CN110563762B

CN110563762B - PPh3Copper complex with dpts, preparation method, application and device thereof

Info

Publication number: CN110563762B
Application number: CN201910774788.4A
Authority: CN
Inventors: 柳利; 郭邦克
Original assignee: Hubei University
Current assignee: Hubei University
Priority date: 2019-08-21
Filing date: 2019-08-21
Publication date: 2022-02-08
Anticipated expiration: 2039-08-21
Also published as: CN110563762A

Abstract

The invention belongs to the technical field of copper complexes, and particularly relates to PPh₃And dpts, and methods of making, using, and devices. The invention provides a mononuclear four-coordination cuprous halide (I) complex containing trimethylsilyl thiophene diphosphine and triphenylphosphine and emitting blue-green to yellow-green light. The luminescent color of the complex can be regulated and controlled by adopting different halogen ligands. Due to the excellent light-emitting performance and good thermal stability of each complex, the series of compounds are expected to be applied to OLED as light-emitting materials with low cost, high efficiency, adjustable color and rich sources.

Description

PPh3Copper complex with dpts, preparation method, application and device thereof

Technical Field

The invention belongs to the technical field of copper complexes, and particularly relates to PPh₃And dpts, and methods of making, using, and devices.

Background

Photoluminescent metal complexes have attracted considerable attention for their potential application in Organic Light Emitting Diodes (OLEDs). Over the past few decades, electroluminescent materials containing copper (I) organic compounds have received much attention as a substitute for expensive, low-reserve iridium, platinum noble metal phosphorescent materials.

Having MLCT and XLCT and low singlet and triplet energy gaps (Δ E)_ST) The copper (I) complex shows Thermal Activation Delayed Fluorescence (TADF) emission, can effectively improve the low spin-orbit coupling effect of copper metal compared with noble metal, successfully traps more triplet excitons, and theoretically can improve the internal quantum efficiency to 100%. Neutral copper (I) complexes containing bidentate, tridentate and heteroleptic types show TADF effect and are attracting more and more attention. Therefore, a copper complex fluorescent material is further developed and applied to the OLED to gradually replace an iridium complex and reduce the material cost.

Disclosure of Invention

In order to solve the defects of the prior art, the invention provides PPh₃And dpts, and methods of making, using, and devices.

The technical scheme provided by the invention is as follows:

PPh₃and dpts, having the general structural formula:

wherein X is I, Br or Cl.

The copper (I) complex provided by the invention respectively emits strong blue green light, green light and yellow green light at room temperature, has good quantum efficiency and thermal stability, and can be used as a fluorescent material of an OLED. And because of the large molecular weight and good thermal stability, OLEDs can be assembled by vacuum evaporation and solution methods.

The complex 1-3 with X being I, Br or Cl respectively emits strong blue green light, green light and yellow green light at room temperature, the maximum emission wavelength is 485-535nm, and the absolute internal quantum efficiency phi of the solid state at room temperature_PL＝ 0.29-0.52。

The invention also provides the PPh provided by the invention₃And dpps, by the following method:

wherein X is I, Br or Cl.

The PPh can be prepared by the method₃And dpts of copper complexes.

The invention also provides the PPh provided by the invention₃And dpts as fluorescent materials.

The complex provided by the invention respectively emits strong blue-green light, green light and yellow-green light at room temperature, and has good quantum efficiency.

Further, the fluorescent material can be used as a heat activation delayed fluorescent material.

In particular, the fluorescent material is used as a blue green, green or yellow green fluorescent material.

Further, the organic light emitting diode material.

The complex provided by the invention can be used for assembling OLEDs by a vacuum evaporation method and a solution method, and the obtained device has high external quantum efficiency.

The invention also provides an OLED device, which at least comprises an organic light-emitting layer, wherein the material of the organic light-emitting layer is selected from any one or more of the complexes provided by the invention.

Preferably, the material of the organic light-emitting layer is a complex in which X is Br.

The complex can be used for assembling an OLED device, and has good thermal stability and high external quantum efficiency. The solution method enables the complex assembled undoped device to emit stable yellow-green light, and CIE (x, y) is (0.43, 0.52). The maximum External Quantum Efficiency (EQE) of the device was 7.74%.

The luminescent material provided by the invention can be applied to OLED as a luminescent material with low cost, high efficiency, adjustable color and rich sources.

Drawings

FIG. 1 shows the reaction of the complex 1 provided by the invention in deuterated chloroform¹H NMR spectrum.

FIG. 2 shows the reaction of complex 2 in deuterated chloroform¹H NMR spectrum.

FIG. 3 shows the reaction of complex 3 in deuterated chloroform¹H NMR spectrum.

FIG. 4 shows nuclear magnetic phosphorus spectra of the complex 1 provided by the invention in deuterated chloroform.

FIG. 5 shows the nuclear magnetic phosphorus spectrum of the complex 2 provided by the invention in deuterated chloroform.

FIG. 6 shows the nuclear magnetic phosphorus spectrum of the complex 3 provided by the invention in deuterated chloroform.

FIG. 7 is a mass spectrum of the complex 1 provided by the present invention.

FIG. 8 is a mass spectrum of the complex 2 provided by the present invention.

FIG. 9 is a mass spectrum of a complex 3 provided by the present invention.

FIG. 10 is an ORTEP diagram of complexes 1-3.

FIG. 11 shows complexes 1-3, dpps and PPh at 298K₃In CH₂Cl₂The absorption spectrum of (1).

FIG. 12 is a graph of the HOMO and LUMO electron clouds of complexes 1-3 with the geometry of the ground state S0 of the molecule optimized.

FIG. 13 is the normalized emission spectrum (a) of complexes 1-3 in the solid state at 295K.

FIG. 14 is a normalized emission spectrum (b) of complexes 1-3 in the solid state at 77K.

FIG. 15 is a CIE diagram of complexes 1-3.

FIG. 16 is a TGA profile of complexes 1-3.

Fig. 17 is a device assembled from complex 2. Wherein: (a) is an energy level diagram of the device; (b) the electroluminescence spectrum and CIE coordinates; (c) current density-voltage-luminance (J-V-L) curves; (d) is an external quantum efficiency-luminance curve.

Detailed Description

The principles and features of this invention are described below in conjunction with examples which are set forth to illustrate, but are not to be construed to limit the scope of the invention.

Reagent: all reagents were commercially available and analytically pure. Tetrahydrofuran (THF) water was re-evaporated over sodium wire under nitrogen atmosphere before use and benzophenone was used as indicator. 2-trimethylsilyl-3, 4-bis (diphenylphosphino) thiophene (dpts) was synthesized according to the reported literature.

The instrument comprises the following steps: the infrared spectrum was obtained by a Nicolet iS10FTIR Fourier transform infrared spectrometer (KBr pellet),¹h and³¹p NMR Spectroscopy Using a Varian 500MHz NMR spectrometer with deuterium-containing reagent lock field and reference, chemical shifts were measured in ppm and hydrogen spectra were measured in SiMe₄As a standard, the phosphorus spectrum is 85% H₃PO₄Is a standard. The high resolution mass spectrum was analyzed by a Bruker Autoflex MALDI-TOF mass spectrometer, and the elemental analysis of C and H was performed by a Vario Micro Cube elemental analyzer. The single crystal structure of the complex 1-3 adopts a Bruker APEX DUO diffractometer. The ultraviolet visible spectrum adopts a Unicam He lambda ios alpha spectrometer, and the photoluminescence spectrum adopts an FLS920 steady-state and time-resolved fluorescence spectrometer. The solid state quantum efficiency is measured by using a Hamamatsu system and an integrating sphere. Thermogravimetric analysis A Perkin-Elmer Diamond TG/DTA thermal analyzer was used.

1.1 Synthesis

1.1.1. Synthesis of Complex 1

Cuprous iodide (72.6mg,0.38mmol) was added to a solution of dpps (200.0mg,0.38mmol) in 30mL of dichloromethane, the mixture was stirred at room temperature for 4 hours in the dark to form a yellow suspension, the precipitate was filtered off, PPh was added to the filtrate₃(100.0mg,0.38mmol) and stirring continued for 2 hours to form a yellow solution, 30mL acetonitrile was slowly added to the reaction along the vial wall and slowly evaporated at room temperature to give yellow-green crystals (310.6mg, 83.4%).¹H NMR(500MHz, CDCl₃)δ:7.90-7.67(m,3H),7.62(s,1H),7.23-7.00(m,24H),6.90-6.70(m,8H), -0.21(s,9H).³¹P NMR(200MHz,CDCl₃)δ:3.99(s,PPh₃),-14.90(d,J＝168 Hz,4-PPh₂),-22.02(d,J＝164Hz,3-PPh₂).Anal.Calcd for C₄₉H₄₅CuIP₃SSi:C, 60.21；H,4.64.Found:C,60.26；H,4.60.HRMS(ESI):m/z calcd for [C₄₉H₄₅CuP₃SSi]⁺,849.1520.Found:849.1547.

1.1.2. Synthesis of Complex 2

Cuprous bromide (54.5mg,0.38mmol) was added to a solution of dpps (200.0mg,0.38mmol) in 30mL of dichloromethane, the mixture was stirred at room temperature for 4 hours in the dark to form a yellow suspension, the precipitate was filtered off, PPh was added to the filtrate₃(100.0mg,0.38mmol) and stirring continued for 2 hours to form a yellow solution, 30mL acetonitrile was slowly added to the reaction along the vial wall and slowly evaporated at room temperature to give yellow-green crystals (294.0mg, 82.9%).¹H NMR(500MHz,CDCl₃)δ: 7.92-7.73(m,4H),7.59(t,J＝5Hz,1H),7.33-7.27(m,4H),7.23(t,J＝7.5Hz, 5H),7.17-7.00(m,15H),6.90-6.65(m,7H),-0.22(s,9H).³¹P NMR(200MHz, CDCl₃)δ:5.20(s,PPh₃),-13.44(d,J＝136Hz,4-PPh₂),-20.81(d,J＝132Hz, 3-PPh₂).Anal.Calcd for C₄₉H₄₅BrCuP₃SSi:C,63.25；H,4.88；Found:C,63.29； H,4.84.HRMS(ESI):m/z calcd for[C₄₉H₄₅CuP₃SSi]⁺,849.1520,found: 849.1548.

1.1.3. Synthesis of Complex 3

Cuprous chloride (37.6mg,0.38mmol) was added to a solution of dpps (200.0mg,0.38mmol) in 30mL of dichloromethane, the mixture was stirred at room temperature for 4 hours in the dark to form a yellow suspension, the precipitate was filtered off, PPh was added to the filtrate₃(100.0mg,0.38mmol) and stirring continued for 2 h to form a yellow solution, 30mL acetonitrile was slowly added to the reaction along the vial wall and slowly evaporated at room temperature to give yellow-green crystals (269.5mg, 79.8%).¹H NMR(500MHz,CDCl₃)δ: 7.97-7.75(m,4H),7.57(t,J＝5Hz,1H),7.33-7.27(m,4H),7.21(t,J＝7.5Hz, 4H),7.15-7.00(m,15H),6.90-6.60(m,8H),-0.23(s,9H).³¹P NMR(200MHz, CDCl₃)δ:5.96(s,PPh₃),-12.56(d,J＝150Hz,4-PPh₂),-20.03(d,J＝150Hz, 3-PPh₂).Anal.Calcd for C₄₉H₄₅ClCuP₃SSi:C,66.43；H,5.12；Found:C,66.47；H, 5.10.HRMS(ESI):m/z calcd for[C₄₉H₄₅CuP₃SSi]⁺,849.1520,found:849.1549.

2 results and analysis

2.1. Synthesis and structural characterization

The synthesis route of the Cu (I) complex is as follows. And adding triphenylphosphine into a dichloromethane mixture of CuX and dpps, and separating and purifying to obtain the complex 1-3, wherein the yield is 79.8-83.4%. All Cu (I) complexes exist stably in a solid form in air, have high purity and are soluble in solvents such as dichloromethane and acetonitrile. The structures of the compounds are characterized by nuclear magnetism, mass spectrum, single crystal X-ray diffraction and the like.

2.1.1. ¹HNMR spectra

FIGS. 1-3 show the reaction of complex 1-3 in deuterated chloroform¹And H NMR spectrum, wherein chemical shift, integral and peak split conditions are consistent with the structure.

2.1.2 ³¹P NMR spectra

FIGS. 4-6 are the deuterium-substituted complexes 1-3Nuclear magnetic phosphorus spectra in chloroform. Three groups of signal peaks appear in the nuclear magnetic phosphorus spectrogram of the complex 1-3, which indicates that three P atoms with different chemical environments exist in the complex 1-3, and PPh on 2 thiophene rings₂The structure is asymmetric. The integrated ratio of the three sets of signal peaks is 1:1:1, indicating that there are 3 different P atoms corresponding to the chemical environment. The chemical shifts of the complexes 1 to 3 are respectively 3.99, -14.90, -22.02; 5.20, -13.44, -20.81 and 5.96, -12.56, -20.03, the low field region 3.99-5.96 is a single peak corresponding to PPh₃The peak of-14.90 to-12.56 and the peak of-22.02 to-20.03 correspond to the P atoms connected to the 4-and 3-positions of the thiophene ring, respectively, and are bimodal, indicating that there is a coupling effect between P and P.

2.1.3HRMS-ESI spectra

The complexes 1-3 are characterized by adopting a high-resolution electrospray ionization mass spectrum, and the spectrum shows that the molecular ion peak of the complex is not seen, and the peak with the highest intensity in the spectrum corresponds to fragment ions of the complex without one halogen atom and is consistent with a theoretical value.

2.1.4 Crystal Structure

TABLE 1 Crystal data for complexes 1-3

TABLE 2 bond Angle (deg) and bond Length of the Crystal Structure of complexes 1-3

Data of

The crystal structure of the complex 1-3 is shown in FIG. 10, and the crystallographic data are shown in tables 1 and 2. X-ray crystallography studies of complexes 1-3 show that the mononuclear copper (I) center is connected to three P atoms and one halogen atom, exhibiting highly distorted tetrahedral coordination. 1. The sum of the angles around the center of cu (i) in fig. 2 and 3 is 422.7 °,420.52 ° and 417.75 °. In complexes 1-3, mononuclear copperThe center is connected to three P and one halogen atom in a highly distorted tetrahedral configuration. The P-Cu-P bond angles are 84.44-89.80 deg., which is quite different from the common tetrahedral bond angles because of the small bite angles present in the dpts ligands. As shown in Table 2, the Cu-X bond length in complexes 1-3 increases with the increase of the Van der Waals radius of the halogen. 2 and 3, the nearest distances of Br-to-H and Cl-to-H are respectively

And

in the solid state, intermolecular C-H … π interactions exist between the benzene rings in 2 and 3, with the closest C-to-H distances of 2.809 and 3, respectively

The closest distance between the C-H bond of the methyl group in 1 and the C atom of the benzene ring is

1, an intermolecular force exists between S and I, and the distance S-to-I is

PPh in 2₂The benzene rings H have intermolecular forces, and the distance between H and H is

S and PPh in 3₂Has a closest distance of 2.964 and a closest distance of 2.964 to the benzene ring H, C, respectively

All these forces cause complex 1 to form 1D, 3D and 2D structures along the a-axis, 2 along the a, b, c-axis and 3 along the a, b-axis.

2.2. Photophysical properties and molecular orbital calculations

Ligands at room temperaturedpts、PPh₃And complexes 1-3 in CH₂Cl₂The absorption spectrum in (2) is shown in FIG. 11. dpps and PPh₃The absorption spectra of (A) and (B) were each 255(ε 2.07X 10)⁴M^-1cm^-1)、263nm(ε＝ 1.04×10⁴M^-1cm^-1) Has a strong absorption band, which is characteristic of thienylphosphine compounds and arylphosphine compounds. The absorption peak is due to a mixed transition of electron transfer of n → pi and pi → pi, the former being electron transition from lone pair electron on P atom to empty anti-bond pi orbital on thiophene ring or benzene ring, the latter being transition from internal electron on phenyl or thiophene ring. The complex 1-3 is (1.59-2.50) multiplied by 10 at 257nm⁴M^-1cm^-1]、280-288nm[ε＝(1.29～2.33)×10⁴M^-1cm^-1]A strong absorption band occurs, and a weaker absorption tail band occurs at 330-390 nm. The HOMO orbitals in complexes 1-3 were mainly distributed on the copper, halogen and phosphorus atoms by TDDFT calculation (FIG. 12), and the LUMO orbitals were mainly distributed on the thiophene rings, indicating that the lowest excited state of complexes 1-3 is composed of MLCT, XLCT and intraligand transitions.

FIG. 13 is an emission spectrum of complexes 1 to 3 in the solid powder state at 295K and 77K, and Table 6 shows the maximum emission wavelength, the lifetimes of 295K and 77K, the quantum efficiency, and the adiabatic excitation energy (S) calculated using T₁And T₁Energy level, and S₁And T₁The energy level difference therebetween). The complexes 1-3 respectively emit strong blue green light, green light and yellow green light at room temperature, the maximum emission wavelength is 485-plus 535nm, and the absolute internal quantum efficiency phi of the solid state at room temperature_PL0.29-0.52. These emission spectra are broad and unstructured, indicating that the emission excited state has charge transfer properties [16 ]]. 1-3 have an emission maximum wavelength (λ max) of 1<2<3, in accordance with the sequence of the halogen ligand field strengths (I)<Br<C l), it is likely that the 1-3 excited state is affected to some extent by the X → pi (ttbp) charge transfer transition. In FIG. 15, the chromaticity coordinates of complexes 1 to 3 were (0.2073, 0.3429), (0.2440, 0.4409) and (0.3629, 0.5147), respectively, based on the fluorescence spectrum of 295K. And the previously reported mononuclear copper (I) halide complex containing dimethylthiophene diphosphine and triphenylphosphineSolid powder of (2) luminescence phase ratio (lambda)_em459-484 nm), the maximum emission wavelength has red-shifted by 26-51 nm. The introduction of 1 trimethylsilyl group is illustrated to have no effect on LUMO orbital level reduction as compared to two methyl groups.

At 77K, the emission wavelengths of complexes 1-3 were 473, 498 and 536nm, respectively. The emission wavelengths of

complexes

1 and 2 were blue-shifted compared to the maximum emission wavelength at room temperature, and the emission wavelength of complex 3 was hardly changed. The blue shift is due to suppression of the distortion of the excited state structure caused by vibration and rotation at low temperature. The complex 1-3 under 295K has a radiation attenuation life (27.6-39.9 mus) of microsecond level, which is1 order of magnitude shorter than the life (101-910 mus) under 77K, and shows a TADF phenomenon. Radiation decay Rate constant (K) of 1-3 at 295K_r) Is 1.03 to 1.34 x 10⁴ s^-1。

Table 6 shows the singlet and triplet energy levels and Δ E (S) of the complexes 1 to 3 obtained by calculation₁ T₁) Energy level difference. The energy level differences of S1 and T1 of complexes 1-3 were 0.1054, 0.1000 and 0.1166eV, respectively, and the small energy level differences provide further evidence that complexes 1-3 had TADF effect.

TABLE 6 photophysical data of complexes 1-3 in the powder state

^aEmission peak wavelength.

^bEmission lifetime, experimental error ± 5%.

^cAbsolute quantum efficiency in solid state, experimental error ± 5%.

^dRadiation decay rate constant, k_r＝Ф/τ

^eUsing the calculated adiabatic excitation energy (S)₁And T₁Energy level, and S₁And T₁Energy level difference between

2.4 thermal Properties

Good thermal stability of the complex to organic hairThe application of the photodiode is very important. The decomposition temperature of the complex 1-3 under nitrogen atmosphere is 226-256 ℃ determined by thermogravimetric analysis (TGA) (figure 16), and the complex has better thermal stability. Complex 3 shows one-step weight loss of about 60% at about 302 ℃, which is attributable to halogen loss and PPh₃A ligand. The weight loss at step 2, around 468 ℃ is attributable to decomposition or loss of the dpps ligand. The

complexes

1 and 2 show one-step weight loss at about 470 ℃, which can be attributed to halogen loss and PPh₃Decomposition or loss of ligands and dpps ligands. These data indicate that these complexes can be used to assemble OLEDs using vacuum evaporation and solution methods.

2.5 electroluminescent Properties

The structure of the device assembled by the solution method is shown in the specification, wherein ITO/PEDOT is PSS (40 nm)/complex 2(30 nm)/TPBi (30nm)/LiF (1nm)/Al (100 nm). The energy diagram of the device is shown in fig. 17a, fig. 17b is the Electroluminescence (EL) spectrum of the device, the maximum emission peak is 564nm, the CIE chromaticity coordinates are (0.43,0.51), and the device emits yellow-green light, and fig. 17c and 17d are the current density-voltage-luminance (J-V-L) curve and the external quantum efficiency-luminance curve of the device, respectively. The maximum External Quantum Efficiency (EQE) of the device is 7.74%, and the maximum brightness is 234.0cd/m²。

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1.PPh₃And dpts, characterized by the general structural formula:

wherein X is I, Br or Cl.

2. The PPh of claim 1₃A method for preparing a copper complex with dpps, characterized in that the method comprises:

wherein X is I, Br or Cl.

3. The PPh of claim 1₃And dpts, characterized in that: as a fluorescent material.

4. Use according to claim 3, characterized in that: as a thermally activated delayed fluorescence material.

5. Use according to claim 3 or 4, characterized in that: as blue green, green or yellow green fluorescent material.

6. Use according to claim 3, characterized in that: as organic light emitting diode materials.

7. An OLED device comprising at least an organic light-emitting layer, characterized in that: the material of the organic light-emitting layer is selected from any one or a mixture of more of the complexes provided in claim 1.

8. The OLED device of claim 7, wherein: the material of the organic light-emitting layer is the complex of Br as X provided in claim 1.