Red Polymer Research Articles

Synthesis of fluorene‐based hyperbranched polymers for solution‐processable blue, green, red, and white light‐emitting devices

AbstractFor the purpose of making hyperbranched polymer (Hb‐Ps)‐based red, green, blue, and white polymer light‐emitting diodes (PLEDs), three Hb‐Ps Hb‐terfluorene (Hb‐TF), Hb‐4,7‐bis(9,9′‐dioctylfluoren‐2‐yl)‐2,1,3‐benzothiodiazole (Hb‐BFBT), and Hb‐4,7‐bis[(9,9′‐dioctylfluoren‐2‐yl)‐thien‐2‐yl]‐2,1,3‐benzothiodiazole (Hb‐BFTBT) were synthesized via [2+2+2] polycyclotrimerization of the corresponding diacetylene‐functionalized monomers. All the synthesized polymers showed excellent thermal stability with degradation temperature higher than 355 °C and glass transition temperatures higher than 50 °C. Photoluminance (PL) and electroluminance (EL) spectra of the polymers indicate that Hb‐TF, Hb‐BFBT, and Hb‐BFTBT are blue‐green, green, and red emitting materials. Maximum brightness of the double‐layer devices of Hb‐TF, Hb‐BFBT, and Hb‐BFTBT with the device configuration of indium tin oxide/poly(3,4‐ethylene dioxythiophene):poly(styrene sulfonate)/light‐emitting polymer/CsF/Al are 48, 42, and 29 cd/m2; the maximum luminance efficiency of the devices are 0.01, 0.02, and 0.01 cd/A. By using host–guest doped system, saturated red electrophosphorescent devices with a maximum luminance efficiency of 1.61 cd/A were obtained when Hb‐TF was used as a host material doped with Os(fptz)2(PPh2Me2)2 as a guest material. A maximum luminance efficiency of 3.39 cd/A of a red polymer light‐emitting device was also reached when Hb‐BFTBT was used as the guest in the PFO (Poly(9,9‐dioctylfluorene)) host layer. In addition, a series of efficient white devices were, which show low turn‐on voltage (3.5 V) with highest luminance efficiency of 4.98 cd/A, maximum brightness of 1185 cd/m2, and the Commission Internationale de l'Eclairage (CIE) coordinates close to ideal white emission (0.33, 0.33), were prepared by using BFBT as auxiliary dopant. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Efficient Flexible Phosphorescent Polymer Light‐Emitting Diodes Based on Silver Nanowire‐Polymer Composite Electrode

Blue, green, and red electrophosphorescent polymer light-emitting diodes have been fabricated on silver nanowire-polymer composite electrode. The devices are 20%-50% more efficient than control devices on ITO/glass and exhibit small efficiency roll-off at high luminances. The blue PLEDs were repeatedly bent to 1.5 mm radius concave or convex with calculated strain in the emissive layer approximately 5% (tensile or compressive).

Confocal Raman microscopy for monitoring the membrane polymerization and thermochromism of individual, optically trapped diacetylenic phospholipid vesicles

Optical‐trapping confocal Raman microscopy allows the 1, 4‐addition reaction of diacetylenic functional groups in 1,2‐bis(10,12‐tricosadiynoyl)‐sn‐glycero‐3‐phosphocholine lipids to be monitored in individual phospholipid vesicles. Optical trapping allows a single vesicle to be observed over time, allowing the direct observation of structural changes in the vesicle membrane during polymerization. Confocal Raman microscopy excludes light collection outside the optical‐trap region avoiding interferences from the surrounding solution, while chemical reactions occurring in the membrane of the trapped vesicle can be measured with high sensitivity. Individual, optically trapped liposomes (0.6 µm in diameter) were exposed to photolysis radiation at 254 nm. Upon exposure to UV light, the cross‐linking polymerization reaction formed a conjugated ene–yne backbone in the bilayer of the optically trapped vesicle. Polymerization produces two different polymers, red and yellow in color, which can be distinguished structurally by their Raman spectra. Rates of red and yellow polymer formation were monitored by the Raman scattering intensities from both C = C stretching vibrations at 1455 cm–1 and 1508 cm–1 and C ≡ C stretching vibrations at 2080 and 2110 cm–1, respectively. Polymer formation rates depended linearly on 254‐nm light intensity, consistent with a one‐photon excited polymerization reacting in a photostationary state. Relative populations of red and yellow polymer in a polymerized vesicle depend sensitively on the sample temperature. From temperature‐dependent Raman spectra, the enthalpy change of the red‐to‐yellow thermochromic response and corresponding structural changes in the polymer could be determined. Copyright © 2011 John Wiley & Sons, Ltd.

Saturated red polymer electrophosphorescent devices with meso-tetrakis (4-n-decanoyl-phenyl) porphyrin platinum (Ⅱ) complex as emitters

在聚2,7-（9,9-二辛基）芴（PFO）和30%的2-（对联苯基）-5-（对叔丁基苯基）-1,3,4-二唑（PBD）主体材料中掺杂短磷光寿命的meso-四（对正葵酰氧基苯基）卟啉铂（TDPPPt）,制成聚合物基发光器件。器件结构为：ITO/PEDOT∶PSS/PVK/PFO＋30%PBD∶TDPPPt/Ca/Al（ITO：氧化铟锡;PEDOT：聚3,4-乙撑二氧噻吩;PSS：聚苯乙烯磺酸盐;PVK：聚乙烯基咔唑）。当客体掺杂浓度≥3%时,器件给出饱和的红色发射。当驱动电压从7 V升高至14 V时,器件发光色度保持不变,CIE（国际发光照明委员会）色坐标稳定在（0.66,0.28）左右。器件的最大亮度和电流效率分别为1 390 cd/m2和1.34 cd/A。在电流密度100×10-3和150×10-3 A/cm2时,电流效率分别为1.18和0.99 cd/A,器件在高电流密度下具有良好的稳定性。

Synthesis and characterization of red light-emitting electrophosphorescent polymers with different triplet energy main chain

Red light-emitting electrophosphorescent polymers with poly(fluorene- alt-carbazole) (PFCz) and poly(3,6-carbazole) (PCz) as the main chain, and the quinoline-based iridium (Ir) complex as the side chain have been synthesized by Suzuki and modified Yamamoto polymerization, respectively. The triplet energy of the polymeric backbone is tuned from 2.1 eV of polyfluorene (PF) to 2.3 eV of PFCz and 2.6 eV of PCz. We find that, with the increasing triplet energy, the lifetime of the triplet excitons gradually increases, but the device efficiency becomes worse. The reason is that the alteration of the main chain structure leads to the increase of the highest occupied molecular orbital (HOMO) level of the polymeric host, which can facilitate the efficient hole injection and transportation. As a consequence of this enhancement of the hole current, charge balance in the emitting layer is destroyed, and correspondingly, the poorer device performance is achieved. Our results, we believe, indicate that besides the triplet energy, charge balance is a crucial determinant to develop high efficiency red light-emitting electrophosphorescent polymers.

Cyclic dimers of tetrafluorobutatriene

1,1,4,4-Tetrafluorobutatriene polymerizes even at −78 °C within a short time yielding a red insoluble polymer. Possible closed-shell cyclic dimers and oligomers resulting from several reaction paths were analyzed by computational methods—with CCSDT/cc-pVTZ as the highest order calculation and several other calculations of lower level. For a better understanding of fluorination effects, the perhydrogen triene dimers were included in this study. The destabilization of the central cumulenic double bond of tetrafluorobutatriene relative to ethylene and the further destabilizing fluorine substitution makes the formation of most of the dimers exothermic with only one exception for the perfluoro derivatives. Astonishingly, the geometry of some of the discussed molecules is highly affected by fluorine substitution, while for others there is nearly no effect on the geometry of the carbon backbone. 19F-NMR shifts of the potential dimers were calculated using the GIAO method.

Red electroluminescent polyfluorenes containing highly efficient 2,1,3-benzoselenadiazole- and 2,1,3-naphthothiadiazole-based red dopants in the side chain

By attaching small amounts of highly efficient D-A-D′-type 2,1,3-benzoselenadiazole and 2,1,3-naphthothiadiazole derivatives to the side chain of a polyfluorene host, we developed two series of red polymers, PFR-xBS and PFR-xNT. By tuning the doping concentration, complete energy transfer from the PF host to the red dopant occurs. The EL spectra of these red polymers show predominantly a red emission, attributed to the dopants. Single-layer devices (ITO/PEDOT:PSS/polymer/Ca/Al) of red polymers realized pure red light with a peak at 620 nm, a luminous efficiency of 2.91 cd A−1 and CIE coordinates of (0.62, 0.36) for PFR-10BS, and a saturated red light with a peak at 632 nm, a luminous efficiency of 3.04 cd A−1 and CIE coordinates of (0.63, 0.35) for PFR-10NT, respectively. To the best of our knowledge, the device performance of PFR-10NT is among the best single-layer saturated red PLEDs based on fluorescent polymers.

Electropolymerization and characterization of an alternatively conjugated donor–acceptor metallopolymer: Poly-[Ru(4′-(4-(Diphenylamino)phenyl)-2,2′:6′,2″-Terpyridine)2]2+

Abstract A functionalized complex [Ru(L)2](PF6)2 {L = 4′-[4-(diphenylamino)phenyl)]-2,2′:6′,2″-terpyridine} was synthesized and characterized by 1H NMR, 13C NMR and elemental analyses. Its oxidative electropolymerization was conducted by continuous cycling of the working electrode potential from 0 to 1.8 V in 0.1 mol L−1 Bu4NClO4/CH3CN solution containing 5.0 × 10−4 mol L−1 monomer. The red hybrid polymer film, characterized by X-ray photoelectron spectroscopy (XPS), exhibited a non-diffusional charge transfer behaviour for Ru(III)/Ru(II) couple and an irreversible redox process of triphenylamine moiety on the Pt working electrode, as well as high stability in monomer-free electrolytic solution. The film thickness was easily tuned by controlling the number of potential sweeping cycle, and the AC impedance of as-formed film increased with cycling number. Morphological characterization of the film on indium tin oxide (ITO) was provided by scan electron microscopy (SEM) and atomic force microscopy (AFM). The donor–acceptor (D–A) polymer film on ITO showed a broad and red-shifted 1MLCT wave in the UV–vis spectrum and a clearly electrochromic behaviour from red to black in the spectroelectrochemical study.

Multichromic polymers of benzotriazole derivatives: Effect of benzyl substitution

Two electroactive monomers 1-benzyl-4,7-di(thiophen-2-yl))-2H-benzo[d][1,2,3]triazole (BBTA) and 2-benzyl-4,7-di(thiophen-2-yl))-2H-benzo[d][1,2,3]triazole (BBTS) were synthesized with satisfactory yields. The effect of substitution site on electrochemical and optical properties was investigated with cyclic voltammetry and spectroelectrochemical studies. Results showed that position of pendant group alters the electronic structure of the resulting polymer causing different optical and electrochemical behaviors. Symmetrically positioned benzyl unit on benzotriazole moiety resulted in a neutral state red polymer, PBBTS, having multi-colored property in its different oxidized and reduced states. Its analogue PBBTA exhibited maximum absorption at 390nm in its neutral state and also revealed multicolored electrochromic property upon stepwise oxidation. Very different optical band gap values were calculated: 1.55eV and 2.25eV for PBBTS and PBBTA, respectively.

Green as it Gets; Donor‐Acceptor type Polymers as the Key to Realization of RGB Based Polymer Display Devices

AbstractSummary: Polymers that have one of the three complementary colors (red, green, and blue, RGB) in the neutral state and high transmissivity in the oxidized state are the key materials towards use in electrochromic devices and displays. Although many neutral state red and blue polymers have been reported up to date, green polymers with highly transmissive oxidized states, high optical contrasts, fast switching times, and advanced long‐term switching stabilities were essentially missing in the literature. This paper reviews our previous efforts towards realization of neutral state green polymers with highly transmissive oxidized state. The key to this problem was found to be the synthesis of donor‐acceptor polymers bearing benzothiadiazole or quinoxaline derivatives as the acceptor and electron rich 3,4‐ethylenedioxythiophene unit as the donor component. Green neutral state polymeric materials with highly transmissive oxidized state with excellent electrochromic properties have been realized with the design and synthesis of these types of materials. A solution processable green polymeric material has also been realized via chemical polymerization that has shown all superior properties of the electrochemically synthesized counterparts.

Pure and Saturated Red Electroluminescent Polyfluorenes with Dopant/Host System and PLED Efficiency/Color Purity Trade‐Offs

AbstractThree kinds of red electroluminescent (EL) polymers based on polyfluorene as blue host and 2,1,3‐benzothiadiazole derivatives with different emission wavelengths as red dopant units on the side chain are designed and synthesized. The influence of the photoluminescence (PL) efficiencies and emission wavelengths of red dopants on the EL efficiencies and color purities of the resulting polyfluorene copolymers of dopant/host system is investigated by adjusting the electron donating ability of the donor units in D‐π‐A‐D typed 2,1,3‐benzothiadiazole derivatives. The devices of these red‐emitting polymers realize remarkable EL efficiency/color purity trade‐offs. The single‐layer devices with the configuration of ITO/PEDOT:PSS/Polymer/Ca/Al show pure red emission at 624 nm with a luminous efficiency of 3.83 cd A−1 and CIE of (0.63, 0.35) for PFR1, saturated red emission at 636 nm with a luminous efficiency of 2.29 cd A−1 and CIE of (0.64, 0.33) for PFR2, respectively. By introduction of an additional electron injection layer PF‐EP(Ethanol soluble phosphonate‐functionalized polyfluorene), high performance pure and saturated red emission two‐layer devices (ITO/PEDOT:PSS/Polymer/PF‐EP/LiF/Al) were achieved with maximum luminous efficiencies of 5.50 cd A−1 and CIE of (0.62, 0.35) for PFR1, 3.10 cd A−1 and CIE of (0.63, 0.33) for PFR2, respectively, which are the best results for pure and saturated fluorescent red EL polymers reported so far.

Production of 3,6-anhydro- l-galactose from agarose by agarolytic enzymes of Saccharophagus degradans 2-40

Saccharophagus degradans 2-40 is capable of hydrolyzing agarose, a red macroalgae-derived polymer, into d-galactose and 3,6-anhydro- l-galactose (L-AHG). Its agarase system is receiving much attention because it can be used to produce fermentable sugar from agarose. L-AHG is commercially unavailable and is considered a rare sugar with a high value. In this study, cells grown on agarose, agar or red macroalgae biomass were found to have a significantly higher agarase activity and AHG-generating activity than those grown on glucose or galactose. From agar-grown cells, both the volumetric activities of agarases and AHG generation in the cell-free lysate were much higher than in the extracellular fraction. Based on the analyses of the enzyme reaction products, from the reaction with the crude enzymes from cell-free lysate, neoagarobiose with a degree of polymerization (DP) 2 appeared to be the only major product in the initial reaction period, but sugars with DPs 2, 4 and 6 were found to be all predominantly produced by the extracellular enzymes in the initial reaction period. Quantitative analysis of AHG using gas chromatography–mass spectrometry with a derivatization step was also found to be highly reproducible and reliable. These results will be useful for producing L-AHG as a rare sugar to investigate its metabolic fate and commercial utilization.

A very simple and chromatic-stable white organic light-emitting diode with a colour conversion hole injection layer based on solution process

A chromatic-stable and easily fabricated white organic light-emitting diode with a colour conversion hole injection layer (CC-HIL) has been investigated. The emission layer (EML) was composed of the fluorescent dye p-bis(p − N,N-diphenyl-aminostyryl)benzene doped into the host 2-(t-butyl)-9,10-di(2-naphthyl)anthracene. A red fluorescent polymer poly(2-methoxy-5-[2′-ethylhexyloxy]-p-phenylenevinylene) (MEH-PPV) with hole transport characteristics and relatively high absorbance to blue electroluminescence was used as the CC-HIL. The CIE colour coordinates at (0.33, 0.35) almost remained unchanged under driving current densities from 20 mA cm−2 to 400 mA cm−2 while the current efficiencies reached 3.5 cd A−1 and 4.65 cd A−1 at 20 mA cm−2 and 400 mA cm−2, respectively. The improved performance was attributed mainly to an enhanced out-coupling efficiency and better carrier balance in the EML.

Efficient multilayer red fluorescent polymer light-emitting diodes by host and guest blend system

Efficient red light polymer light-emitting diodes are obtained by energy transfer from host and guest blend system. Two kinds of blend systems, SPB02:(10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-[1] benzopyrano [6,7,8-ij]quinolizin-11-one)(C545T):4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) and SuperYellow (SY):poly(3,3 ′′′-didodecylquaterthiophene) (PQT-12), are used as the active layers. C545T is a green emitter, acting as an assistant dopant to improve the energy transfer from blue SPB02 host to red DCJTB. The efficiency can achieve to 3.3 cd/A for DCJTB and 3.5 cd/A for PQT-12 system by multilayer device structure with 2,2,2 ′′-(1,3,5-phenylene)-tris(1-phenyl-1H-benzimidazole) (TPBi) as electron transport layer. The SuperYellow:PQT-12 device shows great luminance of 16,930 cd/m 2.

Red polymer light-emitting devices based on dye-dispersed poly (9,9-dioctylfluorene-alt-benzothiadiazole)

A polymer–organic host–guest emitter (POHGE) system for obtaining polymer light-emitting diodes (PLEDs) with pure red emission and high luminance is proposed. The POHGE system was prepared by the fluorescent dye 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetra-methyljulolidy-9-enyl)-4H-pyran (DCJTB) doped in green-emitting polymer poly (9,9-dioctylfluorene-alt-benzothiadiazole) (BTF8). A photoluminescence (PL) quenching phenomenon was observed owing to the higher doping amount of DCJTB dopant. In this study, the red DCJTB dopant emits with high luminance and without concentration quenching when the host BTF8 emitting layer is doped with a small amount of the red guest DCJTB dopant. An optimal amount of DCCJTB dopant was obtained at 2 mg. Devices with a configuration of indium tin oxide (ITO)/poly (ethylenedioxythiophene) doped with poly (styrenesulfonate) (PEDOT:PSS)/BTF8:DCJTB/Ca/Al were fabricated. This device achieved an electroluminescence (EL) efficiency of 1.33 cd/A at 6 V. The emission area is 1.5 × 0.5 cm 2. The devices show the red light emission with a peak at about 630 nm. The color coordinate in Commission Internationale d’Eclairage (CIE) chromaticity is at x = 0.64 and y = 0.36.

Enhancement of Oxidative Stability of Polyfluorenes for Direct Thermal Lithography

A homopolymer of 9,9'-bis[4-(2-(2-tetrahydropyranyloxy)ethoxy)phenyl]fluorene and its copolymers with 3,4-benzothiadiazole and 4,7-di(3(4-n-octylphenyl)-2-thienyl)-2,1,3-benzothiadiazole were synthesized to produce a series of thermally reactive blue, green, and red luminescent polymers. Thermolytic removal of the tetrahydropyran (THP) group from polymer films, rendered the films insoluble due to the formation of hydroxyl groups on the termini of side chains. Thermal removal of the THP was lowered by up to 200 °C, when acid is present in the films. These polymers were found applicable to patterning by NIR direct thermal lithography, in conjunction with a NIR dye and thermal acid generator. The presence of the phenyl groups at the 9-site carbon was found necessary to eliminate fluorenone formation, and enhance the colour purity of the material.

A red luminescent organic–inorganic hybrid network with double-stranded zigzag [Cu4I4]n chains

Abstract A novel red luminescent coordination polymer, [Cu2I2(bmt)]n·nDMF (1), was synthesized from the solution reaction of CuI and heterocyclic thione ligand, benz-1,3-imidazole-2-thione (bmt). Single-crystal analysis shows that its unusual organic–inorganic hybrid framework built-up from the distorted double-stranded zigzag [Cu4I4]n chains with organic bmt ligands. Emission properties of 1 in solid state at room temperature and 10 K were investigated.

A novel narrow band gap red light-emitting cyanovinylene polymer derived from 3,4-dialkoxy thiophene for optoelectronic applications

A novel donor–acceptor type narrow band gap cyanovinylene poly{3,3′-(3,4-ditetradecyloxythiene-2,5-diyl)bis[2-(thiophen-2-yl)prop-2-enenitrile]} has been designed and synthesized through multistep reactions. All the newly synthesized compounds were characterized by using FTIR and 1H NMR spectroscopy followed by elemental analyses. The polymer P is found to be thermally stable up to 300 °C under nitrogen atmosphere. The optical and charge-transporting properties of the polymer were investigated by UV–visible, fluorescence emission spectroscopic and cyclic voltammetric studies. The monomer (M) emits intense green-light in solution state and the polymer (P) exhibited intense red-fluorescence both in solution and solid state. The fluorescence quantum yield of the polymer is determined to be 43%. Cyclic voltammetric studies reveal that the polymer possesses good charge carrying property. The electrochemical band-gap is estimated to be 1.8 eV. The studies reveal that the new cyanovinylene polymer P is a promising material for the development of efficient optoelectronic devices.

Thermally stable red electroluminescent hybrid polymers derived from functionalized silsesquioxane and 4,7‐bis(3‐ethylhexyl‐2‐thienyl)‐2,1,3‐benzothiadiazole

AbstractHyperbranched organic–inorganic hybrid conjugated polymers P1 and P2 were prepared via FeCl3‐oxiditive polymerization of 4,7‐bis(3‐ethylhexyl‐2‐thienyl)‐2,1,3‐benzothiadiazole (A) and octa(3‐ethylhexyl‐2‐thienyl‐phenyl)polyhedral oligomeric silsesquioxane (POSS) (B) at different POSS concentrations. Compared to linear polymer PM derived from A, P1, and P2 exhibit much higher PL quantum efficiency (ϕPL‐f) in condensed state with improved thermal stability. ϕPL‐f of P1 and P2 increased by 80% and 400%, and the thermal degradation temperatures of P1 and P2 are increased by 35 °C and 46 °C, respectively. Light‐emitting diodes were fabricated using P1, P2, and PM. While the electroluminescent spectra of both P1 and PM show λmax at 660 nm, P1 exhibits a much narrower EL spectrum and higher electroluminescence (∼500%) compared with PM at a same voltage and film thickness. The maximum current efficiency of P1 is more than seven times of that of PM. The turn‐on voltages of the LEDs are in the order of P2 > PM > P1. LED prepared by blending P1 with MEH‐PPV shows a maximum luminescence of 2.6 × 103 cd/m2 and a current efficiency of 1.40 cd/A, which are more than twice (1.1 × 103 cd/m2) and five times (0.27 cd/A) of LED of PM/MEH‐PPV blend, respectively. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5661–5670, 2009

Application of heteroleptic iridium complexes with fluorenyl-modified 1-phenylisoquinoline ligand for high-efficiency red polymer light-emitting devices

A series of new heteroleptic iridium complexes bearing fluorenyl-modified 1-phenylisoquinoline as the first ligand and different ancillary ligands has been prepared and characterized. These complexes bis(1-(3-(9,9-dimethyl-fluoren-2-yl)phenyl)isoquinoline-C2,N′)iridium(III)acetylacetonate(Ir(DMFPQ) 2acac)), bis(1-(3-(9,9-dimethyl-fluoren-2-yl)phenyl)isoquinoline-C2,N′)iridium(III)(3-(pyridin-2-yl)-1,2,4-triazolate)(Ir(DMFPQ) 2pt) and bis(1-(3-(9,9-dimethyl-fluoren-2-yl)phenyl)isoquinoline-C2,N′)iridium(III)(2-(2-pyridyl)benzimidazolate)(Ir(DMFPQ) 2pbi) showed red phosphorescent emissions of 615–630 nm in dichloromethane solution. The device fabricated with these complexes doped into a host polyfluorene (PFO) blend with 30% of an electron transport material 2-(4-biphenyl)-5-(4- tert-butylphenyl)-1,3,4-oxadiazole (PBD) showed high device efficiencies. Ir(DMFPQ) 2acac exhibited red emission with an external quantum efficiency( η ext) of 14.3% and luminous efficiency( η c) of 7.8 cd/A at 1.2 mA/cm 2 and the maximum brightness reached 10 006 cd/m 2 (Commission Internationale de I’Eclairage(CIE) chromaticity coordinates: (0.67, 0.32)) at 412 mA/cm 2. Ir(DMFPQ) 2pt showed a η ext of 13.0% and η c of 9.2 cd/A at 17 mA/cm 2, 1532 cd/m 2, and the maximum brightness reached 15085 cd/m 2 (CIE: 0.64, 0.34) at 360 mA/cm 2.