Narrow-band-gap organic acceptor material, near-infrared organic photoelectric detector and preparation method and application of near-infrared organic photoelectric detector

Abstract

The invention relates to the technical field of photoelectric devices, and discloses a narrow-band-gap organic acceptor material, a near-infrared organic photoelectric detector and a preparation method and application of the narrow-band-gap organic acceptor material and the near-infrared organic photoelectric detector. The molecular structure of the narrow-band-gap organic acceptor material is shown as a formula (1), and in the formula (1), X is F or Cl. The narrow-band-gap non-fullerene receptor is obtained by inserting another ethylene double bond pi bridge between a condensed ring donor (D) unit in the center of a CH-series organic receptor and a terminal group of a receptor (A). An electron-rich double bond is introduced into a continuous pi system, so that the effective conjugate length is increased, intramolecular charge transfer (ICT) is enhanced, and a band gap is reduced. In addition, the inherent planar pi bridge limits the rotational degree of freedom and forcibly forms a coplanar geometric structure between the core D unit and the A end group, so that a rigid and coplanar conjugate skeleton is kept; therefore, the narrow-band-gap non-fullerene receptor has excellent thermal stability and high surface electrostatic potential, and intermolecular accumulation of the narrow-band-gap non-fullerene receptor in a solid state is remarkably enhanced.

Description

Technical Field

[0001] This application relates to the field of optoelectronic device technology, specifically to a narrow bandgap organic acceptor material, a near-infrared organic photodetector, its preparation method, and its application. Background Technology

[0002] Human-machine interfaces (HMIs) are undergoing a fundamental shift from contact-based systems to contactless models that enable three-dimensional spatial interaction with machines. As digital environments increasingly merge with physical spaces, these contactless HMIs (C-HMIs) are becoming indispensable in optics-centric fields such as virtual and augmented reality (AR / VR) systems, immersive gaming, industrial automation equipment, and metaverse applications. Solution-processed organic photodetectors (OPDs) benefit from their inherently tunable bandgap (300-3000 nm) and the high absorption coefficient (>10) of organic materials. 5 cm -1 This technology is particularly suitable for C-HMIs that require coverage of the visible to near-infrared region, especially multi-band detection exceeding 1000 nm. Furthermore, the inherent flexibility of organic semiconductors, combined with their excellent heterogeneity, lightweight nature, and skin-adhering properties, enables the fabrication of flexible photodetectors that can be seamlessly integrated into emerging AI-assisted wearable and embedded platforms.

[0003] To achieve broadband detection in these applications, molecular design efforts are increasingly focused on narrowing the band gap of A-DA'DA type small molecule acceptors (SMAs). Several well-established strategies, such as halogenation, side-chain engineering, central core / terminal unit extension, π-conjugation bridging, and multi-component strategies, have been widely used to modulate molecular frontier orbitals and enhance near-infrared absorption. These methods, by introducing π-bridges between electron-donating and electron-withdrawing end groups, are particularly effective in extending the conjugation length and narrowing the band gap for near-infrared OPD above 1000 nm. However, due to steric hindrance or conformational effects, introducing π-bridges can increase torsional degrees of freedom and impair framework planarity, leading to high-energy disorder and trapped states in photoactive films. The resulting trapped states and energy disorder not only exacerbate thermally activated charge leakage in narrow bandgap systems, leading to increased noise and decreased sensitivity, but also hinder charge transport and reduce carrier mobility.

[0004] The aforementioned defects result in existing near-infrared organic photodetectors (NIR-OPD) typically having a response speed slower than 1 µs and insufficient ability to detect ultra-weak light signals, severely hindering their practical application in high-speed, high-sensitivity C-HMIs. Summary of the Invention

[0005] This application provides a narrow bandgap organic acceptor material, a near-infrared organic photodetector, its preparation method and application, aiming to solve the technical problems of slow response speed and low ability to detect ultra-weak light signals in existing organic photodetectors.

[0006] To achieve the above objectives, the present application adopts the following technical solution.

[0007] In a first aspect, this application provides a narrow bandgap organic acceptor material, the molecular structure of which is shown in formula (1): (1) Where X is F or Cl.

[0008] Preferably, the synthesis process of the narrow bandgap organic acceptor material is as follows:

[0009] .

[0010] A second aspect of this application provides a method for preparing the aforementioned narrow-bandgap organic acceptor material, comprising: S1, Dissolve compound 1 in the first solvent to obtain solution A; Dissolve sodium hydride and tributyl(1,3-dioxolane-2-ylmethyl)phosphonium bromide in the first solvent to obtain solution B; Under an inert atmosphere, add solution A dropwise to solution B to carry out the reaction to obtain the reaction solution; S2, the reaction solution was added to hydrochloric acid and stirred to react, then the organic phase was extracted and collected; the organic phase was washed, dried, and then distilled under reduced pressure to obtain the crude product; the crude product was purified by silica gel column chromatography to obtain compound 2; S3, compound 2 and the halogen-containing compound were dissolved in a second solvent, and then acetic anhydride and boron trifluoride diethyl ether complex were added to react; after the reaction, the solid crude product was obtained by vacuum distillation, and then purified by silica gel column chromatography to obtain a narrow bandgap organic acceptor material. The halogen-containing compound is 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-1-yl)malononitrile or 2-(5,6-dichloro-3-oxo-2,3-dihydro-1H-indene-1-yl)malononitrile.

[0011] Preferably, the first solvent comprises tetrahydrofuran; the second solvent comprises toluene; and the extractant comprises dichloromethane. The eluent used for purification by silica gel column chromatography is a mixture of n-hexane and chloroform in a volume ratio of 1:8.

[0012] Preferably, in S1, the molar ratio of compound 1, sodium hydride, and tributyl(1,3-dioxolane-2-ylmethyl)phosphonium bromide is 1.38:5.52:3.04; the reaction temperature is room temperature, and the reaction time is 12~24h; In S3, the molar ratio of compound 2, halogen-containing compound, acetic anhydride, and boron trifluoride diethyl ether complex is 0.83:2.09:2.1; the reaction time is 0.5~1h. In S2, the reaction time is 4~6 hours.

[0013] A third aspect of this application provides a near-infrared organic photodetector, which, from bottom to top, includes a transparent conductive substrate, a hole transport layer, an active layer, an electron transport layer, and a top electrode. The receptor in the active layer is the aforementioned narrow-bandgap organic receptor material.

[0014] Preferably, the transparent conductive substrate is a rigid conductive substrate or a flexible conductive substrate; the rigid conductive substrate is ITO glass, and the flexible conductive substrate is ITO / PET. The donor for the active layer includes any one of PCE10, PBDB-T, or PBDT-TT; The material of the hole transport layer includes any one of PEDOT:PSS, 2PACz, or 3-BPIC-F; The electron transport layer is made of materials including PNDIT-F3N, PDINO, PDINN, PFN-Br, or C. 60 Any one of / BCP; The material of the top electrode is Ag.

[0015] More preferably, the near-infrared organic photodetector is a rigid near-infrared organic photodetector, and its device structure is glass / ITO / PEDOT:PSS / active layer / PNDIT-F3N / Ag, wherein the donor of the active layer is PCE10 and the acceptor is the above-mentioned narrow bandgap organic acceptor material. or, The near-infrared organic photodetector is a flexible near-infrared organic photodetector with a device structure of PET / ITO / PEDOT:PSS / active layer / PNDIT-F3N / Ag, wherein the donor of the active layer is PCE10 and the acceptor is the aforementioned narrow bandgap organic acceptor material.

[0016] A fourth aspect of this application provides the application of the aforementioned near-infrared organic photodetector in a non-contact HMI.

[0017] A fifth aspect of this application provides a flexible non-contact HMI, which is vertically integrated from the aforementioned array of flexible near-infrared organic photodetectors and miniature LED lights.

[0018] Compared with the prior art, the beneficial effects of this application are as follows: This application synthesizes a narrow-bandgap non-fullerene acceptor by inserting another ethylene double bond π-bridge between the central fused-ring donor (D) unit and the acceptor (A) end group of a CH-series organic acceptor. The electron-rich double bond introduces a continuous π-system, increasing the effective conjugation length, enhancing intramolecular charge transfer (ICT), and reducing the bandgap. Furthermore, the inherent planar π-bridge restricts rotational freedom, forcing a coplanar geometry between the core D unit and the A end group, thus maintaining a rigid and coplanar conjugated framework. This results in the narrow-bandgap non-fullerene acceptor exhibiting excellent thermal stability, high surface electrostatic potential, and significantly enhanced intermolecular packing in the solid state.

[0019] The narrow bandgap organic acceptor material of this application broadens the spectral absorption to the NIR-II region by extending the conjugation length, while maintaining the rigid planar framework of the CH series acceptors to promote intermolecular stacking and improve charge mobility; the performance of NIR-OPD can be further optimized by introducing different halogen atoms on the end groups of the narrow bandgap non-fullerene acceptors.

[0020] The NIR-OPD of this application exhibits a wide detection range from 300 to 1100 nm and a high responsivity (0.32 AW at 1000 nm) in self-powered mode. -1 High specific detectivity (8.09 × 10⁻⁶ at 1000 nm) 13 Jones, fast light response (rise / fall time 500 / 500 ns) and linear dynamic range exceeding 154 dB are among the best reported in solution-processed self-powered NIR-II region OPDs. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 The density functional theory (DFT) calculation results are for the receptor material of this application and the existing CH series receptors; Figure 2 The results are normalized thin-film absorption spectra of the receptor material of this application and existing CH series receptors. Figure 3 The results show the thermal stability test results of the acceptor materials ZJ-1 and ZJ-2. Figure 4 The JV curve of a rigid near-infrared organic photodetector in the dark state; Figure 5 This is a responsivity curve of a rigid near-infrared organic photodetector under zero bias. Figure 6 The specific detectivity of a rigid near-infrared organic photodetector at zero bias ( (Line graph) Figure 7 The graph shows the response speed of a rigid near-infrared organic photodetector. Figure 8 The figure shows the test results of the -3 dB cutoff frequency of the rigid near-infrared organic photodetector under 850 nm illumination. Figure 9 The graph shows the test results of the linear dynamic range of the rigid near-infrared organic photodetector. Figure 10 The image shows a 2D GIWAXS plot of the blend film for the active layer of a rigid near-infrared organic photodetector. Figure 11 AFM height diagram of the blend film for the active layer of a rigid near-infrared organic photodetector; Figure 12 A schematic diagram of the structure of a flexible near-infrared organic photodetector and an optical photograph of it in a bent state; Figure 13 The graph shows the performance test results of the flexible near-infrared organic photodetector. Figure 14 This is a structural diagram and a working principle diagram of a flexible non-contact HMI. Detailed Implementation

[0023] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0024] In the following description of this embodiment, the terms "including", "comprising", "having", and "containing" are all open-ended terms, meaning that they include but are not limited to.

[0025] In the following description of this embodiment, the term "and / or" is used to describe the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, B existing alone, and A and B existing simultaneously. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0026] In the following description of this embodiment, the term "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0027] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms "a" and "the" as used in the embodiments of this application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0028] Those skilled in the art should understand that, in the following description of the embodiments of this application, the sequence of numbers does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0029] Those skilled in the art will understand that the numerical ranges in the embodiments of this application should be understood as each intermediate value between the upper and lower limits of the specifically disclosed range. Each smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this application. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0030] Unless otherwise stated, the technical / scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. While this application describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this application. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0031] In a first aspect, this application provides a narrow bandgap organic acceptor material, the molecular structure of which is shown in formula (1): (1) Where X is F or Cl.

[0032] The narrow bandgap organic acceptor material of this application is designated as ZJ-1 when X is F in its structural formula and as ZJ-2 when X is Cl in its structural formula.

[0033] Preferably, the synthesis process of the narrow bandgap organic acceptor material is as follows:

[0034] .

[0035] This application synthesizes a narrow-bandgap non-fullerene acceptor by inserting another ethylene double bond π-bridge between the central fused-ring donor (D) unit and the acceptor (A) terminal group of a CH-series organic acceptor. The mechanism is as follows:

[0036]

[0037] The electron-rich double bond introduces a continuous π system, increasing the effective conjugation length, enhancing intramolecular charge transfer (ICT), and reducing the band gap. Furthermore, the inherent planar π bridge restricts rotational freedom, forcing a coplanar geometry between the core D unit and the A end group, thus maintaining a rigid and coplanar conjugated framework. This results in the narrow-bandgap non-fullerene acceptor of this application exhibiting excellent thermal stability, high surface electrostatic potential, and significantly enhanced intermolecular packing in the solid state.

[0038] The narrow bandgap organic acceptor material of this application broadens the spectral absorption to the NIR-II region by extending the conjugation length, while maintaining the rigid planar framework of the CH series acceptors to promote intermolecular stacking and improve charge mobility; the performance of NIR-OPD can be further optimized by introducing different halogen atoms on the end groups of the narrow bandgap non-fullerene acceptors.

[0039] Secondly, this application provides a method for preparing the aforementioned narrow bandgap organic acceptor material, comprising: S1, Dissolve compound 1 in the first solvent to obtain solution A; Dissolve sodium hydride and tributyl(1,3-dioxolane-2-ylmethyl)phosphonium bromide in the first solvent to obtain solution B; Under an inert atmosphere, add solution A dropwise to solution B to carry out the reaction to obtain the reaction solution; In this application, the first solvent includes tetrahydrofuran; The preferred molar ratio of compound 1, sodium hydride, and tributyl(1,3-dioxolane-2-ylmethyl)phosphonium bromide is 1.38:5.52:3.04; the reaction temperature is room temperature, and the preferred reaction time is 12-24 h.

[0040] S2, the reaction solution was added to hydrochloric acid and stirred to react, then the organic phase was extracted and collected; the organic phase was washed, dried, and then distilled under reduced pressure to obtain the crude product; the crude product was purified by silica gel column chromatography to obtain compound 2; In this application, the reaction time is preferably 4 to 6 hours.

[0041] The extractant includes dichloromethane. The extracted organic phase is washed with a saturated sodium chloride solution and then dried with anhydrous Na₂SO₄; after removing the solvent under reduced pressure, it is purified by silica gel column chromatography to obtain the crude product. Preferably, the eluent used for silica gel column chromatography purification is a mixture of n-hexane and trichloromethane in a volume ratio of 1:8.

[0042] S3, compound 2 and the halogen-containing compound were dissolved in a second solvent, and then acetic anhydride and boron trifluoride diethyl ether complex were added to react; after the reaction, the solid crude product was obtained by vacuum distillation, and then purified by silica gel column chromatography to obtain a narrow bandgap organic acceptor material. In this application, the halogen-containing compound is 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-1-yl)malononitrile or 2-(5,6-dichloro-3-oxo-2,3-dihydro-1H-indene-1-yl)malononitrile.

[0043] The second solvent includes toluene; The preferred molar ratio of compound 2, halogen-containing compound, acetic anhydride and boron trifluoride diethyl ether complex is 0.83:2.09:2.1; the preferred reaction time is 0.5~1h.

[0044] In this application, the eluent used for purification by silica gel column chromatography is preferably a mixture of n-hexane and chloroform in a volume ratio of 1:8.

[0045] Thirdly, this application provides a near-infrared organic photodetector, which, from bottom to top, includes a transparent conductive substrate, a hole transport layer, an active layer, an electron transport layer, and a top electrode. The receptor in the active layer is either the narrow-bandgap organic receptor material ZJ-1 or ZJ-2.

[0046] In this application, no special restrictions are placed on the transparent conductive substrate, hole transport layer, electron transport layer and top electrode of the near-infrared organic photodetector, and any commonly used materials are acceptable.

[0047] Specifically, the donor of the active layer can be any one of PCE10, PBDB-T, or PBDT-TT. The donor of the active layer is preferably PCE10, which has complementary absorption and well-matched energy levels with the organic acceptor materials ZJ-1 and ZJ-2 of this application, thus facilitating efficient exciton dissociation and charge transfer.

[0048] The hole transport layer can be made of any one of PEDOT:PSS, 2PACz, or 3-BPIC-F, preferably PEDOT:PSS; the electron transport layer can be made of PNDIT-F3N, PDINO, PDINN, PFN-Br, or C. 60 Any one of / BCP, preferably PNDIT-F3N; the material of the top electrode is preferably Ag.

[0049] In this application, the transparent conductive substrate can be either a rigid conductive substrate or a flexible conductive substrate. Depending on the material of the transparent conductive substrate, the near-infrared organic photodetector can be either a rigid near-infrared organic photodetector or a flexible near-infrared organic photodetector. Specifically, this application does not impose any particular limitation on the rigid or flexible conductive substrate; commonly used substrate materials in the art can be used. Preferably, the rigid conductive substrate is glass / ITO, and the flexible conductive substrate is preferably PET / ITO.

[0050] This application also provides a rigid near-infrared organic photodetector, the device structure of which is glass / ITO / PEDOT:PSS / active layer / PNDIT-F3N / Ag, wherein the donor of the active layer is PCE10 and the acceptor is ZJ-1 or ZJ-2.

[0051] This application also provides a flexible near-infrared organic photodetector with a device structure of PET / ITO / PEDOT:PSS / active layer / PNDIT-F3N / Ag, wherein the donor of the active layer is PCE10 and the acceptor is ZJ-1 or ZJ-2.

[0052] The near-infrared organic photodetector of this application exhibits a wide detection range from 300 to 1100 nm and a high responsivity (0.32 AW at 1000 nm) in self-powered mode. -1 High specific detectivity (8.09 × 10⁻⁶ at 1000 nm) 13 With its superior performance, fast light response (rise / fall time 500 / 500 ns), and linear dynamic range exceeding 154 dB, the near-infrared organic photodetector of this application is superior to previously reported solution-processed self-powered NIR-II region OPDs. Based on its excellent performance, this near-infrared organic photodetector can be used to fabricate flexible non-contact HMIs.

[0053] Fifthly, this application provides a flexible non-contact HMI, which includes the flexible near-infrared organic photodetector array of this application and a micro LED, which is formed by vertically integrating the array of the flexible near-infrared organic photodetector and the micro LED.

[0054] Specifically, the preparation method of the flexible non-contact HMI includes: Six small-area near-infrared organic photodetector units were fabricated on a flexible substrate to obtain a flexible near-infrared organic photodetector array. A flexible non-contact HMI is obtained by integrating a flexible near-infrared organic photodetector array with a flexible printed circuit board (FPCB) with micro LEDs soldered on.

[0055] The present application will be further illustrated by the following examples.

[0056] Example 1 This embodiment provides receptor material ZJ-1, the preparation method of which includes: S1, under argon protection, compound 1 (0.138 mmol, 1.0 equivalent) was dissolved in tetrahydrofuran (10 mL) to obtain solution A; sodium hydride (0.552 mmol, 4.0 equivalent) and tributyl(1,3-dioxolane-2-ylmethyl)phosphonium bromide (0.304 mmol, 2.2 equivalent) were dissolved in tetrahydrofuran (10 mL) to obtain solution B; solution A was added dropwise to solution B, and the reaction was carried out at room temperature for 12 h to obtain the reaction solution; S2, the reaction solution was poured into 30 mL of 10% HCl and stirred for 4 h. The organic phase was then extracted with dichloromethane. The organic phase was washed with saturated brine and dried with anhydrous Na2SO4 for 1 h. The solvent was then removed under reduced pressure to obtain the crude product. The crude product was purified by silica gel column chromatography using n-hexane / chloroform (v / v = 1:8) as the eluent to give a red solid compound 2 (0.083 mmol, yield 60%).

[0057] In step S3, under argon protection, compound 2 (0.083 mmol, 1.0 equivalent) and 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-yl)malononitrile (0.209 mmol, 2.5 equivalent) were dissolved in toluene (20 mL), followed by the addition of acetic anhydride (0.419 mmol, 5.0 equivalent) and boron trifluoride diethyl ether complex (0.21 mmol, 2.5 equivalent). The mixture was stirred at room temperature for 30 min. After the reaction, the solvent was removed under reduced pressure to obtain a solid crude product. The crude product was purified by silica gel column chromatography using n-hexane / chloroform (v / v = 1:1.5) as the eluent to obtain a black solid, namely the receptor material ZJ-1 (83 mg, yield 56%).

[0058] Example 2 This embodiment provides receptor material ZJ-2.

[0059] The preparation method differs from that in Example 1 in that 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-1-yl)malononitrile in step S3 is replaced with 2-(5,6-dichloro-3-oxo-2,3-dihydro-1H-indene-1-yl)malononitrile, while the rest is the same as in Example 1.

[0060] The receptor material ZJ-1 prepared in Example 1 and the receptor material ZJ-2 prepared in Example 2 were subjected to proton nuclear magnetic resonance (NMR) spectroscopy, and the test data are as follows: ZJ-1 test data: 1 H NMR (400 MHz, CDCl3) 1 H NMR (400 MHz, Chloroform- d ) δ8.63 (d, J = 13.6 Hz, 2H), 8.56 – 8.47 (m, 4H), 8.14 (t, J = 9.3 Hz, 2H), 7.74(d, J = 14.2 Hz, 2H), 7.68 (t, J = 7.5 Hz, 2H), 4.70 (d, J = 8.0 Hz, 4H), 3.06 (t, J = 7.8 Hz, 4H), 2.20 (d, J = 8.9 Hz, 2H), 1.90 (p, J = 7.5 Hz, 4H), 1.40 – 0.68(m, 119H). MS (m / z, MALDI): Calc. for C 108 H 124 F6N8O2S4[M+H] + 1807.86, found:1807.86.

[0061] ZJ-2 test data: 1 H NMR (400 MHz, CDCl3) δ 8.77 (s, 2H), 8.67 (s, 2H), 8.54 (d, J = 11.8 Hz, 2H), 8.17 (d, J = 9.4 Hz, 2H), 7.94 (s, 2H), 7.77 (d, J =14.0 Hz, 2H), 4.69 (d, J= 7.9 Hz, 4H), 3.08 (t, J = 7.3 Hz, 4H), 2.17 (s, 2H), 1.89 (d, J = 8.6 Hz, 4H), 1.50 – 0.41 (m, 101H). MS (m / z, MALDI): Calc. forC 108 H 124 C l4 F2N8O2S4[M+H] + 1873.75, found: 1873.75.

[0062] Test results show that receptor materials ZJ-1 and ZJ-2 were successfully synthesized in Examples 1 and 2.

[0063] The density functional theory (DFT) calculation results of the receptor material in this application and existing CH series receptors are as follows: Figure 1 As shown in the figure. The results indicate that inserting two double bonds effectively extends the conjugation length, forming a larger π-conjugated system, thereby narrowing the band gap of the ZJ series receptors.

[0064] The normalized thin-film absorption spectrum test results of the receptor material in this application and existing CH series receptors are as follows: Figure 2 As shown in the figure. The results indicate that, compared with the CH series receptors, the ZJ series receptors exhibit a significant redshift absorption, with the absorption edge extending from 930 nm (CH-4F) to 1016 nm (ZJ-1) and from 938 nm (CH-4Cl) to 1019 nm (ZJ-2).

[0065] The thermal stability test results of the acceptor materials ZJ-1 and ZJ-2 are as follows: Figure 3 As shown, both receptors exhibit excellent thermal stability, with the thermal decomposition temperatures (T0) of ZJ-1 and ZJ-2 being relatively low. d The temperatures are 322 ℃ and 320 ℃, respectively.

[0066] Example 3 This embodiment provides a rigid near-infrared organic photodetector with a device structure of glass / ITO / PEDOT:PSS / active layer / PNDIT-F3N / Ag. The acceptor material of the active layer is ZJ-1, and the donor material is PCE10. Its fabrication method includes:

[0067] S1, the glass / ITO substrate (17×17 mm) was cleaned in ultrasonic baths of detergent, deionized water, acetone and isopropanol for 15 min each, and then dried with nitrogen; then it was subjected to UV irradiation for 15 min in a UV-ozone treatment machine to obtain the pretreated substrate. S2, spin-coat the PEDOT:PSS solution onto the pretreated substrate at 4300 rpm for 20 seconds, then anneal in air at 150°C for 20 min to form a hole transport layer; S3, dissolve a mixed solution of PEC10 and ZJ-1 in a mass ratio of 1:6, and the additive 1-chloronaphthalene (0.5 wt% of the mixed solution) in chloroform to prepare an active layer solution with a total concentration of 20 mg / mL. Place the solution on a heating plate at 45°C overnight to fully dissolve it. Spin-coat the active layer solution on top of the hole transport layer at 3000 rpm for 30 seconds. Then anneal the device on a hot plate at 100°C for 15 min to form the active layer.

[0068] S4. A methanol solution of PNDIT-F3N (concentration of 1.5 mg / mL) was spin-coated on top of the active layer at 3000 rpm for 20 seconds to form an electron transport layer. S5, in 2×10 -6 A rigid near-infrared organic photodetector was obtained by depositing a 100 nm thick Ag electrode on the surface of the electron transport layer under a vacuum of Pa through thermal evaporation.

[0069] Example 4 This embodiment provides a rigid near-infrared organic photodetector, which differs from Embodiment 3 in that the acceptor material of the active layer is ZJ-2, while the rest is the same as in Embodiment 3.

[0070] Example 5 This embodiment provides a flexible near-infrared organic photodetector with a device structure of ITO / PET / PEDOT:PSS / active layer / PNDIT-F3N / Ag. The acceptor material of the active layer is ZJ-2, and the donor material is PCE10. Its fabrication method includes:

[0071] S1, the polydimethylsiloxane (PDMS) precursor and the curing agent Sylgard 184 are mixed at a mass ratio of 10:1, and the mixture is spin-coated on a glass substrate at 5000 rpm for 30 seconds to form a PDMS sacrificial layer, followed by heat curing at 80°C for 10 min; the ITO / PET substrate layer is then bonded to the PDMS layer to form a flexible substrate; S2, PEDOT:PSS was modified with surfactant FS-30, wherein the volume of FS-30 was 0.5% of the volume of PEDOT:PSS; the modified PEDOT:PSS solution was spin-coated on the pretreated substrate at 4300 rpm for 20 seconds, and then annealed in air at 150°C for 20 min to form a hole transport layer. S3-S5 are the same as in Example 3.

[0072] The performance of the rigid near-infrared organic photodetector (based on ZJ-1) in Example 3 and the rigid near-infrared organic photodetector (based on ZJ-2) in Example 4 was evaluated as follows: 1. JV curve in dark state Test results are as follows Figure 4 As shown. Test results show that the ZJ-2-based device exhibits a voltage rating of 1.19 × 10⁻⁶ under self-powered operation. -10 A cm -2 The extremely low dark current density is significantly lower than that of ZJ-1-based devices (2.98 × 10⁻⁶). -10 A cm -2 The dark current density is reduced by 60%. This reduction in dark current density directly suppresses noise and improves the device's sensitivity to weak light detection.

[0073] 2. Response at zero bias Test results are as follows Figure 5 As shown in the figure. The results show that both devices exhibit broad and high responsivity in the visible and near-infrared regions, with the ZJ-2-based device achieving 0.48 AW at 910 nm under zero bias. -1 The peak R value reaches 0.32 AW at 1000 nm. -1 It is comparable to commercial silicon photodiodes in the NIR-II range.

[0074] 3. Specific detectivity at zero bias ( ) Test results are as follows Figure 6 As shown. The results indicate that both devices exhibit performance exceeding 10 in the visible to near-infrared region. 13 Jones This ensures reliable operation when detecting weak light signals in practical applications. Notably, the ZJ-2-based NIR-OPD achieved an 8.09 × 10¹³ Jones wavelength at 1000 nm. It is almost three times that of the ZJ-1 device (2.72 × 10¹³ Jones) and exceeds the OPD of most solution-processed devices in this spectral range.

[0075] 4. High-speed response Response speed is quantified by response time and -3dB bandwidth, measured by illuminating the NIR-OPD with an 850 nm LED driven by a square wave signal generator, where the effective rise / fall time (t) is... r / t f The duration is defined as the time it takes for the output signal to rise from 10% to 90% of its steady-state value and then fall back to 10%. Test results are as follows... Figure 7As shown. The results show that both devices exhibit high response speeds under zero bias. The device based on ZJ-2 has a faster response time of t... r / t f The value is 500 / 500 ns, which is about 60% higher than that of the ZJ-1 based device (800 / 800 ns).

[0076] The device under 850 nm illumination The test results for the cutoff frequency are as follows Figure 8 As shown. The results indicate that the ZJ-2-based device exhibits fi values ​​of 1.35, 1.42, and 1.02 MHz under illumination at 850, 950, and 1050 nm, respectively. -3 dB This exceeds most reported values, demonstrating significant application potential in delay-free C-HMI systems.

[0077] 5. Linear dynamic range Achieving stable and excellent non-contact HMI operation under different lighting environments requires the NIR-OPD to maintain consistent responsivity, i.e., linear dynamic range, over a wide range of light intensities. The calculation is as follows:

[0078]

[0079] J max and J min These are the photocurrent densities measured at the maximum and minimum light intensities, respectively.

[0080] Test results are as follows Figure 9 As shown, the results indicate that, benefiting from high responsivity and low dark current density, the ZJ-1 and ZJ-2-based NIR-OPDs exhibit excellent LDRs of 156 dB and 154 dB, respectively; the wide LDR ensures stable and reliable operation under six orders of magnitude of illumination intensity.

[0081] Morphological characterization was performed on the rigid near-infrared organic photodetector (based on ZJ-1) of Example 3 and the rigid near-infrared organic photodetector (based on ZJ-2) of Example 4.

[0082] 1.2D GIWAXS characterization The 2D GIWAXS diagrams of the PCE10:ZJ-1 blend film based on ZJ-1 devices and the PCE10:ZJ-2 blend film based on ZJ-2 devices are shown below. Figure 10As shown in the figure, the PCE10:ZJ-2 film exhibits a stronger π-π packing (010) peak and a smaller π-π packing distance (d=3.63 Å) in the out-of-plane (OOP) direction compared to PCE10:ZJ-1 (d=3.67 Å), indicating enhanced short-range ordered molecular packing. Furthermore, the corresponding crystal coherence lengths (CCLs) estimated by the Scherrer equation show that both the π-π packing CCL and the layered packing CCL of the ZJ-2-based BHJ film are increased (13.89 Å, 70.99 Å) compared to the ZJ-1-based BHJ film (13.64 Å, 70.84 Å). These structural improvements enhance intermolecular interactions and facilitate efficient charge transport.

[0083] 2. Characterization by atomic force microscopy The AFM height diagrams of the PCE10:ZJ-1 and PCE10:ZJ-2 blend films are shown below. Figure 11 As shown, both BHJ films exhibit well-mixed nanoscale phase separation, but the ZJ-2-based BHJ film shows a reduced root-mean-square (RMS) roughness (1.18 nm vs. 1.28 nm) and a more continuous interpenetrating network. The reduced surface roughness contributes to better interfacial contact and fewer interfacial defects, which is beneficial for suppressing leakage current and promoting charge separation and transport. Therefore, the introduction of Cl atoms effectively enhances intermolecular stacking and optimizes film morphology, thereby enhancing charge extraction and reducing trap density, which corresponds to the superior response speed and specific detectivity of the ZJ-2-based device.

[0084] A schematic diagram of the flexible NIR-OPD structure in Example 5 and an optical photograph of it in a bent state are shown below. Figure 12 As shown. A performance evaluation was performed, and the results are as follows. Figure 13 As shown, where Figure 13 Figure (b) shows the JV curve in the dark state, (c) shows the stress curve, (d) shows the specific detectivity curve, and (e) shows its photoresponse and recovery time under 850 nm illumination and 50 kHz.

[0085] from Figure 13 It can be seen that the flexible NIR-OPD exhibits an extremely low dark current density of 3.1 × 10⁻⁶. -10 A cm -2 The maximum responsivity (R) is 0.369 A / W (λ=870 nm), and the specific detectivity (R) is high over a wide spectral range from 390 to 1050 nm. The performance exceeds 10¹³ Jones. Furthermore, under 850 nm light modulated at 50 kHz, the flexible NIR-OPD exhibits rapid rise and fall times of 860 ns and 710 ns, respectively.

[0086] After 500 bending cycles at a bending radius of 7.5 mm, the flexible NIR-OPD in Example 5 showed no significant attenuation in photoresponse, response / recovery time, dark current density, responsivity, and specific detectivity.

[0087] Example 7 This embodiment provides a flexible non-contact HMI, the preparation method of which includes: In step S5 of Example 5, an Ag electrode with a thickness of 300 nm was deposited using a mask containing 6 windows to obtain the device. After the device was fabricated, an acetone etching process was used to selectively remove the active layer in the hollowed-out electrode area to form a flexible organic photodetector array containing 6 small-area photodetector units (2×3). Each unit is designed with a central hollow structure, and the effective electrode area is 6.44 mm² (total size 0.3 cm × 0.3 cm, aperture 0.16 cm × 0.16 cm).

[0088] A flexible near-infrared organic photodetector array was integrated with a flexible printed circuit board (FPCB) to which miniature LEDs (λ=850 nm, size 1.6 mm × 0.8 mm) were soldered. Vertical conductivity was achieved through conductive copper foil, resulting in a flexible non-contact HMI. The physical image and working principle diagram of the flexible non-contact HMI prepared in Example 7 are shown below. Figure 14 As shown. The working principle of C-HMI is described as follows: Under the illumination of pulsed near-infrared (NIR) light controlled by the signal generator, the near-infrared light emitted from the micro-LED passes through the hollow part of the photodetector unit, reaches the object, is reflected, and then reaches the effective photosensitive area of ​​the flexible NIR-OPD, thereby generating a photocurrent inversely proportional to the distance to the obstacle.

[0089] The flexible non-contact HMI of this application can be used in fields such as gesture recognition and object detection. For example, the flexible printed circuit board can be shaped like a palm, with micro-LED arrays distributed on the five fingertips, and independently integrated with a flexible near-infrared organic photodetector array to form five independent non-contact HMI modules. To achieve wearable functionality, double-sided tape can be used to adhere the integrated flexible non-contact HMI system to a cotton glove, ensuring overall wearer comfort and enabling the application of a wearable closed-loop non-contact HMI.

[0090] Although this application has been described in detail in this specification with general descriptions and specific embodiments, some modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, such modifications or improvements made without departing from the spirit of this application are all within the scope of protection claimed in this application.

Claims

1. A narrow bandgap organic acceptor material, characterized in that, Its molecular structure is shown in formula (1): (1) Where X is F or Cl.

2. The narrow bandgap organic acceptor material according to claim 1, characterized in that, Its synthesis process is as follows: ； 。 3. The method for preparing the narrow bandgap organic acceptor material according to claim 2, characterized in that, include: S1, Dissolve compound 1 in the first solvent to obtain solution A; Dissolve sodium hydride and tributyl(1,3-dioxolane-2-ylmethyl)phosphonium bromide in the first solvent to obtain solution B; Under an inert atmosphere, add solution A dropwise to solution B to carry out the reaction to obtain the reaction solution; S2, the reaction solution was added to hydrochloric acid and stirred to react, then the organic phase was extracted and collected; the organic phase was washed, dried, and then distilled under reduced pressure to obtain the crude product; the crude product was purified by silica gel column chromatography to obtain compound 2; S3, compound 2 and the halogen-containing compound were dissolved in a second solvent, and then acetic anhydride and boron trifluoride diethyl ether complex were added to react; after the reaction, the solid crude product was obtained by vacuum distillation, and then purified by silica gel column chromatography to obtain a narrow bandgap organic acceptor material. The halogen-containing compound is 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-1-yl)malononitrile or 2-(5,6-dichloro-3-oxo-2,3-dihydro-1H-indene-1-yl)malononitrile.

4. The preparation method according to claim 3, characterized in that, The first solvent comprises tetrahydrofuran; the second solvent comprises toluene; and the extractant comprises dichloromethane. The eluent used for purification by silica gel column chromatography is a mixture of n-hexane and chloroform in a volume ratio of 1:

8.

5. The preparation method according to claim 3, characterized in that, In S1, the molar ratio of compound 1, sodium hydride, and tributyl(1,3-dioxolane-2-ylmethyl)phosphonium bromide was 1.38:5.52:3.04; the reaction temperature was room temperature, and the reaction time was 12-24 h. In S3, the molar ratio of compound 2, halogen-containing compound, acetic anhydride, and boron trifluoride diethyl ether complex is 0.83:2.09:2.1; the reaction time is 0.5~1h. In S2, the reaction time is 4~6 hours.

6. A near-infrared organic photodetector, characterized in that, From bottom to top, it includes a transparent conductive substrate, a hole transport layer, an active layer, an electron transport layer, and a top electrode; The receptor in the active layer is the narrow bandgap organic receptor material as described in claim 1.

7. The near-infrared organic photodetector according to claim 6, characterized in that, The transparent conductive substrate is either a rigid conductive substrate or a flexible conductive substrate; the rigid conductive substrate is ITO glass, and the flexible conductive substrate is ITO / PET. The donor for the active layer includes any one of PCE10, PBDB-T, or PBDT-TT; The material of the hole transport layer includes any one of PEDOT:PSS, 2PACz, or 3-BPIC-F; The electron transport layer is made of materials including PNDIT-F3N, PDINO, PDINN, PFN-Br, or C. 60 Any one of / BCP; The material of the top electrode is Ag.

8. The near-infrared organic photodetector according to claim 7, characterized in that, It is a rigid near-infrared organic photodetector, and its device structure is glass / ITO / PEDOT:PSS / active layer / PNDIT-F3N / Ag, wherein the donor of the active layer is PCE10 and the acceptor is the narrow bandgap organic acceptor material as described in claim 1. or, It is a flexible near-infrared organic photodetector with a device structure of PET / ITO / PEDOT:PSS / active layer / PNDIT-F3N / Ag, wherein the donor of the active layer is PCE10 and the acceptor is the narrow bandgap organic acceptor material as described in claim 1.

9. The application of the near-infrared organic photodetector according to claim 6 in a non-contact HMI.

10. A flexible non-contact HMI, characterized in that, It is vertically integrated from an array of flexible near-infrared organic photodetectors as described in claim 8 and a miniature LED lamp.

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