TiOPc dopant, TiOPc (at) SQ heterojunction and application of TiOPc (at) SQ heterojunction

Abstract

The invention belongs to the technical field of photoelectric materials and application, and particularly relates to a TiOPc doping agent, a TiOPc (at) SQ heterojunction and application of the TiOPc (at) SQ heterojunction. An indoline-based squarylium cyanine dye (SQ) is synthesized and is used as a doping agent of TiOPc, the absorption capacity of TiOPc in a near-infrared region is improved by utilizing the synergistic effect of the SQ and the TiOPc, the charge separation efficiency is optimized, and more excellent photoelectric detection performance is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of optoelectronic materials and applications, and particularly relates to a TiOPc dopant, a TiOPc@SQ heterojunction and applications thereof. Background Art

[0002] Photodetectors (PDs) are a key device that converts incident photons into electronically processable charge carriers. Due to their tunable detection wavelength and compatibility with flexible and lightweight devices, they are widely used in many cutting-edge scientific fields. However, with the deepening of research, the requirements for detector performance are increasing, and the demand for high-performance semiconductor materials is becoming increasingly urgent. Compared with inorganic semiconductors, organic semiconductors have extremely high extinction coefficients and significant advantages in light absorption. Their molecular structure is also easily tunable, allowing for flexible adjustment of absorption spectra to meet the needs of multi-band detection. In this context, organic photodetectors, especially near-infrared organic photodetectors, have attracted widespread attention due to their irreplaceable role in remote sensing, optical communications, and other fields. However, the variety of organic semiconductor materials suitable for the near-infrared region is still limited, resulting in a relative lag in research compared to devices in the ultraviolet and visible regions.

[0003] Heterojunction photosensitive materials not only simultaneously utilize the absorption wavelengths of two photosensitive materials, but also fully utilize the co-sensitization synergistic coupling enhancement effect between the two materials to improve photodetection performance. In addition, the construction of heterojunctions can also utilize the built-in electric field at the heterojunction interface to improve the separation efficiency and transmission rate of photogenerated carriers. Therefore, selecting two suitable photosensitive materials to construct heterojunctions is crucial for the preparation of high-performance photodetectors.

[0004] Currently, the four most commonly used organic photosensitive materials are phthalocyanines, azo compounds, perylene compounds, and squarylium compounds. Phthalocyanines have attracted considerable attention due to their low toxicity, excellent photothermal stability, high carrier generation efficiency, strong light absorption in the visible and near-infrared regions (600–900 nm), and excellent photosensitivity. Their application research has gradually shifted from the traditional printing and dyeing industry to high-tech organic electronics. Titanium phthalocyanine (TiOPc) is a class of organic semiconductor materials with excellent photoelectric properties and is widely used in various photoelectric conversion devices. Among them, Y-type TiOPc (Y-TiOPc) exhibits the best photoinduced charge generation performance (≥90%) in the Vis-NIR region. However, titanium phthalocyanines suffer from poor dispersion, low photoelectric performance, and unstable crystal structure when used in organic photodetectors. These limitations make them unable to meet the requirements for easy dispersion, high photosensitivity, high external quantum efficiency, and high photosensitivity required of organic photosensitive materials. The main reasons for these shortcomings are low photogenerated carrier generation efficiency, insufficient separation efficiency, and low migration rate of the photosensitive organic pigment. Furthermore, due to its inherent structural characteristics, it is prone to aggregation. These deficiencies affect TiOPc's near-infrared photosensitivity and make it unable to meet the needs of higher-sensitivity near-infrared applications. Summary of the Invention

[0005] To address the above problems, the present invention provides a TiOPc dopant, a TiOPc@SQ heterojunction, and its application. By synthesizing an indoline-based squarylium cyanine dye (SQ) and using it as a TiOPc dopant, the systemic interaction of SQ and TiOPc is utilized to enhance the absorption capacity of TiOPc in the near-infrared region, optimize the charge separation efficiency, and achieve better photoelectric detection performance.

[0006] A TiOPc dopant is an indoline-based cyanine dye, and the general structural formula of the indoline-based cyanine dye is shown in Formula I:

[0007] Wherein, the R group is independently a hydrocarbon group having 5 to 25 carbon atoms; and the R group has at least one branch.

[0008] The number of carbon atoms of R is preferably 7 to 12; More preferably, the R groups are independently groups (a) and (b), .

[0009] The preparation method of the indoline-based cyanine dye comprises the following steps: (1) Raw material A (1,2,3,3-tetramethyl-6-nitroindoline) was dissolved in methanol at room temperature, palladium carbon was added, and then stirred at room temperature under a hydrogen atmosphere. The reaction was monitored by TLC. When raw material A disappeared, the reaction was stopped, and the mixture was filtered through celite. The filtrate was concentrated by rotary evaporation to obtain compound B. (2) Compound B was dissolved in dichloromethane at room temperature, triethylamine and dimethylaminopyridine were added, and after cooling to 0°C, an amidation reagent was added, and then stirred at 0°C under a nitrogen atmosphere, and the reaction was monitored by TLC. When compound B disappeared, the reaction was stopped, saturated brine was added, and extraction was performed with dichloromethane. The obtained organic layer was dried over anhydrous sodium sulfate, and the solvent was distilled off using a rotary evaporator to obtain compound C. (3) Compound C was dissolved in a mixed solution of toluene and n-butanol at room temperature, and squaric acid was added. The mixture was stirred under N2 atmosphere and azeotropic reflux conditions, and the reaction was monitored by TLC. When compound C disappeared, the reaction was stopped, the reaction solvent was distilled off using a rotary evaporator, and the mixture was purified by silica gel column chromatography to obtain the target compound D.

[0010] The preparation principle is shown below: .

[0011] Wherein, in step (1), the mass ratio of palladium carbon to raw material A is 0.03~0.09.

[0012] In step (2), the molar ratio of compound B to triethylamine and amidation reagent is 1: (1.8-2.0): (1.4-1.5); The amidation reagent is a carboxylic acid chloride whose substituent is an R group; The molar ratio of dimethylaminopyridine to compound B is 1:(20-22).

[0013] In step (3), the volume ratio of toluene to n-butanol is 1:1; The molar ratio of compound C to squaric acid is 1:0.5.

[0014] The present invention also provides a TiOPc@SQ heterojunction, comprising titanium phthalocyanine and the above-mentioned TiOPc dopant; The indoline-based cyanine dye accounts for 0.3~1.5wt.% of the TiOPc@SQ heterojunction. When the content of the indoline-based cyanine dye is too low, the morphology control of the TiOPc film and the improvement of light absorption in the near-infrared region are small, and the device performance cannot be significantly improved. When the content is too high, the TiOPc film of the device is over-controlled and the molecules are over-aggregated, which in turn reduces the light absorption of the device active layer and affects the device performance.

[0015] Preferably, the TiOPc@SQ heterojunction further includes PVB.

[0016] More preferably, the weight ratio of the charge generating material (TiOPc, SQ) to PVB is (5-8):1.

[0017] Preferably, the TiOPc is Y-TiOPc.

[0018] The preparation method of the Y-TiOPc@SQ heterojunction is as follows: Y-TiOPc and SQ are prepared in PVB and dispersed in 1,2-dichloroethane, and ultrasonicated, ball-milled, and sieved to prepare a Y-TiOPc@SQ photosensitive dispersion; and the Y-TiOPc@SQ heterojunction is obtained by spin coating and annealing.

[0019] The present invention also provides application of the TiOPc@SQ heterojunction in organic photoelectric devices.

[0020] Preferably, the organic photoelectric device is an organic photodetector.

[0021] More preferably, the organic photodetector structure is Au / p -TPD / Y-TiOPc@SQ / ITO.

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) By doping an appropriate amount of square cyanine dye into Y-type phthalocyanine titanium oxide, a Y-TiOPc@SQ heterojunction photoactive layer was successfully constructed. The Y-TiOPc@SQ photodetector exhibited excellent photoelectric performance in the range of 365 nm to 940 nm.

[0023] (2) Due to the doping of SQ, the Y-TiOPc@SQ heterojunction in the photoactive layer not only improves the photodetection performance of TiOPc in the near-infrared region, but also effectively increases the generation efficiency, separation efficiency, and transmission rate of carriers. More importantly, SQ as a dopant increases the number of retained electrons at the photoactive layer / ITO interface, and the resulting energy level bending reduces the hole transport barrier, thereby improving the efficiency of hole tunnel injection from the external circuit.

[0024] (3) Organic optoelectronic devices exhibit fast, stable, and reproducible photocurrent responses, indicating their good reliability and practicality.

[0025] (4) The intermediate B of the cyanine dye is synthesized by a clean and environmentally friendly hydrogenation method, which is conducive to the realization of green and sustainable synthesis of organic optoelectronic materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1(a) 3D optimized molecular structure and (b) orbital energy levels of SQ1 in Example 1 of the present invention; Figure 2 (a) 3D optimized molecular structure and (b) orbital energy levels of SQ2 in Example 2 of the present invention; Figure 3 Schematic diagram of the preparation process of organic photodetectors using Y-TiOPc and Y-TiOPc@SQ as active layers; Figure 4 The photoresponsivity curve of the organic photodetector with different proportions of SQ1 as the active layer at -20V; Figure 5 The photoresponsivity curve of the organic photodetector with different ratios of SQ2 as the active layer at -20V; Figure 6 The external quantum efficiency curve of organic photodetectors with different proportions of SQ1 as the active layer at -20V; Figure 7 The external quantum efficiency curve of organic photodetectors with different proportions of SQ2 as the active layer at -20V; Figure 8 The specific detectivity curve of the organic photodetector with different proportions of SQ1 as the active layer at -20V; Figure 9 The specific detectivity curve of the organic photodetector with different ratios of SQ2 as the active layer at -20V; Figure 10 This is the time-current curve of the organic photodetector with Y-TiOPc as the active layer at -5V; Figure 11 This is the time-current curve of the organic photodetector with Y-TiOPc@0.5%SQ1 as the active layer at -5V; Figure 12 This is the time-current curve of the organic photodetector with Y-TiOPc@0.8%SQ2 as the active layer at -5V. DETAILED DESCRIPTION

[0027] The following further illustrates the specific implementation of the present invention with reference to the accompanying drawings and examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that if there are any processes not specifically described below, they can be implemented or understood by those skilled in the art with reference to the existing technology.

[0028] The practice of the present invention can employ conventional techniques of organic synthetic chemistry. In the following examples, efforts have been made to ensure the accuracy of the numbers used (including amounts, temperatures, reaction times, etc.), but some experimental errors and deviations should be taken into account. The temperatures used in the following examples are expressed in ° C, the pressure is atmospheric pressure or near atmospheric pressure, and the room temperature is 25 ± 2 ° C. All solvents used are analytical or chromatographically pure. Unless otherwise indicated, all reagents were obtained from commercial sources.

[0029] The Y-TiOPc preparation method in the following examples and comparative examples is as follows: A 5% TiOPc / H2SO4 solution (16 mL at 0°C) was dropwise added to 250 mL of a 30°C H2O / o-dichlorobenzene (v / v = 1 / 1) microemulsion. After stirring for 6 hours, the microemulsion was demulsified with methanol, separating a colorless aqueous phase and a blue o-dichlorobenzene phase. The o-dichlorobenzene phase was diluted with 250 mL of methanol to precipitate Y-TiOPc NPs. The precipitate was then washed with methanol and water until the conductivity of the wash water was <5 μS cm -1 Finally, Y-TiOPc NPs were obtained by vacuum freeze-drying.

[0030] In the following examples and comparative examples, PVB was purchased from Shanghai Jingchun Biochemical Technology Co., Ltd., 98%; p -TPD was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., 98%; ITO was purchased from South China Xiangcheng Technology Co., Ltd., size: 40*40*1.1mm, center etching 40*6mm, film thickness: 185 nm, transmittance: ≥84%.

[0031] In the following examples, the wavelength-photoresponsivity curve, wavelength-external quantum efficiency curve, wavelength-specific detectivity curve, and time-current curve test methods are referenced from the literature: Li X, Wan J, Tang Y, et al. Boosting the UV–vis–NIR Photodetection Performance of MoS2 through the Cavity Enhancement Effect and Bulk Heterojunction Strategy[J]. ACS Applied Materials&Interfaces, 2024, 16(22): 29003-29015. The effective exposure area of ​​the Y-TiOPc-PD and Y-TiOPc@SQ-PD devices in the following examples and comparative examples is 0.12 cm 2 .

[0032] As an example, the structural formula of the indoline-based cyanine dye prepared in the following examples is shown below: .

[0033] Example 1: Preparation of Indoline-Based Squaraine Dye SQ1 and Y-TiOPc@SQ1 Heterojunction The chemical synthesis route of SQ1 is shown below, and the specific reaction steps and reaction conditions are as follows: .

[0034] (1) Synthesis of compound 2 Compound 1 (1,2,3,3-tetramethyl-6-nitroindolinol) (4.144 g, 0.0188 mol), 82.88 mL of methanol, and palladium on carbon (5% Pd) (0.166 g) were added to a 250 mL eggplant-shaped flask and stirred at room temperature under a hydrogen atmosphere. The reaction was monitored until the starting material (compound 1) disappeared, then stopped. The product was filtered through celite and the filtrate was concentrated on a rotary evaporator. This yielded compound 2 (3.148 g, 0.0165 mol, 88% yield).

[0035] (2) Synthesis of compound 3 Under a nitrogen atmosphere, compound 2 (3.084 g, 0.0162 mol), 75 mL of dichloromethane, 3.046 g (0.0301 mol) of triethylamine, and 0.097 g (0.0008 mol) of dimethylaminopyridine were added to a 250 mL three-necked round-bottom flask. The reaction solution was cooled to 0°C, and 2-propylpentanoyl chloride (3.738 g, 0.0230 mol) was added. The mixture was then stirred at 0°C under a nitrogen atmosphere, and the reaction was monitored by TLC. After completion of the reaction, 75 mL of saturated brine was added, and the mixture was extracted with 150 mL of dichloromethane. The resulting organic layer was dried over anhydrous sodium sulfate, and the filtrate was filtered and the solvent was removed by rotary evaporation. This yielded compound 3 (3.845 g, 0.0121 mol, 75% yield).

[0036] (3) Synthesis of SQ1 A 500 mL single-necked round-bottom flask equipped with a Dean-Stark tube was charged with compound 3 (2.775 g, 0.0088 mol), 44 mL of toluene, 44 mL of n-butanol, and 0.5 g (0.0044 mol) of squaric acid. The mixture was stirred under a nitrogen atmosphere and azeotropic reflux, and the reaction was monitored by TLC. After completion of the reaction, the solvent was removed by rotary evaporation, and the product was purified by silica gel column chromatography (developing solvent: n-hexane:ethyl acetate = 7:3). The dye SQ1 (2.190 g, 0.0031 mol, 70% yield) was obtained.

[0037] (4) Preparation of Y-TiOPc@SQ1 heterojunction First, 0.01 g of PVB was added to each of the five beakers. Then, 74.775 mg of Y-TiOPc and 0.225 mg (0.3 wt.%) of SQ1, 74.625 mg of Y-TiOPc and 0.375 mg (0.5 wt.%) of SQ1, 74.400 mg of Y-TiOPc and 0.600 mg (0.8 wt.%) of SQ1, and 73.875 mg of Y-TiOPc and 1.125 mg (1.5 wt.%) of SQ1 were added to the above beakers, respectively, and dispersed in 7.5 mL of 1,2-dichloroethane. After ultrasonic treatment for 15 min, the mixture was ball-milled at 700 r / min for 2 h and sieved (300 mesh) to prepare 10 Photosensitive dispersions of Y-TiOPc@0.3%SQ1, Y-TiOPc@0.5%SQ1, Y-TiOPc@0.8%SQ1, and Y-TiOPc@1.5%SQ1 at mg / mL.

[0038] The above photosensitive dispersion was spin-coated and annealed at 80 °C for 10 min to prepare the Y-TiOPc@SQ1 heterojunction.

[0039] Example 2: Preparation of Indoline-Based Squarylium Dye SQ2 and Y-TiOPc@SQ2 Heterojunction The chemical synthesis route of SQ2 is shown below, and the specific reaction steps and reaction conditions are as follows: .

[0040] (1) Synthesis of compound 2 Compound 1 (1,2,3,3-tetramethyl-6-nitroindoline) (4.044 g, 0.0184 mol), 80.88 mL of methanol, and palladium on carbon (5% Pd) (0.324 g) were added to a 250 mL eggplant-shaped flask and stirred at room temperature under a hydrogen atmosphere. The reaction was monitored until the starting material (compound 1) disappeared, then stopped. The product was filtered through celite, and the filtrate was concentrated on a rotary evaporator. This yielded compound 2 (3.212 g, 0.0169 mol, 92% yield).

[0041] (2) Synthesis of compound 4 Under a nitrogen atmosphere, compound 2 (3.200 g, 0.0168 mol), 80 mL of dichloromethane, 3.249 g (0.0321 mol) of triethylamine, and 0.100 g (0.0008 mol) of dimethylaminopyridine were added to a 250 mL three-necked round-bottom flask. The reaction solution was cooled to 0°C, and 2-ethylhexanoyl chloride (3.979 g, 0.0245 mol) was added. The mixture was then stirred at 0°C under a nitrogen atmosphere, and the reaction was monitored by TLC. After completion of the reaction, 80 mL of saturated brine was added, and the mixture was extracted with 160 mL of dichloromethane. The resulting organic layer was dried over anhydrous sodium sulfate, and the filtrate was filtered and the solvent was removed by rotary evaporation. This yielded compound 4 (3.934 g, 0.0124 mol, 74% yield).

[0042] (3) Synthesis of SQ2 A 500 mL single-necked round-bottom flask equipped with a Dean-Stark tube was charged with compound 4 (3.295 g, 0.0104 mol), 52 mL of toluene, 52 mL of n-butanol, and 0.592 g (0.0052 mol) of squaric acid under a nitrogen atmosphere. The mixture was stirred under azeotropic reflux conditions and monitored by TLC. After completion of the reaction, the solvent was removed by rotary evaporation, and the product was purified by silica gel column chromatography (developing solvent: n-hexane:ethyl acetate = 7:3). The dye SQ2 (2.662 g, 0.0037 mol, 72% yield) was obtained.

[0043] (4) Preparation of Y-TiOPc@SQ2 heterojunction First, 0.01 g of PVB was added to each of the five beakers. Then, 74.775 mg of Y-TiOPc and 0.225 mg (0.3 wt.%) of SQ2, 74.625 mg of Y-TiOPc and 0.375 mg (0.5 wt.%) of SQ2, 74.400 mg of Y-TiOPc and 0.600 mg (0.8 wt.%) of SQ2, and 73.875 mg of Y-TiOPc and 1.125 mg (1.5 wt.%) of SQ2 were added to the above beakers, respectively, and dispersed in 7.5 mL of 1,2-dichloroethane. After ultrasonic treatment for 15 min, the mixture was ball-milled at 700 r / min for 2 h and sieved (300 mesh) to prepare 10 Photosensitive dispersions of Y-TiOPc@0.3%SQ2, Y-TiOPc@0.5%SQ2, Y-TiOPc@0.8%SQ2, and Y-TiOPc@1.5%SQ2 at mg / mL.

[0044] The above photosensitive dispersion was spin-coated and annealed at 80 °C for 10 min to prepare the Y-TiOPc@SQ2 heterojunction.

[0045] Comparative Example 1 like Figure 3 (a) is a schematic flow chart of the preparation method of an organic photodetector using Y-TiOPc as the active layer. The specific preparation process of the photodetector of this comparative example is as follows: The ITO glass was cleaned with a detergent and sonicated in distilled water, acetone, and ethanol for 15 minutes, with the acetone and ethanol sonication repeated twice. The ITO glass was dried with a N2 stream before use.

[0046] 0.075 g Y-TiOPc and 0.01 g PVB were dispersed in 7.5 mL 1,2-dichloroethane and ultrasonicated for 15 min, then ball milled at 700 r / min for 2 h. The ball-milled dispersion was sieved (300 mesh) to prepare a 10 mg / mL Y-TiOPc photosensitive dispersion. p -TPD was added to 1 mL of dichloromethane and ultrasonicated for 15 min to prepare 100 mg / mL p -TPD solution. The cleaned ITO glass was blown dry with N2 and then treated with UV ozone for 10 min, and then the ITO substrate was fixed on a desktop coating machine. Each time, Y-TiOPc photosensitive dispersion (0.5 mL) was spin-coated onto the surface of the ITO substrate at a speed of 500 r / min (10 s) and then 1500 r / min (10 s), and annealed at 80 ° C for 10 min. A total of 8 layers were applied to prepare the photoactive layer. p -TPD (0.2 mL) was spin-coated onto the surface of the photoactive layer to prepare a hole transport layer, which was then annealed at 60 °C for 1 h. Finally, an Au electrode was deposited on the surface of the photoactive layer by magnetron sputtering at 20 mA for 1.5 min at room temperature. p -TPD layer on the film.

[0047] The final device structure is Au / p -TPD / Y-TiOPc / ITO Y-TiOPc-PD. Wavelength-light responsivity curve test (see attached Figure 4 ), wavelength-external quantum efficiency curve test (see attached Figure 6 ), wavelength-specific detection rate curve test (see attached Figure 8 ) and time-current curve test (see attached Figure 10 ), the device performance parameters are shown in Table 1-3.

[0048] Table 1 Organic photodetectors based on Y-TiOPc as active layer at -20 V and 0.01 mW / cm 2 Photoresponsivity value under the conditions (A / W)

[0049] Table 2 Organic photodetectors based on Y-TiOPc as active layer at -20 V and 0.01 mW / cm 2 External quantum efficiency value under conditions (%)

[0050] Table 3 Organic photodetectors based on Y-TiOPc as active layer at -20 V and 0.01 mW / cm 2 The specific detection rate value under the condition (×10 11 Jones

[0051] Example 3 The Y-TiOPc@SQ1 heterojunction obtained in Example 1 is used as an example to illustrate the application of SQ1 as a dopant for titanium phthalocyanine in organic photodetectors.

[0052] This embodiment is the same as Comparative Example 1, except that the Y-TiOPc photosensitive dispersion is replaced by the photosensitive dispersions Y-TiOPc@0.3%SQ1, Y-TiOPc@0.5%SQ1, Y-TiOPc@0.8%SQ1, and Y-TiOPc@1.5%SQ1 prepared in Example 1.

[0053] The final device structure is Au / p -TPD / Y-TiOPc@SQ1 / ITO Y-TiOPc@SQ1-PD (device structure see attached Figure 3 (b)). The wavelength-light response curve test was carried out (see Appendix Figure 4 ), wavelength-external quantum efficiency curve test (see attached Figure 6 ), wavelength-specific detection rate curve test (see attached Figure 8 ) and the active layer is Y-TiOPc@0.5%SQ1 time-current curve test (see attached Figure 11), the device performance parameters are shown in Tables 4-6. As can be seen from the table, when SQ1 is doped at 0.3 wt.%, 0.5 wt.%, 0.8 wt.%, and 1.5 wt.% on top of TiOPc, the device performance trend is initially increasing and then decreasing. This is because increasing the SQ1 doping ratio modulates the film morphology of the active layer, enhancing the synergistic effect of TiOPc and SQ1. This increases the light absorption of the active layer, generating more photogenerated excitons. This improves the exciton separation efficiency, resulting in more freely moving charges and enhanced carrier transport and collection efficiency, thus significantly improving device performance. However, when the SQ1 doping ratio exceeds 0.5 wt.%, device performance degrades. This is because further SQ1 doping disrupts the film morphology of the active layer, affecting the device's light absorption, exciton generation, exciton transport and separation, and free charge transport and collection, leading to a decline in device performance. Y-TiOPc@0.5%SQ1-PD performs best in terms of photoresponsivity, external quantum efficiency and specific detectivity, so 0.5 wt.%SQ1 is the optimal mixing ratio of the photoactive layer. Figure 11 It can be seen that within 100 switching cycles, the rise and fall times of Y-TiOPc@0.5%SQ1-PD from 365 nm to 940 nm are both in the millisecond level, and the time-current curve is fast, stable and reproducible, indicating that Y-TiOPc@0.5%SQ1-PD has excellent photoresponse characteristics in the entire UV-Vis-NIR spectral range.

[0054] Table 4 Organic photodetectors based on Y-TiOPc@SQ1 as active layer at -20 V and 0.01 mW / cm 2 Photoresponsivity value under the conditions (A / W)

[0055] Table 5 Organic photodetectors based on Y-TiOPc@SQ1 as active layer at -20 V and 0.01 mW / cm 2 External quantum efficiency value under conditions (%)

[0056] Table 6 Organic photodetectors based on Y-TiOPc@SQ1 as active layer at -20 V and 0.01 mW / cm 2 The specific detection rate value under the condition (×10 11 Jones

[0057] Example 4 The Y-TiOPc@SQ2 heterojunction obtained in Example 2 is used as an example to illustrate the application of SQ2 as a dopant for titanium phthalocyanine in organic photodetectors.

[0058] This embodiment is the same as Comparative Example 1, except that the Y-TiOPc photosensitive dispersion is replaced by the photosensitive dispersions Y-TiOPc@0.3%SQ2, Y-TiOPc@0.5%SQ2, Y-TiOPc@0.8%SQ2, and Y-TiOPc@1.5%SQ2 prepared in Example 2.

[0059] The final device structure is Au / p -TPD / Y-TiOPc@SQ2 / ITO Y-TiOPc@SQ2-PD (device structure see attached Figure 3 (b)). The wavelength-light response curve test was carried out (see Appendix Figure 5 ), wavelength-external quantum efficiency curve test (see attached Figure 7 ), wavelength-specific detection rate curve test (see attached Figure 9 ) and the active layer is Y-TiOPc@0.8%SQ2 time-current curve test (see attached Figure 12 ), the device performance parameters are shown in Tables 7-9. As can be seen from the table, when 0.3wt.%, 0.5wt.%, 0.8wt.%, and 1.5wt.% of SQ2 are doped on the basis of TiOPc, the performance trend of the device increases first and then decreases. Y-TiOPc@0.8%SQ2-PD performs best in terms of photoresponsivity, external quantum efficiency, and specific detectivity. Therefore, 0.8wt.%SQ2 is the optimal mixing ratio for the photoactive layer. From the attached Figure 12 It can be seen that within 100 switching cycles, the rise and fall times of Y-TiOPc@0.8%SQ2-PD from 365 nm to 940 nm are both in the millisecond order, and the time-current curve is fast, stable, and reproducible, indicating that Y-TiOPc@0.8%SQ2-PD has excellent photoresponse characteristics in the entire UV-Vis-NIR spectral range.

[0060] Table 7 Organic photodetectors based on Y-TiOPc@SQ2 as active layer at -20 V and 0.01 mW / cm 2 Photoresponsivity value under the conditions (A / W)

[0061] Table 8 Organic photodetectors based on Y-TiOPc@SQ2 as active layer at -20 V and 0.01 mW / cm 2 External quantum efficiency value under conditions (%)

[0062] Table 9 Organic photodetectors based on Y-TiOPc@SQ2 as active layer at -20 V and 0.01 mW / cm 2 The specific detection rate value under the condition (×10 12 Jones

[0063] To further explore the synergistic effect of Y-TiOPc and SQ in the Y-TiOPc@SQ heterojunction, the present invention uses Gaussian09 software package to simulate the structure and highest occupied molecular orbital (HOMO) / lowest unoccupied molecular orbital (LUMO) energy levels of SQ1 and SQ2 at the B3LYP / 6-31G* level through density functional theory calculations. Figure 1 and Figure 2 Shown are (a) the optimized three-dimensional molecular structures and (b) the orbital energy levels of SQ1 and SQ2. The figure shows that the indoline rings on either side are essentially coplanar with the squarylium core, resulting in a planar main skeleton. These HOMO-LUMO orbitals are primarily distributed along the central squarylium skeleton, the indoline rings, and the amide groups. The orbitals along the main skeleton are highly symmetrical, indicating that electron delocalization occurs from the donor group to the center of the molecule. The calculated HOMO / LUMO energy levels of SQ1 and SQ2 are identical, at -4.71 / -2.54 eV, respectively, with a band gap of 2.17 eV. This is because the only difference between the two molecules is the alkyl group. The smaller band gap implies higher optical absorption coefficients and better electrical conductivity, making the material suitable for optoelectronic device applications.

[0064] According to the test results of Examples 3 and 4 and Comparative Example 1, the present invention uses Y-TiOPc@SQ heterojunction as the active layer, which has better photoelectric performance than Y-TiOPc. The reason is that the present invention uses SQ as a dopant. (1) The SQ dopant introduces an indoline derivative structure at the 1,3-position of the squarylium nucleus to form a DAD configuration, and adjusts the optical properties and solubility of the squarylium cyanine dye by changing the donor structure of the indoline derivative substituted with an amide group. (2) The absorption and emission wavelengths of the squarylium cyanine provided by the present invention are both in the near-infrared region, with strong absorption and narrow emission bands, and high solubility in organic solvents. (3) The HOMO / LUMO energy levels of the squarylium cyanine provided by the present invention match the HOMO / LUMO energy levels of Y-TiOPc (-5.7 eV / -4.0 eV). This energy level matching feature enables the two to better play a synergistic role, thereby significantly improving the photoelectric performance in the fields of optoelectronic devices. In addition, (1) compared with other electron-donating groups, the indoline group in the SQ dopant has a larger molar extinction coefficient, better fluorescence performance, stronger electron-donating ability, better coplanarity with squaric acid, and relatively higher stability; (2) the SQ dopant further introduces a substituted hydrocarbon group on the indoline group to perform branched modification of the amide group, which has better solubility performance.

[0065] The above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications may be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A TiOPc dopant, characterized in that: The TiOPc dopant is an indoline-based cyanine dye, and its general structural formula is shown in Formula I: Wherein, the R group is independently a hydrocarbon group having 5 to 25 carbon atoms; and the R group has at least one branch.

2. The TiOPc dopant according to claim 1, characterized in that The number of carbon atoms in the R group is 7 to 12; Preferably, the R groups are independently of formula (a) or formula (b); 。 3. The TiOPc dopant according to claim 1, characterized in that The preparation method of the indoline-based cyanine dye comprises the following steps: (1) Raw material A was dissolved in methanol at room temperature, palladium carbon was added, and then stirred under a hydrogen atmosphere at room temperature. The reaction was monitored by TLC. When raw material A disappeared, the reaction was stopped, and the mixture was filtered through celite. The filtrate was concentrated by rotary evaporation to obtain compound B. The raw material A is 1,2,3,3-tetramethyl-6-nitroindoline; (2) Compound B was dissolved in dichloromethane at room temperature, triethylamine and dimethylaminopyridine were added, and after cooling to 0°C, an amidation reagent was added, and then stirred at 0°C under a nitrogen atmosphere, and the reaction was monitored by TLC. When compound B disappeared, the reaction was stopped, saturated brine was added, and extraction was performed with dichloromethane. The obtained organic layer was dried over anhydrous sodium sulfate, and the solvent was distilled off using a rotary evaporator to obtain compound C. (3) Compound C was dissolved in a mixed solution of toluene and n-butanol at room temperature, and squaric acid was added. The mixture was stirred under N2 atmosphere and azeotropic reflux conditions, and the reaction was monitored by TLC. When compound C disappeared, the reaction was stopped, the reaction solvent was distilled off using a rotary evaporator, and the mixture was purified by silica gel column chromatography to obtain the target compound D. The target compound D is an indoline-based cyanine dye.

4. The TiOPc dopant according to claim 3, characterized in that In step (1), the mass ratio of palladium carbon to raw material A is 0.03~0.

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5. The TiOPc dopant according to claim 3, characterized in that The amidation reagent is a carboxylic acid chloride whose substituent is an R group; Preferably, in step (2), the molar ratio of compound B to triethylamine and amidation reagent is 1: (1.8-2.0): (1.4-1.5); The molar ratio of dimethylaminopyridine to compound B is 1:(20-22).

6. The TiOPc dopant according to claim 3, characterized in that In step (3), the volume ratio of toluene to n-butanol is 1:1; The molar ratio of compound C to squaric acid is 1:0.

5.

7. A TiOPc@SQ heterojunction, characterized in that: include, Titanyl phthalocyanine, the TiOPc dopant according to any one of claims 1 to 6; The TiOPc dopant accounts for 0.3-1.5 wt.% of the TiOPc@SQ heterojunction.

8. The TiOPc@SQ heterojunction according to claim 7, characterized in that The TiOPc@SQ heterojunction also includes PVB, The weight ratio of the charge generating material to PVB is (5-8):1; The charge generating materials are TiOPc and SQ.

9. Use of the TiOPc dopant according to any one of claims 1 to 6 or the TiOPc@SQ heterojunction according to any one of claims 7 to 8 in an organic optoelectronic device, characterized in that: The organic photoelectric device is an organic photodetector.

10. The use in an organic optoelectronic device according to claim 9, characterized in that: The organic photodetector structure is Au / p -TPD / Y-TiOPc@SQ / ITO.

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