A planar heterojunction organic photodetector regulated by PVDF ferroelectric material

Abstract

The application discloses a planar heterojunction organic photoelectric detector regulated by ferroelectric material. The positive type / negative type device structure of the organic photoelectric detector comprises, in sequence, a transparent substrate, a transparent electrode, an anode / cathode modification layer, a photosensitive layer (ferroelectric material, organic donor material and organic acceptor material), a cathode / anode modification layer and a metal electrode. The planar heterojunction realized by orthogonal solvents can reduce the dark current by constructing an intrinsic heterojunction barrier layer, the position of the PVDF ferroelectric material is designed and introduced and regulated, the strong internal electric field characteristics constructed by the dielectric and polarization of the ferroelectric material are utilized to improve the exciton dissociation efficiency and the injection barrier of external charges, the dark current of the device is significantly reduced while the light response is improved, and the detection performance of the organic photoelectric detector is greatly improved.

Description

[0001] This invention relates to the field of organic photodetectors, and more specifically to a planar heterojunction organic photodetector controlled by PVDF ferroelectric material. Background Technology

[0002] Photodetectors are fundamental components for converting light signals into electrical signals and have wide applications in both military and civilian fields. Due to their mature manufacturing processes, stable performance, and high integration, traditional inorganic semiconductor photodetectors dominate the market. However, because traditional photodetectors are generally grown from crystalline inorganic semiconductor materials on rigid planes and substrates, they suffer from many inherent drawbacks, such as complex manufacturing processes and a lack of mechanical properties. In contrast, organic semiconductor materials possess unique performance and technological advantages, such as tunable energy levels, mechanical flexibility, large-area manufacturing, solution processing, and low cost. In an era where electronic products are becoming increasingly thinner, more flexible, and more intelligent, organic photodetectors will play a crucial role in real-time health and environmental monitoring, human-computer interaction, and flexible displays.

[0003] Dark current, a key parameter of photodetectors, determines their detection performance. The dark current in a device is primarily generated by intrinsic defects in the organic semiconductor material, the deposition method during film formation, and charge disturbances caused by external circuit injection. High dark current directly affects the detector's ability to detect weak light, making the output signal difficult to distinguish. Traditional methods for reducing dark current in organic detectors mainly involve material structure design, optimizing molecular ordering, and optimizing interface materials. While these methods can suppress dark current and improve photoresponse, they also introduce disadvantages such as complex fabrication processes and numerous defects in organic photodetectors.

[0004] Therefore, the methods mentioned above for reducing dark current in organic photodetectors are not ideal, and there is an urgent need to develop new device structures to suppress dark current without affecting other key parameters.

[0005] After decades of development, bulk heterojunction-based organic photodetectors are widely considered the optimal device structure due to their high performance. Bulk heterojunctions are composed of a blend of donor and acceptor materials, achieving abundant donor-acceptor contact areas and thus excellent exciton dissociation and photoelectric conversion efficiencies. However, bulk heterojunction structures also have several drawbacks. Firstly, the morphology of the active layer in bulk heterojunction-based structures is often difficult to control, the optimal morphology is hard to replicate, and human intervention is significant. Secondly, devices based on bulk heterojunction structures contain "islands" of donor and acceptor phases that are not connected to the upper and lower electrodes; simultaneously, "peninsulas" also exist in these devices, with the donor "peninsula" contacting the cathode and the acceptor "peninsula" contacting the anode. These morphological characteristics lead to significant non-twin recombination losses and affect detector performance. Furthermore, as the detector or module area increases, these losses are further exacerbated, resulting in a significant difference in efficiency between small-area devices and large-area modules. With the rapid development of non-fullerene materials in recent years, research has found that some organic solar cells using planar heterojunctions exhibit superior performance and lower dark current compared to bulk heterojunction structures. Furthermore, reducing the acceptor contact area does not significantly decrease exciton dissociation efficiency. This phenomenon will benefit organic photodetectors by achieving low dark current without affecting other parameters, thus achieving high detection performance. In addition, the introduction of high-dielectric PVDF ferroelectric materials to form an internal electric field further suppresses dark current. PVDF ferroelectric materials are a type of dielectric material with polarization characteristics. Applying an external electric field polarizes the ferroelectric material, causing the internal electric dipoles to align neatly, generating an internal electric field. Therefore, introducing ferroelectric materials allows the strong localized electric field generated by their residual polarization to modulate the internal properties of the active layer, promoting effective exciton dissociation and ensuring high photocurrent output. It also acts as a hole / electron blocking layer to suppress external charge injection and reduce dark current. Therefore, the synergistic effect of combining PVDF ferroelectric materials and planar heterojunctions will significantly reduce the dark current of organic photodetectors and achieve high detectivity. Summary of the Invention

[0006] The purpose of this invention is to provide a planar heterojunction organic photodetector controlled by PVDF ferroelectric material. This new technology is a solution that can efficiently suppress dark current in organic photodetectors while improving photocurrent response.

[0007] To address the shortcomings of existing technologies and solve the problems of high dark current and low sensitivity in organic photodetectors, a method is proposed to obtain a highly sensitive, low-power, and fast-detection organic photodetector using a planar heterojunction detector made of PVDF ferroelectric material. This method can reduce the dark current by more than two orders of magnitude and improve the sensitivity by two to three orders of magnitude.

[0008] Based on the different positive / inverting device structures of organic photodetectors, this invention plans to employ six different schemes to improve the detector structure. The device is characterized by being arranged sequentially as follows:

[0009] Transparent substrate;

[0010] A transparent electrode, wherein the transparent electrode is disposed on the surface of the transparent substrate;

[0011] An anode (cathode) modification layer is disposed on the surface of the transparent electrode; an intermediate active layer is disposed on the surface of the anode (cathode) modification layer.

[0012] A cathode (anode) modification layer is disposed on the surface of the intermediate layer; a metal electrode is disposed on the surface of the cathode (anode) modification layer.

[0013] This invention discloses a planar heterojunction organic photodetector regulated by PVDF ferroelectric material. The device is characterized in that the transparent substrate includes, but is not limited to, one of glass, PET, PEN, and PDMS, with a thickness of 0.01–5 mm.

[0014] This invention discloses a method for a planar heterojunction organic photodetector regulated by PVDF ferroelectric material. The device is characterized in that the transparent electrode includes, but is not limited to, one of indium tin oxide (ITO), fluorine-doped SnO2 (FTO), metal nanowires, and conductive oxides, with a thickness of 10–1000 nm.

[0015] This invention discloses a planar heterojunction organic photodetector regulated by PVDF ferroelectric material. The device is characterized in that: in the anode (cathode) modification layer, the lower anode modification layer includes, but is not limited to, one of the following anode modification layers: conductive polymer (PEDOT:PSS), metal oxide, etc.; the lower cathode modification layer includes, but is not limited to, one of the following cathode modification layers: zinc oxide (ZnO) and its modifiers, etc., with a thickness of 1–100 nm.

[0016] This invention discloses a planar heterojunction organic photodetector regulated by PVDF ferroelectric material. The device is characterized in that: the PVDF ferroelectric material used in the intermediate active layer includes, but is not limited to, PVDF, PVDF-TrFE, and their modified materials, with a ferroelectric material layer thickness of 1-20 nm; the organic donor layer in the intermediate active layer uses, but is not limited to, one of commonly used polymer donors (D18, PM6, PM7, PBDB-T, J71, PTB7-Th, P3HT) and small molecule donors (BTR, BTR-Cl, B1); the organic acceptor layer in the intermediate layer uses, but is not limited to, one of commonly used non-fullerene acceptors (ITIC, IT-4F, IEICO-4F, Y6, BTP-eC9, L8-BO, Y6-BO-4Cl, N2200, PZ1, PYIT) and fullerene acceptors (PC71BM, ICBA), with each layer thickness ranging from 1 to 500 nm.

[0017] This invention discloses a planar heterojunction organic photodetector regulated by PVDF ferroelectric material. Its positive device is characterized in that the relative positions of the PVDF ferroelectric material introduced into the intermediate active layer with the organic donor layer and the organic acceptor layer, from bottom to top, are: organic donor + PVDF ferroelectric material layer and organic acceptor layer.

[0018] This invention discloses a planar heterojunction organic photodetector regulated by PVDF ferroelectric material. Its positive device is characterized in that the relative positions of the PVDF ferroelectric material introduced into the intermediate active layer with the organic donor layer and the organic acceptor layer, from bottom to top, are: organic donor layer, PVDF ferroelectric material layer, and organic acceptor layer.

[0019] This invention discloses a planar heterojunction organic photodetector regulated by PVDF ferroelectric material. Its positive device is characterized in that the relative positions of the PVDF ferroelectric material, the organic donor layer, and the organic acceptor layer in the intermediate active layer, from bottom to top, are: organic donor layer, PVDF ferroelectric material + organic acceptor layer.

[0020] This invention discloses a planar heterojunction organic photodetector regulated by PVDF ferroelectric material. Its inversion device is characterized in that the relative positions of the PVDF ferroelectric material, the organic donor layer, and the organic acceptor layer in the intermediate active layer, from bottom to top, are: organic acceptor layer, PVDF ferroelectric material + organic donor layer.

[0021] This invention discloses a planar heterojunction organic photodetector regulated by PVDF ferroelectric material. Its inversion device is characterized in that the relative positions of the PVDF ferroelectric material introduced into the intermediate active layer with the organic donor layer and the organic acceptor layer, from bottom to top, are: organic acceptor + PVDF ferroelectric material layer and organic donor layer.

[0022] This invention discloses a planar heterojunction organic photodetector regulated by PVDF ferroelectric material. Its inversion device is characterized in that the relative positions of the PVDF ferroelectric material, the organic donor layer, and the organic acceptor layer in the intermediate active layer, from bottom to top, are: organic acceptor layer, PVDF ferroelectric material layer, and organic donor layer.

[0023] This invention discloses a planar heterojunction organic photodetector regulated by PVDF ferroelectric material. The device is characterized in that: the upper anode modification layer includes, but is not limited to, one of molybdenum trioxide (MoO3); the upper cathode modification layer includes, but is not limited to, one of PFN, PFN-Br, PDIN, PDINO, PDINN, etc., with a thickness of 1–100 nm.

[0024] This invention discloses a planar heterojunction organic photodetector regulated by PVDF ferroelectric material. The device is characterized in that the metal electrode includes, but is not limited to, one of Al, Ag, Au, Zn, and Ge, with a thickness ranging from 1 to 1000 nm.

[0025] Beneficial effects of this invention:

[0026] This invention discloses a planar heterojunction organic photodetector controlled by PVDF ferroelectric material. The planar heterojunction structure reduces external charge infiltration, thereby lowering dark current and reducing bimolecular load defects, thus increasing photocurrent. Furthermore, by introducing and controlling the position of the ferroelectric material, the high dielectric constant and strong internal electric field of the ferroelectric material are utilized to improve exciton dissociation efficiency and the external charge injection barrier. This significantly reduces dark current while improving photoresponse, resulting in a substantial improvement in the detection performance of the organic photodetector. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the organic photodetector of Example 1 of the present invention; in the figure, 1 is a transparent conductive substrate, 2 is an anode modification layer, 3 is an organic donor layer, 4 is a ferroelectric material PVDF layer, 5 is an organic acceptor layer, 6 is a cathode modification layer, and 7 is a metal electrode.

[0028] Figure 2This is a schematic diagram of the structure of the organic photodetector of Comparative Example 1 of the present invention; in the figure, 1 is a transparent conductive substrate, 2 is an anode modification layer, 3 is an organic donor-organic acceptor blend layer, 4 is a cathode modification layer, and 5 is a metal electrode.

[0029] Figure 3 This is a schematic diagram of the structure of the organic photodetector of Comparative Example 2 of the present invention; in the figure, 1 is a transparent conductive substrate, 2 is an anode modification layer, 3 is an organic donor layer, 4 is an organic acceptor layer, 5 is a cathode modification layer, and 6 is a metal electrode.

[0030] Figure 4 The molecular structure diagrams of the materials used in the organic photodetectors in Example 1 and Comparative Examples 1 and 2 of this invention are shown.

[0031] Figure 5 The energy level diagrams of the materials used in the organic photodetectors in Example 1 and Comparative Examples 1 and 2 of this invention are shown.

[0032] Figure 6 The images show the thin film absorption spectra of the materials used in the organic photodetectors of Example 1 and Comparative Examples 1 and 2 of this invention.

[0033] Figure 7 The dark current curves of the organic photodetectors in Example 1 and Comparative Examples 1 and 2 of this invention are shown. Specific Implementation

[0034] This embodiment 1 discloses a method for constructing a planar heterojunction organic photodetector using PVDF ferroelectric material. The device structure comprises, in sequence: glass as a transparent substrate, ITO as a transparent electrode, PEDOT:PSS as an anode modification layer, PM6 as an organic donor layer, PVDF as a ferroelectric material layer, Y6-BO-4Cl as an organic acceptor layer, PDINN as a cathode modification layer, and Ag as a metal electrode.

[0035] Before fabricating the device corresponding to Example 1, the patterned ITO glass needs to be ultrasonically cleaned with ITO cleaning agent, deionized water, acetone, and isopropanol, then dried and subjected to plasma treatment for 20 minutes to improve surface cleanliness and increase the work function of ITO.

[0036] The device corresponding to Example 1 uses PEDOT:PSS, an aqueous solution of CleviosPVP.Al4083, purchased from Heraeus GmbH, Germany. Before use, the PEDOT:PSS aqueous solution is filtered through a 0.25μm filter and then deposited on the treated ITO conductive glass surface by spin coating at a speed of 4000r / min for 30s. It is then annealed at 150℃ for 15min to remove moisture and optimize the surface morphology.

[0037] In the device corresponding to Example 1, the concentration of PM6 used in the organic donor layer is 9 mg / mL, the solvent is chloroform, and the mixture is stirred at 50°C for 2 hours. The organic donor material solution is coated by spin coating, with a spin coating speed of 1500-5000 r / min, preferably 3000 r / min, and a spin coating time of 30 s.

[0038] The device corresponding to Example 1 uses the following materials for the PVDF ferroelectric material + organic acceptor layer: the concentration of PVDF ferroelectric material and Y6-BO-4Cl is 10 mg / mL, the solvent is tetrahydrofuran, and the mixture is stirred at 50°C for 2-4 hours. 0.5% diiodooctane is added as an additive to the acceptor + ferroelectric material solution. The coating method is spin-coating, with a spin-coating speed of 1000-8000 r / min, preferably 3000 r / min, a spin-coating time of 30 s, and then heat-annealing at 100°C for 10 min.

[0039] In the device corresponding to Example 1, the concentration of PNINN material used in the cathode modification layer is 1 mg / mL, the solvent used is methanol, and the mixture is stirred at room temperature for 2 hours. The solution coating method of the cathode modification layer is spin coating, the spin coating speed is 3000 r / min, and the spin coating time is 25 s.

[0040] In the device corresponding to Example 1, the Ag material used for the metal electrode is deposited by vapor deposition. Before vapor deposition, the vacuum level in the vapor deposition chamber must be lower than 5 × 10⁻⁶. -3 Pa, the evaporation rate is 0.5-1 A / s, and the thickness of the evaporated electrode Ag is 10-100 nm, with the most preferred thickness being 100 nm.

[0041] Specific comparison example 1:

[0042] The device structure corresponding to Comparative Example 1 includes, in sequence: glass as a transparent substrate, ITO as a transparent electrode, PEDOT:PSS as an anode modification layer, PM6:Y6-BO-4Cl blend as an intermediate layer, PDINN as a cathode modification layer, and Ag as a metal electrode.

[0043] Before fabrication, the patterned ITO glass of Comparative Example 1 needs to be ultrasonically cleaned with ITO cleaning agent, deionized water, acetone, and isopropanol, then dried and subjected to plasma treatment for 2 minutes to improve surface cleanliness and increase the work function of ITO.

[0044] The device corresponding to Comparative Example 1 uses PEDOT:PSS, an aqueous solution of CleviosPVP.Al4083, purchased from Heraeus GmbH, Germany. Before use, the PEDOT:PSS aqueous solution is filtered through a 0.25μm filter and then deposited on the treated ITO conductive glass surface by spin coating at a speed of 4000r / min for 30s. It is then annealed at 150℃ for 15min to remove moisture and optimize the surface morphology.

[0045] In the device corresponding to Comparative Example 1, the donor material PM6 and the acceptor material Y6-BO-4Cl used in the intermediate active layer have a weight ratio of 1:1.2. A solution is prepared with a donor concentration of 7 mg / mL and chloroform as the solvent. The solution is stirred at 50°C for 2 hours. 0.5% diiodooctane is added to the mixed solution as an additive. The intermediate layer mixed solution is coated by spin coating at a speed of 1500-5000 r / min, preferably 3000 r / min, for a spin coating time of 30 s, followed by heat annealing at 100°C for 10 min.

[0046] The device corresponding to Comparative Example 1 uses a cathode modification layer with a PNINN concentration of 1 mg / mL and methanol as the solvent. The mixture is stirred at room temperature for 2 hours. The cathode modification layer is coated by spin coating at a speed of 3000 r / min for 25 s.

[0047] In the device corresponding to Comparative Example 1, the Ag material used for the metal electrode is deposited by vapor deposition. Before vapor deposition, the vacuum level in the vapor deposition chamber must be below 5 × 10⁻⁶. -3 Pa, the evaporation rate is 0.5-1 A / s, and the thickness of the evaporated electrode Ag is 10-100 nm, with the most preferred thickness being 100 nm.

[0048] Specific Comparison Example 2:

[0049] The device structure of Comparative Example 2 includes, from bottom to top, the following components: glass as a transparent substrate, ITO as a transparent electrode, PEDOT:PSS as an anode modification layer, PM6 as an organic donor layer, Y6-BO-4Cl as an organic acceptor layer, PDINN as a cathode modification layer, and Ag as a metal electrode.

[0050] Before fabrication, the patterned ITO glass corresponding to Comparative Example 2 needs to be ultrasonically cleaned with ITO cleaning agent, deionized water, acetone, and isopropanol, then dried and subjected to plasma treatment for 2 minutes to improve surface cleanliness and increase the work function of ITO.

[0051] The device corresponding to Comparative Example 2 uses PEDOT:PSS, an aqueous solution of CleviosPVP.Al4083, purchased from Heraeus GmbH, Germany. Before use, the PEDOT:PSS aqueous solution is filtered through a 0.25μm filter and then deposited on the treated ITO conductive glass surface by spin coating at a speed of 4000r / min for 30s. It is then annealed at 150℃ for 15min to remove moisture and optimize the surface morphology.

[0052] The device corresponding to Comparative Example 2 uses PM6 material with a concentration of 9 mg / mL in the organic donor layer, chloroform as the solvent, and is stirred at 50°C for 2 hours. The organic donor material solution is coated by spin coating at a speed of 1500–5000 r / min, preferably 3000 r / min, for a spin coating time of 30 s.

[0053] In the device corresponding to Comparative Example 2, the concentration of Y6-BO-4Cl in the organic acceptor layer is 12 mg / mL, the solvent is tetrahydrofuran, and the mixture is stirred at 50°C for 2 hours. 0.5% diiodooctane is added to the acceptor solution as an additive. The organic acceptor material solution is coated by spin coating at a speed of 1500-5000 r / min, preferably 2500 r / min, for a spin coating time of 30 s, followed by heat annealing at 100°C for 10 min.

[0054] The device corresponding to Comparative Example 2 uses a cathode modification layer with a PNINN concentration of 1 mg / mL and methanol as the solvent. The mixture is stirred at room temperature for 2 hours. The cathode modification layer is coated by spin coating at a speed of 3000 r / min for 25 s.

[0055] In the device corresponding to Comparative Example 2, the Ag material used for the metal electrode is deposited by vapor deposition. Before vapor deposition, the vacuum level in the vapor deposition chamber must be below 5 × 10⁻⁶. -3 Pa, evaporation rate is The thickness of the vapor-deposited electrode Ag is 10-100 nm, with 100 nm being the most preferred.

[0056] Performance of Example 1 and Comparative Examples 1 and 2

[0057] Appendix Figure 1 Figures 2 and 3 show schematic diagrams of the corresponding device structures in Example 1 and Comparative Examples 1 and 2, all of which are positive devices;

[0058] Appendix Figure 7The figures show the photoresponse curves of the devices corresponding to Example 1 and Comparative Examples 1 and 2. It can be seen that the device prepared by using the intermediate active layer of the planar heterojunction of PVDF ferroelectric material in Example 1 has a significantly improved photoresponse compared with the device that directly mixes the donor-acceptor bulk heterojunction and the intermediate active layer of the donor-acceptor planar heterojunction.

[0059] In Example 1, the device fabricated using the intermediate active layer of a planar heterojunction made of PVDF ferroelectric material showed a nearly two-order-of-magnitude reduction in dark current at a -2V bias compared to the device fabricated by directly mixing the donor-acceptor bulk heterojunction and the intermediate active layer of the donor-acceptor planar heterojunction.

[0060] In Example 1, the device fabricated with the intermediate active layer of the planar heterojunction of PVDF ferroelectric material showed a nearly one-order-of-magnitude increase in detectivity at a bias voltage of -2V compared to devices fabricated with the intermediate active layer of the donor-acceptor bulk heterojunction and the donor-acceptor planar heterojunction.

[0061] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Other equivalent changes and modifications made to the methods that do not depart from the essence of the present invention are considered equivalent substitutions and are included within the protection scope of the present invention.

Claims

1. A planar heterojunction organic photodetector regulated by PVDF ferroelectric material, characterized in that, Bottom-up settings: Transparent substrate; A transparent electrode, wherein the transparent electrode is disposed on the surface of the transparent substrate; An anode modification layer or a cathode modification layer is disposed on the surface of the transparent electrode; An intermediate active layer is disposed on the surface of the anode modification layer or the cathode modification layer; A cathode modification layer or an anode modification layer, wherein the cathode modification layer or an anode modification layer is disposed on the surface of the intermediate active layer; A metal electrode, wherein the metal electrode is disposed on the surface of a cathode modification layer or an anode modification layer; The intermediate active layer contains PVDF ferroelectric material, organic donor material and organic acceptor material, and the relative positions of the PVDF ferroelectric material in the intermediate active layer with the organic donor layer and the organic acceptor layer from bottom to top are organic donor layer, PVDF ferroelectric material layer and organic acceptor layer. The thickness of the PVDF ferroelectric material layer is 0.5-50 nm.

2. The planar heterojunction organic photodetector controlled by PVDF ferroelectric material according to claim 1, characterized in that the transparent substrate comprises one of transparent glass, PET, PEN, and PDMS, and its thickness is 0.01~3mm.

3. The planar heterojunction organic photodetector controlled by PVDF ferroelectric material according to claim 1, characterized in that the transparent electrode comprises one of indium tin oxide, fluorine-doped SnO2, and metal nanowires, with a thickness of 10~1000 nm.

4. The planar heterojunction organic photodetector controlled by PVDF ferroelectric material according to claim 1, characterized in that the lower anode modification layer comprises a conductive polymer PEDOT:PSS and a metal oxide; the lower cathode modification layer comprises zinc oxide and its modifier, and its thickness is 1~100 nm.

5. A planar heterojunction organic photodetector regulated by PVDF ferroelectric material according to claim 1, characterized in that the PVDF ferroelectric material in the intermediate active layer includes one of PVDF, PVDF-TrFE and their modified materials; the organic donor material in the intermediate active layer includes one of polymer donors D18, PM6, PM7, PBDB-T, J71, PTB7-Th, P3HT and small molecule donors BTR, BTR-Cl, B1; the organic acceptor material in the intermediate active layer includes one of non-fullerene acceptors ITIC, IT-4F, IEICO-4F, Y6, BTP-eC9, L8-BO, Y6-BO-4Cl, N2200, PZ1, PYIT and fullerene acceptors PC71BM, ICBA, with each layer having a thickness of 1~500 nm.

6. A planar heterojunction organic photodetector regulated by PVDF ferroelectric material according to claim 1, characterized in that, The solvents for dissolving the organic donor layer material and the organic acceptor layer material are one or more of chloroform, dichloromethane, benzene, toluene, xylene, chlorobenzene, dichlorobenzene, tetrahydrofuran, furan, methylfuran, dimethyl sulfoxide, N,N-dimethylformamide, and N-methylpyrrolidone.

7. A planar heterojunction organic photodetector regulated by PVDF ferroelectric material according to claim 1, characterized in that, The solvents used to dissolve the organic donor layer material, the PVDF ferroelectric material layer, and the organic acceptor layer material are orthogonal solvents, meaning that the upper solvent cannot dissolve the lower film.

8. The planar heterojunction organic photodetector controlled by PVDF ferroelectric material according to claim 1, characterized in that the upper anode modification layer includes molybdenum trioxide; the upper cathode modification layer includes one of PFN, PFN-Br, PDIN, PDINO, and PDINN, and its thickness is 0.1~100 nm.

9. A planar heterojunction organic photodetector controlled by PVDF ferroelectric material according to claim 1, characterized in that the metal electrode comprises one of Al, Ag, and Au, and its thickness is 10~1000 nm.

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