TiOPc dopant, tiOPc@SQ heterojunction and application thereof

Abstract

The application belongs to the technical field of photoelectric materials and application, and particularly relates to a TiOPc dopant, a TiOPc@SQ heterojunction and application thereof. An indolyl squarine dye (SQ) is synthesized, and the SQ is used as a dopant of TiOPc. The synergistic effect of the SQ and the TiOPc is used to improve the absorption capacity of the TiOPc in a near-infrared region, optimize a charge separation efficiency, and realize more excellent photoelectric detection performance.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic materials and applications, specifically relating to a TiOPc dopant, a TiOPc@SQ heterojunction, and their applications. Background Technology

[0002] Photodetectors (PDs) are key devices that convert incident photons into electronically processable charge carriers. Due to their tunable detection wavelengths and compatibility with flexible / lightweight devices, they have wide applications in many cutting-edge technologies. However, as research progresses, the demands on detector performance are increasing, leading to a growing need for high-performance semiconductor materials. Compared to inorganic semiconductors, organic semiconductors possess extremely high extinction coefficients, exhibiting significant advantages in light absorption. Furthermore, their molecular structures are easily modulated, allowing for flexible adjustment of the absorption spectrum to meet multi-band detection requirements. Against this backdrop, organic photodetectors, especially near-infrared organic photodetectors, have attracted widespread attention due to their irreplaceable role in remote sensing control and optical communication. However, the types of organic semiconductor materials suitable for the near-infrared band are still relatively limited, resulting in a relative lag in research compared to devices in the ultraviolet and visible light regions.

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

[0004] Currently, commonly used organic photosensitive materials mainly include four types: phthalocyanine compounds, azo compounds, perylene compounds, and squaric acid compounds. Among them, phthalocyanine compounds have attracted much attention due to their low toxicity, good photothermal stability, high carrier generation efficiency, strong light absorption and excellent photosensitivity in the visible and near-infrared light regions (600~900 nm). Their application research has gradually shifted from the traditional printing and dyeing industry to the high-tech organic electronics field. Titanium phthalocyanine oxide (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) shows the best photoinduced charge generation performance (≥90%) in the Vis-NIR region. However, when titanium phthalocyanine oxide is used in organic photodetectors, it suffers from poor dispersibility, low photoelectric performance, and unstable crystal form, which cannot meet the requirements of easy dispersibility, high photoresponsivity, high external quantum efficiency, and high photosensitivity of organic photosensitive materials. The main reasons for these shortcomings are the low photogenerated carrier generation efficiency, insufficient separation efficiency, and low migration rate of the photosensitive organic pigment. Furthermore, due to its structural characteristics, it is prone to aggregation. These deficiencies affect the near-infrared photosensitivity of TiOPc, failing to meet the requirements for higher sensitivity near-infrared applications. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides a TiOPc dopant, a TiOPc@SQ heterojunction, and their applications. By synthesizing an indoline-based squaric acid cyanine dye (SQ) and using it as a TiOPc dopant, the systemic interaction between SQ and TiOPc enhances the absorption capacity of TiOPc in the near-infrared region, optimizes charge separation efficiency, and achieves superior photoelectric detection performance.

[0006] A TiOPc dopant is an indolinyl squaric acid cyanine dye, the general structural formula of which is shown in Formula I:

[0007]

[0008] Wherein, the R group is independently a hydrocarbon group having 5 to 25 carbon atoms; the R group has at least one branch.

[0009] The number of carbon atoms in R is preferably 7 to 12;

[0010] More preferably, the R group is independently a group (a) and (b).

[0011] .

[0012] The preparation method of the indolinel squaric acid cyanine dye includes the following steps:

[0013] (1) Dissolve raw material A (1,2,3,3-tetramethyl-6-nitroindoline) in methanol at room temperature, add palladium on carbon, and then stir under hydrogen atmosphere at room temperature. Monitor the reaction by TLC. Stop the reaction when raw material A disappears, filter with diatomaceous earth, and concentrate the filtrate with a rotary evaporator to obtain compound B.

[0014] (2) Compound B was dissolved in dichloromethane at room temperature, and triethylamine and dimethylaminopyridine were added. After cooling to 0°C, an amidation reagent was added. The mixture was then stirred under a nitrogen atmosphere at 0°C, and the reaction was monitored by TLC. When compound B disappeared, the reaction was stopped, saturated brine was added, and the mixture was extracted with dichloromethane. The resulting organic layer was dried with anhydrous sodium sulfate, and the solvent was distilled off using a rotary evaporator to obtain compound C.

[0015] (3) Dissolve compound C in a mixed solution of toluene and n-butanol at room temperature, add squaric acid, stir under N2 atmosphere and reflux of azeotrope, and monitor the reaction by TLC; stop the reaction when compound C disappears, distill off the reaction solvent using a rotary evaporator, and purify by silica gel column chromatography to obtain target compound D.

[0016] The preparation principle is shown in the following formula:

[0017] .

[0018] In step (1), the mass ratio of palladium on carbon to raw material A is 0.03 to 0.09.

[0019] In step (2), the molar ratio of compound B to triethylamine and amidating agent is 1:(1.8~2.0):(1.4~1.5).

[0020] The amidating agent is a carboxyl chloride with an R substituent;

[0021] The molar ratio of dimethylaminopyridine to compound B is 1:(20~22).

[0022] In step (3), the volume ratio of toluene to n-butanol is 1:1;

[0023] The molar ratio of compound C to squaric acid is 1:0.5.

[0024] The present invention also provides a TiOPc@SQ heterojunction, comprising titanium phthalocyanine oxide and the above-mentioned TiOPc dopant;

[0025] The indolinyl squaric acid cyanine dye accounts for 0.3~1.5 wt.% of the TiOPc@SQ heterojunction. When the content of indolinyl squaric acid cyanine dye is too low, the morphology regulation of the TiOPc film and the improvement of near-infrared light absorption are small, and the device performance cannot be significantly improved. When the content is too high, the TiOPc film of the device is over-regulated and the molecules are over-aggregated, which reduces the light absorption of the active layer of the device and affects the device performance.

[0026] Preferably, the TiOPc@SQ heterojunction also includes PVB.

[0027] More preferably, the weight ratio of charge-generating materials (TiOPc, SQ) to PVB is (5~8):1.

[0028] Preferably, the TiOPc is γ-TiOPc.

[0029] The preparation method of the Y-TiOPc@SQ heterojunction is as follows: Y-TiOPc and SQ are dispersed in PVB and then in 1,2-dichloroethane. The mixture is ultrasonicated, ball-milled, and sieved to prepare a Y-TiOPc@SQ photosensitive dispersion. The Y-TiOPc@SQ heterojunction is obtained by spin coating and annealing.

[0030] This invention also provides the application of the above-mentioned TiOPc@SQ heterojunction in organic optoelectronic devices.

[0031] Preferably, the organic optoelectronic device is an organic photodetector.

[0032] More preferably, the organic photodetector structure is Au / p -TPD / Y-TiOPc@SQ / ITO.

[0033] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0034] (1) By doping Y-type titanium phthalocyanine with an appropriate amount of squaric acid cyanine dye, a heterojunction photoactive layer of Y-TiOPc@SQ was successfully constructed. The photodetector of Y-TiOPc@SQ exhibits excellent photoelectric performance in the range of 365 nm to 940 nm.

[0035] (2) Due to the doping of SQ, the Y-TiOPc@SQ heterojunction in the photoactive layer can not only improve the photoelectric detection performance of TiOPc in the near-infrared region, but also effectively improve the carrier generation efficiency, separation efficiency and transport rate. 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 hole tunneling injection efficiency from the external circuit.

[0036] (3) Organic optoelectronic devices exhibit fast, stable and reproducible photocurrent response, indicating that they have good reliability and practicality.

[0037] (4) Intermediate B of squaric acid cyanine dye is synthesized by a clean and environmentally friendly hydrogenation method, which is conducive to the synthesis of green and sustainable organic optoelectronic materials. Attached Figure Description

[0038] Figure 1 The three-dimensional optimized molecular structure and orbital energy levels of SQ1 in Example 1 of this invention are shown in (a) and (b) respectively.

[0039] Figure 2 The three-dimensional optimized molecular structure and orbital energy levels of SQ2 in Example 2 of this invention are shown in (a) and (b) respectively.

[0040] Figure 3 This is a schematic diagram of the fabrication process of an organic photodetector with Y-TiOPc and Y-TiOPc@SQ as active layers;

[0041] Figure 4 The photoresponsivity curves of organic photodetectors with different proportions of SQ1 as the active layer at -20V are shown.

[0042] Figure 5 The photoresponsivity curves of organic photodetectors with different proportions of SQ2 as the active layer at -20V are shown.

[0043] Figure 6 The external quantum efficiency curves of organic photodetectors with different proportions of SQ1 as active layers at -20V are shown.

[0044] Figure 7 The external quantum efficiency curves of organic photodetectors with different proportions of SQ2 as active layers at -20V are shown.

[0045] Figure 8 The specific detectivity curves of organic photodetectors with different proportions of SQ1 as the active layer at -20V are shown.

[0046] Figure 9 The specific detectivity curves of organic photodetectors with different proportions of SQ2 as the active layer at -20V;

[0047] Figure 10 This is a time-current curve of an organic photodetector with Y-TiOPc as the active layer at -5V.

[0048] Figure 11 The time-current curve of an organic photodetector with Y-TiOPc@0.5%SQ1 as the active layer at -5V is shown.

[0049] Figure 12 The time-current curve of an organic photodetector with Y-TiOPc@0.8%SQ2 as the active layer is shown at -5V. Detailed Implementation

[0050] The specific implementation of the present invention will be further described below 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 any processes not specifically described in detail below are those that can be implemented or understood by those skilled in the art by referring to the prior art.

[0051] The present invention can be practiced using conventional techniques in organic synthetic chemistry. In the following examples, efforts have been made to ensure the accuracy of the figures used (including quantities, temperatures, reaction times, etc.), but some experimental errors and deviations should be considered. Temperatures used in the following examples are expressed in °C, pressures are at or near atmospheric pressure, and room temperature is 25 ± 2 °C. All solvents used are of analytical or chromatographic purity. Unless otherwise stated, all reagents were obtained through commercial channels.

[0052] The preparation method of γ-TiOPc in the following examples and comparative examples is as follows: A 5% (w / w) TiOPc / H2SO4 solution (0 °C, 16 mL) was added dropwise to 250 mL of H2O / o-dichlorobenzene (v / v = 1 / 1) microemulsion at 30 °C. After stirring for 6 hours, the microemulsion was demulsified with methanol, separating the colorless aqueous phase and the blue o-dichlorobenzene phase. The o-dichlorobenzene phase was diluted with 250 mL of methanol, precipitating γ-TiOPc NPs. Then, the precipitate was washed with methanol and water until the conductivity of the wash water was <5 μS cm⁻¹. -1 Finally, γ-TiOPc NPs were obtained by vacuum freeze-drying.

[0053] In the following examples and comparative examples, PVB was purchased from Shanghai Jingchun Biochemical Technology Co., Ltd., and its content was 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 etched 40*6mm, film thickness: 185 nanometers, transmittance: ≥84%.

[0054] In the following embodiments, the wavelength-photoresponse curve, wavelength-external quantum efficiency curve, wavelength-specific detectivity curve, and time-current curve testing methods are referenced in: 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.

[0055] In the following examples and comparative examples, the effective exposed area of ​​the Y-TiOPc-PD and Y-TiOPc@SQ-PD devices is 0.12 cm². 2 .

[0056] As an example, the structural formula of the indolinel squaric acid cyanine dye prepared in the following embodiments is shown below:

[0057] .

[0058] Example 1: Preparation of indoline-based squaric acid cyanine dye SQ1 and Y-TiOPc@SQ1 heterojunction

[0059] The chemical synthesis route of SQ1 is shown below, with specific reaction steps and conditions as follows:

[0060] .

[0061] (1) Synthesis of compound 2

[0062] Compound 1 (1,2,3,3-tetramethyl-6-nitroindoline) (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 flask. The mixture was then stirred at room temperature under a hydrogen atmosphere. The reaction was monitored until the starting material (compound 1) disappeared, at which point the reaction was stopped, and the mixture was filtered through diatomaceous earth. The filtrate was concentrated using a rotary evaporator. The result was compound 2 (3.148 g, 0.0165 mol, yield 88%).

[0063] (2) Synthesis of compound 3

[0064] 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. After cooling the reaction solution to 0 °C, 2-propylpentanoyl chloride (3.738 g, 0.0230 mol) was added. The mixture was then stirred under a nitrogen atmosphere at 0 °C, and the reaction was monitored by TLC. After the reaction was complete, 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 to remove the solvent using a rotary evaporator. The result yielded compound 3 (3.845 g, 0.0121 mol, yield 75%).

[0065] (3) Synthesis of SQ1

[0066] A Dean-Stark tube was fitted into a 500 mL single-necked round-bottom flask, and 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 were added. The mixture was stirred under N2 atmosphere and reflux with an azeotropic solution, and the reaction was monitored by TLC. After the reaction was complete, the reaction solvent was distilled off using a rotary evaporator, and the product was purified by silica gel column chromatography (developing solvent: n-hexane:ethyl acetate = 7:3). The result yielded dye SQ1 (2.190 g, 0.0031 mol, yield 70%).

[0067] (4) Preparation of Y-TiOPc@SQ1 heterojunction

[0068] First, 0.01 g of PVB was added to each of 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 beakers 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 Photosensitizing 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.

[0069] The above photosensitive dispersion was spin-coated and annealed at 80°C for 10 min to prepare Y-TiOPc@SQ1 heterojunction.

[0070] Example 2: Preparation of indoline-based squaric acid cyanine dye SQ2 and Y-TiOPc@SQ2 heterojunction

[0071] The chemical synthesis route of SQ2 is shown below, with specific reaction steps and conditions as follows:

[0072] .

[0073] (1) Synthesis of compound 2

[0074] 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 flask. The mixture was then stirred at room temperature under a hydrogen atmosphere. The reaction was monitored until the starting material (compound 1) disappeared, at which point the reaction was stopped, and the mixture was filtered through diatomaceous earth. The filtrate was concentrated using a rotary evaporator. The result was compound 2 (3.212 g, 0.0169 mol, yield 92%).

[0075] (2) Synthesis of compound 4

[0076] 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. After cooling the reaction solution to 0 °C, 2-ethylhexanoyl chloride (3.979 g, 0.0245 mol) was added. The mixture was then stirred under a nitrogen atmosphere at 0 °C, and the reaction was monitored by TLC. After the reaction was complete, 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 to remove the solvent using a rotary evaporator. The result yielded compound 4 (3.934 g, 0.0124 mol, yield 74%).

[0077] (3) Synthesis of SQ2

[0078] A Dean-Stark tube was installed in a 500 mL single-necked round-bottom flask. Under a nitrogen atmosphere, 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 were added. The mixture was stirred under reflux as an azeotrope, and the reaction was monitored by TLC. After the reaction was complete, the reaction solvent was distilled off using a rotary evaporator, and the product was purified by silica gel column chromatography (developing solvent: hexane:ethyl acetate = 7:3). The result yielded dye SQ2 (2.662 g, 0.0037 mol, yield 72%).

[0079] (4) Preparation of Y-TiOPc@SQ2 heterojunction

[0080] First, 0.01 g of PVB was added to each of five beakers. Then, 74.775 mg Y-TiOPc and 0.225 mg (0.3 wt.%) SQ2, 74.625 mg Y-TiOPc and 0.375 mg (0.5 wt.%) SQ2, 74.400 mg Y-TiOPc and 0.600 mg (0.8 wt.%) SQ2, and 73.875 mg Y-TiOPc and 1.125 mg (1.5 wt.%) SQ2 were added to the beakers 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 Photosensitizing 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.

[0081] The above photosensitive dispersion was spin-coated and annealed at 80°C for 10 min to prepare Y-TiOPc@SQ2 heterojunction.

[0082] Comparative Example 1

[0083] like Figure 3 As shown in (a), this is a schematic diagram of the fabrication process of an organic photodetector with Y-TiOPc as the active layer. The specific fabrication process of this comparative photodetector is as follows:

[0084] Clean the ITO glass with a cleaning agent and sonicate it in distilled water, acetone, and ethanol for 15 minutes. Repeat the sonication process twice with acetone and ethanol. Dry the ITO glass with nitrogen before use.

[0085] 0.075 g Y-TiOPc and 0.01 g PVB were dispersed in 7.5 mL of 1,2-dichloroethane, sonicated for 15 min, and 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 photosensitizing dispersion. 0.1 g p -TPD was added to 1 mL of dichloromethane and sonicated for 15 min to prepare 100 mg / mL of [a specific drug / concentrate]. p -TPD solution. After cleaning, the ITO glass was dried with N2 and treated with UV ozone for 10 min. Then, the ITO substrate was fixed on a benchtop spin coater. Each time, 0.5 mL of Y-TiOPc photosensitizing dispersion was spin-coated onto the ITO substrate surface at a speed of 500 r / min (10 s) followed by 1500 r / min (10 s). The coatings were annealed at 80℃ for 10 min, and a total of 8 layers were coated to prepare the photoactive layer. p - A hole transport layer was prepared by spin-coating 0.2 mL of TPD onto the surface of the photoactive layer and annealed at 60 °C for 1 h. Finally, an Au electrode was deposited at room temperature by magnetron sputtering at 20 mA for 1.5 min. p - On the TPD layer thin film.

[0086] The final fabricated device structure is Au / p Y-TiOPc-PD of -TPD / Y-TiOPc / ITO. Wavelength-photoresponse curves were tested (see attached). Figure 4 Wavelength-external quantum efficiency curve test (see appendix) Figure 6 Wavelength-specific detectivity curve test (see appendix) Figure 8 ) and time-current curve testing (see appendix) Figure 10 The device performance parameters are shown in Table 1-3.

[0087] Table 1. Organic photodetectors based on Y-TiOPc as the active layer at -20 V and 0.01 mW / cm² 2 Photoresponsivity (A / W) under the given conditions

[0088]

[0089] Table 2 Organic photodetectors based on Y-TiOPc as the active layer at -20 V and 0.01 mW / cm 2 External quantum efficiency value (%) under the given conditions

[0090]

[0091] Table 3 Organic photodetectors based on Y-TiOPc as the active layer at -20 V and 0.01 mW / cm 2Specific detectivity under the given conditions (×10) 11 Jones)

[0092]

[0093] Example 3

[0094] The application of SQ1 as a dopant of titanium phthalocyanine in organic photodetectors is illustrated using the Y-TiOPc@SQ1 heterojunction obtained in Example 1 as an example.

[0095] This embodiment is the same as Comparative Example 1, except that the Y-TiOPc photosensitive dispersion is replaced with the Y-TiOPc@0.3%SQ1, Y-TiOPc@0.5%SQ1, Y-TiOPc@0.8%SQ1, and Y-TiOPc@1.5%SQ1 photosensitive dispersions prepared in Example 1.

[0096] The final fabricated device structure is Au / p Y-TiOPc@SQ1-PD of -TPD / Y-TiOPc@SQ1 / ITO (device structure shown in appendix) Figure 3 (b) Wavelength-photoresponse curves were tested (see Appendix). Figure 4 Wavelength-external quantum efficiency curve test (see appendix) Figure 6 Wavelength-specific detectivity curve test (see appendix) Figure 8 Time-current curves of Y-TiOPc@0.5%SQ1 active layer were tested (see attached). Figure 11 The device performance parameters are shown in Table 4-6. As can be seen from the table, the device performance initially increases and then decreases when doped with 0.3 wt.%, 0.5 wt.%, 0.8 wt.%, or 1.5 wt.% SQ1 on TiOPc. This is because increasing the SQ1 doping ratio modulates the film morphology of the active layer, enhancing the synergistic effect between TiOPc and SQ1. This increases the light absorption performance of the active layer, generating more photoexcitons, improving exciton separation efficiency and thus generating more free-moving charges, and enhancing carrier transport and collection efficiency, thereby significantly improving device performance. However, when the doping ratio exceeds 0.5 wt.% SQ1, the device performance decreases. 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 exhibits the best performance in terms of photoresponsivity, external quantum efficiency, and specific detectivity; therefore, 0.5 wt.%SQ1 is the optimal mixing ratio for the photoactive layer. (See attached...) Figure 11It 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 range. The time-current curves are fast, stable and reproducible, which indicates that Y-TiOPc@0.5%SQ1-PD has excellent photoresponse characteristics in the entire ultraviolet-visible-near-infrared spectral range.

[0097] Table 4 shows the performance of organic photodetectors based on Y-TiOPc@SQ1 as the active layer at -20 V and 0.01 mW / cm². 2 Photoresponsivity (A / W) under the given conditions

[0098]

[0099] Table 5 shows the performance of organic photodetectors based on Y-TiOPc@SQ1 as the active layer at -20 V and 0.01 mW / cm². 2 External quantum efficiency value (%) under the given conditions

[0100]

[0101] Table 6 shows the performance of organic photodetectors based on Y-TiOPc@SQ1 as the active layer at -20 V and 0.01 mW / cm². 2 Specific detectivity under the given conditions (×10) 11 Jones)

[0102]

[0103] Example 4

[0104] The application of SQ2 as a dopant of titanium phthalocyanine in organic photodetectors is illustrated using the Y-TiOPc@SQ2 heterojunction obtained in Example 2 as an example.

[0105] This embodiment is the same as Comparative Example 1, except that the Y-TiOPc photosensitive dispersion is replaced with the Y-TiOPc@0.3%SQ2, Y-TiOPc@0.5%SQ2, Y-TiOPc@0.8%SQ2, and Y-TiOPc@1.5%SQ2 photosensitive dispersions prepared in Example 2.

[0106] The final fabricated device structure is Au / p Y-TiOPc@SQ2-PD of -TPD / Y-TiOPc@SQ2 / ITO (device structure shown in appendix) Figure 3 (b) Wavelength-photoresponse curves were tested (see Appendix). Figure 5 Wavelength-external quantum efficiency curve test (see appendix) Figure 7 Wavelength-specific detectivity curve test (see appendix) Figure 9Time-current curves of Y-TiOPc@0.8%SQ2 active layer were tested (see attached). Figure 12 The device performance parameters are shown in Table 7-9. As can be seen from the table, doping TiOPc with 0.3 wt.%, 0.5 wt.%, 0.8 wt.%, and 1.5 wt.% SQ2 initially increases and then decreases. Y-TiOPc@0.8%SQ2-PD exhibits the best performance in terms of photoresponsivity, external quantum efficiency, and specific detectivity. Therefore, 0.8 wt.% SQ2 is the optimal mixing ratio for the photoactive layer. (See attached table for details.) 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 range. The time-current curves are fast, stable and reproducible, which indicates that Y-TiOPc@0.8%SQ2-PD has excellent photoresponse characteristics in the entire ultraviolet-visible-near-infrared spectral range.

[0107] Table 7 shows the performance of organic photodetectors based on Y-TiOPc@SQ2 as the active layer at -20 V and 0.01 mW / cm². 2 Photoresponsivity (A / W) under the given conditions

[0108]

[0109] Table 8 shows the performance of organic photodetectors based on Y-TiOPc@SQ2 as the active layer at -20 V and 0.01 mW / cm². 2 External quantum efficiency value (%) under the given conditions

[0110]

[0111] Table 9 shows the performance of organic photodetectors based on Y-TiOPc@SQ2 as the active layer at -20 V and 0.01 mW / cm². 2 Specific detectivity under the given conditions (×10) 12 Jones)

[0112]

[0113] To further explore the synergistic effect of Y-TiOPc and SQ in the Y-TiOPc@SQ heterojunction, this invention utilizes the 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 using density functional theory. Figure 1 and Figure 2The figures show (a) the optimized 3D molecular structure and (b) the orbital energy levels of SQ1 and SQ2. As can be seen from the figures, the indoline rings on both sides are essentially in the same plane as the squaric acid core, indicating a planar molecular backbone. These HOMO-LUMO orbitals are mainly distributed on the central backbone, indoline ring, and amide group of squaric acid cyanine, and the orbitals of the backbone are highly symmetrical, indicating that electron delocalization occurs from the donor group to the molecular center. The calculated HOMO / LUMO energy levels of SQ1 and SQ2 are the same, -4.71 eV and -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 means that the material has a high optical absorption coefficient and good electrical conductivity, making it suitable for optoelectronic applications.

[0114] According to the detection results of Examples 3 and 4 and Comparative Example 1, the Y-TiOPc@SQ heterojunction used as the active layer in this invention has superior photoelectric performance compared to Y-TiOPc. The reason is that this invention uses SQ as a dopant. (1) The SQ dopant introduces an indoline derivative structure at the 1,3-position of the squaric acid core to form a DAD configuration. By changing the donor structure of the indoline derivative substituted with an amide group, the optical performance and solubility of the squaric acid cyanine dye are adjusted. (2) The squaric acid cyanine provided by this invention has absorption and emission wavelengths in the near-infrared region, with strong absorption and narrow emission bands, and high solubility in organic solvents. (3) The HOMO / LUMO energy level of the squaric acid cyanine provided by this invention matches the HOMO / LUMO energy level (-5.7 eV / -4.0 eV) of Y-TiOPc. This energy level matching characteristic allows the two to better exert a synergistic effect, thereby significantly improving photoelectric performance in optoelectronic devices and other fields. In addition, (1) the indoline group in the SQ dopant has a large molar extinction coefficient, good fluorescence performance, stronger electron-donating ability, better coplanarity with squaric acid, and relatively high stability compared to other electron-donating groups; (2) the amide group that can be branched by introducing a substituted hydrocarbon group on the indoline group in the SQ dopant has better solubility.

[0115] The above embodiments of the present invention are merely illustrative examples to clearly illustrate the invention, and are not intended to limit the implementation of the invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all possible implementations. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A TiOPc@SQ heterojunction, characterized in that, TiOPc doped with phthalocyanine titanium oxide, TiOPc dopant; The TiOPc dopant accounts for 0.3-1.5 wt.% of the TiOPc@SQ heterojunction; the TiOPc dopant is an indolyl squarylium cyanine dye, and the general structure is shown as Formula I: The R group is independently formula (a) or formula (b); 。 2. The TiOPc@SQ heterojunction according to claim 1, characterized in that, The preparation method of the indolyl squarylium cyanine dye comprises the following steps: (1) Dissolve raw material A in methanol at room temperature, add palladium-carbon, then stir under hydrogen atmosphere at room temperature, and monitor the reaction by TLC; when the raw material A disappears, stop the reaction, filter with diatomite, and concentrate the filtrate with a rotary evaporator to obtain compound B; The raw material A is 1,2,3,3-tetramethyl-6-nitroindoline; (2) Dissolve compound B in dichloromethane at room temperature, add triethylamine and dimethylamino pyridine, cool to 0℃, then add amide reagent, and stir under nitrogen atmosphere at 0℃, and monitor the reaction by TLC; when the compound B disappears, stop the reaction, add saturated brine, and extract with dichloromethane; dry the obtained organic layer with anhydrous sodium sulfate, and distill off the solvent with a rotary evaporator to obtain compound C; (3) Dissolve compound C in a mixed solution of toluene and n-butanol at room temperature, add squaric acid, stir under N2 atmosphere and azeotrope heating reflux condition, and monitor the reaction by TLC; when the compound C disappears, stop the reaction, distill off the reaction solvent with a rotary evaporator, and purify with silica gel column chromatography to obtain target compound D; The target compound D is the indolyl squarylium cyanine dye.

3. The TiOPc@SQ heterojunction according to claim 2, characterized in that, In step (1), the mass ratio of palladium-carbon to raw material A is 0.03-0.

09.

4. The TiOPc@SQ heterojunction according to claim 2, wherein, The amide reagent is carboxylic acid chloride with R group as the substituent; The molar ratio of dimethylamino pyridine to compound B is 1:(20-22).

5. The TiOPc@SQ heterojunction according to claim 4, wherein, In step (2), the molar ratio of compound B to triethylamine and amide reagent is 1:(1.8-2.0):(1.4-1.5).

6. The TiOPc@SQ heterojunction according to claim 2, wherein, 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. The TiOPc@SQ heterojunction according to claim 1, wherein, The TiOPc@SQ heterojunction further comprises PVB, The weight ratio of charge generating material to PVB is (5-8):1; The charge generating material is TiOPc and TiOPc dopant.

8. Use of the TiOPc@SQ heterojunction according to any one of claims 1-7 in an organic optoelectronic device, wherein, The organic optoelectronic device is an organic photodetector.

9. The use in an organic optoelectronic device according to claim 8, wherein, The organic photodetector structure is Au / p - TPD / Y-TiOPc @ SQ / ITO.

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