Ionic metal iridium complex and its preparation method and application

Abstract

The present invention relates to an ionic metal iridium complex and its preparation method and application, belonging to the field of optoelectronic technology, and solves the problems in the prior art that the chiral compounds of the light-emitting layer of electro-circularly polarized light-emitting devices are difficult to prepare and have low luminous efficiency. An ionic metal iridium complex, the ionic metal iridium complex is composed of an octahedral iridium complex cation and a chiral camphorsulfonate anion. Chiral camphorsulfonate anions are introduced into the ionic metal iridium complex of the present invention. Under the drive of an electric field, the migration and accumulation of chiral anions lead to an increase in the chirality of the film, and further transfer to cationic excitons to emit circularly polarized light, so that the material shows electrically amplified circularly polarized luminescence; the ionic metal iridium complex as a luminescent material has high phosphorescence efficiency and ion mobility, which is conducive to effective charge injection and electroluminescence.

Description

Technical Field

[0001] The present invention relates to the field of optoelectronic technology, and in particular to an ionic metal iridium complex and a preparation method and application thereof. Background Art

[0002] Circularly polarized light has been widely used in fields such as three-dimensional displays, spintronics, and quantum computing. Circularly polarized light is typically produced by filtering natural light through linear polarizers and quarter-wave plates, but this often results in a significant loss of brightness. Furthermore, chiral organic light-emitting diodes (CP-OLEDs) capable of electro-optical conversion and spintronic light-emitting diodes assisted by an external magnetic field can directly emit circularly polarized light. Currently, research on chiral circularly polarized photoluminescent (CPPL) materials has made significant progress. In contrast, the development of devices that produce circularly polarized electroluminescence (CPEL) has lagged far behind, severely hindering the practical application of chiral materials in optoelectronic technology. Although high-efficiency CPELs based on liquid crystal devices have been achieved, these devices often suffer from low emission efficiency, temperature-dependent performance, poor color purity, and poor contrast. Therefore, in recent years, CP-OLEDs based on chiral emission materials have attracted widespread research interest due to their advantages such as low energy consumption, high emission efficiency, and good controllability of emission color.

[0003] Two daunting and pressing challenges remain in current CPEL device research. The first is the difficulty and high cost of synthesizing chiral materials suitable for high-efficiency OLEDs. For example, ionic transition metal complexes (iTMCs) are widely used as emitters in green and red OLEDs in academia and industry due to their potential to fully capture electrically generated singlet and triplet excitons. However, the synthesis of chiral iTMCs typically involves separation by chiral high-performance liquid chromatography (HPLC) or chiral separation using chiral auxiliary ligands to obtain the corresponding diastereomers, a complex and costly process. The second challenge is the severe attenuation of the chirality of chiral materials in electrical devices relative to their counterparts in solutions and thin films. The reasons for this problem are complex and currently unexplained. The propagation of device light across different interfaces and reflection from metal electrodes are believed to be partly responsible for the attenuation of chirality in CP-OLEDs. Furthermore, these two challenges also exist in the recently developed high-efficiency chiral OLEDs based on thermally activated delayed fluorescence (TADF) emitters. Summary of the Invention

[0004] In view of the above analysis, the embodiments of the present invention aim to provide an ionic metal iridium complex and its preparation method and application, so as to solve the problems in the prior art of difficult preparation of chiral compounds in the light-emitting layer of electro-circularly polarized light-emitting devices and low luminous efficiency.

[0005] In one aspect, the present invention provides an ionic metal iridium complex, wherein the ionic metal iridium complex consists of an octahedral iridium complex cation and a chiral camphorsulfonate anion.

[0006] Furthermore, the structural formula of the ionic metal iridium complex is shown in formula (I),

[0007]

[0008] Wherein, in formula (I), “*” represents the chirality of camphorsulfonate, and camphorsulfonate is left-handed (-) or right-handed (+);

[0009] Said R is one of H, halogen or C1-C6 alkyl;

[0010] R' is one of H, a benzene ring, or a C1-C6 alkyl group.

[0011] In a second aspect, the present invention provides a method for preparing an ionic metal iridium complex. The method comprises dissolving an iridium complex having a chloride anion and silver camphorsulfonate in an organic solvent, heating under reflux to perform an ion exchange reaction, and recrystallizing the ionic metal iridium complex. Furthermore, the molar ratio of the iridium complex having a chloride anion to the silver camphorsulfonate is 1:1 to 1.5.

[0012] Furthermore, the silver camphorsulfonate is left-handed (-) or right-handed (+) silver camphorsulfonate.

[0013] Furthermore, the organic solvent is one or more of methanol, acetonitrile, tetrahydrofuran, dichloromethane, dioxane, dimethylformamide or ethanol.

[0014] Furthermore, the heating temperature is 40-100° C., and the reflux time is 0.5-1 h.

[0015] Furthermore, the recrystallization solvent is one or more of dichloromethane, acetonitrile, methanol, ethanol, acetone, tetrahydrofuran, propanol, ether, petroleum ether or n-hexane.

[0016] In a third aspect, the present invention provides an application of an ionic metal iridium complex in a circularly polarized luminescent material, a circularly polarized luminescent device or a circularly polarized luminescent layer.

[0017] Furthermore, the circularly polarized luminescent material is made into the luminescent layer of a circularly polarized luminescent electrochemical cell.

[0018] Furthermore, the ionic metal iridium complex is mixed with a chiral ionic liquid or the ionic metal iridium complex is used to prepare a light-emitting layer.

[0019] Furthermore, the ionic metal iridium complex or the ionic metal iridium complex mixed with the chiral ionic liquid is coated on the smooth layer to prepare a light-emitting layer, and then a double-layer circularly polarized light-emitting electrochemical cell is formed with a transparent substrate and a metal electrode.

[0020] Furthermore, the chiral ionic liquid is 1-butyl-3-methylimidazole camphorsulfonate, and the camphorsulfonate anion is left-handed (-) or right-handed (+).

[0021] Furthermore, the smoothing layer is formed by coating PMMA or PEDOT:PSS dissolved in ethanol, isopropanol or n-butanol.

[0022] Furthermore, when the ionic metal iridium complex and the chiral ionic liquid are mixed and coated on the smooth layer to prepare the light-emitting layer, the molar ratio of the chiral ionic liquid to the ionic metal iridium complex is 0.25-2.

[0023] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0024] (1) The ionic metal iridium complex of the present invention has good solubility in strong polar solvents such as dimethylformamide and alcohols, as well as weak polar solvents such as toluene, chlorobenzene, dichlorotoluene, and chloroform;

[0025] (2) The ionic metal iridium complex prepared by the method of the present invention has high phosphorescence efficiency and ion mobility as a luminescent material, which is conducive to effective charge injection and electroluminescence;

[0026] (3) Compared with traditional classical chiral complexes, the ionic metal iridium complex of the present invention has a simple preparation method and low cost, and as a chiral luminescent material, it shows good circularly polarized electroluminescent performance in a luminescent electrochemical cell and can be widely used in the fields of circularly polarized luminescent electrochemical cells;

[0027] (4) Chiral camphorsulfonate anions are introduced into the ionic metal iridium complex of the present invention. Under the driving force of the electric field, the migration and accumulation of the chiral anions lead to an increase in the chirality of the film, and further transfer to cationic excitons to emit circularly polarized light, so that the material shows electrically amplified circularly polarized luminescence;

[0028] (5) The present invention introduces a chiral ionic liquid containing the same camphorsulfonate ion as the ionic metal iridium complex into the luminescent layer of the circularly polarized luminescent electrochemical cell, further improving the performance of the luminescent electrochemical cell and the luminescence asymmetry factor (g EL );

[0029] (6) The circularly polarized luminescent electrochemical cell described in the present invention has a simple double-layer structure, which reduces the possibility of light passing through different interfaces in the OLED causing the chirality to weaken compared to multi-layer OLEDs;

[0030] (7) The electrochemical cell made of the ionic metal iridium complex of the present invention has good luminous efficiency and luminous asymmetry factor, with a maximum external quantum efficiency (EQEmax) of 1.9-5.43% and a luminous asymmetry factor (g EL ) is 1~2.5×10 -3 .

[0031] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0033] Figure 1 The electroluminescence spectra of the luminescent electrochemical cell based on the ionic metal iridium complex of formula (II-1) prepared in Example 3 under different pulse voltages;

[0034] Figure 2 The electroinduced circularly polarized luminescence spectrum of the luminescent electrochemical cell based on the ionic metal iridium complexes of formula (II-1) and formula (II-2) prepared in Example 3;

[0035] Figure 3 Characterization spectra of the performance of the light-emitting electrochemical cells of the ionic metal iridium complexes of formula (II-1) prepared in Examples 3 and 4;

[0036] Figure 4 Electroinduced circularly polarized luminescence spectra of the luminescent electrochemical cells based on the ionic metal iridium complexes of formula (II-1) and formula (II-2) prepared in Example 3 and Example 4. DETAILED DESCRIPTION

[0037] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0038] A specific embodiment of the present invention discloses an ionic metal iridium complex, which is composed of an octahedral iridium complex cation and a chiral camphorsulfonate anion.

[0039] It should be noted that chiral camphorsulfonate anions are introduced into the ionic metal iridium complex of the present invention. Under the driving force of the electric field, the migration and accumulation of the chiral anions lead to an increase in the chirality of the film, and further transfer to the cationic excitons to emit circularly polarized light. When the ionic metal iridium complex is used as a luminescent material, it shows electrically amplified circularly polarized luminescence.

[0040] Specifically, the structural formula of the ionic metal iridium complex is shown in formula (I),

[0041]

[0042] Wherein, in formula (I), “*” represents the chirality of camphorsulfonate, and camphorsulfonate is left-handed (-) or right-handed (+);

[0043] Said R is one of H, halogen or C1-C6 alkyl;

[0044] R' is one of H, a benzene ring, or a C1-C6 alkyl group.

[0045] In a preferred embodiment, R is H or halogen, and R' is H or a C1-C6 alkyl group.

[0046] In a more preferred embodiment, R is H or F, and R' is H or tert-butyl.

[0047] It should be noted that the ionic metal iridium complex described in the present invention has good solubility in strong polar solvents such as dimethylformamide and alcohols, as well as weak polar solvents such as toluene, chlorobenzene, dichlorotoluene, and chloroform, has high phosphorescence efficiency and ion mobility, and the preparation method is simple.

[0048] In a second aspect, the present invention provides a method for preparing an ionic metal iridium complex, comprising dissolving an iridium complex whose anion is a chloride ion and silver camphorsulfonate in an organic solvent, heating under reflux to perform an ion exchange reaction, and recrystallizing to obtain the ionic metal iridium complex.

[0049] It should be noted that after heating under reflux for the ion exchange reaction, the reaction mixture needs to be cooled to room temperature, filtered to remove the generated silver chloride precipitate, and the filtrate is concentrated and then recrystallized using a solvent.

[0050] Specifically, by adopting the above method, the yield of the ionic metal iridium complex is ≥75%.

[0051] Specifically, the molar ratio of the iridium complex whose anion is chloride ion to silver camphorsulfonate is 1:1 to 1.5.

[0052] Exemplarily, the molar ratio of the iridium complex having a chloride anion to silver camphorsulfonate is 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, or 1:1.5.

[0053] Specifically, the silver camphorsulfonate is left-handed (-) or right-handed (+) silver camphorsulfonate.

[0054] Specifically, the organic solvent is one or more of methanol, acetonitrile, tetrahydrofuran, dichloromethane, dioxane, dimethylformamide or ethanol.

[0055] Specifically, the heating temperature is 40-100°C, such as 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, and 100°C, and the reflux time is 0.5-1h, such as 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, and 1.0h.

[0056] Specifically, the recrystallization solvent is one or more of dichloromethane, acetonitrile, methanol, ethanol, acetone, tetrahydrofuran, propanol, ether, petroleum ether or n-hexane.

[0057] In a third aspect, the present invention provides an application of an ionic metal iridium complex in a circularly polarized luminescent material, a circularly polarized luminescent device or a circularly polarized luminescent layer.

[0058] It should be noted that the ionic metal iridium complex of the present invention has high phosphorescence efficiency and ion mobility as a luminescent material, which is conducive to effective charge injection and electroluminescence.

[0059] Specifically, the circularly polarized luminescent material is made into the luminescent layer of a circularly polarized luminescent electrochemical cell.

[0060] Specifically, the ionic metal iridium complex is mixed with a chiral ionic liquid or the ionic metal iridium complex is used to prepare a light-emitting layer.

[0061] Specifically, the ionic metal iridium complex or the ionic metal iridium complex mixed with the chiral ionic liquid is coated on the smooth layer to prepare a light-emitting layer, which is then combined with a transparent substrate and a metal electrode to form a double-layer circularly polarized light-emitting electrochemical cell. It should be noted that the circularly polarized light-emitting electrochemical cell of the present invention is prepared by the following method:

[0062] (1) preparing a smoothing layer on a transparent electrical substrate using a precursor solution by spin coating technology;

[0063] (2) spin coating an ionic metal iridium complex or a mixture of an ionic metal iridium complex and a chiral ionic liquid on the smooth layer as a light-emitting layer;

[0064] (3) The top electrode LiF / Al was prepared on the light-emitting layer by vacuum thermal evaporation.

[0065] It should be noted that in step (1), the transparent conductive substrate is ITO glass, the coating thickness is 120nm-250nm, the square resistance of the substrate is approximately 13-17Ω / sq, and the transmittance is 84-92%. The spin coating precursor solution can be prepared by dissolving PMMA or PEDOT:PSS in ethanol, isopropanol, or n-butanol.

[0066] The concentration of the precursor solution can be 1:1 (m / m), 1:3 (m / m), or 1:10 (m / m), where m / m is the mass ratio of the raw material to the solvent, for example, the mass ratio of PMMA to ethanol is 1:10.

[0067] Specifically, the spin coating speed is 1000-4000 rpm, such as 1000 rpm, 1500 rpm, 2000 rpm, 2500 rpm, 3000 rpm, 3500 rpm, and 4000 rpm; the spin coating time is 30-60 s, such as 30 s, 35 s, 40 s, 45 s, 50 s, 55 s, and 60 s; the annealing temperature is 100-200 ° C, such as 100 ° C, 110 ° C, 120 ° C, 130 ° C, 140 ° C, 150 ° C, 160 ° C, 170 ° C, 180 ° C, 190 ° C, and 200 ° C; and the annealing time is 10-60 min, such as 10 min, 20 min, 30 min, 40 min, 50 min, and 60 min.

[0068] In a preferred solution, the spin coating speed is 3000 rpm, the spin coating time can be 30 s, the annealing temperature is 120° C., and the annealing time is 30 minutes.

[0069] In the above step (2), the raw material of the light-emitting layer is a mixture of the ionic metal iridium complex and the chiral ionic liquid or the ionic metal iridium complex.

[0070] It should be noted that in step (2), when preparing the light-emitting layer, the mixture of the ionic metal iridium complex and the chiral ionic liquid or the ionic metal iridium complex needs to be dissolved in solvent A to form a solution and then spin-coated. The solution concentration can be 15 mg / mL, 20 mg / mL, or 30 mg / mL. The selected solvent A can be one or more of acetonitrile, dimethylformamide (DMF), and propanol. The spin coating speed can be 1000-3000 rpm, such as 1500 rpm, 2000 rpm, 2500 rpm, or 3000 rpm, and the spin coating time is 30-60 s, such as 30 s, 35 s, 40 s, 45 s, 50 s, 55 s, or 60 s. The preferred speed is 2000 rpm, and the spin time is 30 s.

[0071] Specifically, the chiral ionic liquid is 1-butyl-3-methylimidazole camphorsulfonate, and the camphorsulfonate radical is left-handed (-) or right-handed (+).

[0072] Specifically, when the ionic metal iridium complex and the chiral ionic liquid are mixed and coated on the smooth layer to prepare the light-emitting layer, the molar ratio of the chiral ionic liquid to the ionic metal iridium complex is 0.25-2.

[0073] Exemplarily, the molar ratio of the chiral ionic liquid to the type metal iridium complex is 0.25, 0.5, 1, or 2.

[0074] It should be noted that the chiral ionic liquid described in the present invention is referred to as IL.

[0075] It should be noted that the present invention introduces a chiral ionic liquid containing the same camphorsulfonate ion as the ionic metal iridium complex into the luminescent layer of the circularly polarized luminescent electrochemical cell, further improving the performance of the luminescent electrochemical cell and the luminescence asymmetry factor (g EL ).

[0076] It should be noted that the strategy of using chiral anions in the present invention overcomes the lengthy and complex preparation process and high chiral separation costs of traditional chiral materials, and thus has the advantages of simplicity, high efficiency and low cost. In addition, when the chiral ionic liquid containing the same chiral camphorsulfonate ion is introduced for device optimization, the luminous efficiency and luminescence asymmetry factor (g) of the luminescent electrochemical cell are further improved. EL ).

[0077] The luminescence asymmetry factor (g EL ) = [ellipticity / (32980 / ln10)] / total electroluminescence intensity at the maximum electrocircularly polarized luminescence intensity.

[0078] It should be noted that the electrochemical cell made of the ionic metal iridium complex of the present invention has good luminous efficiency and luminous asymmetry factor, with a maximum external quantum efficiency (EQEmax) of 1.9-5.43% and a luminous asymmetry factor (g EL ) is 1~2.5×10 -3 .

[0079] Therefore, this strategy of combining chiral anions and chiral ionic liquids is of great value in the development of high-efficiency circularly polarized electroluminescent devices, and this type of chiral electroluminescent material will have very good application prospects in the field of optoelectronic devices.

[0080] Example 1

[0081] An ionic metal iridium complex having a structural formula (II) is specifically as follows:

[0082]

[0083] The synthetic route of the ionic metal iridium complex represented by formula (II) in this embodiment is as follows:

[0084]

[0085] (1) preparing an ionic metal iridium complex having a structural formula shown in formula (II-1);

[0086]

[0087] Dissolve 70 mg of (2,2'-bipyridyl)bis(2-phenylpyridinium)iridium chloride and 34 mg of dextrorotatory (+)silver camphorsulfonate in 10 mL of methanol and heat under reflux at 65°C for 2 hours under nitrogen. After cooling to room temperature, the resulting silver chloride precipitate was removed by filtration. The filtrate was concentrated and recrystallized from acetonitrile / ether to obtain 74 mg of yellow flaky crystals of formula (II-1) in an 83% yield.

[0088] The obtained product was characterized as follows:

[0089] 1H NMR (400MHz, CD3CN): δ8.56(d,J=8.2Hz,2H),8.13(td,J=8.0,1.5Hz,2H),8.06(d,J=8.2Hz,2H),7.98(d,J=5.4Hz ,2H),7.89–7.77(m,4H),7.61(d,J=5.8Hz,2H),7.50(dd,J=7.4,5.9Hz,2H),7.09–6.98(m,4H),6.91(dd,J=8.0,6 .8Hz,2H),6.28(d,J=7.6Hz,2H),3.02(d,J=14.6Hz,1H),2.78-2.70(m,1H),2.54(d,J=14.6Hz,1H),2.31–2.22(m ,2H),1.99-1.94(m,1H),1.82(d,J=18.2Hz,1H),1.52–1.44(m,1H),1.34-1.28(m,1H),1.09(s,3H),0.80(s,3H).

[0090] (2) preparing an ionic metal iridium complex having a structural formula shown in formula (II-2);

[0091]

[0092] Dissolve 70 mg of (2,2′-bipyridyl)bis(2-phenylpyridinium)iridium chloride and 34 mg of silver (-) camphorsulfonate in 10 mL of methanol and heat under reflux at 65°C for 2 hours under nitrogen. After cooling to room temperature, remove the resulting silver chloride precipitate by filtration. Concentrate the filtrate and recrystallize it from acetonitrile / ether to obtain 70 mg of yellow flaky crystals of formula (II-2) in a 79% yield.

[0093] The obtained product was characterized as follows:

[0094] 1H NMR (400MHz, CD3CN): δ8.56(d,J=8.2Hz,2H),8.13(td,J=8.0,1.5Hz,2H),8.06(d,J=8.2Hz,2H),7.98(d,J=5.4Hz ,2H),7.89–7.77(m,4H),7.61(d,J=5.8Hz,2H),7.50(dd,J=7.4,5.9Hz,2H),7.09–6.98(m,4H),6.91(dd,J=8.0,6 .8Hz,2H),6.28(d,J=7.6Hz,2H),3.02(d,J=14.6Hz,1H),2.78-2.70(m,1H),2.54(d,J=14.6Hz,1H),2.31–2.22(m ,2H),1.99-1.94(m,1H),1.82(d,J=18.2Hz,1H),1.52–1.44(m,1H),1.34-1.28(m,1H),1.09(s,3H),0.80(s,3H).

[0095] Example 2

[0096] An ionic metal iridium complex having a structural formula (III) is specifically as follows:

[0097]

[0098] The synthetic route of the ionic metal iridium complex represented by formula (III) in this embodiment is as follows:

[0099]

[0100] (1) Prepare an ionic metal iridium complex having the structural formula (III-1):

[0101]

[0102] 88 mg of (4,4'-di-tert-butyl-2,2'-bipyridyl)bis(2-(2,4-difluorophenyl)pyridinium) chloride and 34 mg of silver (+) camphorsulfonate were dissolved in 10 mL of acetonitrile and heated under reflux at 80°C for 1 hour under nitrogen. After cooling to room temperature, the resulting silver chloride precipitate was removed by filtration. The filtrate was concentrated and recrystallized from acetonitrile / ether to obtain 80 mg of yellow-green rod-shaped crystals of formula (III-1) in a 75% yield.

[0103] The obtained product was characterized as follows:

[0104] 1H NMR (400MHz, CD3CN): δ8.52(d,J=1.7Hz,2H),8.32(d,J=8.4Hz,2H),7.95–7.85(m,4H),7.61(dd,J=5.8,0.8Hz,2 H),7.53(dd,J=5.9,2.0Hz,2H),7.11(ddd,J=7.3,5.9,1.3Hz,2H),6.69(ddd,J=12.6,9.4,2.4Hz,2H),5.73(dd,J =8.6,2.4Hz,2H),3.02(d,J=14.7Hz,1H),2.79–2.71(m,1H),2.54(d,J=14.7Hz,1H),2.31–2.22(m,2H),1.99-1. 96(m,1H),1.81(d,J=18.1Hz,1H),1.51–1.44(m,1H),1.42(s,18H),1.36–1.31(m,1H),1.10(s,3H),0.80(s,3H).

[0105] (2) Prepare an ionic metal iridium complex having the structural formula (III-2):

[0106]

[0107] Dissolve 88 mg of (4,4'-di-tert-butyl-2,2'-bipyridyl)bis(2-(2,4-difluorophenyl)pyridinium) chloride and 34 mg of silver (-) camphorsulfonate in 10 mL of acetonitrile and reflux at 80°C for 1 hour under nitrogen. After cooling to room temperature, the resulting silver chloride precipitate was removed by filtration. The filtrate was concentrated and recrystallized from acetonitrile / ether to obtain 83 mg of yellow-green flaky crystals of formula (III-2) in a 77% yield.

[0108] The obtained product was characterized as follows:

[0109] 1H NMR (400MHz, CD3CN): δ8.52(d,J=1.7Hz,2H),8.32(d,J=8.4Hz,2H),7.95–7.85(m,4H),7.61(dd,J=5.8,0.8Hz,2 H),7.53(dd,J=5.9,2.0Hz,2H),7.11(ddd,J=7.3,5.9,1.3Hz,2H),6.69(ddd,J=12.6,9.4,2.4Hz,2H),5.73(dd,J =8.6,2.4Hz,2H),3.02(d,J=14.7Hz,1H),2.79–2.71(m,1H),2.54(d,J=14.7Hz,1H),2.31–2.22(m,2H),1.99-1. 96(m,1H),1.81(d,J=18.1Hz,1H),1.51–1.44(m,1H),1.42(s,18H),1.36–1.31(m,1H),1.10(s,3H),0.80(s,3H).

[0110] Example 3 Preparation of electrochemical cell

[0111] The ionic metal iridium complex of formula (II-1) or formula (II-2) prepared in claim 1 of the present embodiment is used to prepare an electrochemical cell, and the specific method is as follows:

[0112] (1) A smooth layer of PEDOT:PSS was prepared on a transparent electrical substrate ITO glass by spin coating, wherein the ITO coating thickness was 120 nm to 250 nm, the sheet resistance of the substrate was 15 Ω / sq, and the transmittance was 88%. PEDOT:PSS was dissolved in ethanol with a mass concentration of 15%, and the coating was performed at a spin speed of 3000 rpm for 30 seconds and annealed at a temperature of 120°C for 30 minutes.

[0113] (2) spin coating the ionic metal iridium complex as a light-emitting layer on the PEDOT:PSS layer, wherein the spin coating speed is 2000 rpm and the spin coating time is 30 s;

[0114] (3) The top electrode LiF / Al was prepared on the light-emitting layer by vacuum thermal evaporation.

[0115] Example 4 Preparation of electrochemical cell

[0116] The preparation method of the electrochemical cell of this embodiment is the same as that of Example 3, except that in step (2), the ionic metal iridium complex and the chiral ionic liquid are used to prepare the light-emitting layer, the molar ratio of the ionic metal iridium complex and the chiral ionic liquid (IL) is 2:1, the chiral ionic liquid is 1-butyl-3-methylimidazole camphorsulfonate, and the camphorsulfonate ion is left-handed (-) or right-handed (+).

[0117] Test Example 1

[0118] (1) The electroluminescence spectra of the luminescent electrochemical cell based on the ionic metal iridium complex of formula (II-1) prepared in Example 3 were tested under different pulse voltages, such as Figure 1 shown.

[0119] from Figure 1 As can be seen in the figure, the device exhibits an orange emission with a maximum emission peak at 592nm, consistent with the photoluminescence spectrum of the light-emitting layer film, indicating phosphorescence emission from the ionic metal iridium complex. The electroluminescence spectra and the voltage dependence of the peak intensity under different pulse voltages show that the device's orange-yellow emission intensity increases nonlinearly with voltage before 13V, after which the brightness decreases significantly, reaching the device's tolerable voltage and current limits.

[0120] The inventors also conducted the above test on the ionic metal iridium complex of formula (II-2), and the electroluminescence spectrum was basically consistent with that of formula (II-1). Due to limited space, they are not listed one by one.

[0121] (2) The electroinduced circularly polarized luminescence spectra of the luminescent electrochemical cells of the ionic metal iridium complexes of formula (II-1) and formula (II-2) prepared in Example 3 were tested respectively. Figure 2 As shown. According to the chirality of the camphorsulfonic acid anion, the luminescent electrochemical cell based on the ionic metal iridium complex of formula (II-1) and formula (II-2) presents a mirror-symmetrical electro-induced circularly polarized luminescence spectrum, indicating that under the driving voltage, the chirality of the anion is successfully transferred to the cationic complex chromophore, achieving effective electro-induced circularly polarized emission, and the luminescence asymmetry factor (|g EL |) is 1.0×10 -3 .

[0122] Test Example 2

[0123] (1) The current-voltage (IV) characteristics of the device were measured using a semiconductor parameter analyzer (Keithley 2400 source meter). The luminance was recorded in real time using a luminance meter (Photo Research, PR 735). The light-driven voltage characteristic curve and the external quantum efficiency-current density characteristic curve were measured using a computer-controlled source measurement unit and a spectroradiometer. Current efficiency is the ratio of the device's luminous intensity to the injected current. EQE is calculated as the ratio of the number of emitted photons to the number of injected electrons.

[0124] The above method was used to test the performance of the luminescent electrochemical cells prepared in Examples 3 and 4. Figure 3As shown, the maximum brightness of the luminescent electrochemical cell based on formula (II-1) prepared in Example 3 is 3754 cd / m 2 , the current efficiency is 4.07 cd / A, and the maximum external quantum efficiency (EQEmax) is 1.96%; Example 4 introduces a chiral 1-butyl-3-methylimidazolium camphorsulfonate ionic liquid into the light-emitting layer, and uniformly mixes and dissolves it with the ionic metal iridium complex of formula (II-1) in ethanol according to a specific molar ratio. The same device process as Example 3 is used to prepare a light-emitting electrochemical cell, which significantly improves the electroluminescent performance of the light-emitting electrochemical cell, and the maximum brightness is 7010 cd / m 2 The current efficiency was 10.60 cd / A, and the maximum external quantum efficiency (EQEmax) was 4.08%. Compared with Example 3, the introduction of the ionic liquid in Example 4 improved the electroluminescence performance of the electrochemical cell by 2.1 times.

[0125] The present inventors have found through experiments that the performance of the light-emitting electrochemical cell of formula (II-2) is basically consistent with that of formula (II-1). Due to limited space, they are not listed one by one.

[0126] (2) The electrochemical cells prepared in Examples 3 and 4 were tested for their electrochemically induced circularly polarized luminescence spectra. Figure 4 shown.

[0127] The maximum emission peak position of the electrochemical cell prepared using formula (II-1) in Example 4 is 582 nm, which is slightly blue-shifted compared with the electrochemical cell prepared using formula (II-1) in Example 3. In addition, the electrochemical circularly polarized luminescence intensity is significantly enhanced. EL Increased to 2.28×10 -3 This shows that the introduction of chiral ionic liquid increases the concentration of chiral anions in the light-emitting layer film, which not only improves the luminous efficiency of the device, but also enhances its electro-induced circularly polarized luminescence performance, thus achieving both high luminous efficiency and |g EL |This paper provides technical guidance for the design and preparation of high-value electro-circularly polarized light-emitting devices.

[0128] In addition, from Figure 4 It can be seen that the circularly polarized luminescence spectrum analysis of the electrochemical cell prepared using formula (II-2) is basically consistent with that of the electrochemical cell prepared using the above formula (II-1).

[0129] Need to explain, Figure 3 and 4Formula (II-1) represents a luminescent electrochemical cell prepared based on the ionic metal iridium complex of formula (II-1), formula (II-1) + IL represents a luminescent electrochemical cell prepared based on the ionic metal iridium complex of formula (II-1) and a chiral ionic liquid, formula (II-2) represents a luminescent electrochemical cell prepared based on the ionic metal iridium complex of formula (II-2), and formula (II-2) + IL represents a luminescent electrochemical cell prepared based on the ionic metal iridium complex of formula (II-2) and a chiral ionic liquid.

[0130] The inventors also conducted the above test on the ionic metal iridium complexes prepared in other examples, and the results were basically the same. Due to limited space, they are not listed one by one.

[0131] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. An ionic metal iridium complex, characterized in that The ionic metal iridium complex is composed of an octahedral iridium complex cation and a chiral camphorsulfonate anion; the structural formula of the ionic metal iridium complex is shown in formula (I), Wherein, "*" in formula (I) represents the chirality of camphorsulfonate, which is left-handed (-) or right-handed (+). The R is one of H and halogen; R' is one of H and C1-C6 alkyl.

2. A method for preparing the ionic metal iridium complex according to claim 1, characterized in that: The iridium complex whose anion is chloride ion and silver camphorsulfonate are dissolved in an organic solvent, heated under reflux to carry out ion exchange reaction, and recrystallized to obtain the ionic metal iridium complex.

3. The method for preparing the ionic metal iridium complex according to claim 2, wherein: The molar ratio of the iridium complex whose anion is chloride ion to silver camphorsulfonate is 1:1-1.

5.

4. The method for preparing the ionic metal iridium complex according to claim 2 or 3, characterized in that: The silver camphorsulfonate is left-handed (-) or right-handed (+) silver camphorsulfonate.

5. The method for preparing the ionic metal iridium complex according to claim 2 or 3, characterized in that: The organic solvent is one or more of methanol, acetonitrile, tetrahydrofuran, dichloromethane, dioxane, dimethylformamide or ethanol.

6. The method for preparing the ionic metal iridium complex according to claim 2 or 3, characterized in that: The heating temperature is 40-100°C and the reflux time is 0.5-1h.

7. The method for preparing the ionic metal iridium complex according to claim 2 or 3, characterized in that: The recrystallization solvent is one or more of dichloromethane, acetonitrile, methanol, ethanol, acetone, tetrahydrofuran, propanol, ether, petroleum ether or n-hexane.

8. Use of the ionic metal iridium complex according to claim 1 or the ionic metal iridium complex prepared by any one of the methods of claims 2 to 7 in a circularly polarized luminescent material, a circularly polarized light-emitting device or a circularly polarized light-emitting layer.

9. The use according to claim 8, characterized in that The circularly polarized luminescent material is made into the luminescent layer of the circularly polarized luminescent electrochemical cell.

10. The use according to claim 9, characterized in that The ionic metal iridium complex is mixed with a chiral ionic liquid or the ionic metal iridium complex is used to prepare a light-emitting layer.

11. The use according to claim 10, characterized in that The ionic metal iridium complex or the ionic metal iridium complex mixed with chiral ionic liquid is coated on the smooth layer to prepare a luminescent layer, and then a double-layer circularly polarized luminescent electrochemical cell is formed with a transparent substrate and a metal electrode.

12. The use according to claim 10 or 11, characterized in that The chiral ionic liquid is 1-butyl-3-methylimidazole camphorsulfonate, and the camphorsulfonate radical is left-handed (-) or right-handed (+).

13. The use according to claim 11, characterized in that The smooth layer is formed by coating PMMA or PEDOT:PSS dissolved in ethanol, isopropanol or n-butanol.

14. The use according to claim 10, characterized in that When the ionic metal iridium complex and the chiral ionic liquid are mixed and coated on the smooth layer to prepare the light-emitting layer, the molar ratio of the chiral ionic liquid to the ionic metal iridium complex is 0.25-2.

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