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Sixun Zheng - One of the best experts on this subject based on the ideXlab platform.

  • star shaped poly ɛ caprolactone with Polyhedral Oligomeric Silsesquioxane core
    Polymer, 2006
    Co-Authors: Yonghong Liu, Xingtian Yang, Weian Zhang, Sixun Zheng
    Abstract:

    Abstract A readily available octa(3-chloropropyl) Polyhedral Oligomeric Silsesquioxane (POSS) [(ClCH2CH2CH2)8Si8O12] framework was used to prepare octa(3-hydroxypropyl) POSS [(HOCH2CH2CH2)8Si8O12], which was further used as an initiator to synthesize star poly(ɛ-caprolactone) with POSS core via ring-opening polymerization catalyzed by Stannous (II) octanoate [Sn(Oct)2]. The organic–inorganic star PCLs were characterized by means of gel permeation chromatograph (GPC), Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). The wide-angle X-ray diffraction (WAXRD) experiments indicate that the presence of POSS cores did not alter the crystal structure of PCL. The star PCLs exhibited enhanced melting temperatures in comparison with the linear counterpart. The isothermal crystallization kinetics shows that both the overall crystallization rate and the spherulitic growth rate of the star PCLs increased with increasing the concentration of POSS (or with decreasing the arm lengths of the stars). The fold surface free energy of the star PCLs decreased with increasing the concentration of POSS. These results could be interpreted based on the effect of the heterogeneous nucleation of POSS cores, which accelerates the process of crystallization.

  • inorganic organic nanocomposites of polybenzoxazine with octa propylglycidyl ether Polyhedral Oligomeric Silsesquioxane
    Journal of Polymer Science Part A, 2006
    Co-Authors: Yonghong Liu, Sixun Zheng
    Abstract:

    Octa(propylglycidyl ether) Polyhedral Oligomeric Silsesquioxane (OpePOSS) was used to prepare the polybenzoxazine (PBA-a) nanocomposites containing Polyhedral Oligomeric Silsesquioxane (POSS). The crosslinking reactions involved with the formation of the organic-inorganic networks can be divided into the two types: (1) the ring-opening polymerization of benzoxazine and (2) the subsequent reaction between the in situ formed phenolic hydroxyls of PBA-a and the epoxide groups of OpePOSS. The morphology of the nanocomposites was investigated by means of scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. Differential scanning calorimetry and dynamic mechanical analysis showed that the nanocomposites displayed higher glass-transition temperatures than the control PBA-a. In the glassy state, the nanocomposites containing less than 30 wt % POSS displayed an enhanced storage modulus, whereas the storage moduli of the nanocomposites containing more than 30 wt % POSS were lower than that of the control PBA-a. The dynamic mechanical analysis results showed that all the nanocomposites exhibited enhanced storage moduli in the rubbery states, which was ascribed to the two major factors, that is, the nanoreinforcement effect of POSS cages and the additional crosslinking degree resulting from the intercomponent reactions between PBA-a and OpePOSS. Thermogravimetric analysis indicated that the nanocomposites displayed improved thermal stability.

  • epoxy nanocomposites with octa propylglycidyl ether Polyhedral Oligomeric Silsesquioxane
    Polymer, 2005
    Co-Authors: Yonghong Liu, Sixun Zheng, Kangming Nie
    Abstract:

    Abstract The POSS-containing nanocomposites of epoxy resin were prepared via the co-curing reaction between octa(propylglycidyl ether) Polyhedral Oligomeric Silsesquioxane (OpePOSS) and the precursors of epoxy resin. The curing reactions were started from the initially homogeneous ternary solution of diglycidyl ether of bisphenol A (DGEBA), 4,4′-Diaminodiphenylmethane (DDM) and OpePOSS. The nanocomposites containing up to 40 wt% of POSS were obtained. The homogeneous dispersion of POSS cages in the epoxy matrices was evidenced by scanning electronic microscopy (SEM), transmission electronic microscopy (TEM) and atomic force microscopy (AFM). Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) showed that at the lower POSS concentrations (

  • polyurethane networks nanoreinforced by Polyhedral Oligomeric Silsesquioxane
    Macromolecular Rapid Communications, 2005
    Co-Authors: Hongzhi Liu, Sixun Zheng
    Abstract:

    Octaaminophenyl Polyhedral Oligomeric Silsesquioxane (OapPOSS) was used as a crosslinking agent together with 4,4-methylenebis-(2-chloroaniline) to prepare polyurethane networks containing POSS. Fourier transform infrared spectroscopy (FT-IR), dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) were employed to characterize the POSS-reinforced polyurethane. The POSS-containing PU networks displayed enhanced glass transition temperatures (Tgs) and the storage moduli of the networks of the glassy state and rubber plateaus were also observed to be significantly higher than that of the control polyurethane although only a small amount of POSS was incorporated into the systems. The results can be ascribed to the significant nanoscale reinforcement effect of POSS cages on the polyurethane matrix. TGA results showed the thermal stability was also improved with incorporation of POSS into the system.

  • a novel photocrosslinkable Polyhedral Oligomeric Silsesquioxane and its nanocomposites with poly vinyl cinnamate
    Chemistry of Materials, 2004
    Co-Authors: Yong Ni, Sixun Zheng
    Abstract:

    A novel photosensitive octacinnamamidophenyl Polyhedral Oligomeric Silsesquioxane (OcapPOSS) was synthesized via the reaction between cinnamoyl chloride and octaaminophenyl Polyhedral Oligomeric Silsesquioxane (OapPOSS). The photosensitive OapPOSS was characterized by Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), and ultraviolet (UV)-visible spectroscopy. The full miscibility of OcapPOSS with the photosensitive polymer poly(vinyl cinnamate) (PVCIN) allows one to prepare the PVCIN−OcapPOSS hybrid nanocomposites. By initiating in situ UV photocrosslinking reaction of PVCIN in the presence of the photosensitive OcapPOSS, the PVCIN−POSS nanocomposites were obtained with the content of POSS up to 40 wt %. In terms of the result of FTIR spectroscopy, it is noted that the photocrosslinking rates of the PVCIN/POSS hybrids were slightly lower than those of the precursors, which could be ascribed to the nanoreinforcement of POSS cages on the polymer matrix. The inclusion of POSS cages could r...

Yonghong Liu - One of the best experts on this subject based on the ideXlab platform.

  • star shaped poly ɛ caprolactone with Polyhedral Oligomeric Silsesquioxane core
    Polymer, 2006
    Co-Authors: Yonghong Liu, Xingtian Yang, Weian Zhang, Sixun Zheng
    Abstract:

    Abstract A readily available octa(3-chloropropyl) Polyhedral Oligomeric Silsesquioxane (POSS) [(ClCH2CH2CH2)8Si8O12] framework was used to prepare octa(3-hydroxypropyl) POSS [(HOCH2CH2CH2)8Si8O12], which was further used as an initiator to synthesize star poly(ɛ-caprolactone) with POSS core via ring-opening polymerization catalyzed by Stannous (II) octanoate [Sn(Oct)2]. The organic–inorganic star PCLs were characterized by means of gel permeation chromatograph (GPC), Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). The wide-angle X-ray diffraction (WAXRD) experiments indicate that the presence of POSS cores did not alter the crystal structure of PCL. The star PCLs exhibited enhanced melting temperatures in comparison with the linear counterpart. The isothermal crystallization kinetics shows that both the overall crystallization rate and the spherulitic growth rate of the star PCLs increased with increasing the concentration of POSS (or with decreasing the arm lengths of the stars). The fold surface free energy of the star PCLs decreased with increasing the concentration of POSS. These results could be interpreted based on the effect of the heterogeneous nucleation of POSS cores, which accelerates the process of crystallization.

  • inorganic organic nanocomposites of polybenzoxazine with octa propylglycidyl ether Polyhedral Oligomeric Silsesquioxane
    Journal of Polymer Science Part A, 2006
    Co-Authors: Yonghong Liu, Sixun Zheng
    Abstract:

    Octa(propylglycidyl ether) Polyhedral Oligomeric Silsesquioxane (OpePOSS) was used to prepare the polybenzoxazine (PBA-a) nanocomposites containing Polyhedral Oligomeric Silsesquioxane (POSS). The crosslinking reactions involved with the formation of the organic-inorganic networks can be divided into the two types: (1) the ring-opening polymerization of benzoxazine and (2) the subsequent reaction between the in situ formed phenolic hydroxyls of PBA-a and the epoxide groups of OpePOSS. The morphology of the nanocomposites was investigated by means of scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. Differential scanning calorimetry and dynamic mechanical analysis showed that the nanocomposites displayed higher glass-transition temperatures than the control PBA-a. In the glassy state, the nanocomposites containing less than 30 wt % POSS displayed an enhanced storage modulus, whereas the storage moduli of the nanocomposites containing more than 30 wt % POSS were lower than that of the control PBA-a. The dynamic mechanical analysis results showed that all the nanocomposites exhibited enhanced storage moduli in the rubbery states, which was ascribed to the two major factors, that is, the nanoreinforcement effect of POSS cages and the additional crosslinking degree resulting from the intercomponent reactions between PBA-a and OpePOSS. Thermogravimetric analysis indicated that the nanocomposites displayed improved thermal stability.

  • epoxy nanocomposites with octa propylglycidyl ether Polyhedral Oligomeric Silsesquioxane
    Polymer, 2005
    Co-Authors: Yonghong Liu, Sixun Zheng, Kangming Nie
    Abstract:

    Abstract The POSS-containing nanocomposites of epoxy resin were prepared via the co-curing reaction between octa(propylglycidyl ether) Polyhedral Oligomeric Silsesquioxane (OpePOSS) and the precursors of epoxy resin. The curing reactions were started from the initially homogeneous ternary solution of diglycidyl ether of bisphenol A (DGEBA), 4,4′-Diaminodiphenylmethane (DDM) and OpePOSS. The nanocomposites containing up to 40 wt% of POSS were obtained. The homogeneous dispersion of POSS cages in the epoxy matrices was evidenced by scanning electronic microscopy (SEM), transmission electronic microscopy (TEM) and atomic force microscopy (AFM). Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) showed that at the lower POSS concentrations (

Shiaowei Kuo - One of the best experts on this subject based on the ideXlab platform.

  • multifunctional Polyhedral Oligomeric Silsesquioxane poss based hybrid porous materials for co2 uptake and iodine adsorption
    Polymers, 2021
    Co-Authors: Mohamed Gamal Mohamed, Lizong Dai, Meiyin Tsai, Chihfeng Wang, Chihfeng Huang, Martin Danko, Tao Chen, Shiaowei Kuo
    Abstract:

    In this study, two different types of hybrid porous organic polymers (POPs), Polyhedral Oligomeric Silsesquioxane tetraphenylpyrazine (POSS-TPP) and tetraphenylethene (POSS-TPE), were successfully synthesized through the Friedel−Crafts polymerization of tetraphenylpyrazine (TPP) and tetraphenylethene (TPE), respectively, with octavinylSilsesquioxane (OVS) as node building blocks, in the presence of anhydrous FeCl3 as a catalyst and 1,2-dichloroethane at 60 °C. Based on N2 adsorption and thermogravimetric analyses, the resulting hybrid porous materials displayed high surface areas (270 m2/g for POSS-TPP and 741 m2/g for POSS-TPE) and outstanding thermal stabilities. Furthermore, as-prepared POSS-TPP exhibited a high carbon dioxide capacity (1.63 mmol/g at 298 K and 2.88 mmol/g at 273 K) with an excellent high adsorption capacity for iodine, reaching up to 363 mg/g, compared with the POSS-TPE (309 mg/g).

  • functional polyimide Polyhedral Oligomeric Silsesquioxane nanocomposites
    Polymers, 2018
    Co-Authors: Mohamed Gamal Mohamed, Shiaowei Kuo
    Abstract:

    The preparation of hybrid nanocomposite materials derived from Polyhedral Oligomeric Silsesquioxane (POSS) nanoparticles and polyimide (PI) has recently attracted much attention from both academia and industry, because such materials can display low water absorption, high thermal stability, good mechanical characteristics, low dielectric constant, flame retardance, chemical resistance, thermo-redox stability, surface hydrophobicity, and excellent electrical properties. Herein, we discussed the various methods that have been used to insert POSS nanoparticles into PI matrices, through covalent chemical bonding and physical blending, as well as the influence of the POSS units on the physical properties of the PIs.

  • polybenzoxazine Polyhedral Oligomeric Silsesquioxane poss nanocomposites
    Polymers, 2016
    Co-Authors: Mohamed Gamal Mohamed, Shiaowei Kuo
    Abstract:

    The organic/inorganic hybrid materials from Polyhedral Oligomeric Silsesquioxane (POSS, inorganic nanoparticles) and polybenzoxazine (PBZ) have received much interesting recently due to their excellent thermal and mechanical properties, flame retardance, low dielectric constant, well-defined inorganic framework at nanosized scale level, and higher performance relative to those of non-hybrid PBZs. This review describes the synthesis, dielectric constants, and thermal, rheological, and mechanical properties of covalently bonded mono- and multifunctionalized benzoxazine POSS hybrids, other functionalized benzoxazine POSS derivatives, and non-covalently (hydrogen) bonded benzoxazine POSS composites.

  • polyimide and Polyhedral Oligomeric Silsesquioxane nanocomposites for low dielectric applications
    Polymer, 2005
    Co-Authors: Yuanjyh Lee, Shiaowei Kuo, Jiehming Huang, Fengchih Chang
    Abstract:

    Abstract A novel polyimide (PI) hybrid nanocomposite containing Polyhedral Oligomeric Silsesquioxane (POSS) with well defined architecture has been prepared by copolymerization of octakis(glycidyldimethylsiloxy)octaSilsesquioxane (Epoxy–POSS), 4,4′-oxydianiline diamine (ODA), and 4,4′-carbonyldiphthalic anhydride (BTDA). In these nanocomposite materials, the equivalent ratio of the Epoxy–POSS and ODA are adjustable, and the resultant PI–POSS nanocomposites give variable thermal and mechanical properties. More importantly, we intend to explore the possibility of incorporating POSS moiety through the Epoxy–POSS into the polyimide network to achieve the polyimide hybrid with lower dielectric constant (low- k ) and thermal expansion. The lowest dielectric constant achieved of the POSS/PI material (PI-10P) is 2.65 by incorporating 10 wt% Epoxy–POSS (pure PI, k =3.22). In addition, when contents of the POSS in the hybrids are 0, 3, 10 wt% (PI-0P, PI-3P, PI-10P), and the resultant thermal expansion coefficients (TEC) are 66.23, 63.28, and 58.25 ppm/°C, respectively. The reduction in the dielectric constants and the resultant thermal expansion coefficients of the PI–POSS hybrids can be explained in terms of creating Silsesquioxane cores of the POSS and the free volume increase by the presence of the POSS–tethers network resulting in a loose PI structure.

  • syntheses thermal properties and phase morphologies of novel benzoxazines functionalized with Polyhedral Oligomeric Silsesquioxane poss nanocomposites
    Polymer, 2004
    Co-Authors: Yuanjyh Lee, Shiaowei Kuo, Jemkun Chen, Fengchih Chang
    Abstract:

    We have successfully synthesized a novel benzoxazine ring-containing Polyhedral Oligomeric Silsesquioxane (BZ-POSS) monomer by two routes: (1) hydrosilylation of a vinyl-terminated benzoxazine using the hydro-silane functional group of a Polyhedral Oligomeric Silsesquioxane (H-POSS) and (2) reaction of a primary amine-containng POSS (Amine-POSS) with phenol and formaldehyde. The benzoxazine-containing POSS (BZ-POSS) monomer can be copolymerized with other benzoxazine monomers through ring-opening polymerization under conditions similar to that used for polymerizing pure benzoxazines. Thermal properties of these POSS-containing organic/inorganic polybenzoxazine nanocomposites have been improved over the pure polybenzoxazine analyzed by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The BZ-POSS monomer is poorly miscible with the benzoxazine monomer and tends to aggregate and forms its own domains, both before and after polymerization. At a higher BZ-POSS content, gross aggregation occurs and results in a lower than expected improvement in the thermal properties.

Charles U Pittman - One of the best experts on this subject based on the ideXlab platform.

  • cyanate ester Polyhedral Oligomeric Silsesquioxane poss nanocomposites synthesis and characterization
    Chemistry of Materials, 2006
    Co-Authors: Kaiwen Liang, Hossein Toghiani, Joseph H Koo, Charles U Pittman
    Abstract:

    Cyanate ester (PT-15, Lonza Corp.) composites containing the blended Polyhedral Oligomeric Silsesquioxane (POSS), TriSilanolPhenyl-POSS (C42H38O12Si7), were prepared containing PT-15/POSS 99/1, 97/3, 95/5, 90/10, and 85/15 w/w ratios. The composites were characterized by FT-TR, X-ray diffraction (XRD), small-angle neutron scattering (SANS), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (X-EDS), transmission electron microscopy (TEM), dynamic mechanical thermal analysis (DMTA), and three-point bending flexural tests. TriSilanolPhenyl-POSS was throughly dispersed into uncured liquid PT-15 resin. After curing, XRD, SANS, and X-EDS measurements were consistent with partial molecular dispersion of a portion of the POSS units in the continuous matrix phase while the remainder forms POSS aggregates. Larger aggregates are formed at higher loadings. SANS, SEM, and TEM show that POSS-enriched nanoparticles are present in the PT-15/POSS composites. The storage bending moduli, E‘, and the g...

  • viscoelastic and mechanical properties of epoxy multifunctional Polyhedral Oligomeric Silsesquioxane nanocomposites and epoxy ladderlike polyphenylSilsesquioxane blends
    Macromolecules, 2001
    Co-Authors: Lichang Wang, Hossein Toghiani, T L Daulton, Kiyohito Koyama, Charles U Pittman
    Abstract:

    Aliphatic epoxy composites with multifunctional Polyhedral Oligomeric Silsesquioxane (POSS) ((C6H5CHCHO)4(Si8O12)(CHCHC6H5)4) nanophases (epoxy/POSS 95/5 and 75/25) and epoxy blends with the prepolymer of ladderlike polyphenylSilsesquioxane (PPSQ) (95/5, 90/10, and 85/15) were prepared by solution casting and then curing. These composites and blends were studied by dynamic mechanical thermal analysis (DMTA) and mechanical testing. The POSS units incorporated into the epoxy network are well dispersed in the composite, probably on the molecular scale, even at high POSS content (25 wt %) based on TEM observations. However, the aliphatic epoxy/PPSQ blends exhibit good miscibility only at low PPSQ content (≤10 wt %). Phase separation was clearly observed when the PPSQ content was 15%. Incorporation of the POSS macromer into this epoxy network by curing at upper temperatures of 120 and 150 °C broadened the temperature range of glass transition of the resulting composites but has almost no influence on their Tg ...

  • Polyhedral Oligomeric Silsesquioxane (POSS) Polymers and Copolymers: A Review
    Journal of Inorganic and Organometallic Polymers, 2001
    Co-Authors: Lichang Wang, Charles U Pittman
    Abstract:

    This review describes the synthesis and properties of homopolymers and copolymers of monomers containing inorganic–organic hybrid Polyhedral Oligomeric Silsesquioxane (POSS) structures. Monomers, such as styryl-POSS, methacrylate-POSS, norbornyl-POSS, vinyl-POSS, epoxy-POSS, and siloxane-POSS, are included. Both monofunctional and multifunctional monomers are included. Thermoplastic and thermoset systems are considered. Thermal, rheological, and dynamic mechanical properties are described. The synthesis of POSS macromers (monomers) is briefly described. POSS chemicals have been used to prepare nanosized designed novel composites with a variety of potential applications. This review, covering 111 references, is descriptive and not designed to be totally comprehensive. However, the major existing reviews of certain subtopics are noted, allowing the reader to gain a general introduction while providing the information to permit more comprehensive coverage.

Andrey L. Rogach - One of the best experts on this subject based on the ideXlab platform.

  • Aqueous-Based Cadmium Telluride Quantum Dot/Polyurethane/Polyhedral Oligomeric Silsesquioxane Composites for Color Enhancement in Display Backlights
    2017
    Co-Authors: Julian Schneider, Tetiana Dudka, Yuan Xiong, Zhenguang Wang, Nikolai Gaponik, Andrey L. Rogach
    Abstract:

    Colloidal quantum dots (QDs) are gaining prominence in the lighting and display industry, due to their tunable and saturated emission colors. Their primary application is currently in optical enhancement films for large sized liquid crystal displays, improving the performance in terms of color reproduction and optical efficiency. While most current QD materials in this regard are synthesized and processed in organic media, this work introduces aqueous-based CdTe QDs as a viable alternative for display applications. After discussing relevant aspects of the aqueous synthesis, we demonstrate the fabrication of all-water processed free-standing CdTe QD/polyurethane films, with high flexibility and transparency. Additional introduction of Polyhedral Oligomeric Silsesquioxane results in a better dispersion of the QDs in the polymer matrix and improves the optical properties and especially photo/thermal stabilities of the composites, which is crucial regarding their application in display backlights

  • Polyhedral Oligomeric Silsesquioxane enhances the brightness of perovskite nanocrystal based green light emitting devices
    Journal of Physical Chemistry Letters, 2016
    Co-Authors: He Huang, Hong Lin, Andrei S. Susha, Wallace C. H. Choy, Stephen V Kershaw, Andrey L. Rogach
    Abstract:

    The beneficial role of the insulating material Polyhedral Oligomeric Silsesquioxane (POSS) as a solution additive or an additional hole-blocking layer to enhance the performance of electroluminescent green light-emitting devices (LEDs) based on CsPbBr3 perovskite nanocrystals is demonstrated. POSS improves the surface coverage and the morphological features of the films deposited either from supernatant or suspension of perovskite nanocrystals. The external quantum efficiency and the luminance efficiency of LEDs with an additional POSS layer reach 0.35% and 1.20 cd/A, respectively, constituting a more than 17-fold enhancement to the reference devices without POSS; the LED peak luminance reaches 2983 cd/m2, and the device stability is improved. The POSS acts as a hole-blocking layer between the perovskite nanocrystals and TPBi, keeping both electrons and holes located within the active layer for an efficient recombination.

  • water resistant cspbx3 nanocrystals coated with Polyhedral Oligomeric Silsesquioxane and their use as solid state luminophores in all perovskite white light emitting devices
    Chemical Science, 2016
    Co-Authors: He Huang, Zhenguang Wang, Andrei S. Susha, Bingkun Chen, Tak Fu Hung, Haizheng Zhong, Andrey L. Rogach
    Abstract:

    We present an approach towards stable solid-state perovskite based luminophores with different emission colors via surface protection of CsPbX3 (X = Br or I) with a Polyhedral Oligomeric Silsesquioxane (POSS). This treatment results in water resistant perovskite nanocrystal powders, and prevents otherwise easy anion exchange between perovskite nanocrystals of different compositions mixed together in the solid state, which allows us to preserve their distinct emission spectra. We subsequently used mixtures of green-emitting POSS–CsPbBr3 and red-emitting POSS–CsPb(Br/I)3 nanocrystal powders to fabricate single layer all-perovskite down conversion white light-emitting devices.

  • Polyhedral Oligomeric Silsesquioxane Enhances the Brightness of Perovskite Nanocrystal-Based Green Light-Emitting Devices
    2016
    Co-Authors: He Huang, Hong Lin, Stephen V. Kershaw, Andrei S. Susha, Wallace C. H. Choy, Andrey L. Rogach
    Abstract:

    The beneficial role of the insulating material Polyhedral Oligomeric Silsesquioxane (POSS) as a solution additive or an additional hole-blocking layer to enhance the performance of electroluminescent green light-emitting devices (LEDs) based on CsPbBr3 perovskite nanocrystals is demonstrated. POSS improves the surface coverage and the morphological features of the films deposited either from supernatant or suspension of perovskite nanocrystals. The external quantum efficiency and the luminance efficiency of LEDs with an additional POSS layer reach 0.35% and 1.20 cd/A, respectively, constituting a more than 17-fold enhancement to the reference devices without POSS; the LED peak luminance reaches 2983 cd/m2, and the device stability is improved. The POSS acts as a hole-blocking layer between the perovskite nanocrystals and TPBi, keeping both electrons and holes located within the active layer for an efficient recombination