A blue thermally induced delayed fluorescence polymer and a preparation method and application thereof

Abstract

This invention relates to the field of organic light-emitting materials, specifically a blue thermally induced delayed fluorescence polymer, its preparation method, and its applications. The polymer provided by this invention has a structure of Formula 1, in which diphenylsilane and acridine in the TADF light-emitting unit are directly linked, sp... 3 Hybridized silicon atoms can effectively break the conjugation of the polymer backbone, increasing the triplet energy level. Introducing alkyl substituents at the ortho-position of the diphenylsilane and TADF unit linkage sites increases the torsion angle of the aromatic ring, further enhancing the triplet energy level and reducing the energy difference between the singlet and triplet states. Simultaneously, the increased molecular rigidity suppresses nonradiative transitions. Experimental results show that this type of polymer not only possesses a high triplet energy level but also high fluorescence quantum efficiency, exhibiting efficient blue thermally induced delayed fluorescence emission. Furthermore, the polymer preparation method provided by this invention is simple, and the resulting polymer exhibits excellent solubility and film-forming properties.

Description

Technical Field

[0001] This invention relates to the field of organic light-emitting materials, specifically a blue thermally induced delayed fluorescence polymer, its preparation method, and its applications. Background Technology

[0002] Thermally induced delayed fluorescence (TADF) materials have small singlet-triplet energy level differences (ΔE). ST Tripletic excitons can be converted into singlet excitons through a reverse intersystem crossing process, achieving 100% exciton utilization and effectively improving the efficiency of organic light-emitting diodes (OLEDs). Compared to phosphorescent complexes, TADF materials are pure organic compounds, making it easier to control their luminescence properties through structural design and modification. Furthermore, they do not require precious metals, making them more suitable for commercial applications. Since Professor Adachi of Kyushu University in Japan made a breakthrough in the molecular design and device application of organic TADF materials in 2012, this field has attracted widespread attention from the academic and industrial communities both domestically and internationally. Numerous TADF luminescent materials have been reported, with corresponding device performance even surpassing that of phosphorescent OLEDs. Among them, small TADF molecule materials, through careful control and optimization of the device manufacturing process using vacuum evaporation technology, have demonstrated superior performance. However, the stringent processing conditions increase the complexity of device production, posing challenges to the manufacturing of high-resolution and large-area devices and increasing production costs.

[0003] Polymers possess excellent solubility and film-forming properties. When used as luminescent materials in electroluminescent devices, they can be fabricated using simple solution processing methods such as spin coating, inkjet printing, and printing, showing great application potential in large-size and flexible displays. Currently, green to red TADF OLED devices have achieved satisfactory performance, with external quantum efficiencies exceeding 25%. However, the development of blue TADF polymers lags far behind. As one of the three primary color materials, blue materials are essential for realizing full-color, high color rendering index OLED devices; therefore, developing efficient blue thermally induced delayed fluorescence polymers is crucial.

[0004] Currently, TADF polymers are mainly constructed by combining donor and acceptor units into the polymer backbone or side chains. The strong interaction between the donor and acceptor units reduces the energy level of the singlet state, resulting in a redshift of the emission spectrum, which complicates blue emission. At the same time, the triplet energy level of the blue TADF luminescent unit is usually higher than that of the conjugated backbone of the main-chain TADF polymer, which makes it impossible to prevent the reverse transfer of triplet energy from the TADF unit to the backbone, thus causing non-radiative recombination in the backbone. Although the design of non-conjugated backbone side-chain TADF polymers can effectively solve this problem, the insulation of the non-conjugated backbone itself significantly limits the device performance of OLEDs. Another problem with blue TADF polymers is the accumulation of long-lived triplet excitons, which makes the excitons more vulnerable to the annihilation process, thus having a negative impact on the device efficiency. Therefore, how to obtain a polymer with a simple synthesis method and high photoluminescence efficiency to achieve efficient blue TADF emission is the technical problem to be solved currently. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a blue thermally activated delayed fluorescence polymer, its preparation method and application. The blue thermally activated delayed fluorescence polymer provided by the present invention has blue TADF emission and high luminescence efficiency.

[0006] The present invention provides a blue thermally activated delayed fluorescence polymer having a structure of Formula 1:

[0007]

[0008] Wherein, R1 and R3 are independently selected from C6-C 30 aryl;

[0009] R2 and R4 are independently selected from H or C1-C8 alkyl;

[0010] R5, R6 and R7 are independently selected from C1-C 20 alkyl or C6-C 30 aryl;

[0011] A is selected from C6-C with electron-withdrawing ability 50 aryl;

[0012] n is 2-200;

[0013] 0 < x < 0.5; preferably 0.01 ≤ x < 0.5. <0,

[0014] The blue thermally induced delayed fluorescence polymer of the present invention may or may not have end-capping groups. In some embodiments of the present invention, if the blue thermally induced delayed fluorescence polymer of the present invention has end-capping groups, then it is a blue thermally induced delayed fluorescence polymer having the structure of Formula 1-a;

[0015]

[0016] Wherein, R1 to R7, A, x, and n are the same as described above and will not be repeated; R0 is a capping group. In one embodiment of the present invention, the capping group is phenyl, thiophene, or pyridyl, preferably unsubstituted phenyl.

[0017] R1 and R3 in this invention are independently selected from C6 to C6. 30 Aromatic group. Preferably, R1 and R3 are independently selected from unsubstituted C6-C6 groups. 30 Aromatic group, or C1-C 20 Alkyl groups and C1-C 20 At least one substituted C6-C of the alkoxy group 30 Aromatic group. More preferably, R1 and R3 are independently selected from phenyl, tolyl, ethylphenyl, butylphenyl, hexylphenyl, octylphenyl, methoxyphenyl, or dimethylaminephenyl. In some embodiments of the invention, R1 and R3 are the same. In some embodiments of the invention, R1 and R3 are both phenyl.

[0018] In this invention, R2 and R4 are independently selected from H or C1-C8 alkyl groups. Preferably, R2 and R4 are independently selected from H, methyl, ethyl, propyl, butyl, pentyl, or hexyl. In some embodiments of this invention, R2 and R4 are the same. In some embodiments of this invention, both R2 and R4 are methyl. When both R2 and R4 are methyl, this invention increases the torsion angle between the diphenylsilane and acridine ring, reduces the conjugation degree of the donor group of the light-emitting unit, and improves the triplet energy level of the main chain; at the same time, it increases molecular rigidity, effectively weakens nonradiative transitions, and greatly improves the photoluminescence quantum yield (PLQY).

[0019] The R5 mentioned in this invention is selected from C1 to C2. 20 Alkyl or C6-C 30 Aromatic group. Preferably, R5 is selected from unsubstituted C1-C1 groups. 20 Alkyl, unsubstituted C6-C 30 Aromatic group, or C1-C 20 Alkyl groups and C1-C 20 At least one substituted C6-C of the alkoxy group 30Aromatic group. More preferably, R5 is selected from acetyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecanyl, butylphenyl, hexylphenyl, octylphenyl, decylphenyl, undecylphenyl, tridecylphenyl, heptadecanylphenyl, hexoxyphenyl, octylphenyl, decoxyphenyl, undecyloxyphenyl, tridecyloxyphenyl, or heptadecanyloxyphenyl.

[0020] R6 and R7 in this invention are independently selected from C1 to C2. 20 Alkyl or C6-C 30 Aromatic group. Preferably, R6 and R7 are independently selected from unsubstituted C1 to C1 groups. 20 Alkyl, unsubstituted C6-C 30 Aromatic group, or C1-C 20 Alkyl groups and C1-C 20 At least one substituted C6-C of the alkoxy group 30 Aromatic group. More preferably, R6 and R7 are independently selected from methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, phenyl, methylphenyl, butylphenyl, hexylphenyl, octylphenyl, decylphenyl, methoxyphenyl, hexoxyphenyl, octylphenyl, or decoxyphenyl. In some embodiments of the present invention, R6 and R7 are the same. In some embodiments of the present invention, both R6 and R7 are selected from n-hexyl (-C6H) 13 ).

[0021] The A in this invention is selected from C6 to C6, which have electron-withdrawing capabilities. 50 The aromatic group. Preferably, A is a C6-C6 group containing an electron-withdrawing group. 50 The aromatic group. More preferably, A is a C6-C6 group containing an electron-withdrawing group. 30 The aromatic group. More preferably, the A is selected from groups having the formula Aa;

[0022]

[0023] Wherein, R8 is selected from unsubstituted triazine, cyano-substituted triazine, trifluoromethyl-substituted triazine, C1-C14... 20 Alkyl-substituted triazine, C6-C 30 Aromatic group-substituted triazine group, unsubstituted pyrimidinyl group, cyano-substituted pyrimidinyl group, trifluoromethyl-substituted pyrimidinyl group, C1-C 20 Alkyl-substituted pyrimidinyl, C6-C 30 Aromatic group-substituted pyrimidinyl, unsubstituted pyridinyl, cyano-substituted pyridinyl, trifluoromethyl-substituted pyridinyl, C1-C 20 Alkyl-substituted pyridyl, C6-C30 Aromatic group-substituted pyridinyl group;

[0024] Alternatively, A may be selected from groups having the formula Ab;

[0025]

[0026] Wherein, R9 is selected from unsubstituted C1 to C2. 20 Aromatic or cyano-substituted C1-C 20 Aromatic or trifluoromethyl substituted C1-C 20 Aromatic group;

[0027] Alternatively, A may be selected from groups having the formula Ac;

[0028]

[0029] Wherein, the R 10 and R 11 Independently selected from C1 to C 20 The aromatic group, and the R 10 and R 11 Whether R, B, and R form a ring or not, 10 The three components, R, B, and the phenyl group containing B, may or may not form a ring. 11 The R group, along with B and the phenyl group containing B, may or may not form a ring. Specifically, the R group... 10 and R 11 R and its constituent elements B may or may not form a six-membered ring. 10 The three components, R, B, and the phenyl group containing B, may form a six-membered ring or be acyclic. 11 The R group, along with B and the phenyl group containing B, may form a six-membered ring or be acyclic. More specifically, the R group... 10 and R 11 The R and its constituent elements B form a six-membered heterocyclic ring or acyclic ring. 10 The three components, R, B, and the phenyl group containing B, form a six-membered heterocycle or are acyclic. 11 The three components, B and B, form a six-membered heterocycle or an acyclic ring; the heterocycle is an oxygen-containing heterocycle.

[0030] More preferably, A has the structures shown in formulas A-1, A-2, A-3, A-4, A-5, A-6, A-7, A-8, A-9, A-10, A-11 and A-12:

[0031]

[0032]

[0033] Among them, R12 Independently selected from C1 to C 20 Alkyl or C6-C 30 Aromatic group.

[0034] The number-average molecular weight M of the blue thermally induced delayed fluorescence polymer described in this invention n The fluorescence intensity is 4.0 kDa to 8.0 kDa. In some embodiments of the present invention, the blue thermally induced delayed fluorescence polymer is a polymer with the structure shown in formula (Ia), formula (Ib), formula (Ic), formula (Id), formula (Ie), formula (If), formula (Ig), formula (Ih), formula (Ii), or formula (Ij);

[0035]

[0036]

[0037]

[0038]

[0039] Among them, -C8H appears in equations Ia to Ij 17 All represent octyl groups, and the -C6H appears. 13 All of them represent positive hexobase.

[0040] In some embodiments of the present invention, the blue thermally induced delayed fluorescence polymer has a capping group, wherein the capping group is a phenyl group, which is a polymer with the structure shown in formula (I-1), formula (I-2), formula (I-3), formula (I-4), formula (I-5), formula (I-6), formula (I-7), formula (I-8), formula (I-9) or formula (I-10).

[0041]

[0042]

[0043]

[0044]

[0045] Among them, C8H appears in Equations I-1 to I-10 17 All represent octyl groups, and the C6H groups that appear... 13 All of them represent positive hexobase.

[0046] This invention also provides a method for preparing the blue thermally induced delayed fluorescence polymer described in any of the above technical solutions, comprising the following steps:

[0047] The compounds having the structure of formula B, the structure of formula M, and the structure of formula N were polymerized to obtain a blue thermally induced delayed fluorescence polymer having the structure of formula 1.

[0048]

[0049] X1 is selected from pinacol boronic acid ester group, borate group, methyltin or butyltin, preferably pinacol boronic acid ester group;

[0050] X2 and X3 are independently selected from Br or I, preferably Br;

[0051] Wherein, R1 to R7 and A are the same as described above, and will not be repeated. Preferably, compounds having the structure of formula Ba, the structure of formula Ma, and the structure of formula Na are polymerized to obtain a blue thermally induced delayed fluorescence polymer having the structure of formula 1;

[0052]

[0053] R1 to R7 and A are the same as described above, and will not be repeated here.

[0054] This invention first polymerizes compounds having the structure of formula B, the structure of formula M, and the structure of formula N. Specifically, under a protective gas atmosphere, the compounds having the structure of formula B, the structure of formula M, and the structure of formula N are mixed in an organic solvent to carry out a polymerization reaction, obtaining a blue thermally induced delayed fluorescence polymer having the structure of formula 1. This invention does not have special requirements for the copolymerization conditions; copolymerization methods known in the art are all acceptable. The catalyst for copolymerization is preferably a palladium catalyst, more preferably a divalent palladium catalyst, and most preferably a bis(tri-o-methylphenylphosphine)dichloride palladium (Pd[P(o-tol)3]2Cl2) and tris(dibenzylacetone)dipalladium (Pd2(dba)3) / 2-biscyclohexylphosphine-2′,6′-dimethoxybiphenyl (SPhos) catalyst.

[0055] After polymerization, the product obtained in this invention can be capped to obtain a blue thermally induced delayed fluorescence polymer with the structure of Formula 1-a. This invention does not specifically limit the capping method, but uses methods well-known to those skilled in the art.

[0056] The present invention also provides an organic electroluminescent device, comprising a first electrode, a second electrode, and an organic layer between the first electrode and the second electrode, wherein the organic layer contains the blue thermally induced delayed fluorescence polymer described in any of the above technical solutions.

[0057] This invention provides a blue thermally induced delayed fluorescence polymer, its preparation method, and its applications. The polymer provided by this invention has a structure of Formula 1, in which diphenylsilane and acridine in the TADF luminescent unit are directly linked, sp... 3 Hybridized silicon atoms can effectively break the conjugation of the polymer backbone, increasing the triplet energy level. Introducing alkyl substituents at the ortho-position of the diphenylsilane and TADF unit linkage sites increases the torsion angle of the aromatic ring, further enhancing the triplet energy level and reducing the energy difference between the singlet and triplet states. Simultaneously, the increased molecular rigidity suppresses nonradiative transitions. Experimental results show that this type of polymer not only possesses a high triplet energy level but also high fluorescence quantum efficiency, exhibiting highly efficient blue thermally induced delayed fluorescence emission. Furthermore, the polymer preparation method provided by this invention is simple, and the resulting polymer exhibits excellent solubility and film-forming properties, making it promising for application in solution-processed electroluminescent devices and enabling industrial production. Attached Figure Description

[0058] Figure 1 The following are fluorescence spectra of the polymers in Examples 1-5 in toluene solution;

[0059] Figure 2 The following are fluorescence spectra of the polymers in Examples 6-10 in toluene solution;

[0060] Figure 3 The images show the film fluorescence spectra of the polymers in Examples 1-5;

[0061] Figure 4 The images show the film fluorescence spectra of the polymers in Examples 6-10;

[0062] Figure 5 The transient decay spectra of the polymer films in Examples 1-5 under an argon atmosphere are shown.

[0063] Figure 6 The transient decay spectra of the polymer films of Examples 6-10 under an argon atmosphere are shown. Detailed Implementation

[0064] This invention discloses a blue thermally induced delayed fluorescence polymer, its preparation method, and its applications. Those skilled in the art can refer to this document and appropriately modify the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments, and those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0065] The present invention will be further described below with reference to the embodiments:

[0066] Example 1

[0067] Synthesis of Polymer I-1:

[0068] (1) Preparation of bis(4-boranopinacol ester phenyl)diphenylsilane

[0069] The reaction formula is as follows:

[0070]

[0071] The specific steps are as follows: Under argon atmosphere, bis(4-bromophenyl)diphenylsilane (1 mmol, 0.49 g) was dissolved in 10 mL THF, cooled to -78 °C, and n-butyllithium (1.2 mL, 3 mmol) was added dropwise. After reacting at -78 °C for 1 hour, pinacol isopropoxyborate (0.8 mL, 4 mmol) was added to the reaction system, and the mixture was allowed to return to room temperature naturally. The reaction was allowed to proceed overnight, quenched with 10 mL of deionized water, extracted with ethyl acetate, washed three times with water, dried over anhydrous sodium sulfate, filtered, and the solvent was removed by vacuum distillation to obtain the crude product. Recrystallization from ethanol yielded 0.35 g of bis(4-boranopinacol phenyl)diphenylsilane, with a yield of 60%. 1 H NMR (500MHz, CDCl3) δ7.83-7.78(m,4H),7.59-7.56(m,4H),7.55(dd,J=8.0,1.4Hz,4H),7.45-7.40(m,2H),7.39-7.34(m,4H),1.35(s,24H). 13 C NMR (126MHz, CDCl3) δ137.57,136.39,135.66,133.86,129.61,127.86,83.84,30.93,24.86.

[0072] (2) Synthesis of polymer I-1

[0073] The reaction formula is as follows:

[0074]

[0075] The specific steps are as follows: Under argon atmosphere, M1 (1.0 mmol, 0.588 g), M2 (0.10 mmol, 0.077 g), M3 (0.90 mmol, 0.507 g), and Pd[P(o-tol)3]2Cl2 (0.05 mmol, 40 mg) were dissolved in 8 mL of dry THF solution. The mixture was heated to 75 °C and stirred for 0.5 hours. Then, 1.5 mL of deoxygenated 2 M potassium phosphate aqueous solution was added. After reflux for 18 hours, a phenylboronic acid solution (15 mg / 2 mL) dissolved in tetrahydrofuran was added, and the reaction was continued for 5 hours. Then, 1 mL of bromobenzene solution was added, and the reaction was continued for 5 hours. Finally, a sodium diethylaminothiocarbamate chelating agent (1 g / 15 mL) dissolved in water was added, and the reaction was continued for 10 hours. After the reaction was cooled to room temperature, it was quenched with deionized water, extracted with dichloromethane, washed three times with deionized water, dried over anhydrous sodium sulfate, filtered, concentrated under reduced pressure to about 2 mL, added dropwise to methanol, and polymer was precipitated. After filtration and extraction with acetone for 24 hours, the residue was collected, dissolved again in a small amount of dichloromethane, and precipitated in methanol to give 0.54 g of the target polymer I-1, with a yield of 63%.

[0076] GPC measurement of number-average molecular weight M n It has a molecular weight of 4.2 kDa and a molecular weight distribution index (PDI) of 1.80.

[0077] Among them, C8H 17 It is an octyl group, C6H 13 To establish a sound foundation for oneself.

[0078] Example 2

[0079] Synthesis of Polymer I-2:

[0080] The reaction formula is as follows:

[0081]

[0082] The specific steps are similar to those for polymer I-1, except that the monomer feed ratio M1:M2:M3 is changed to 1:0.2:0.8, resulting in 0.58g of polymer I-2 with a yield of 62%.

[0083] GPC measurement of number-average molecular weight M n It has a molecular weight of 4.1 kDa and a molecular weight distribution index (PDI) of 1.87.

[0084] Among them, C8H 17 It is an octyl group, C6H 13 To establish a sound foundation for oneself.

[0085] Example 3

[0086] Synthesis of Polymer I-3:

[0087] The reaction formula is as follows:

[0088]

[0089] The specific steps are similar to those for polymer I-1, except that the monomer feed ratio M1:M2:M3 is changed to 1:0.4:0.6, resulting in 0.56g of polymer I-3 with a yield of 57%.

[0090] GPC measurement of number-average molecular weight M n It has a molecular weight of 5.6 kDa and a molecular weight distribution index (PDI) of 1.82.

[0091] Among them, C8H 17 It is an octyl group, C6H 13 To establish a sound foundation for oneself.

[0092] Example 4

[0093] Synthesis of Polymer I-4:

[0094] The reaction formula is as follows:

[0095]

[0096] The specific steps are similar to those for polymer I-1, except that the monomer feed ratio M1:M2:M3 is changed to 1:0.6:0.4, resulting in 0.62g of polymer I-4 with a yield of 61%.

[0097] GPC measurement of number-average molecular weight M n It has a molecular weight of 6.3 kDa and a molecular weight distribution index (PDI) of 1.73.

[0098] Among them, C8H 17 It is an octyl group, C6H 13 To establish a sound foundation for oneself.

[0099] Example 5

[0100] Synthesis of Polymer I-5:

[0101] The reaction formula is as follows:

[0102]

[0103] The specific steps are similar to those for polymer I-1, except that the monomer feed ratio M1:M2:M3 is changed to 1:0.8:0.2, resulting in 0.70g of polymer I-5 with a yield of 66%.

[0104] GPC measurement of number-average molecular weight M n It has a molecular weight of 7.0 kDa and a molecular weight distribution index (PDI) of 1.74.

[0105] Among them, C8H 17 It is an octyl group, C6H13 To establish a sound foundation for oneself.

[0106] Example 6

[0107] Synthesis of Polymer I-6:

[0108] (1) Synthesis of bis(4-bromo-3-methylphenyl)diphenylsilane

[0109] The reaction formula is as follows:

[0110]

[0111] The specific steps are as follows: Under argon atmosphere, 1-bromo-4-iodo-2-methylbenzene (44 mmol, 6.3 mL) and 70 mL of dry tetrahydrofuran were added to a 250 mL reaction flask. The mixture was cooled to -78 °C, and n-butyllithium (45 mmol, 18 mL) was added dropwise. The reaction was continued at -78 °C for 1 hour. Then, dichlorodiphenylsilane (20 mmol, 4.3 mL) was slowly added, and the reaction system was gradually restored to room temperature for 10 hours. The reaction was quenched with deionized water, extracted with dichloromethane, and the organic phase was washed three times with water, dried with anhydrous sodium sulfate, filtered, and distilled under reduced pressure to obtain the crude product. The crude product was purified by silica gel column chromatography to obtain 8.32 g of di(4-bromo-3-methylphenyl)diphenylsilane, with a yield of 80%. 1 H NMR (500MHz, CDCl3) δ7.59-7.50(m,6H),7.50-7.43(m,2H),7.43-7.35(m,6H),7.20(dd,J=7.9,1.2Hz,2H),2.38(s,6H). 13 C NMR (126MHz, CDCl3) δ138.43,137.46,136.25,135.17,133.35,133.08,132.00,129.87,128.03,127.46,22.98.

[0112] (2) Synthesis of bis(4-boranoyl pinacol-3-methylphenyl)diphenylsilane

[0113] The reaction formula is as follows:

[0114]

[0115] The specific steps are as follows: Under argon atmosphere, bis(4-bromo-3-methylphenyl)diphenylsilane (1 mmol, 0.52 g) was dissolved in 10 mL of THF, cooled to -78 °C, and n-butyllithium (1.2 mL, 3 mmol) was added dropwise. After reacting at -78 °C for 1 hour, pinacol isopropoxyborate (0.8 mL, 4 mmol) was added to the reaction system. After reacting for 8 hours, the reaction was quenched with water, extracted with ethyl acetate, washed three times with water, dried over anhydrous sodium sulfate, filtered, and distilled under reduced pressure to obtain the crude product. Recrystallization from ethanol yielded 0.37 g of bis(4-boranoyl)-3-methylphenyl)diphenylsilane, with a yield of 60%. 1 H NMR (500MHz, CDCl3) δ7.74 (d, J = 7.3Hz, 2H), 7.56-7.51 (m, 4H), 7.43-7.38 (m, 2H), 7.38-7.31 (m, 8H), 2.48 (s, 6H), 1.34 (s, 24H). 13 C NMR (126MHz, CDCl3) δ143.67,137.55,137.02,136.43,134.80,134.20,132.82,129.47,127.78,83.50,24.90,22.33.

[0116] (3) Preparation of polymer I-6

[0117] The reaction formula is as follows:

[0118]

[0119] The specific steps are as follows: Under argon atmosphere, M4 (1 mmol, 0.616 g), M2 (0.10 mmol, 0.077 g), and M3 (0.90 mmol, 0.507 g) were dissolved in 8 mL of dry THF solution. Catalyst Pd2(dba)3 (0.05 mmol, 46 mg) and phosphine ligand Sphos (0.20 mmol, 82 mg) were added. The mixture was gradually heated to 75 °C and stirred for 0.5 hours. Then, 1.5 mL of deoxygenated 2 M potassium phosphate aqueous solution was added. After reflux for 18 hours, a phenylboronic acid solution (15 mg / 2 mL) dissolved in tetrahydrofuran was added, and the reaction continued for 5 hours. Then, 1 mL of bromobenzene solution was added, and the reaction continued for 5 hours. Finally, a sodium diethylaminothiocarbamate chelating agent (1 g / 15 mL) dissolved in water was added, and the reaction continued for 10 hours. After the reaction was cooled to room temperature, it was quenched with deionized water, extracted with dichloromethane, washed three times with deionized water, dried over anhydrous sodium sulfate, filtered, concentrated under reduced pressure to about 2 mL, added dropwise to methanol, and the polymer precipitated. After filtration and extraction with acetone for 24 hours, the residue was collected, dissolved again in a small amount of dichloromethane, and precipitated in methanol to give 0.68 g of the target polymer I-6, with a yield of 72%.

[0120] GPC measurement of number-average molecular weight M n It has a molecular weight of 5.3 kDa and a molecular weight distribution index (PDI) of 1.87.

[0121] Among them, C8H 17 It is an octyl group, C6H 13 To establish a sound foundation for oneself.

[0122] Example 7

[0123] Synthesis of Polymer I-7:

[0124] The reaction formula is as follows:

[0125]

[0126] The specific steps are similar to those for polymer I-6, except that the monomer feed ratio M4:M2:M3 is changed to 1:0.2:0.8, resulting in 0.75g of polymer I-7 with a yield of 78%.

[0127] GPC measurement of number-average molecular weight M n It has a molecular weight of 4.3 kDa and a molecular weight distribution index (PDI) of 1.81.

[0128] Among them, C8H 17 It is an octyl group, C6H 13 To establish a sound foundation for oneself.

[0129] Example 8

[0130] Synthesis of Polymer I-8:

[0131] The reaction formula is as follows:

[0132]

[0133] The specific steps are similar to those for polymer I-6, except that the monomer feed ratio M4:M2:M3 is changed to 1:0.4:0.6, resulting in 0.73g of polymer I-8 with a yield of 72%.

[0134] GPC measurement of number-average molecular weight M n It has a molecular weight of 7.0 kDa and a molecular weight distribution index (PDI) of 1.74.

[0135] Among them, C8H 17 It is an octyl group, C6H 13 To establish a sound foundation for oneself.

[0136] Example 9

[0137] Synthesis of Polymer I-9:

[0138] The reaction formula is as follows:

[0139]

[0140] The specific steps are similar to those for polymer I-6, except that the monomer feed ratio M4:M2:M3 is changed to 1:0.6:0.4, resulting in 0.89g of polymer I-9 with a yield of 85%.

[0141] GPC measurement of number-average molecular weight M n It has a molecular weight of 4.7 kDa and a molecular weight distribution index (PDI) of 1.91.

[0142] Among them, C8H 17 It is an octyl group, C6H 13 To establish a sound foundation for oneself.

[0143] Example 10

[0144] Synthesis of Polymer I-10:

[0145] The reaction formula is as follows:

[0146]

[0147] The specific steps are similar to those for polymer I-6, except that the monomer feed ratio M4:M2:M3 is changed to 1:0.8:0.2, resulting in 0.83g of polymer I-10 with a yield of 76%.

[0148] GPC measurement of number-average molecular weight M n It has a molecular weight of 5.9 kDa and a molecular weight distribution index (PDI) of 1.82.

[0149] Among them, C8H 17 It is an octyl group, C6H 13 To establish a sound foundation for oneself.

[0150] Comparative Example 1

[0151] Polymer molecular structure:

[0152]

[0153] GPC measurement of number-average molecular weight M n It has a value of 13.0 kDa and a molecular weight distribution index (PDI) of 2.2.

[0154] Wherein, C2H5 is ethyl, C5H 11 It is n-pentyl.

[0155] Example 11

[0156] Measurement of photophysical properties:

[0157] The luminescence properties of the polymers obtained in Examples 1-10 of this invention and the polymer in Comparative Example 1 were tested, and the results are shown in the figure. Figures 1-4 ,in, Figure 1 The following are fluorescence spectra of the polymers from Examples 1-5 in toluene solution. Figure 2 The following are fluorescence spectra of the polymers from Examples 6-10 in toluene solution. Figure 3 The images show the film fluorescence spectra of the polymers in Examples 1-5. Figure 4 The images show the film fluorescence spectra of the polymers in Examples 6-10.

[0158] The test results are shown in Table 1. Table 1 presents the luminescence performance test results of the polymers described in Examples 1-10 of this invention and the polymer of Comparative Example 1. Wherein, λ ma x represents the peak value of film fluorescence emission; E T This is the first triplet excited state energy level; ΔE ST The PLQY value was calculated from fluorescence and phosphorescence spectroscopy measurements; PLQY represents the quantum efficiency of light emission in the polymer film under an argon atmosphere. The test results show that by rationally designing the main-chain comonomer, TADF luminescent unit, and polymerization method, blue fluorescence emission can be achieved, and these polymers possess high triplet energy levels and very small ΔE. ST This is sufficient to achieve thermally induced delayed fluorescence while maintaining a high PLQY.

[0159] Figure 5 The transient decay spectra of the polymer films in Examples 1-5 under an argon atmosphere are shown. Figure 6 The transient decay spectra of the polymer films in Examples 6-10 are shown in an argon atmosphere. The transient decay spectroscopy results show that the luminescence mechanism of the polymers all contains short-lived transient emission and long-lived delayed emission, indicating that they exhibit thermally induced delayed fluorescence. For example, the polymer shown in Example 8 in Table 1 has a transient emission lifetime of 19 ns (accounting for 27%) and a delayed emission lifetime of 10.7 μs (accounting for 77%), with a fluorescence quantum efficiency close to 100% and an emission wavelength at 473 nm, achieving highly efficient blue thermally induced delayed fluorescence emission.

[0160] The emission spectrum of the polymer in Comparative Example 1 was tested, and the results showed that its emission wavelength was at 514 nm. This is because when the carbazole unit is directly connected to the TADF unit, the degree of conjugation of the polymer backbone increases, which causes a red shift in the spectrum and a decrease in the triplet energy level to 2.53 eV, which is significantly lower than that of the polymer in this invention where the diphenylsilane and TADF unit are directly connected (2.74-2.90 eV).

[0161] Table 1

[0162]

[0163] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A blue thermally induced delayed fluorescence polymer with the structure of Formula 1: Formula 1; in, R1 and R3 are independently selected from C6~C 30 Aromatic group; R2 and R4 are independently selected from H or C1~C8 alkyl groups; R5, R6, and R7 are independently selected from C1 to C2. 20 Alkyl groups or C6~C 30 Aromatic group; The A is selected from C6~C, which have electron-withdrawing capabilities. 50 Aromatic group; The value of n is 2 to 200; The 0 <x<0.5; The A is selected from groups having the formula Aa; Equation Aa; Wherein, R8 is selected from unsubstituted triazine, cyano-substituted triazine, trifluoromethyl-substituted triazine, C1~C13 ... 20 alkyl-substituted triazine group, C6~C 30 Aromatic group-substituted triazine group, unsubstituted pyrimidinyl group, cyano-substituted pyrimidinyl group, trifluoromethyl-substituted pyrimidinyl group, C1~C 20 Alkyl-substituted pyrimidinyl, C6~C 30 Aromatic group-substituted pyrimidinyl, unsubstituted pyridinyl, cyano-substituted pyridinyl, trifluoromethyl-substituted pyridinyl, C1~C 20 Alkyl-substituted pyridyl, C6~C 30 Aromatic group-substituted pyridinyl group; Alternatively, A may be selected from groups having the formula Ab; Formula Ab; Wherein, R9 is selected from unsubstituted C1~C 20 Aromatic or cyano-substituted C1~C 20 Aromatic or trifluoromethyl substituted C1~C 20 Aromatic group; Alternatively, A may be selected from groups having the formula Ac; Formula Ac; Wherein, the R 10 and R 11 Independently selected from C1~C 20 The aromatic group, and the R 10 and R 11 Whether R, B, and R form a ring or not, 10 The three components, R, B, and the phenyl group containing B, may or may not form a ring. 11 The three components, B and B, may form a ring or not.

2. The blue thermally induced delayed fluorescence polymer according to claim 1, characterized in that, The A has the structures of formulas A-1, A-2, A-3, A-4, A-5, A-6, A-7, A-8, A-9, A-10, A-11 and A-12: Formula A-1; Formula A-2; Formula A-3; Formula A-4; Formula A-5; Formula A-6; Formula A-7; Formula A-8; Formula A-9; Formula A-10; Formula A-11; Formula A-12; Among them, R 12 Independently selected from C1~C 20 Alkyl or C6~C 30 Aromatic group.

3. The blue thermally induced delayed fluorescence polymer according to claim 1, characterized in that, R2 and R4 are independently selected from H, methyl, ethyl, propyl, butyl, pentyl, or hexyl.

4. The blue thermally induced delayed fluorescence polymer according to claim 3, characterized in that, Both R2 and R4 are methyl groups.

5. The blue thermally induced delayed fluorescence polymer according to claim 1, characterized in that, R1 and R3 are independently selected from unsubstituted C6~C. 30 Aromatic group, or C1~C 20 Alkyl and C1~C 20 At least one substituted C6~C of the alkoxy group 30 Aromatic group; R5, R6, and R7 are independently selected from unsubstituted C1~C1. 20 Alkyl, unsubstituted C6~C 30 Aromatic group, or C1~C 20 Alkyl and C1~C 20 At least one substituted C6~C of the alkoxy group 30 Aromatic group.

6. The blue thermally induced delayed fluorescence polymer according to claim 5, characterized in that, R1 and R3 are independently selected from phenyl, tolyl, ethylphenyl, butylphenyl, hexylphenyl, octylphenyl, methoxyphenyl, or dimethylaminephenyl; The R5 is selected from acetyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecanyl, butylphenyl, hexylphenyl, octylphenyl, decylphenyl, undecylphenyl, tridecylphenyl, heptadecanylphenyl, hexoxyphenyl, octoxyphenyl, decoxyphenyl, undecyloxyphenyl, tridecyloxyphenyl, or heptadecanyloxyphenyl; R6 and R7 are independently selected from methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, phenyl, methylphenyl, butylphenyl, hexylphenyl, octylphenyl, decylphenyl, methoxyphenyl, hexoxyphenyl, octylphenyl, or decoxyphenyl.

7. The blue thermally induced delayed fluorescence polymer according to claim 1, characterized in that, It is a polymer having a structure of formula (Ia), formula (Ib), formula (Ic), formula (Id), formula (Ie), formula (If), formula (Ig), formula (Ih), formula (Ii), or formula (Ij); Equation (Ia); Formula (Ib); Formula (Ic); Formula(Id); Equation (Ie); Formula(If); Formula (Ig); Formula (Ih); Formula (Ii); Formula (Ij).

8. The method for preparing the blue thermally induced delayed fluorescence polymer according to any one of claims 1 to 7, characterized in that, Includes the following steps: The compounds having the structure of formula B, the compound having the structure of formula M, and the compound having the structure of formula N were polymerized to obtain a blue thermally induced delayed fluorescence polymer having the structure of formula 1. Formula B; Formula M; Formula N; X1 is selected from pinacol boronic acid ester group, borate group, methyltin or butyltin; X2 and X3 are independently selected from Br or I.

9. A light-emitting device, characterized in that, It includes a first electrode, a second electrode, and an organic layer between the first electrode and the second electrode, wherein the organic layer contains the blue thermally induced delayed fluorescence polymer as described in any one of claims 1 to 7.

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