Bias voltage regulation-based dual-band narrow-band photoelectric detector and preparation method thereof

Abstract

The invention provides a dual-band narrow-band photoelectric detector with adjustable bias polarity and a preparation method thereof. The device adopts a multi-layer stacking design, and comprises a transparent substrate, a bottom electrode, a near-infrared active layer, a middle transmission layer, a visible light active layer and an optical microcavity layer integrated with a top electrode from bottom to top. And the active layer is a bulk heterojunction formed by an organic polymer donor and a fullerene receptor. By adjusting the polarity of the bias voltage, flexible switching of the detection wave band can be realized: the near-infrared active layer is activated under the forward bias voltage, and the near-infrared active layer works in the visible light wave band under the reverse bias voltage. The optical microcavity layer forms a narrow-band transmission peak based on the Fabry-Perot resonance effect, only photons with specific wavelengths are allowed to efficiently penetrate, other wavebands are reflected and suppressed, and therefore spectrum narrowing detection is achieved. According to the invention, electrical regulation and optical filtering are combined, so that the precision and adaptability of dual-band detection are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of photodetector technology, specifically to a dual-band narrowband photodetector based on bias control and its fabrication method. Background Technology

[0002] Photodetectors are semiconductor devices that convert optical signals into electrical signals, and are widely used in optical communication, sensing, imaging, environmental monitoring, and military fields. With the rise of organic semiconductor materials, their tunable spectral absorption range, the flexibility they offer due to their low hardness, and the reduced production costs resulting from solution-based processes, demonstrate promising application prospects in the field of photodetectors.

[0003] Traditional organic photodetectors are limited by their material systems, resulting in typically narrow spectral response ranges that cannot cover multi-band or narrow-band detection requirements. Therefore, to expand the detection bands and achieve more complex optical signal recognition and analysis, developing dual-band organic photodetectors capable of responding in different bands with low crosstalk and high precision has become an important research direction.

[0004] As Professor Li Ning described in *Cell Reports Physical Science. 2021, 3, 100711*, a dual-band photodetector fabricated using back-to-back stacking of two active layers enables detection in both visible and near-infrared bands under different polarity biases. However, Professor Lei Yanlian also mentioned in *Adv. Funct. Mater. 2025, 35, 2500628* that dual-band photodetectors require further in-depth research on spectral crosstalk and high-precision detection. Summary of the Invention

[0005] The purpose of this invention is to provide a dual-band narrowband photodetector based on bias control and its fabrication method, which can realize dual-band narrowband detection of visible light and near-infrared light under reverse bias and forward bias respectively.

[0006] The technical solution for realizing the present invention is as follows: a dual-band narrowband photodetector based on bias control, comprising, from bottom to top, a transparent substrate, a bottom electrode layer, a near-infrared active layer, an intermediate transmission layer, a visible light active layer, and an optical microcavity layer with an integrated top electrode; wherein, the near-infrared active layer and the visible light active layer are both composed of a bulk heterostructure formed by fully mixing organic donor materials and organic acceptor materials.

[0007] Furthermore, the transparent substrate is a rigid substrate, and a bottom electrode layer is fabricated on the transparent substrate; the material of the bottom electrode layer is indium tin oxide, and the thickness is 100 nm to 150 nm.

[0008] The bottom electrode is an ITO thin film with insulating channels. The ITO thin film pattern consists of two region blocks a and four region blocks b. Region block a is a rectangle with a width of 4.4 mm and a length of 10 mm. Region block b has an L-shaped structure, which is divided into a first rectangular block and a second rectangular block. The first rectangular block has a width of 3 mm and a length of 9.4 mm, and the second rectangular block has a width of 4 mm and a length of 9.2 mm. The four region blocks b are paired up to form a U-shaped structure. One side of the U-shaped structure is open, and the center of the other side has a gap that is not closed. The openings of the two U-shaped structures are opposite to each other. Region block a is set inside the opening of the U-shaped structure and does not contact region block b.

[0009] The film thickness is 100 nm to 150 nm and the resistance is 30-40 Ω. By applying positive and negative voltages to the two regions a and b respectively, a closed circuit loop can be formed through the top electrode.

[0010] Furthermore, the near-infrared active layer uses PBDB-T as the organic donor material and IEICO-4F as the acceptor material, forming a bulk heterojunction with a response wavelength range of 650 nm-900 nm; the visible light active layer uses P3HT as the organic donor material and PC as the acceptor material. 71 The response wavelength range of the bulk heterojunction formed by the BM mixture is 400 nm-700 nm.

[0011] Furthermore, the intermediate transport layer is made of PDOT:PSS with a thickness of 50 nm to 70 nm; the optical microcavity layer is a sandwich stacked structure of Ag / NPB / Ag, with Ag thickness of 20 nm to 25 nm and NPB thickness of 100 nm to 130 nm.

[0012] Furthermore, the dual-band narrowband photodetector operates in near-infrared detection mode under positive bias, responding to the near-infrared band of 750-900 nm; and operates in visible light detection mode under reverse bias, exhibiting a significant narrowband response to the visible light band of 400-500 nm.

[0013] A method for fabricating a dual-band narrowband photodetector based on bias voltage control includes the following steps:

[0014] Step 1: ITO is etched on the upper surface of a transparent substrate. The transparent substrate with indium tin oxide is ultrasonically cleaned in a series of detergents, deionized water, acetone and isopropanol. Then it is dried under a nitrogen flow to obtain a bottom electrode layer with surface impurities removed.

[0015] Step 2, Preparation of active layer solution: Combine organic donor PBDB-T, acceptor IEICO-4F, organic donor P3HT, and acceptor PC. 71BM was mixed at mass ratios of 100:3 and 100:1 and ground into powder. The powder was then placed in two reagent bottles and dissolved with organic solvents to obtain organic solutions with total mass concentrations of 30 mg / mL and 40 mg / mL, respectively. The organic solutions were sealed and heated at 100–120 °C, and stirred with a magnetic rotor to promote dissolution. After heating and stirring for at least 6 hours, near-infrared active layer solution and visible light active layer solution were obtained.

[0016] Step 3: In a nitrogen atmosphere, spin-coat a near-infrared active layer solution onto the upper surface of the bottom electrode layer. After spin-coating, perform thermal annealing to obtain the near-infrared active layer.

[0017] Step 4: In an air atmosphere, spin-coat the surface of the near-infrared active layer with PEDOT:PSS solution. After spin-coating, perform thermal annealing to obtain the intermediate transport layer.

[0018] Step 5: In a nitrogen atmosphere, spin-coat a visible light active layer solution onto the upper surface of the intermediate transport layer. After spin-coating, perform thermal annealing to obtain the visible light active layer.

[0019] Step 6: An optical microcavity layer composed of Ag / NPB / Ag is sequentially deposited on the upper surface of the visible light active layer using a vacuum thermal evaporation method. The second Ag layer serves as the top electrode of the device, thereby obtaining a dual-band narrowband photodetector based on bias control.

[0020] Step 7: In a nitrogen atmosphere, encapsulate the bias-controlled dual-band narrowband photodetector using optical adhesive and transparent glass.

[0021] Furthermore, in step 2, the organic solvent is chlorobenzene or o-dichlorobenzene.

[0022] Furthermore, in step 3, the spin coating speed of the near-infrared active layer is 1000 rpm, the acceleration is 600 rpm / s, the spin coating time is 50~60s, the heat annealing temperature is 100~130℃, and the heat annealing time is 10~15 min.

[0023] Furthermore, in step 4, when spin-coating the PEDOT:PSS solution onto the near-infrared active layer, the spin-coating speed is 800-1000 rpm, the acceleration is 600 rpm / s, the spin-coating time is 70-80 s, the heat annealing temperature is 100-130℃, and the heat annealing time is 8-10 min.

[0024] Furthermore, in step 5, the spin coating speed of the visible light active layer is 1000 rpm, the acceleration is 600 rpm / s, the spin coating time is 50~60s, the heat annealing temperature is 100~130℃, and the heat annealing time is 10~15 min.

[0025] Furthermore, in step 6, when the optical microcavity layer is prepared by vacuum thermal evaporation, the evaporation rate of Ag is 0.1–0.2 Å / s for the first 10 nm and 1–1.5 Å / s for the remaining thickness; the evaporation rate of NPB is 1–1.5 Å / s.

[0026] Compared with the prior art, the significant advantages of this invention are:

[0027] (1) In this invention, the donor material of the near-infrared active layer is PBDB-T and the acceptor material is IEICO-4F; the donor material of the visible light active layer is P3HT and the acceptor material is PC. 71 BM. Two active layers are vertically stacked and separated by a PEDOT:PSS interlayer. This combination allows the corresponding active layer to be activated by applying voltages of different polarities, and holes are transmitted through the interlayer, enabling dual-band detection. Furthermore, by coupling an optical microcavity structure through vapor deposition, its high transmittance for specific wavelengths is utilized to achieve high-precision detection of the corresponding wavelength band.

[0028] (2) The dual-band narrowband photodetector operates in near-infrared detection mode under positive bias and responds to the near-infrared band of 750-900nm; it operates in visible light detection mode under reverse bias and has a significant narrowband response to the visible light band of 400-500nm.

[0029] (3) The photodetector provided by this invention uses a polymer-based heterojunction structure for both active layers, and an intermediate transport layer is introduced between the two active layers. Under forward bias, the visible light active layer acts as a low-resistance channel and contributes almost nothing to the photocurrent, while the photogenerated charge generated in the near-infrared active layer becomes the key to dominating the photocurrent. Under near-infrared illumination, the photogenerated electrons in the near-infrared active layer are trapped by localized states formed by a small number of acceptors. The trapped electrons induce band bending at the interface between the bottom electrode and the near-infrared active layer, significantly reducing the hole injection barrier, thereby promoting a large number of hole injections and enhancing the overall photocurrent, ultimately achieving efficient detection in the near-infrared band; similarly, under reverse bias, the near-infrared active layer acts as a low-resistance channel. The photogenerated charge generated in the visible light active layer and the band bending effect at the interface between the visible light active layer and the silver electrode promote a large number of hole tunneling injections, thereby enhancing the overall photocurrent response and achieving detection in the visible light band.

[0030] (4) This invention breaks through the limitation of the single working mode of traditional organic photodetectors. Through the design of the detector interface structure, it achieves the advantages of simple structure and low cost, and can flexibly meet the high-precision detection requirements of near-infrared light and visible light. Attached Figure Description

[0031] Figure 1This is a structural diagram of the dual-band narrowband photodetector in this invention.

[0032] Figure 2 This is an image showing the optical transmittance of the optical microcavity layer.

[0033] Figure 3 The graph shows the external quantum efficiency (EQE) of the photodetector as a function of the incident light wavelength; where (a) is the photodetector at a bias voltage of 15V and (b) is the photodetector at a bias voltage of -15V.

[0034] Figure 4 The figures show the current-voltage characteristics of the photodetector in bright and dark states.

[0035] Figure 5 This is a graph showing the specific detectivity (D*) of a photodetector as a function of incident light wavelength when the photodetector operates in two modes.

[0036] Figure 6 This is the ITO etching pattern for the bottom electrode of the photodetector. Detailed Implementation

[0037] To more clearly illustrate the technical solution, innovative advantages, and specific implementation methods of the present invention, the technical details of the present invention will be systematically described and analyzed in depth below in conjunction with the embodiments and accompanying drawings.

[0038] A dual-band narrowband photodetector based on bias control, the schematic diagram of which is shown below. Figure 1 As shown, from bottom to top, the layers are: transparent substrate (Glass), bottom electrode layer (ITO), near-infrared active layer (PBDB-T:IEICO-4F), intermediate transport layer (PEDOT:PSS), and visible light active layer (P3HT:PC). 71 The organic donor material and the organic acceptor material are mixed and dissolved in an organic solvent to form a bulk heterojunction, which significantly shortens the exciton diffusion distance, significantly improves the charge separation efficiency, and effectively balances the charge generation, transport and collection processes.

[0039] The transparent substrate is a rigid substrate with dimensions of 20*20mm. A bottom electrode layer is fabricated on the transparent substrate; the bottom electrode layer is made of indium tin oxide and has a thickness of 100 nm to 150 nm.

[0040] Combination Figure 6The bottom electrode is an ITO thin film with insulating channels. The ITO thin film pattern consists of two region blocks a and four region blocks b. Region block a is a rectangle with a width of 4.4 mm and a length of 10 mm. Region block b is an L-shaped structure, which is divided into a first rectangular block and a second rectangular block. The first rectangular block has a width of 3 mm and a length of 9.4 mm, and the second rectangular block has a width of 4 mm and a length of 9.2 mm. The four region blocks b are paired up to form a U-shaped structure. One side of the U-shaped structure is an open end, and the center of the other side has a gap (the gap width is 20-9.4-9.4=1.2 mm) and is not closed. The two U-shaped openings are opposite to each other, and region block a is set inside the open end of the U-shaped structure. Region block a does not contact region block b.

[0041] The film thickness is 100 nm to 150 nm and the resistance is 30-40 Ω. By applying positive and negative voltages to the two regions a and b respectively, a closed circuit loop can be formed through the top electrode.

[0042] Furthermore, the near-infrared active layer uses PBDB-T as the organic donor material and IEICO-4F as the acceptor material, forming a bulk heterojunction with a response wavelength range of 650 nm-900 nm; the visible light active layer uses P3HT as the organic donor material and PC as the acceptor material. 71 The response wavelength range of the bulk heterojunction formed by the BM mixture is 400 nm-700 nm.

[0043] Furthermore, the intermediate transport layer is made of PDOT:PSS with a thickness of 50 nm to 70 nm; the optical microcavity layer is a sandwich stacked structure of Ag / NPB / Ag, with Ag thickness of 20 nm to 25 nm and NPB thickness of 100 nm to 130 nm.

[0044] Furthermore, the dual-band narrowband photodetector operates in near-infrared detection mode under positive bias, responding to the near-infrared band of 750-900 nm; and operates in visible light detection mode under reverse bias, exhibiting a significant narrowband response to the visible light band of 400-500 nm.

[0045] Example 1

[0046] A method for fabricating a dual-band narrowband photodetector based on bias voltage control includes the following steps:

[0047] Step 1: Etch ITO on the upper surface of the transparent substrate and perform ultrasonic cleaning on the surface.

[0048] Ultrasonic cleaning shall be performed in the following order:

[0049] (1) Wipe the transparent substrate of the etched ITO with a paper towel soaked in isopropyl alcohol and apply directional airflow treatment with a bulb syringe to remove obvious impurities on the surface.

[0050] (2) Place the transparent substrate in an ultrasonic cleaner and add detergent; ultrasonically clean for 10 min.

[0051] (3) Place the transparent substrate in an ultrasonic cleaner and add deionized water; ultrasonically clean for 10 min.

[0052] (4) Place the transparent substrate in an ultrasonic cleaner and add acetone; ultrasonically clean for 10 min.

[0053] (5) Place the transparent substrate in an ultrasonic cleaner and add isopropanol; ultrasonically clean for 10 min.

[0054] The cleaned transparent substrate was placed in a drying oven and dried with nitrogen. This resulted in a bottom electrode layer with surface impurities removed.

[0055] Step 2: Preparation of the active layer solution: PBDB-T and IEICO-4F were used as the donor and acceptor materials for the near-infrared active layer, respectively, along with P3HT and PC. 71 BM was used as the donor and acceptor materials for the visible light active layer, with mass ratios of 100:3 and 100:1, and total mass concentrations of donor and acceptor of 30 mg / ml and 40 mg / ml, respectively. The organic donor and organic acceptor blends were thoroughly ground into powder, transferred to two reagent bottles, and dissolved using o-dichlorobenzene as the organic solvent. After sealing, the bottles were heated at 100°C and stirred with a magnetic rotor (100 r / min) to promote dissolution. After heating and stirring for 8 hours, near-infrared active layer solution and visible light active layer solution were obtained.

[0056] Step 3: Prepare a near-infrared active layer on the upper surface of the bottom electrode layer by spin coating. Spin coat the near-infrared active layer solution onto the bottom electrode layer in a nitrogen atmosphere. The spin coating speed is 1000 rpm, the acceleration is 600 rpm / s, the spin coating time is 60s, the heat annealing temperature is 100-130℃, and the heat annealing time is 10min to form the near-infrared active layer.

[0057] Step 4: In an air atmosphere, after completing Step 3, spin-coat a PEDOT:PSS solution onto the surface of the near-infrared active layer using a spin-coating process. The spin-coating speed is 1000 rpm, the acceleration is 600 rpm / s, and the spin-coating time is 80 s. The heat annealing temperature is 100℃, and the heat annealing time is 10 min to obtain the intermediate transport layer. Step 5: Prepare a visible light active layer on the surface of the intermediate transport layer using a spin-coating method. In a nitrogen atmosphere, spin-coat the visible light active layer solution onto the intermediate transport layer. The spin-coating speed is 1000 rpm, the acceleration is 600 rpm / s, the spin-coating time is 60 s, and the heat annealing temperature is 100-130℃ for 10 min to form the visible light active layer.

[0058] Step 6: An optical microcavity layer is prepared by vapor deposition on the surface of the visible light active layer using a vapor deposition method at a deposition pressure of 10. - 4 Pa, with materials of Ag / NPB / Ag in sequence and thicknesses of 25 / 130 / 25 nm; thus, a dual-band narrowband photodetector based on bias voltage modulation is obtained.

[0059] Evaporation is carried out in a vacuum evaporation furnace. The device to be treated is placed on a turntable at the top of the furnace chamber, with the side containing the interface layer facing down. The prescribed amount of evaporation material particles are placed in a tungsten boat. The vacuum degree inside the furnace is ≤10. -4 Pa, turntable speed 5 r / min; during the vapor deposition process, the growth rate of NPB was set to 1 Å / s, the growth rate of Ag in the first 10 nm was 0.15 Å / s, and the growth rate in the last 15 nm was 1 Å / s.

[0060] Step 7: Carefully apply the optical adhesive to the edge of the transparent glass, move it into the glove box, and encapsulate the vapor-deposited detector in a nitrogen atmosphere. Then, use an ultraviolet lamp to cure it for 5 minutes to complete the encapsulation operation.

[0061] The performance of the photodetector prepared in this embodiment was tested, analyzed, and characterized. The results are as follows: From Figure 2 As can be seen from the optical microcavity transmittance curve, when the light source is incident from the top electrode of the device, it efficiently transmits light with wavelengths of 400-500 nm and 750-850 nm, and has a good suppression effect on light in other wavelength bands, which lays the foundation for the narrowband response of the device.

[0062] from Figure 3The external quantum efficiency characteristic curves show that under forward bias, the detector operates in near-infrared mode, exhibiting a significant narrowband response in the 750-900nm near-infrared band; under reverse bias, the photodetector operates in visible light mode, responding to the 400-500nm visible light band. This demonstrates that the detector can operate simultaneously in both near-infrared and visible light modes, broadening its application range.

[0063] Figure 4 The photodetector prepared for this embodiment operates at 450 nm and 54 mW / cm². 2 Visible light and 810 nm, 138 mW / cm 2 Under near-infrared light irradiation, the current-voltage curves in the bright and dark states are obtained from... Figure 4 The bright and dark current-voltage characteristic curves show that the photodetector has a significant bright-dark current ratio under forward and reverse bias, and has a significant light response in the corresponding wavelength band, ensuring the detection performance of the photodetector.

[0064] Furthermore, the detector's single-mode detection performance under both positive and negative bias was analyzed, specifically the detectivity D* performance. The results are as follows: Figure 5 As shown.

[0065] from Figure 3 and Figure 5 It can be seen that the provided photodetector has high external quantum efficiency (EQE) and detectivity (D*) in different operating modes.

[0066] Specifically, under reverse bias, the photodetector operates in visible light detection mode, achieving an external quantum efficiency (EQE) of approximately 1050% in the 400-500 nm visible light band, and a specific detectivity of up to 9 × 10⁻⁶. 9 Jones. Under forward bias, the photodetector operates in near-infrared detection mode, achieving an external quantum efficiency (EQE) of 70% and a specific detectivity of 6 × 10⁻⁶ at a wavelength of 810 nm. 9 Jones.

[0067] This invention successfully developed a novel dual-band narrowband photodetector. By precisely controlling the ratio and concentration of the active layer material, controllable defect states are innovatively introduced, breaking through the limitations of the single operating mode of traditional devices. The detector is fabricated using a solution method, which is simple, low-cost, and exhibits excellent reproducibility. The device demonstrates outstanding stability, while also possessing high external quantum efficiency and specific detectivity.

[0068] The specific embodiments of the present invention are not limited to the above-described examples. Without departing from the core ideas of the present invention, those skilled in the art can make various modifications and adjustments to the technical solutions. Unless otherwise specified, the technical features disclosed in the specification can be implemented using functionally equivalent alternatives; the technical features and method steps involved can be freely combined and applied, unless they are mutually exclusive.

Claims

1. A dual-band narrowband photodetector based on bias voltage control, characterized in that: The layers arranged from bottom to top are a transparent substrate, a bottom electrode layer, a near-infrared active layer, an intermediate transport layer, a visible light active layer, and an optical microcavity layer with an integrated top electrode; wherein, the near-infrared active layer and the visible light active layer are both composed of a bulk heterostructure formed by fully mixing organic donor materials and organic acceptor materials.

2. The dual-band narrowband photodetector based on bias control as described in claim 1, characterized in that: The transparent substrate is a rigid substrate, and the bottom electrode layer is fabricated on the transparent substrate; The bottom electrode is an ITO thin film with insulating channels. The ITO thin film pattern consists of two region blocks a and four region blocks b. Region block a is a rectangle with a width of 4.4 mm and a length of 10 mm. Region block b has an L-shaped structure, which is divided into a first rectangular block and a second rectangular block. The first rectangular block has a width of 3 mm and a length of 9.4 mm, and the second rectangular block has a width of 4 mm and a length of 9.2 mm. The four region blocks b are paired up to form a U-shaped structure. One side of the U-shaped structure is open, and the center of the other side has a gap that is not closed. The openings of the two U-shaped structures are opposite to each other. Region block a is placed inside the opening of the U-shaped structure and does not contact region block b. The film thickness is 100 nm to 150 nm and the resistance is 30-40 Ω. By applying positive and negative voltages to the two regions a and b respectively, a closed circuit loop can be formed through the top electrode.

3. The dual-band narrowband photodetector based on bias control as described in claim 1, characterized in that: In the near-infrared active layer, the organic donor material is PBDB-T, the acceptor material is IEICO-4F, and the bulk heterojunction formed by the mixture has a response wavelength range of 650 nm-900 nm. In the visible light active layer, the organic donor material is P3HT, and the acceptor material is PC. 71 The response wavelength range of the bulk heterojunction formed by the BM mixture is 400 nm-700 nm.

4. The dual-band narrowband photodetector based on bias control as described in claim 1, characterized in that: The intermediate transport layer is made of PDOT:PSS with a thickness of 50 nm to 70 nm; the optical microcavity layer is a sandwich stacked structure of Ag / NPB / Ag with an Ag thickness of 20 nm to 25 nm and an NPB thickness of 100 nm to 130 nm.

5. The dual-band narrowband photodetector based on bias control as described in any one of claims 1 to 4, characterized in that: The dual-band narrowband photodetector operates in near-infrared detection mode under positive bias, responding to the near-infrared band of 750-900 nm; and operates in visible light detection mode under reverse bias, exhibiting a significant narrowband response to the visible light band of 400-500 nm.

6. A method for fabricating a dual-band narrowband photodetector based on bias voltage control, characterized in that, Includes the following steps: Step 1: Etch indium tin oxide on the upper surface of a transparent substrate. The transparent substrate with indium tin oxide is ultrasonically cleaned in a series of detergents, deionized water, acetone and isopropanol. Then it is dried under a nitrogen flow to obtain a bottom electrode layer with surface impurities removed. Step 2, Preparation of active layer solution: Combine organic donor PBDB-T, acceptor IEICO-4F, organic donor P3HT, and acceptor PC. 71 BM was mixed at mass ratios of 100:3 and 100:1 and ground into powder. The powder was then placed in two reagent bottles and dissolved with organic solvents to obtain organic solutions with total mass concentrations of 30 mg / mL and 40 mg / mL, respectively. The organic solutions were sealed and heated at 100–120 °C, and stirred with a magnetic rotor to promote dissolution. After heating and stirring for at least 6 hours, near-infrared active layer solution and visible light active layer solution were obtained. Step 3: In a nitrogen atmosphere, spin-coat a near-infrared active layer solution onto the upper surface of the bottom electrode layer. After spin-coating, perform thermal annealing to obtain the near-infrared active layer. Step 4: In an air atmosphere, spin-coat the PEDOT:PSS solution onto the upper surface of the near-infrared active layer. After spin-coating, perform thermal annealing to obtain the intermediate transport layer. Step 5: In a nitrogen atmosphere, spin-coat a visible light active layer solution onto the upper surface of the intermediate transport layer. After spin-coating, perform thermal annealing to obtain the visible light active layer. Step 6: An optical microcavity layer composed of Ag / NPB / Ag is sequentially deposited on the upper surface of the visible light active layer using a vacuum thermal evaporation method. The second Ag layer serves as the top electrode of the device, thereby obtaining a dual-band narrowband photodetector based on bias control. Step 7: In a nitrogen atmosphere, encapsulate the bias-controlled dual-band narrowband photodetector using optical adhesive and transparent glass.

7. The fabrication method of the dual-band narrowband photodetector based on bias control as described in claim 6, characterized in that, In step 2, the organic solvent is chlorobenzene or o-dichlorobenzene.

8. The method for fabricating a dual-band narrowband photodetector based on bias control as described in claim 6, characterized in that, In step 3, the spin coating speed of the near-infrared active layer is 1000 rpm, the acceleration is 600 rpm / s, the spin coating time is 50~60s, the heat annealing temperature is 100~130℃, and the heat annealing time is 10~15 min.

9. The fabrication method of the dual-band narrowband photodetector based on bias control as described in claim 6, characterized in that, In step 4, when spin-coating the PEDOT:PSS solution onto the near-infrared active layer, the spin-coating speed is 800-1000 rpm, the acceleration is 600 rpm / s, the spin-coating time is 70-80 s, the heat annealing temperature is 100-130℃, and the heat annealing time is 8-10 min.

10. The fabrication method of the dual-band narrowband photodetector based on bias control as described in claim 6, characterized in that, In step 5, the spin coating speed of the visible light active layer is 1000 rpm, the acceleration is 600 rpm / s, the spin coating time is 50~60s, the heat annealing temperature is 100~130℃, and the heat annealing time is 10~15 min. In step 6, when the optical microcavity layer is prepared by vacuum thermal evaporation, the evaporation rate of Ag is 0.1 to 0.2 Å / s for the first 10 nm and 1 to 1.5 Å / s for the remaining thickness; the evaporation rate of NPB is 1 to 1.5 Å / s.

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