Patent Application
20220045285
Described herein are platinum(II)-based red emitters and their use in OLED applications.
Platinum-based organic light-emitting-diode (OLED) emitters are potential alternatives to conventional iridium emitters, with numerous reports of high phosphorescence quantum yields and emission colors spanning the entire visible spectrum. To realize their commercial introduction, the chemical stability and production cost of platinum OLED emitter must be addressed. Tetradentate Pt(II)-Schiff base complexes are appealing in these endeavors due to their enhanced stability and their ease of synthesis. The structure of Pt(II)-Schiff base complexes can be readily modified to emit in the red spectral region with a high spectral purity, which is advantageous for red OLED applications. For example, Che et al., Chem. Eur. J., 2010, 16, 233; Opt. Lett., 2013, 38, 2373; Chem. Asian. J., 2014, 9, 984, disclose several Pt(II)-Schiff base complexes to fabricate singularly doped nearly pure red OLED devices (CIEx,y: 0.61-0.65, 0.34-0.38) that exhibited maximum current efficiency (CE) up to 17.36 cd/A. Wong et al., J. Mater. Chem., 2012, 22, 16448 discloses a red device based on a Pt(II)-Schiff base complex (CIEx,y: 0.68, 0.32) with maximum CE of 1.3 cd/A. Unfortunately, the photoluminescent quantum yield, a parameter strongly correlates to the device efficiency and all of the disclosed red-emitting Pt(II)-Schiff base complexes never exceeds 0.3. Therefore, Pt(II)-Schiff base complexes require a different molecular design to achieve an enhanced photoluminescent quantum yield to realize more efficient red OLEDs.
In an embodiment of the invention, red-emitting platinum(II) Schiff base complexes that show high photoluminescent quantum yield have the chemical structure:
where Pt has an oxidation state of II complexed to a tetradentate ligand where: X1-X4 are independently carbon, nitrogen, silicon or phosphorous; R1-R12 are independently selected from hydrogen, halogen, hydroxyl, unsubstituted alkyl, substituted alkyl, cycloalkyl, unsubstituted aryl, substituted aryl, acyl, alkoxy, acyloxy, amino, nitro, acylamino, aralkyl, cyano, carboxyl, thio, styryl, aminocarbonyl, carbamoyl, aryloxycarbonyl, phenoxycarbonyl, or alkoxycarbonyl; and E is an emission intensity enhancement group comprising an aromatic group conjugated to the ligand's phenyl groups, where adjacent R1-R12 and E groups can independently form a 5-8 member ring.
An embodiment of the invention is directed to a red OLED devices including a platinum(II) emitter of Structure I. Advantageously, the OLED devices show high efficiency.
Disclosure herein, terms, abbreviations or other shorthand are defined below. Any term, abbreviation or shorthand not defined is understood to have the ordinary meaning used by a skilled artisan contemporaneous with the submission of this application.
“Amino” refers to a primary, secondary, or tertiary amine which may be optionally substituted. Specifically included are secondary or tertiary amine nitrogen atoms which are members of a heterocyclic ring. Also specifically included, for example, are secondary or tertiary amino groups substituted by an acyl moiety. Some non-limiting examples of an amino group include —NR′R″ wherein each of R′ and R″ is independently H, alkyl, aryl, aralkyl, alkaryl, cycloalkyl, acyl, heteroalkyl, heteroaryl or heterocycyl.
“Alkyl” refers to a fully saturated acyclic monovalent radical containing carbon and hydrogen, and which may be branched or a straight chain. Examples of alkyl groups include, but are not limited to, alkyl having 1-20, 1-10 or 1-6 carbon atoms, methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, n-heptyl, n-hexyl, n-octyl, and n-decyl.
“Alkylamino” means a radical —NHR or —NR2 where each R is independently an alkyl group. Representative examples of alkylamino groups include, but are not limited to, methylamino, (1-methylethyl)amino, methylamino, dimethylamino, methylethylamino, and di(1-methylethyl)amino.
The term “hydroxyalkyl” means an alkyl radical as defined herein, substituted with one or more, preferably one, two or three hydroxy groups. Representative examples of hydroxyalkyl include, but are not limited to, hydroxymethyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 1-(hydroxymethyl)-2-methylpropyl, 2-hydroxybutyl, 3-hydroxybutyl, 4-hydroxybutyl, 2,3-dihydroxypropyl, 2-hydroxy-1-hydroxymethylethyl, 2,3-dihydroxybutyl, 3,4-dihydroxybutyl and 2-(hydroxymethyl)-3-hydroxy-propyl, preferably 2-hydroxyethyl, 2,3-dihydroxypropyl, and 1-(hydroxymethyl)-2-hydroxyethyl.
The term “alkoxy,” as used herein, refers the radical —OR, where R is alkyl. Exemplary alkoxy groups include, but are not limited to, methoxy, ethoxy, and propoxy.
“Aromatic” or “aromatic group” refers to aryl or heteroaryl.
“Aryl” refers to optionally substituted carbocyclic aromatic groups (e.g., having 6-20 carbon atoms). In some embodiments, the aryl group includes phenyl, biphenyl, naphthyl, substituted phenyl, substituted biphenyl or substituted naphthyl. In other embodiments, the aryl group is phenyl or substituted phenyl.
“Heteroaryl” refers to an aromatic group having at least one non-carbon atom in at least one five or six membered aromatic ring of the group. The heteroaryl group may be substituted or unsubstituted. Some non-limiting examples of heteroaryl include furanyl, thiophenyl, pyrrolyl, imidazolyl, pyrazolyl, oxazolyl, thiazolyl, triazolyl, oxadiazolyl, thiadiazolyl, dioxazolyl, dithiazolyl, tetrazolyl, pyridinyl, pyrimidinyl, phosphininyl, diazinyl, oxazinyl, thiazinyl, dioxinyl, indolyl, isoindolyl, indolizinyl, quinolinyl, isoquinolinyl, purinyl, carbaxolyl, and dibenzofuranyl, where the attachment can be by the substitution for hydrogen of the heteroaryl group.
“Aralkyl” refers to an alkyl group which is substituted with an aryl group. Some non-limiting examples of aralkyl include benzyl and phenethyl.
“Acyl” refers to a monovalent group of the formula —C(═O)H, —C(═O)-alkyl, —C(═O)-aryl, —C(═O)-aralkyl, —C(═O)-alkaryl.
“Halogen” refers to fluorine, chlorine, bromine and iodine.
“Styryl” refers to a univalent radical C6H5—CH═CH— derived from styrene.
“Substituted” as used herein to describe a compound or chemical moiety refers to that at least one hydrogen atom of that compound or chemical moiety is replaced with a second chemical moiety. Non-limiting examples of substituents are those found in the exemplary compounds and embodiments disclosed herein, as well as halogen; alkyl; heteroalkyl; alkenyl; alkynyl; aryl; heteroaryl; hydroxy; alkoxyl; amino; nitro; thiol; thioether; imine; cyano; amido; phosphonato; phosphine; carboxyl; thiocarbonyl; sulfonyl; sulfonamide; ketone; aldehyde; ester; oxo; haloalkyl (e.g., trifluoromethyl); carbocyclic cycloalkyl, which can be monocyclic or fused or non-fused polycyclic (e.g., cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl) or a heterocycloalkyl, which can be monocyclic or fused or non-fused polycyclic (e.g., pyrrolidinyl, piperidinyl, piperazinyl, morpholinyl or thiazinyl); carbocyclic or heterocyclic, monocyclic or fused or non-fused polycyclic aryl (e.g., phenyl, naphthyl, pyrrolyl, indolyl, furanyl, thiophenyl, imidazolyl, oxazolyl, isoxazolyl, thiazolyl, triazolyl, tetrazolyl, pyrazolyl, pyridinyl, quinolinyl, isoquinolinyl, acridinyl, pyrazinyl, pyridazinyl, pyrimidinyl, benzimidazolyl, benzothiophenyl or benzofuranyl); amino (primary, secondary or tertiary); o-lower alkyl; o-aryl, aryl; aryl-lower alkyl; —CO2CH3; —CONH2; —OCH2CONH2; —NH2; —SO2NH2; —OCHF2; —CF3; —OCF3; —NH(alkyl); —N(alkyl)2; —NH(aryl); —N(alkyl)(aryl); —N(aryl)2; —CHO; —CO(alkyl); —CO(aryl); —CO2(alkyl); and —CO2(aryl); and such moieties can also be optionally substituted by a fused-ring structure or bridge, for example —OCH2O—. These substituents can optionally be further substituted with a substituent selected from such groups. All chemical groups disclosed herein can be substituted, unless it is specified otherwise. For example, “substituted” alkyl, alkenyl, alkynyl, aryl, hydrocarbyl or heterocyclo moieties described herein are moieties which are substituted with a hydrocarbyl moiety, a substituted hydrocarbyl moiety, a heteroatom, or a heterocyclo. Further, substituents may include moieties in which a carbon atom is substituted with a heteroatom such as nitrogen, oxygen, silicon, phosphorus, boron, sulfur, or a halogen atom. These substituents may include halogen, heterocyclo, alkoxy, alkenoxy, alkynoxyl, aryloxy, hydroxy, protected hydroxy, keto, acyl, acyloxy, nitro, amino, amido, cyano, thiol, ketals, acetals, esters and ethers.
Platinum(II) Emitters
In embodiments of the invention, the platinum(II) emitters having the chemical structures of Structure I:
where Pt has an oxidation state of II complexed to a tetradentate ligand where: X1-X4 are independently carbon, nitrogen, silicon or phosphorous; R1-R12 are independently selected from hydrogen, halogen, hydroxyl, unsubstituted alkyl, substituted alkyl, cycloalkyl, unsubstituted aryl, substituted aryl, acyl, alkoxy, acyloxy, amino, nitro, acylamino, aralkyl, cyano, carboxyl, thio, styryl, aminocarbonyl, carbamoyl, aryloxycarbonyl, phenoxycarbonyl, or alkoxycarbonyl; and E is an emission intensity enhancement group comprising an aromatic group conjugated to the ligand's phenyl groups, where adjacent R1-R12 and E groups can independently form a 5-8 member ring.
In an embodiment of the invention, E of the Pt(II) complex is
wherein R13-R17 are independently unsubstituted alkyl, a substituted alkyl, cycloalkyl, an unsubstituted aryl, a substituted aryl, alkoxy or amino group.
In another embodiment of the invention, E of the Pt(II) complex is
wherein R18 and R31 are independently hydrogen, methyl, isopropyl or phenyl group; R19-R30 are independently hydrogen, halogen, hydroxyl, an unsubstituted alkyl, a substituted alkyl, cycloalkyl, an unsubstituted aryl, a substituted aryl, acyl, alkoxy, acyloxy, amino, nitro, acylamino, aralkyl, cyano, carboxyl, thio, styryl, aminocarbonyl, carbamoyl, aryloxycarbonyl, phenoxycarbonyl, or an alkoxycarbonyl group. Each pair of adjacent R groups of R19-R30 can independently form 5-8 member ring(s).
In an embodiment of the invention the R1, R2 R11 and R12 of the Pt(II) complex are not amino or a portion of a substituted nitrogen heterocyclic aromatic where the nitrogen is bonded to the aromatic ring.
The platinum(II) emitters according to embodiments of the invention are as follows:
An embodiment of the invention is directed to a Schiff base ligand of structure II:
where: X1-X4 are independently carbon, nitrogen, silicon or phosphorous; R1-R12 are independently selected from hydrogen, halogen, hydroxyl, unsubstituted alkyl, substituted alkyl, cycloalkyl, unsubstituted aryl, substituted aryl, acyl, alkoxy, acyloxy, amino, nitro, acylamino, aralkyl, cyano, carboxyl, thio, styryl, aminocarbonyl, carbamoyl, aryloxycarbonyl, phenoxycarbonyl, or alkoxycarbonyl; and E is an emission intensity enhancement group comprising an aromatic group conjugated to the ligand's phenyl groups, where adjacent R1-R12 and E groups can independently form a 5-8 member ring.
In an embodiment of the invention, E of the Schiff base tetradentate ligand is
wherein R13-R17 are independently unsubstituted alkyl, a substituted alkyl, cycloalkyl, an unsubstituted aryl, a substituted aryl, alkoxy or amino group.
In another embodiment of the invention, E of the Schiff base tetradentate ligand is
wherein R18 and R31 are independently hydrogen, methyl, isopropyl or phenyl group; R19-R30 are independently hydrogen, halogen, hydroxyl, an unsubstituted alkyl, a substituted alkyl, cycloalkyl, an unsubstituted aryl, a substituted aryl, acyl, alkoxy, acyloxy, amino, nitro, acylamino, aralkyl, cyano, carboxyl, thio, styryl, aminocarbonyl, carbamoyl, aryloxycarbonyl, phenoxycarbonyl, or an alkoxycarbonyl group. Each pair of adjacent R groups of R19-R30 can independently form 5-8 member ring(s).
In an embodiment of the invention the R1, R2 R11 and R12 of the Schiff base tetradentate ligand are not amino or a portion of a substituted nitrogen heterocyclic aromatic where the nitrogen is bonded to the aromatic ring.
In an embodiment of the invention, the platinum (II) emitter with chemical structure of Structure I can be prepared by reaction of the corresponding ligand of Structure II with a platinum salt in the presence of suitable solvent(s) and under suitable conditions.
Following are examples that illustrate embodiments for practicing the invention. These examples should not be construed as limiting. All percentages are by weight and all solvent mixture proportions are by volume unless otherwise noted.
A mixture of the Schiff base ligand (1 equiv) and sodium acetate (2 equiv) is dissolved in minimum amount of hot DMF. Potassium tetrachloroplatinate (1 equiv) in hot DMSO is added and the reaction mixture maintained at 80° C. overnight.
If precipitate forms, it is collected via filtration, recrystallized in hot DMF and washed with CH2Cl2. If no precipitate forms, solvent is removed under reduced pressure. Water is added to the reaction mixture and extracted with CH2Cl2. The crude product was purified by chromatography on alumina column (CH2Cl2/hexane). Further purification by recrystallization in hexane is carried out if necessary.
The synthetic method in Example 201 was adopted. The crude product was purified by chromatography on an alumina column (CH2Cl2/hexane=1:1). Further purification was carried out by recrystallization in hexane. Red product was obtained in 0.06 g (46% yield).
1H NMR (500 MHz, CDCl3) δ 8.78 (s, 2H), 7.92 (dd, J=5.9, 3.4 Hz, 2H), 7.71 (d, J=7.1 Hz, 4H), 7.66 (d, J=0.8 Hz, 2H), 7.56 (d, J=8.3 Hz, 2H), 7.47 (t, J=7.3 Hz, 4H), 7.43 (d, J=7.1 Hz, 2H), 7.30-7.27 (m, 2H), 7.02 (dd, J=8.3, 1.3 Hz, 2H). 13C NMR (101 MHz, CDCl3) δ 148.92, 148.56, 145.90, 140.90, 135.84, 129.72, 129.12, 128.31, 127.86, 121.65, 121.42, 117.12, 116.08.
The synthetic method in Example 201 was adopted. Red precipitate was formed and was collected via filtration, recrystallized in hot DMF and washed with CH2Cl2. Red product was obtained in 0.16 g (71% yield).
1H NMR (400 MHz, CDCl3) δ 8.91 (s, 2H), 8.02 (dd, J=6.1, 3.5 Hz, 2H), 7.61 (d, J=8.2 Hz, 2H), 7.37 (dd, J=6.3, 3.2 Hz, 2H), 7.19 (s, 2H), 6.93 (s, 4H), 6.57 (d, J=8.1 Hz, 2H), 2.33 (s, 6H), 2.05 (s, 12H). 13C NMR (101 MHz, CDCl3) δ 166.69, 150.32, 149.27, 146.04, 139.26, 137.59, 135.88, 135.34, 128.81, 128.42, 124.31, 121.17, 119.82, 116.05, 21.84, 21.21.
The synthetic method in Example 201 was adopted. The crude product was purified by chromatography on alumina column (CH2Cl2/hexane=1:1). Further purification was carried out by recrystallization in MeOH. Red product was obtained in 0.05 g (29% yield).
1H NMR (500 MHz, CDCl3) δ 8.93 (s, 1H), 8.85 (s, 1H), 8.06 (d, J=8.6 Hz, 1H), 7.77 (d, J=0.9 Hz, 0H), 7.62 (d, J=8.2 Hz, 1H), 7.53 (d, J=8.2 Hz, 1H), 7.19 (d, J=8.1 Hz, 3H), 7.02 (s, 2H), 6.93 (s, 2H), 6.92 (s, 2H), 6.58 (dd, J=8.2, 1.3 Hz, 1H), 6.54 (dd, J=8.2, 1.3 Hz, 1H), 2.38 (s, 3H), 2.33 (s, 3H), 2.32 (s, 3H), 2.08 (s, 6H), 2.06 (s, 6H), 2.03 (s, 6H). 13C NMR (126 MHz, CDCl3) δ 165.92, 165.81, 149.55, 149.47, 148.56, 148.30, 145.43, 143.93, 141.13, 138.45, 138.44, 137.70, 136.97, 136.76, 135.89, 135.08, 135.04, 134.54, 134.49, 128.62, 128.36, 128.00, 123.47, 120.43, 120.37, 119.05, 119.01, 116.05, 115.17, 21.04, 21.03, 20.77, 20.41, 20.35.
The synthetic method in Example 201 was adopted. The crude product was purified by chromatography on alumina column (CH2Cl2/hexane=1:4). Red product was obtained in 0.37 g (58% yield).
1H NMR (400 MHz, CDCl3) δ 8.88 (s, 2H), 8.00 (dd, J=6.0, 3.2 Hz, 2H), 7.82 (d, J=7.2 Hz, 2H), 7.76 (s, 2H), 7.54 (s, 2H), 7.49-7.41 (m, 4H), 7.41-7.35 (m, 2H), 7.32 (dd, J=5.8, 3.1 Hz, 2H), 1.54 (s, 12H).
The synthetic method in Example 201 was adopted. The crude product was purified by chromatography on alumina column (CH2Cl2/hexane=1:4). Red product was obtained in 0.64 g (60% yield).
1H NMR (300 MHz, CDCl3) δ 13.39 (s, 2H), 8.73 (s, 2H), 7.80-7.66 (m, 4H), 7.45-7.28 (m, 14H), 1.96 (t, J=8.2 Hz, 8H), 1.18-0.97 (m, 8H), 0.76-0.55 (m, 20H).
The synthetic method in Example 201 was adopted. The crude product was purified by chromatography on alumina column (CH2Cl2/hexane=1:4). Red product was obtained in 1.0 g (69% yield).
1H NMR (400 MHz, CD2Cl2) δ 13.38 (s, 2H), 8.75 (s, 2H), 7.75 (s, 2H), 7.36 (m, 14H), 1.98 (t, J=7.9 Hz, 8H), 1.06 (m, 24H), 0.76 (t, J=6.7 Hz, 12H), 0.65 (d, J=20.9 Hz, 8H).
The synthetic method in Example 201 was adopted. Red precipitate was collected via filtration, washed sequentially with water, MeOH, and CH2Cl2. Red product was obtained in 0.12 g (30% yield).
1H NMR (500 MHz, CDCl3) δ 8.92 (s, 1H), 8.84 (s, 1H), 8.07 (d, J=8.5 Hz, 1H), 7.80 (t, J=6.4 Hz, 2H), 7.77 (d, J=7.4 Hz, 3H), 7.45 (s, 1H), 7.44-7.30 (m, 7H), 7.13 (d, J=8.3 Hz, 1H), 7.00 (s, 2H), 2.37 (s, 3H), 2.07 (s, 6H), 1.98 (t, J=8.2 Hz, 4H), 1.93 (t, J=7.9 Hz, 4H), 1.19-1.01 (m, 8H), 0.83-0.62 (m, 20H). 13C NMR (126 MHz, CDCl3) δ 166.42, 166.29, 152.82, 152.79, 149.78, 149.71, 148.33, 148.17, 145.44, 143.94, 140.53, 140.07, 140.03, 138.93, 137.44, 137.19, 135.84, 128.98, 128.96, 128.24, 127.86, 127.16, 127.13, 127.10, 123.15, 121.40, 120.83, 120.74, 115.83, 114.98, 112.81, 53.82, 53.76, 40.86, 40.84, 27.38, 26.19, 26.17, 23.13, 23.10, 21.03, 20.74, 13.84, 13.82.
The synthetic method in Example 201 was adopted. Red precipitate was collected via filtration, re-dissolved in a large amount of CH2Cl2, and washed with water. The solution was concentrated and red precipitate was collected via filtration. Red product was obtained in 1.4 g (57% yield).
1H NMR (400 MHz, DMSO) δ 9.41 (s, 2H), 8.38 (s, 2H), 7.85 (d, J=8.2 Hz, 2H), 7.73 (d, J=8.1 Hz, 4H), 7.59-7.26 (m, 12H), 7.26-7.04 (m, 14H), 7.00 (d, J=8.0 Hz, 4H). 13C NMR (126 MHz, CDCl3) δ 165.62, 148.18, 147.66, 147.38, 146.80, 144.93, 134.99, 133.10, 129.36, 127.68, 127.17, 124.91, 123.35, 122.97, 120.52, 119.28, 115.63, 115.15.
The synthetic method in Example 201 was adopted. The crude product was purified by chromatography using an alumina column and a CH2Cl2 mobile phase. Further purification was done by recrystallization in hexane. Red product was obtained in 0.05 g (70% yield).
1H NMR (500 MHz, CDCl3) δ 8.86 (s, 2H), 7.98 (dd, J=6.1, 3.2 Hz, 2H), 7.58 (d, J=8.2 Hz, 2H), 7.33 (dd, J=6.2, 3.2 Hz, 2H), 7.28 (t, J=7.9 Hz, 8H), 7.22 (s, 2H), 7.16 (d, J=7.7 Hz, 8H), 7.02 (t, J=7.3 Hz, 4H), 6.81 (s, 4H), 6.59 (dd, J=8.2, 1.1 Hz, 2H), 1.99 (s, 12H). 13C NMR (126 MHz, CDCl3) δ 163.37, 161.39, 147.87, 146.99, 146.54, 142.82, 136.54, 135.63, 132.26, 129.14, 127.67, 124.28, 122.71, 122.52, 120.74, 119.67, 118.59, 117.87, 20.79.
The synthetic method in Example 201 was adopted. Red precipitate was collected via filtration and washed sequentially with water, MeOH and CH2Cl2. Red product was obtained in 0.06 g (45% yield).
1H NMR (500 MHz, CDCl3) δ 8.92 (s, 2H), 8.16 (d, J=7.3 Hz, 4H), 8.02 (s, 2H), 7.96 (d, J=7.3 Hz, 4H), 7.81 (s, 2H), 7.77-7.62 (m, 6H), 7.53 (d, J=7.6 Hz, 4H), 7.44 (t, J=7.0 Hz, 4H), 7.38 (s, 2H), 7.31 (t, J=7.1 Hz, 4H), 7.16 (d, J=7.6 Hz, 2H). 1H NMR (500 MHz, DMSO) δ 9.58 (s, 2H), 8.48 (s, 2H), 8.25 (d, J=7.7 Hz, 4H), 8.13 (d, J=7.5 Hz, 4H), 8.02 (d, J=8.4 Hz, 2H), 7.76 (d, J=7.8 Hz, 4H), 7.55 (s, 2H), 7.53-7.39 (m, 10H), 7.35-7.21 (m, J=7.4 Hz, 6H). 13C NMR (at 370K, 126 MHz, DMSO) δ 165.59, 151.15, 146.30, 145.34, 140.88, 139.04, 137.86, 136.76, 128.90, 128.37, 127.59, 126.66, 123.58, 122.00, 120.80, 120.63, 119.14, 117.13, 115.74, 110.23.
aMeasured in dichloromethane solution at 2 × 10-5 M. b Measured by integration sphere. sh denotes shoulder of emission band.
The above data demonstrate red-emitting Pt(II) Schiff base complex of Structure I having a emission intensity enhancement group, E, display high Φem greater than 0.38.
Materials: PEDOT:PSS [poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid)](Clevios P AI 4083) was purchased from Heraeus, PVK (polyvinylcarbazole) from Sigma-Aldrich, OXD-7 [(1,3-bis[(4-tert-butylphenyl)-1,3,4-oxadiazolyl]phenylene)], and TPBi [2,2′,2″-(1,3,5-benzenetriyl)-tris(1-phenyl-1-H-benzimidazole)] from Luminescence Technology Corp. All of the materials were used as received.
Substrate cleaning: Glass slides with pre-patterned ITO electrodes used as substrates of OLEDs were cleaned in an ultrasonic bath of Decon 90 detergent and deionized water, rinsed with deionized water, and then cleaned in sequential ultrasonic baths of deionized water, acetone, and isopropanol, and subsequently dried in an oven for 1 h.
Fabrication and characterization of devices: PEDOT:PSS were spin-coated onto the cleaned ITO-coated glass substrate and baked at 120° C. for 20 minutes to remove the residual water solvent in a clean room. Blends of emitting layer were spin-coated from chlorobenzene atop the PEDOT:PSS layer inside a N2-filled glove box. The thickness for all EMLs was about 60 nm. Afterwards, the were annealed at 110° C. for 10 min inside the glove box and subsequently transferred into a Kurt J. Lesker SPECTROS vacuum deposition system without exposing to air. Finally, TPBi (40 nm), LiF (1.2 nm), and Al (100 nm) were deposited in sequence by thermal evaporation at a pressure of 10−8 mbar. EQE, PE, CE, and CIE coordinates were measured using a Keithley 2400 source-meter and an absolute external quantum efficiency measurement system (C9920-12, Hamamatsu Photonics). All devices were characterized at room temperature without encapsulation. EQE and power efficiency were calculated by assuming a Lambertian distribution.
Table 3 compares model complex 1 and model complex 2, having no E group, to Emitter 102, 108 and 110 in terms of Φem in solution, maximum CE, PE and EQE as well as CIE of the corresponding devices. As can been seen, Emitter 102, 108 and 110 exhibit superior Φem, maximum CE, PE and EQE resulting from the existence of E group at the specified position.
aMeasured in CH2Cl2 at room temperatue.
bChem. Eur. J., 2010, 16, 233.
cChem. Asian. J., 2014, 9, 2984.
With respect to any figure or numerical range for a given characteristic, a figure or a parameter from one range may be combined with another figure or a parameter from a different range for the same characteristic to generate a numerical range.
Other than in the operating examples, or where otherwise indicated, all numbers, values and/or expressions referring to quantities of ingredients, reaction conditions, etc., used in the specification and claims are to be understood as modified in all instances by the term “about.”
It should be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application.
It should be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and the scope of the appended claims. In addition, any elements or limitations of any invention or embodiment thereof disclosed herein can be combined with any and/or all other elements or limitations (individually or in any combination) or any other invention or embodiment thereof disclosed herein, and all such combinations are contemplated with the scope of the invention without limitation thereto.
All patents, patent applications, provisional applications, and publications referred to or cited herein are incorporated by reference in their entirety, including all figures and tables, to the extent they are not inconsistent with the explicit teachings of this specification.
Following are examples that illustrate procedures for practicing the invention. These examples should not be construed as limiting. All percentages are by weight and all solvent mixture proportions are by volume unless otherwise noted.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2019/114666 | 10/31/2019 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62753448 | Oct 2018 | US |
