et al. 2020

Adv Materials Technologies

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hence have drawn a lot of attention as down-conversion materials for white lightemitting diodes (WLEDs). [7][8][9][10] For practical applications, the cost-effectiveness, the optical performance, and the stability of PQDs should be further improved. [4] Particularly, PQDs suffer from low chemical and optical stabilities, resulting in their fast degradation under exposure to moisture, heat, and light irradiance. [11,12] Accordingly, PQDs exhibit much lower stability than conventional rare-earth-based phosphor materials. [13,14] Current research efforts therefore aim at enhancing the stability of PQDs by covering them in inorganic materials, including CdS, [15] zeolite, [16,17] glass, [18,19] CaF 2 , [20] Al 2 O 3 , [21][22][23] SiO 2 , [24][25][26][27][28][29] and TiO 2 . [30] Generally, the protective shells of PQDs are prepared using these inorganic materials by in situ synthesis. While protected PQDs with high chemical, thermal, and irradiation stabilities have been obtained, [28] the water stability of PQDs prepared with these inorganic shells still indicate a lot of room for improvement. For instance, the PL intensity of CaF 2 shell-integrated green PQDs reduces to <50% after a water-resistance test of ≈40 h. [20] Consequently, and until now, PQDs with high water stability are achieved by embedding them in enclosed organic polymer and glass matrices. [18,19,[31][32][33][34][35][36][37][38][39] The hydrophobic surface and dense polymer chains of the matrix can effectively protect the PQDs from the external environment, considerably enhancing their At present, most of lead halide perovskite quantum dots (PQDs) embedded in an enclosed organic polymer or glass matrix can achieve high water stability, yet this limits their subsequent integration with light-emitting diodes (LEDs) and other functional materials. Herein, a postadsorption process using superhydrophobic aerogel inorganic matrix (S-AIM) with open structures is presented to enhance water stability of PQDs and compose newfunctions to them such as magnetism. The CsPbBr 3 PQDs integrated with the S-AIM (AeroPQDs) exhibit a high relative photoluminescence quantum yield (PLQY, 75.6%) of 90.9% compared to pristine PQDs (PLQY, 83.2%). They preserve their initial PL intensity after 11 days of soaking in water and achieve a high relative PLQY stability (50.5%) after soaking for 3.5 months. The hydrophobic (rough) surface of the matrix, its pores with a well-matched mean diameter that promotes the homogeneous integration of PQDs and hinders the penetration of water as well as the oleophylic functional groups covering the surface of these pores are the three factors responsible for the high water stability. Finally, AeroPQDs are easily integrated with other functional nanomaterials, such as Fe 3 O 4 nanoparticles for magnetic manipulation, due to their open structure.

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Section: Resultssupporting

confidence: 64%

Highly Efficient and Water‐Stable Lead Halide Perovskite Quantum Dots Using Superhydrophobic Aerogel Inorganic Matrix for White Light‐Emitting Diodes

Song

et al. 2020

Adv Materials Technologies

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“…However, in photoelectric devices with QDs as the down-conversion materials, the working temperature is usually higher than room temperature due to P–N junction heating. Therefore, the thermal stability of QDs is essential (Lee et al, 2018 ; Li et al, 2018 ). Figure 4 shows the PL spectra of CIS/ZnS QDs in Figure 2C (with OA ligand of 4 mL) at different temperatures.…”

Section: Resultsmentioning

confidence: 99%

Simple Synthesis of CuInS2/ZnS Core/Shell Quantum Dots for White Light-Emitting Diodes

Jiang

Wang

et al. 2020

Front. Chem.

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In this study, the CuInS 2 /ZnS core/shell quantum dots (QDs) were prepared via simple and environmentally friendly solvothermal synthesis and were used as phosphors for white light-emitting diodes (WLEDs). The surface defect of the CuInS 2 core QDs were passivated by the ZnS shell by forming CuInS 2 /ZnS core/shell QDs. By adjusting the Cu/In ratio and the nucleation temperature, the photoluminescence (PL) peak of the CuInS 2 QDs was tunable in a range of 651–775 nm. After coating the ZnS layer and modifying oleic acid ligands, the PL quantum yield increased to 85.06%. The CuInS 2 /ZnS QD powder thermal stability results showed that the PL intensity of the QDs remained 91% at 100°C for 10 min. High color rendering index values (CRI, 90) and correlated color temperature of 4360 K for the efficient WLEDs were fabricated using CuInS 2 /ZnS QDs and (Ba,Sr) 2 SiO 4 :Eu 2+ as color converters in combination with a blue GaN light-emitting diode chip.

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“…White light‐emitting diodes (WLEDs) are commonly fabricated by combining inorganic phosphors with a blue or UV LED . However, it is not easy to achieve a tailored and full‐spectrum white light with currently available phosphors.…”

Section: Optical Properties Of Cdzns/zns Cdznses/zns and Cdse/cds/zmentioning

confidence: 99%

Highly Luminescent Quantum Dots in Remote‐Type Liquid‐Phase Color Converters for White Light‐Emitting Diodes

Choi

Han

et al. 2018

Adv Materials Technologies

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QDs. [14][15][16][17] However, they have less than optimal optical properties due to nonradiative recombination by defects. [12,18] As a result, despite the safety issues, Cdbased QDs are still attracting much attention and are seen as promising candidate materials for versatile applications in nonbiological environments owing to their outstanding performance with respect to tunable luminescence across the ultraviolet-visible-near-infrared (UV-vis-NIR) region, broad absorption bands with narrow emission bands, high quantum yields, [19] chemical stability, and photostability. [20,21] It is important to note that QDs have been passivated with higher bandgap semiconductor layers, such as ZnS and CdS, to increase the quantum yield. In the core-shell type QDs, the shell provides physical and chemical stabilities, as well as photostability to the core QDs, which is important for minimizing cytotoxicity, and also offers platforms for ligand exchange and further functionalization. [22] White light-emitting diodes (WLEDs) are commonly fabricated by combining inorganic phosphors with a blue or UV LED. [23,24] However, it is not easy to achieve a tailored and fullspectrum white light with currently available phosphors. The light spectra emitted by phosphor-based WLEDs are tuned by adjusting weight ratios of phosphors with different emission wavelengths. QDs behave like phosphors but their emissive colors are controlled by varying the size and composition. QDs have emerged as a good alternative to the phosphors in LEDs. Quantum dots (QDs) can be integrated into a solid-phase color converter (SCC) for white light-emitting diodes (WLEDs). However, the development of QD-based SCCs is prevented by the limitations of the QDs themselves, nonuniform dispersion or aggregation of the QDs, and heat accumulation by low thermal conductivity of the solid matrix. Herein, the development of new high-quality CdZnSeS/ZnS QDs in a one spot synthesis is reported that have high photoluminescence quantum yield (up to 100% for green wavelengths), narrow emission spectra (full width at half maximum< 27.3 nm), and good color tunability in the green region, 496-586 nm. Seven different color QDs are used to fabricate liquid-phase color converters (LCCs) for application in WLEDs with a remote configuration. The best LCC-based WLEDs show not only intense bright day white light (correlated color temperature = 6029 K) with a maximum luminous efficacy of 222.7 lm W −1 , but also excellent color quality (color rendering index = 95.1, as well as R9 = 94.4, and R13 = 97.1), which is very important in medical diagnostic lighting, dressing and display room lighting, painting and accent lighting. These results indicate remarkable progress both in the synthesis of high-quality QDs and in the development of WLEDs for high-performance commercial lighting devices.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/admt.201800235.Semiconductor nanocrystals, namely quantum dots (QDs) have created many innova...

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Photonic Crystal Phosphors Integrated on a Blue LED Chip for Efficient White Light Generation

Cited by 54 publications

References 29 publications

Highly Efficient and Water‐Stable Lead Halide Perovskite Quantum Dots Using Superhydrophobic Aerogel Inorganic Matrix for White Light‐Emitting Diodes

Highly Efficient and Water‐Stable Lead Halide Perovskite Quantum Dots Using Superhydrophobic Aerogel Inorganic Matrix for White Light‐Emitting Diodes

Simple Synthesis of CuInS2/ZnS Core/Shell Quantum Dots for White Light-Emitting Diodes

Highly Luminescent Quantum Dots in Remote‐Type Liquid‐Phase Color Converters for White Light‐Emitting Diodes

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