Quantum Dots and Nanocrystal- Embedded Glasses for Display Applications

bulletin cover story Quantum dots and nanocrystal- embedded glasses for display applications

lasses are widely used in display applications, as substrates for thin By Yoon Hee Nam, Hansol Lee, and Woon Jin Chung G film transistor arrays and color filters or cover windows. In addition, glasses and glass-ceramics The current high demand and fast-growing market for more now also are being considered as active materi- realistic images and vivid motion pictures drives the need for als for manipulating the primary colors of light high-quality picture displays. Quantum dots and nanocrystal- sources, further expanding their potential appli- embedded glasses show a lot of promise for this purpose. cation in display technologies. Current cutting-edge systems, such as liquid crystal displays (LCD) using quantum dots (QDs) and organic light emitting diodes (OLED), rely on organic materials or QDs synthesized by wet-chemistry to produce and control the primary colors of lights, such as red, green, and blue (RGB). It is well known that organic materials suffer from inherently weak chemical and thermal stabilities and complicated synthesis process, while inorganic glasses or glass-ceramics possess high chemical and thermal stability. These properties give glasses durability as well as long-term stability, and their relatively easy fabrication process reduces production cost. These advantages are opening new opportunities for glass-based materials as light generating materials, replacing conventional QDs. In this overview, the recent use of conventional QDs in displays is reviewed, and the development and current status of quantum dots and nanocrystal-embedded glasses for display applications are dis- cussed, along with their challenges and future prospects.

Color gamut of displays The current high demand and fast-growing market for more realistic images and vivid motion pictures is driving the need for high-quality picture displays, which rely on several key features,

28 Celebrating 100 years www.ceramics.org | American Ceramic Society Bulletin, Vol. 100, No. 1 including resolution, brightness, high dynamic range, and color gamut. Color gamut, which represents the range of color reproduction within the visible color space, is especially important as displays with ultrahigh-definition (UHD) resolution (3840 × 2160 in pixels) become more popular in the market. Credit: Yang et al., Mater. Today (Ref. 1) The color gamut of a display is defined by a triangle area enclosing the primary RGB colors. The standard color gamut for cathode-ray tubes was defined by the National Television Systems Committee (NTSC) within the CIE 1931 chromaticity diagram in 1953. With the development of new display technologies

since the 1990s, such as plasma dis- Credit: Yang et al., Mater. Today (Ref. 1) play panel and LCD, the International Credit: Nam, Lee, and Chung Telecommunication Union Radio com- Figure 1. (a) Electroluminescence and photoluminescence (EL+PL) spectra of RG-LED. munication organization recommended (b) EL spectra of QD-LEDs and OLEDs. (Reprinted with permission from Ref. 1. a new color gamut for high-definition Copyright 2018 Elsevier Ltd.) (c) Color gamuts of NTSC, Rec 709, Adobe RGB 1998, TVs (HDTV) with 1920 × 1080 resolu- and Rec 2020 standards within the CIE 1931 chromaticity diagram. tion, which is known as Rec. 709 (or BT. 709), as found in the chromaticity The RGB colors of conventional used with a combination of white OLED diagram of Figure 1c. LCDs are determined by a combination and color filters to produce RGB colors, The International Electrotechnical of color filters and the emission spectra and accordingly have a limited color 1 Commission announced standard RGB of a white LED, which is comprised of gamut following behind QD-based (sRGB) for computer displays, and it a blue LED with green and red ceramic LCDs in terms of brightness and color 2+ has a color reproduction range similar phosphors (RG-LED). b-Si6AlON8:Eu reproduction range. 2+ 2+ to Rec. 709. Adobe and Digital Cinema and CaAlSiN3:Eu (CASN:Eu ) were Initiatives, LLC also suggested definitions mostly used in commercial RG-LEDs QDs for displays for color gamut, those being Adobe RGB as the green and red phosphors, respec- QDs are semiconductor nanocrys- for publication and DCI-P3 for digital tively. However, because of their broad tals with diameters (typically < 10 nm) cinema colors, respectively. Thanks to emission bands, the LCD with RG-LED smaller than their Bohr radius, and they technological advances in the display have broad emission spectra, as drawn in include group II-VI (e.g., CdS, CdSe, industry, a new standard was required for Figure 1a. This emission spectra results in CdTe) and III-V (e.g., InP) compounds. the UHDTV environment, and thus the a color gamut of about 75% of NTSC. Since their first discovery by Alexey 2 International Telecommunication Union Scientists achieved significant improve- Ekimov in the 1980s, researchers exten- Radio suggested a wider color range, ment of the color gamut using QDs, sively investigated QDs and made several which is known as Rec. 2020 (or which have narrow emission bandwidth observations. For example, QDs have a BT. 2020), whose area corresponds to and tunable emission peak wavelengths. high theoretical quantum efficiency, up 150% of the NTSC area. As schematically illustrated in Figure 1, to 100%, and narrow emission band- It should be noted that the HDTV when QDs are used as color converting width of less than 50 nm, thanks to their color gamut corresponds to about 72% phosphors, well separated emission spec- strong quantum confinement effect. of NTSC, which most conventional tra can be obtained, providing a wide Their emission peak wavelength can be 1 LCD-based HDTVs provide. Rec. 2020 color gamut higher than 100% NTSC. easily tuned from ultraviolet to infrared for UHD was defined by monochromatic QDs thus were applied by major panel by varying their shape, size, or chemical 3 630, 532, and 467 nm lights for red, makers such as Samsung in advanced composition, as shown in Figure 2. green, and blue, respectively. Accordingly, LCD displays known as QLED-TVs. QDs are normally synthesized in a col- to realize UHD color gamut, it is highly Displays based on active-matrix loidal form by wet chemical approaches important to adjust the peak emission OLEDs (AMOLED) also can supply using chemical reactors, such as batch 4 wavelengths of the RGB colors and RGB colors with narrower emission reactors and continuous reactors. Among reduce their emission bandwidth or full bands than conventional RG-LEDs and batch reactors, hot injection organometal- width at half maximum for high color provide a high color gamut. However, lic synthesis is most widely used to obtain saturation (or color purity). for large sized panels, AMOLEDs are monodisperse colloidal QDs (cQDs),

American Ceramic Society Bulletin, Vol. 100, No. 1 | www.ceramics.org Celebrating 100 years 29 Quantum dots and nanocrystal-embedded glasses for display applications

ment film, which is then placed on top of a light guiding panel film, which delivers blue LED light.8 However, like OLEDs, QDs can also exhibit electroluminescence when they are used as an emission layer with an organic hole transport layer and electron transport layers, to create an LED (QD-LED or Credit: Anikeeva et al., Nano Lett. (Ref. 3) EL-QD).5 Although QD-LEDs still need to overcome several obstacles, including low external quantum efficiency and long term stability, they are being extensively studied for next generation displays with high picture quality. Recently, perovskite structured

Credit: Pu et al., Ind. Eng. Chem. Res. (Ref. 4) quantum dots or nanocrystals based Credit: Lee et al., Adv. Mater. Technol (Ref. 8)

on CsPbX3 (X=Cl, Br, and I) have been Figure 2. (a) Schematic diagram (left), actual photographs (top), and electrolumines- extensively studied to replace conven- cence and photoluminescence (EL+PL) spectra (bottom) of colloidal QDs. Solid lines rep- tional semiconductor-based QDs. Unlike resent EL spectra while dashed lines represent PL spectra. (Reprinted with permission conventional cQDs, perovskite quantum from Ref. 3. Copyright 2009 American Chemical Society.) (b) Schematic diagram (left), dots or nanocrystals (PQDs or PNCs) actual photographs (top), and PL spectra (bottom) of PNCs. (Reprinted with permission have intrinsic defect tolerance due to from Ref. 4. Copyright 2015 American Chemical Society.) (c) Color gamuts of RG-LED (phosphorous LED), QD-LED (Cd-QD LED), and PNC-LED (PQD-LED). (Reprinted with per- their characteristic electronic band struc- mission from Ref. 8. Copyright 2020 Wiley.) ture, and thus exhibit high PLQY, up to 100%, without any shell-like passivation which are obtained by the pyrolysis of stability and photoluminescence quantum layers.8,9 As shown in Figure 2, they also organometallic precursors rapidly injected yield (PLQY). Multishell cQDs (e.g., have high color tunability by varying into a hot organic coordination solvent at CdSe/ZnSe/ZnS) or ternary/quaternary size and composition, as well as a nar- 4 a temperature of 120–360°C. alloyed cQDs (e.g., CdSxSe1–x, ZnxCd1–xSe, row emission bandwidth, covering wider To improve batch-to-batch reproduc- ZnxCd1–xSySe1–y) demonstrated significant range up to about 140% of the NTSC ibility, a one-pot noninjection colloidal enhancement of PLQY, up to 80~100%, color gamut.9 synthesis method at low temperature was by successfully decreasing defects caused PNCs have at least 2.5 times higher 4 5,6 also suggested for various QDs. An aque- by lattice mismatch. Although cadmi- absorption coefficient than cadmium- ous synthesis method, in which QDs are um-based QDs with core/shell structure based or InP-based QDs, and can be directly synthesized within a water-based showed highest QY, cadmium-free or easily fabricated without core/shell solvent, also was suggested for biologi- heavy metal-free QDs were required due structure even at room temperature, cal and clinical applications. Synthesis to the European Union’s Restriction of unlike conventional cQDs, which approaches in continuous reactors, which Hazardous Substances regulations. require high temperature (200~350°C) provide more controlled reactions in large Among various alternative QDs, and multishells for defect passivation.8,9 scale production, include QD synthesis in including copper indium sulfide (CIS) They are currently being considered as a microfluidics, high-gravity technique, and QDs, carbon nanodots, and InP-based cost-effective alternative for conventional 4 thermospray synthesis. QDs (e.g., InP (or InZnP)/ZnSeS and QDs, and their potential feasibility as Monodispersed cQDs with large spe- InP (or InZnP)/ZnSe/ZnS core/shell color converting materials in LCDs, or cific surface area are highly vulnerable QDs), InP-based QDs showed wide color as emission layers in electroluminescence to environmental factors, which can tunability, high quantum yield, and nar- devices, were successfully demonstrated.8 7 degrade their luminescence conversion row emission bandwidth. Accordingly, Like cQDs, PNCs are mostly synthe- efficiency via the nonradiative recombi- they are currently used in commercial sized by hot injection methods, but other 5,6 nation of excitons. To protect cQDs QLED-TVs, in spite of their complicated methods, such as ligand assisted repre- from external environmental conditions synthesis process and relatively inferior cipitation for room temperature synthesis and reduce nonradiative recombination, emission properties, which are lower and mechanochemical methods for scal- researchers developed core/shell struc- than cadmium-based QDs. able production, were also suggested.8,9 It tured QDs, including CdSe/ZnS and When QDs are used in LCD back- should be noted that chemically synthe- CdSe/ZnSe with an encapsulation layer light units within conventional QLED- sized cQDs and PNCs inevitably require and wider band gap energy. TVs, the green and red QDs are typical- an organic ligand-based passivation layer The core/shell structured QDs success- ly embedded within a polyethylene tet- such as trioctylphosphine oxide to pre- fully demonstrated improved chemical raphthlate film to form a QD enhance- vent agglomeration and oxidation of the

30 Celebrating 100 years www.ceramics.org | American Ceramic Society Bulletin, Vol. 100, No.1 QDs, and to facilitate dispersion within various organic solvents.1,9 Due to the weak chemical and thermal stability of the organic ligands, it is highly important to prevent the perme- ation of air and moisture. Accordingly, conventional cQDs including QD enhancement films require multiple encapsulation layers, resulting in addi- tional production cost. Moreover, due to the ionic bond nature of PNCs, they are vulnerable to exposure to light and heat as well as oxygen and moisture, and thus require various encapsulation strategies to improve stability. These strategies include inorganic or polymer encapsulation, perovskite shell engineering, ligand, Credit: Han et al., Chem. Commun . (Ref. 11) and defect engineering.8 Figure 3. (a) Absorption (dashed lines) and photoluminescence (solid lines) spectra of QDEG, and actual photographs (inset figures) with varying heat treatment duration QD embedded glasses (QDEG) times. (b) Comparison of thermal stability of QDEG, cQD, and various color converting for displays materials. (c) Schematic diagram of a QDEG mounted blue LED chip and changes in its color coordinate depending on the heat treatment duration time and the thickness of To improve the long-term stability the QDEGs along with their actual photographs (right). (Reprinted with permission from of QDs, it is essential to avoid the use Ref. 11. Copyright 2016 The Royal Society of Chemistry.) of organic ligands. This feat can be accomplished by using an inorganic glass QDEG was mounted on top of a blue matrix as an alternative. LED as a color converter, the resultant Various semiconductor-based QDs color coordination of the LEDs could can be formed within conventional thus be tuned by changing the heat treat- oxide glasses via conventional nucleation ment condition and thickness of the and growth mechanisms, although so QDEGs. Because the QDEG is comprised far they mostly are used as saturation of completely inorganic materials, it filters or studied for infrared (IR) appli- showed highly improved thermal stability cations.10 The potential feasibility of QD compared with cQDs and maintained its embedded glasses (QDEGs) as a white emission intensity up to 200°C. No mean- light source was only recently demon- ingful degradation in photoluminescence strated, by the successful fabrication of intensity was observed even after almost CdSe/CdS core/shell structured QDs two years in ambient atmosphere condi- 11

within silicate glasses. tions, under which cQDs cannot survive Credit: Han et al., Int. J. Appl. Glass Sci (Ref. 12) 11 For example, silicate glass with a SiO2- without proper passivation layers. Figure 4. Color gamut of RG-LED, single Na2O-BaO-ZnO composition including When the color gamut of a LED with CdO, ZnSe, and ZnS was prepared using a CdSe/CdS QDEG was inspected for QDEG, and pattern structured QDEG a conventional melting and quenching display application after adjusting the (pQDEG). The inset figures represent actual photographs of QDEGs and LEDs method at 1,350°C and then heat treat- heat treatment duration time and thick- mounted with them. ed at 520°C to form QDs within the ness of the QDEG, the QDEG-LED cov- glass. High-resolution transmission elec- ered 74% of NTSC, which corresponds of two different sizes within the glass tron microscope (HR-TEM) and Raman to the HD color range of conventional matrix under the same heat treatment spectroscopy revealed the successful for- RG-LEDs (Figure 4). This performance condition. Thus, to obtain dual emission mation of CdSe/CdS structured QDs. demonstrated its practical feasibility as bands, two QDEGs with different thermal Thanks to the encapsulation of defect a color converting material for display history were prepared and bonded with traps by the CdS shell, PLQY was signifi- applications.12 However, the color gamut each other to form a pattern structured cantly improved, from 3% without the was limited due to a broad single emis- QDEG. A QDEG for red emission was CdS shell to 20%. sion band centered at about 530 nm. To pre-heat treated and aligned with a sec- As seen in Figure 3, adjusting the heat improve the color gamut, the fabrication ond QDEG that was not heat treated. treatment condition can change the QD of the QDEG should produce separated Bonding of the two QDEGs by viscous size and the color of the glass as well as green and red emission bands. flow and QD formation within the the emission peak wavelength. When the Unlike cQDs, it is hard to form QDs QDEGs took place during the heat treat-

American Ceramic Society Bulletin, Vol. 100, No. 1 | www.ceramics.org Celebrating 100 years 31 Quantum dots and nanocrystal-embedded glasses for display applications

required for quantum yield enhancement. This approach may include elimi- nating nonradiative quenching elements by reducing surface defects on the QDs or by sophisticated control of their size and distribution within the glass matrix. Although ZnSe QDEGs were recently reported to exhibit visible emission under ultraviolet excitation,17 meaningful color conversion of blue LEDs was only reported with cadmium-based QDs so far. Thus, cadmium-free QDEGs also need to be developed for practical applications.

Perovskite nanocrystal embedded glasses (PNEG) for displays Like semiconductor-based QDEGs, PNCs or PQDs can be formed within oxide glasses via nucleation and growth. The first report of perovskite nanocrystal embedded glasses (PNEG) in phosphate glass has thus attracted considerable attention.18 Due to the intrinsic insen- sitivity of PNCs to defects, high PLQYs Credit: Pang et al., J. Mater. Chem of up to 80% were achieved in boro- Fig. 5. (a) Absorption, photoluminescence, and photoluminescence excitation spectra of germanate glass with CsPbX3 (X=Cl, Br CsPbBr3 PNEG. (b) Comparison of photostability of CsPbBr3 PNEG and PNCs. 19 (c) Electroluminescence and photoluminescence (EL+PL) spectra. (d) Color gamut of a and I) PNCs. Varying the PNC size 4+ via heat treatment conditions, such as wLED with CsPbBr3 PNEG stacked with Cs2SiF6:Mn phosphor in glass (PiG) as a red emitting converter. (Reprinted with permission from Ref. 20. Copyright 2019 The Royal temperature and duration time, or by Society of Chemistry.) the compositional variation of halides such as chlorine, bromine, and iodine ment at the same time. The green and red TEM equipped with electron energy loss can easily manipulate the peak emission emission bands were well separated when spectroscopy and local electrode atom wavelength of PNCs, resulting in narrow the ratio of green-to-red area was adjusted probe confirmed the evolution of the bandwidths of less than about 30 nm, using the heat treatment condition. As Cd1–xZnxSe layer on the surface of the as shown in Figure 5. Moreover, com- a result, the color gamut of the pattern CdSe QDs, which effectively reduced the plete inorganic glass passivation highly structured QDEG was improved, up to broad emission band related to surface improved the stability of PNCs against 12 14 79% of NTSC, as shown in Figure 4. defects. Further increases in the color heat, light, aging, and moisture com- However, despite achieving the dual gamut of the QDEGs can thus be antici- pared to colloidal PNCs (cPNCs).20 band emission, it should be noted that pated with proper manipulation of the While cPNCs can be easily decom- the color gamut was not satisfactory for emission bandwidth. posed after extended exposure by light UHD applications because of the rela- Considering the high PLQY of cQDs and heat, the emission intensity of tively broad emission bandwidth of the (higher than 90%), the relatively low PNEGs can be restored after the external QDEGs compared to cQDs. The broad PLQY of QDEGs (less than 20%) is stress is removed, showing reversible emission bandwidth of the QDEGs was another obstacle that should also be properties. They also showed limited attributed to the relatively broad distribu- improved before their practical applica- decay in emission intensity even after tion of QD sizes within the glass matrix tion. Compositions that form QDs with- being in water for 45 days.10 The robust- and surface defect related emissions. in silicate, such as CdO, ZnSe, and ZnS, ness and high potential of PNEGs as Management of QD size distribution were optimized for quantum yield adjust- a robust color converter were demon- within a glass matrix was observed with ment but showed little increase in quan- strated by using them to compose a 15 rare earth dopants, due to the preferential tum yield, up to 25%. The formation white LED.10 Due to the weak stability of nucleation of QDs near rare earth oxide of CdS/Cd1–xZnxS sandwich structured PNEGs with CsPbI , which can give red 13 3 clusters. Emission bandwidth narrowing QDs within silicate glass successfully emission, CsPbBr PNEGs were used as 16 3 by silver ion exchange was reported, after increased quantum yield up to 57%. the green phosphor while ceramic phos- 532 nm continuous wave laser irradiation, However, to compete with conventional phors such as CASN:Eu2+ or KSF:Mn4+ producing a CdSe/Cd1–xZnxSe structure. cQDs, a novel approach to QDEG is

32 Celebrating 100 years www.ceramics.org | American Ceramic Society Bulletin, Vol. 100, No.1 are used as the red phosphor to prepare LaF3 to enhance blue LED absorption by Samsung Display in late 2021, and a white LED. Their color coordinate, via scattering, and it successfully com- an OLED using QDs or PNCs as an color rendering index, and correlated posed a white LED when the glass- emission layer (QD-LED) as well as color temperature can be easily tuned by ceramic was mounted on top of a blue microLED displays using QDs as color 21 3+ 3 3 adjusting the green-to-red phosphor ratio. LED. Green (Pr : P0→ H4) and red converters are also being extensively 3+ 1 3 3 3 When CsPbBr3 PNEG powders were (Pr : D2→ H4/ P0→ H6) emissions with investigated for next generation high- mixed with CASN:Eu2+ and pasted on a narrow emission band were obtained end display devices. As the demand a blue LED using organic resin, almost using the single glass-ceramic plate, for QD-based displays increases due to pure white LED with color coordinates enabling a color gamut even up to 120% their wide color gamut, interest in their of (0.33,0.35), a high color render- of NTSC, which clearly demonstrated robustness, long-term reliability. and ing index of about 92, and reasonable its potential for display application. reduced production cost will continue luminous efficiency of up to 60 lm/W However, the weak conversion efficiency to expand commercial opportunities for was obtained.10 The wide color gamut of the rare earth-doped glass-ceramics nanostructured glasses. of PNEGs for display applications was resulted in very low luminous efficiency, also successfully demonstrated when of less than few lm/W of the wLED, and Acknowledgements the CsPbBr3 PNEG powder was mixed this property still remains as a big hurdle This work was supported by the with KSF:Mn4+.10 The narrow emission for their practical employment. National Research Foundation of band of the green PNEG and KSF:Mn4+ Korea (NRF) grant funded by the enabled a color gamut covering 130% Challenges and perspectives Korea government (MSIT). (NRF- of the NTSC, suggesting PNEGs were Nanostructured inorganic oxide glasses 2019R1A2C1007621). highly feasible for display applications. such as QDEGs or PNEGs have unique To further improve the stability of strengths, offering high resistance against About the authors PNEGs, our group recently introduced external factors such as moisture, oxygen, Yoon Hee Nam, Hansol Lee, and various structures, including phosphor and heat. These properties give them Woon Jin Chung are master’s student, in glass and remote phosphor, and long-term stability, which conventional Ph.D. student, and professor, respec- investigated other glass matrices, such colloidal-based QDs or PNCs cannot tively, in the Institute for Rare Metals as borosilicate glasses, to demonstrate beat, and is crucial for practical display and Division of Advanced Materials their practical feasibility with wide color applications. Along with the stability, Engineering at Kongju National gamut up to 131%. their relatively easy fabrication process University in Cheonan, Republic of and encapsulation-free characteristics can Korea. Contact Chung at Oxyfluoride glasses for displays significantly reduce production costs. [email protected]. Oxyfluoride glasses with various fluo- Overall, nanostructured glasses are good ride nanocrystals including CaF2, BaF2, potential candidates for use in displays, References 1 SrF2, PbF2, and LaF3 are reported to replacing conventional RG-LEDs or cQD- Z. Yang, M. Gao, W. Wu, X. Yang, X. W. improve the visible emission intensity based white light sources. Sun, J. Zhang, H.-C. Wang, R.-S. Liu, C.-Y. and color conversion efficiency of vari- However, to enter the commercial Han, H. Yang, W. Li, “Recent advances in ous doped rare earth ions, including market, several challenges need to be quantum dot-based light-emitting devices: Pr3+, Eu2+, Eu3+, Tb3+, Dy3+, and Ho3+. properly addressed, including their Challenges and possible solutions,” Mater. Modification of the local environment relatively low PLQY under 450 nm Today, 24, 69–93, (2019). near the rare earth ions by the forma- excitation, low luminous efficacy, and 2A. I. Ekimov, A. A. Onuschenko, “Quantum tion of fluoride nanocrystals can provide cadmium or lead-free QDs (or PNCs). size effect in three-dimensional microscopic lower phonon energy and increase the Although extensive studies are still semiconductor crystals,” JETP Lett., 34, quantum efficiency of the doped rare required to solve those problems, 345–349, (1981). earth ions. Additionally, the parity- there is much room yet to be explored. 3P. O. Anikeeva, J. E. Halpert, M. G. forbidden 4f-4f transition of rare earth Considering their high potential and Bawendi, and V. Bulovic, “Quantum dot ions can result in a very narrow emission very early stage of investigation, nano- light-emitting devices with electroluminescence tunable over the entire visible spec- bandwidth, suitable for high color satu- structured glasses will remain as strong trum,” Nano Lett., 9(7), 2532–2536, (2009). ration. However, most of the previous competitors to cQDs or cPNCs for 4 reports used ultraviolet wavelengths or several decades. Y. Pu, F. Cai, D. Wang, J.-X. Wang, and J.-F. Chen, “Colloidal synthesis of semiconductor lasers for excitation, and white LEDs Currently, QDs on glass are being quantum dots toward large-scale production: with a blue LED chip are not properly considered to replace QD enhance- A review,” Ind. Eng. Chem. Res., 57, 1790– demonstrated yet due to the low absorp- ment films in premium displays, to 1802, (2018). tion cross section of the rare earth ions reduce display panel thickness as well 5P. Wang, Y. Zhang, C. Ruan, L. Su, H. Cui, (around 450 nm). as production cost. A new OLED dis- and W. W. Yu, “A few key technologies of Recently, our group heavily crystal- play using QDs as green and red color quantum dot light-emitting diodes for dis- lized a Pr3+-doped oxyfluoride glass with filters (QD-OLED) is set to be released

American Ceramic Society Bulletin, Vol. 100, No. 1 | www.ceramics.org Celebrating 100 years 33 Quantum dots and nanocrystal-embedded glasses for display applications play,” IEEE J. Sel. Top. Quantum Electron., 23, on quantum-dot-embedded silicate glasses for 17K. Li, C. Liu, Z. Zhao, Z. Deng, M. Xia, 2000312, (2017). white light-emitting-diodes,” Chem. Commun., Y. Ye, “Optical properties of Cu ions-doped 6Y. Shirasaki, G. J. Supran, M. G. Bawendi, 52, 3564, (2016). ZnSe quantum dots in silicate glasses,” J. Am. and V. Bulobic, “Emergence of colloidal 12K. Han, J. Heo, W.B. Im, and W.J. Chung, Ceram. Soc., 101, 5080–5088, (2018). quantum-dot light-emitting technologies,” “Cd-S-Se quantum dot embedded glasses 18B. Ai, C. Liu, J. Wang, J. Xie, J. Han, and Nat. Photonics, 7, 13–23, (2013). with dual emissions for wide color gamut X. Zhao, “Precipitation and optical proper- 7 white LED,” Int. J. Appl. Glass Sci., Submitted ties of CsPbBr quantum dots in phosphate E. Jang, Y. Kim, Y.-H. Won, H. Jang, and 3 S.-M. Choi, “Environmentally friendly InP- (2020) glasses,” J. Am. Ceram. Soc., 1–3, (2016). based quantum dots for efficient wide color 13K. Han, J. Heo, and W. J. Chung, “The 19Y. Ye, W. Zhang, Z. Zhao, J. Wang, C. Liu, gamut displays,” ACS Energy Lett., 5, 1316– effect of rare earth on color conversion prop- Z. Deng, X. Zhao, and J. Han, “Highly lumi- 1327, (2020). erties of Cd-S-Se quantum dot embedded nescent cesium lead halide perovskite nano- 8H. Lee, J. Park, S. Kim, S.-C. Lee, Y.-H. silicate glasses for white LED,” Opt. Mater., crystals stabilized in glasses for light-emitting Kim, and T.-W. Lee, “Perovskite emitters as a Accepted (2020) applications,” Adv. Opt. Mater., 1801663, platform material for down-conversion appli- sH. Lee, W. J. Park, J. C. Han, C.-G. Park, (2019). cations,” Adv. Mater. Technol., 5, 2000091, and J. Heo, “Identification of core/shell 20X. Pang, H. Zhang, L. Xie, T. Xuan, Y. Sun, (2020). structure in Cd-Zn-Se QDs inside silicate S. Si, B. Jing, W. Chen, J. Zhuang, C. Hu, 9H. Huang, M. I. Bodnarchuk, S. V. Kershaw, glasses using 3D elemental distribution analy- Y. Liu, B. Lei, and X. Zhang, “Precipitating M. V. Kovlenko, and A. L. Rogach, “Lead sis,” J. Am. Ceram. Soc., 104, 294–301, (2021). CsPbBr3 quantum dots in boro-germanate halide perovskite nanocrystals in the research 15K. Han, W. B. Im, J. Heo, and W. J. glass with a dense structure and inert envi- spotlight: Stability and defect tolerance,” ACS Chung, “Compositional dependency of ronment toward highly stable and efficient Energy Lett., 2, 2071–2083, (2017). Cd-S-Se quantum dots within silicate glass narrow-band green emitters for wide-color- gamut liquid crystal displays,” J. Mater. Chem. 10 on color conversion for a white LED,” J. Am. J. Xue, X. Wang, J. H. Jeong, and X. Yan, C, 7, 13139, (2019). “Fabrication, photoluminescence and applica- Ceram. Soc., 102, 1703–1709, (2019). 21 tions of quantum dots embedded glass ceram- 16M. Xia, C. Liu, J. Han, and X. Zhao, H. Lee, W. J. Chung, and W. B. Im, “Pr3+- ics,” Chem. Eng. J., 383, 123082, (2020). “Formation of CdS/Cd ZnxS sandwich- doped oxyfluoride glass ceramic as a white 1-x LED color converter with wide color gamut,” 11K. Han, W. B. Im, J. Heo, and W. J. Chung, structured quantum dots with high quantum J. Lumin., Submitted (2020). 10 0 “A complete inorganic colour converter based efficiency in silicate glasses,” J. Lumin., 186, 30–33, (2017). NEW ACerS Learning Center online course Ceramic Manufacturing Technology with Carl Frahme Ph.D., FACerS

ACerSONLINE LEARNINGCenter

Starts Feb. 2, 2021 To learn more and to register, visit ceramicsorglearning-center

34 Celebrating 100 years www.ceramics.org | American Ceramic Society Bulletin, Vol. 100, No.1