Wide-spectrum photoelectric detector based on crystalline silicon-organic composite heterojunction

Abstract

The invention relates to the technical field of photoelectric detection, and discloses a wide-spectrum photoelectric detector based on a crystalline silicon-organic composite heterojunction, which comprises a crystalline silicon avalanche photodiode (APD) layer and an organic semiconductor active layer. Through an energy band matching design, the organic layer covers the surface of the micro-nano structure of the crystalline silicon APD to form a synergistic photoelectric response interface. The structure utilizes the high gain characteristic of the crystalline silicon APD and the broadband spectrum absorption advantage of the organic material to realize the broadband spectrum detection from visible light to near infrared light. In addition, the light capture efficiency is remarkably enhanced through the micro-nano structure design, and the exciton dissociation efficiency is improved through interface electric field regulation and control. The invention solves the problems of narrow spectral range and low sensitivity of the traditional photoelectric detector, and is suitable for medical health monitoring and high-speed optical communication systems.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photoelectric detection, and particularly relates to a wide-spectrum photoelectric detector based on a crystalline silicon-organic composite heterojunction. BACKGROUND

[0002] With the increasing demand for high-performance photoelectric detectors in the fields of optical communication, environmental monitoring, biomedical imaging, and wearable devices, developing photoelectric detectors with wide spectral response, high sensitivity, and low dark current has become a research hotspot. Although traditional single-crystal silicon avalanche photodiodes (APDs) have high gain and response speed, their spectral response range is mainly concentrated in the visible and near-infrared regions, and their detection capability in the short-wave infrared (SWIR) band is weak. In order to expand their spectral response range, silicon-based APDs are usually combined with other materials such as germanium (Ge or GeSn) and indium gallium arsenide (InGaAs). However, InGaAs detectors, although exhibiting high gain and fast response in the near-infrared band (900 nm-1700 nm), usually require a thermoelectric cooler (TEC) to suppress thermal noise, which increases the system cost. In addition, InGaAs detectors face many challenges in realizing the combination of wide-spectrum and narrow-spectrum detection, including complex material structure, manufacturing difficulty caused by thick absorption layer structure, optical and electrical cross-talk problems, and negative effects of buffer layers on quantum efficiency in the visible band.

[0003] In contrast, organic photoelectric detectors exhibit a breakthrough advantage due to their adjustable band gap, good flexibility, and easy processing. Through molecular design, organic materials can precisely tailor the band gap, and a single active layer can cover the visible to near-infrared band without the need for multi-material heterojunction integration. Solution processing technology supports low-cost, large-area preparation, and lightweight characteristics naturally compatible with flexible substrates (such as PET, PI), providing a lightweight, high-curvature adaptation solution for wearable devices. In recent years, organic photoelectric detectors have made significant progress in both wide-spectrum and narrow-spectrum detection. For example, by developing wide-spectrum absorbing materials or combining multiple materials with complementary absorption spectra, researchers have successfully prepared organic photoelectric detectors with wide-spectrum response in the 400-1000 nm range. In addition, the narrow-spectrum detection field has also made breakthroughs by synthesizing narrow-absorption organic materials or regulating light absorption and charge transport, and the performance of some devices has approached that of InGaAs detectors.

[0004] While organic photodetectors offer significant advantages in spectral response range and flexibility, they still suffer from limitations in carrier mobility, response speed, and stability. Therefore, researchers have begun exploring organic-inorganic hybrid photodetectors to combine the strengths of both. In recent years, significant progress has been made in the study of organic-silicon heterojunctions, particularly in improving photoelectric conversion efficiency and light capture efficiency. For example, by introducing organic materials or designing micro / nanostructures on silicon substrates, researchers have successfully constructed high-performance silicon / organic hybrid photodetectors, significantly improving charge carrier separation efficiency and overall performance.

[0005] Crystalline silicon-organic composite heterojunction photodetectors, by combining the high carrier mobility and stability of crystalline silicon with the tunable bandgap and flexibility of organic materials, hold promise for achieving efficient light capture and carrier separation across a broad spectral range from visible to near-infrared. However, current research in this field still faces numerous challenges, including optimizing the interface properties between crystalline silicon and organic materials, improving the film quality of organic layers on crystalline silicon micro / nanostructures, and achieving efficient light field distribution optimization. While the existing patent CN105720197B achieves self-driven detection, it lacks an APD gain mechanism and has a limited spectral range; its sensor electrode is a metal gate electrode, which is prone to reduced transmittance due to structural obstruction. This patent, however, employs a planar electrode design, where the ultrathin planar electrode and reflective layer work synergistically to achieve secondary light absorption, improving light capture efficiency. Regarding silicon surface passivation, the alkylation treatment in the CN105720197B patent has limited effectiveness and low exciton dissociation efficiency. This patent, on the other hand, effectively improves the exciton dissociation rate through methods such as SAM passivation.

[0006] This patent aims to solve the problems existing in the prior art through innovations such as the micro-nano structure design of crystalline silicon-organic composite heterojunctions and the optimization of film deposition processes, and to develop a high-performance crystalline silicon-organic composite heterojunction broadband photodetector to meet the requirements of modern photoelectric detection technology for high performance, high stability and broadband response. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the purpose of this invention is to provide a broadband photodetector based on a crystalline silicon-organic composite heterojunction. Through innovative micro / nano structure design and interface optimization, this invention solves the problems of limited spectral response range, large dark current, and insufficient stability in existing technologies. This invention significantly enhances light capture efficiency and optimizes carrier separation by introducing a periodic nanopillar array structure on the surface of the crystalline silicon APD layer; improves the film quality of the organic semiconductor active layer by modifying the sidewalls of the nanopillar array with self-assembled monolayers to passivate crystalline silicon interface defects; achieves broadband spectral response and high sensitivity by optimizing the film formation process of the organic semiconductor active layer and doping with quantum dot materials; and improves the light absorption capability of the device through the design of planar electrodes and a reflective layer. The broadband photodetector of this invention exhibits excellent detection performance in the visible to near-infrared band and is suitable for various applications such as optical communication, environmental monitoring, biomedical imaging, and wearable devices.

[0008] The technical solution of the present invention is as follows:

[0009] In a first aspect, the present invention provides a broadband photodetector based on a crystalline silicon-organic composite heterojunction, comprising:

[0010] Crystalline silicon avalanche photodiode (APD) layer, including P ++ District, primary district, N ++ District, P + District, of which P + The surface of the region has a periodic array of nanopillars;

[0011] Organic semiconductor active layer: covering the nanopillar array, composed of a blend of donor and acceptor materials;

[0012] Charge blocking layer: Covering the surface of the organic semiconductor active layer, composed of a composite of electron transport material and hole blocking material;

[0013] Plate electrode: composed of a continuous conductive layer, covering the surface of the charge blocking layer;

[0014] Reflective layer: composed of highly reflective metal or metal oxide, located above the planar electrode;

[0015] Three-terminal stacked structure: the N ++ The region serves as a common electrode, connecting the crystalline silicon APD subunit and the organic active layer subunit in series.

[0016] Furthermore, the crystalline silicon APD subunit responds to the visible light band of 300 nm to 1100 nm; the organic active layer subunit responds to the near-infrared band of 1100 nm to 1600 nm.

[0017] The detector has two operating modes by adjusting the bias voltage:

[0018] First operating mode: Under reverse bias voltage of -1 V to -5 V, the crystalline silicon APD subunit and the organic active layer subunit work together to achieve broadband detection in the 300 nm to 1600 nm band.

[0019] Second operating mode: Under reverse bias voltage of -5 V to -15 V, the independent response characteristics of the two sub-units are activated by voltage regulation to achieve spectral selective detection in the visible and near-infrared bands.

[0020] Furthermore, the mechanism for implementing the broadband detection mode (cooperative working mode) is as follows:

[0021] Condition: Apply a low reverse bias (e.g., V). bias = -5 V).

[0022] Electric field distribution: When a reverse bias voltage, such as -5V, is applied to the device, the electric field strength E in the depletion region of the crystalline silicon APD layer is relatively weak (e.g., E ~ 5 × 10⁻⁶). 4 (V / cm), at which point the interfacial electric field between the organic active layer and the crystalline silicon APD layer is insufficient to completely separate their operating wavelengths.

[0023] Carrier pathways: 1) Visible light (300-1100 nm): The crystalline silicon APD layer directly absorbs photons, generating electron-hole pairs. Under the drive of the electric field, electrons rapidly enter the APD layer, triggering avalanche gain (gain factor ≥ 10). 3 2) Near-infrared light (1100-1600 nm): Photons not absorbed by the crystalline silicon APD penetrate into the organic active layer and are absorbed by organic materials (such as Y6 acceptors, band gap 0.7 eV) and quantum dots (such as PbS, band gap 0.4 eV). The resulting excitons dissociate into holes (organic layer) and electrons (crystalline silicon APD) at the interface.

[0024] Synergistic effect: Electrons are amplified by the avalanche gain of the crystalline silicon APD, and holes are collected by the planar electrode. The spectral responses of the two materials are superimposed to achieve a wide spectrum detection of 300-1600 nm.

[0025] Furthermore, the mechanism for implementing the multi-band detection mode (selective separation mode) is as follows:

[0026] Condition: Adjust to a specific reverse bias (e.g., V) bias = -15 V).

[0027] Electric field distribution: The electric field strength of the crystalline silicon APD layer is significantly enhanced (E ≥ 10). 5 (V / cm), causing the depletion region to extend to the vicinity of the organic layer interface, forming a strong electric field barrier effect.

[0028] Carrier pathways: 1) Crystalline silicon APD layer (300-1100 nm): The electric field is concentrated in the depletion region of the crystalline silicon APD. Electrons are accelerated within the APD layer, triggering avalanche gain. Holes are strongly confined to the crystalline silicon region, inhibiting their diffusion into the organic layer. At this point, the crystalline silicon APD layer dominates visible light detection, while the organic layer stops responding to near-infrared light due to electric field isolation. 2) Organic active layer (1100-1600 nm): When a periodic pulsed bias voltage (such as V) is applied... bias (By periodically switching to 0 V), the electric field of the crystalline silicon APD layer temporarily disappears, allowing near-infrared photons to penetrate to the organic layer and be absorbed. Excitons dissociate into holes (collected by the planar electrode) and electrons (collected through the APD layer). By controlling the bias voltage in a time sequence, alternating selective detection of visible and near-infrared light can be achieved.

[0029] Furthermore, the nanopillar array of the crystalline silicon APD layer is prepared by reactive ion etching (RIE). The nanopillars have a diameter of 80-350 nm, a height of 300-700 nm, a period of 150-600 nm, and a wall roughness ≤10 nm. Smaller diameters and appropriate periods enhance light scattering and trapping, reducing reflection losses. The height of the nanopillars determines the path length of light propagation within the structure; taller nanopillars increase the light absorption path, thereby improving light absorption efficiency. Controlling the sidewall roughness helps reduce light scattering losses, ensuring effective light propagation within the nanopillar array.

[0030] Furthermore, the ratio of the period of the nanopillar array in the APD layer to the incident light wavelength (300-1600 nm) is 0.3-2.0; the periodic nanopillar design matches the light wavelength to increase the optical path and reduce scattering loss.

[0031] Furthermore, the donor materials of the organic semiconductor active layer include, but are not limited to, PTB7-Th, PM6, PBDB-T, DIP, CuPc or their derivatives, and the acceptor materials include, but are not limited to, Y6, PC71BM, ITIC, N2200, COi8DFIC or combinations thereof. The donor-to-acceptor mass ratio is 1:0.8 to 1:3.5, the band gap is 0.7-1.2 eV, and the thickness is 500-1000 nm. A low acceptor ratio (1:0.8 to 1:1) is suitable for highly crystalline donor materials (such as DIP and CuPc), avoiding excessive dilution of the donor network and maintaining the continuity of the hole transport path by reducing the acceptor ratio. A high acceptor ratio (1:3 to 1:3.5) is suitable for narrow band gap acceptors (such as COi8DFIC and ITIC-4F), enhancing near-infrared absorption and electron transport capabilities, but requires interface engineering (such as SAM modification) to suppress hole recombination. If the ratio exceeds 1:3.5, excessive acceptor aggregation may lead to excessive phase separation and a decrease in exciton dissociation efficiency; while when the ratio is below 1:0.8, the donor network is discontinuous, and hole mobility is significantly reduced. The mass ratio range of 1:0.8 to 1:3.5 offers the following core advantages: Optimized phase separation scale: Within this range, the active layer forms a phase separation structure on the scale of 20-50 nm, matching the exciton diffusion length (approximately 10-20 nm) and reducing charge recombination. Balanced carrier mobility: The donor-acceptor ratio directly affects the matching of hole and electron mobilities. For example, in the PM6:Y6 system, at a ratio of 1:1.2, hole mobility is close to electron mobility, avoiding space charge accumulation. Near-infrared light (1100-1600 nm) has a longer wavelength and a greater light penetration depth (typically on the order of micrometers). A thicker organic layer (e.g., 500-1000 nm) can significantly improve the absorption efficiency of near-infrared photons. In broadband co-detection mode, the crystalline silicon APD is mainly responsible for visible light (300-1100 nm), while the thicker organic layer can focus on absorption in the near-infrared band. By optimizing the material composition (e.g., a donor PM6 to acceptor Y6 mass ratio of 1:1.5) and bandgap matching (0.7-1.2 eV), the thicker organic layer can ensure near-infrared absorption while avoiding excessive absorption of visible light, allowing unabsorbed visible light to penetrate to the crystalline silicon APD layer and trigger avalanche gain (gain factor ≥10). 3 This design achieves spectral specialization through bandgap engineering: the crystalline silicon APD dominates visible light detection, while the organic layer specializes in near-infrared light. With a thickness of 500-1000 nm, the thinner organic layer ensures efficient light absorption within it, while allowing unabsorbed light to enter the crystalline silicon APD layer for further absorption. This design enables the device to simultaneously utilize the efficient absorption of near-infrared light by the organic layer and the absorption of visible light by the crystalline silicon, thus achieving a broad spectral response.

[0032] Furthermore, the organic active layer is doped with 0.1%-5% by mass of quantum dot material, including but not limited to PbS, CdSe, CsPbBr3, and InAs quantum dots, with a particle size of 3-5 nm, to enhance absorption and carrier multiplication in the 300-1500 nm spectral range. Quantum doping enhances light absorption through localized plasmon resonance. The band gap of the quantum dots is tunable, enabling them to absorb light of different wavelengths and generate additional carriers. This localized plasmon resonance not only enhances light absorption but also significantly improves the generation efficiency of photogenerated carriers through carrier multiplication (i.e., one photon generates multiple carrier pairs).

[0033] Furthermore, the sidewalls of the nanopillar array are modified with self-assembled monolayers (SAMs). The SAM molecules include functionalized materials containing anchoring groups such as phosphate groups, thiol groups, or silane groups, including but not limited to APTES, PFDT, 2PACz, MeO-2PACz, MPA, or their derivatives. These SAMs passivate silicon interface defects through chemical bonding and regulate the work function shift by 0.1-0.5 eV. The thickness is 1-10 nm. The phosphate groups form stable Si-OP covalent bonds with hydroxyl groups (-OH) on the silicon surface, passivating interface defect states; or the anchoring groups coordinate with silicon dangling bonds (such as Si-), suppressing deep-level traps, reducing interfacial recombination losses, and regulating the surface work function through molecular dipole effects to optimize energy level matching with the organic layer.

[0034] Furthermore, the planar electrode includes, but is not limited to, ITO, AZO, IZO, PEDOT:PSS, with a thickness of 20-100 nm; the reflective layer includes, but is not limited to, a high-reflectivity metal layer selected from Al, Ag, or their alloys, with a thickness of 20-50 nm; or a metal oxide layer selected from TiO2, ZnO, or their alternating layers, with a single layer thickness of 0.1-5 nm, a total thickness of 10-50 nm, and a reflectivity ≥90%@300-1600 nm.

[0035] Furthermore, the charge blocking layer includes, but is not limited to, C60-C60:MoO3-BCP, TiO2 / BCP / Alq3, and ZnO / Bphen / Ag stacks, with each layer having a thickness of 5-50 nm. This layer is used to suppress hole injection and reduce the interfacial recombination rate by ≥50%. The selection of these materials and thickness optimization ensure effective carrier separation and transport, thereby improving the device's response speed and stability.

[0036] Secondly, the method for preparing the detector includes the following steps:

[0037] a. Fabrication of pn junctions and etching of nanopillar arrays on crystalline silicon substrates: n+ doped regions are formed on p-type crystalline silicon substrates by ion implantation or diffusion processes to form pn junctions; a periodic nanopillar array is formed by reactive ion etching (RIE) with SF6 / C4F8 mixed gas (volume ratio 1:3) as etchant at RF power of 200 W and pressure of 10 mTorr, with a diameter of 80-350 nm, a height of 300-700 nm, a period of 150-600 nm, and a sidewall roughness ≤10 nm; a 0.1-1 mM SAM solution is prepared, and a monomolecular passivation layer with a thickness of 1-10 nm is prepared by spin coating, dip coating, or blade coating.

[0038] b. Dissolve the donor and acceptor materials in a chlorobenzene solution (concentration 20 mg / mL) at a mass ratio of 1:0.8 to 1:3.5, and dop with 3% PbS quantum dots (particle size 3-5 nm) and ultrasonically disperse for 30 minutes; form a film on the surface of the nanopillar array by spin coating, slit coating, or blade coating, and then anneal at 150°C for 20 minutes in a nitrogen atmosphere to optimize the phase separation morphology and form an organic active layer with a thickness of 500-1000 nm.

[0039] c. Prepare a multilayer charge blocking layer on the surface of the organic active layer by means of vapor deposition or other methods, including but not limited to C60-C60:MoO3-BCP, TiO2 / BCP / Alq3, ZnO / Bphen / Ag stacks, with each layer having a thickness of 5-50 nm, to suppress hole injection and reduce the interfacial recombination rate by ≥50%.

[0040] d. Spin-coat a PEDOT:PSS solution (50 nm thick) onto the surface of the charge barrier layer at 3000 rpm for 30 seconds, and anneal at 150°C for 10 minutes to form a planar electrode;

[0041] e. An Ag layer (20-50 nm thick) is deposited on the surface of the flat electrode by magnetron sputtering to form a reflective layer.

[0042] Working Principle: This invention provides a broadband photodetector based on a crystalline silicon-organic composite heterojunction and its fabrication method. When photons irradiate the detector surface, due to the type II band alignment formed between the crystalline silicon APD layer and the organic layer, excitons separate at the interface. Electrons are guided to the crystalline silicon APD layer, while holes remain in the organic layer. The high electric field of the crystalline silicon APD layer triggers an avalanche multiplication effect, significantly improving carrier gain and enhancing detection sensitivity. Simultaneously, the nanopillar array structure enhances light capture efficiency, and quantum doping further improves light absorption and carrier generation efficiency through localized plasmon resonance. The planar electrode and reflective layer enhance secondary light absorption. Finally, the optical signal is efficiently converted into an electrical signal and output through the above mechanism, achieving high-sensitivity detection over a wide spectral range.

[0043] Compared with the prior art, the beneficial effects of this invention are as follows:

[0044] Compared with traditional detectors, this invention has the following significant advantages:

[0045] 1. This invention achieves a broad spectral response from the visible to near-infrared bands by combining the high carrier mobility of crystalline silicon with the tunable bandgap of organic materials. Compared to traditional silicon-based APDs, which have weaker detection capabilities in the short-wave infrared band and typically require combination with materials such as Ge or InGaAs, this invention covers a wide spectral range without the need for additional materials.

[0046] 2. This invention utilizes the avalanche gain mechanism of crystalline silicon APD layers and optimizes doping concentration to achieve high-sensitivity detection. Simultaneously, interface passivation and multilayer blocking structures effectively reduce dark current and improve the signal-to-noise ratio. While traditional InGaAs detectors offer high gain, they require thermoelectric coolers to suppress thermal noise, increasing system costs. This invention achieves superior performance without the need for additional cooling equipment.

[0047] 3. This invention significantly enhances light scattering and trapping through a nanopillar array structure, and quantum doping further improves light absorption, especially in the short-wave infrared band, achieving higher photon utilization, which is significantly better than traditional detectors.

[0048] 4. The solution processing technology of the organic semiconductor layer of the present invention supports low-cost, large-area fabrication, reduces manufacturing complexity and system cost, and has significant advantages over the high manufacturing cost and complex process of traditional InGaAs detectors. Attached Figure Description

[0049] The accompanying drawings are provided to further illustrate the invention and are used in conjunction with the following embodiments to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0050] Figure 1This is a schematic diagram of the structure of the broadband photodetector of the crystalline silicon-organic composite heterojunction of the present invention;

[0051] Figure 1 Chinese: 1.P ++ 1. District, 2. Intrinsic District, 3. P + District 4.N ++ 5. Organic semiconductor active layer, 6. Charge blocking layer, 7. Planar electrode, 8. Reflective layer;

[0052] Figure 2 The light field distribution for FDTD simulation;

[0053] Figure 3 This is a comparison diagram of the external quantum properties of the composite APD and the silicon-based APD of the present invention;

[0054] Figure 4 This is a comparison chart of the responsivity characteristics of the composite APD and the silicon-based APD of this invention;

[0055] Figure 5 This is a graph showing the specific detectivity performance under different operating modes. Detailed Implementation

[0056] To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0057] In a first aspect, the present invention provides a broadband photodetector based on a crystalline silicon-organic composite heterojunction, such as... Figure 1 As shown, it is characterized by comprising the following structures stacked sequentially:

[0058] Crystalline silicon avalanche photodiode (APD) layer, including P ++ District, primary district, N ++ District, P + District, of which P + The surface of the region has a periodic array of nanopillars;

[0059] Organic semiconductor active layer: covering the nanopillar array, composed of a blend of donor and acceptor materials;

[0060] Charge blocking layer: Covering the surface of the organic semiconductor active layer, composed of a composite of electron transport material and hole blocking material;

[0061] Plate electrode: composed of a continuous conductive layer, covering the surface of the charge blocking layer;

[0062] Reflective layer: composed of highly reflective metal or metal oxide, located above the planar electrode;

[0063] Three-terminal stacked structure: the N ++ The region serves as a common electrode, connecting the crystalline silicon APD subunit and the organic active layer subunit in series.

[0064] The crystalline silicon APD subunit responds to the visible light band of 300 nm to 1100 nm; the organic active layer subunit responds to the near-infrared band of 1100 nm to 1600 nm.

[0065] The detector has two operating modes by adjusting the bias voltage:

[0066] First operating mode: Under reverse bias voltage of -1 V to -5 V, the crystalline silicon APD subunit and the organic active layer subunit work together to achieve broadband detection in the 300 nm to 1600 nm band.

[0067] Second operating mode: Under reverse bias voltage of -5 V to -15 V, the independent response characteristics of the two sub-units are activated by voltage regulation to achieve spectral selective detection in the visible and near-infrared bands.

[0068] The nanopillar array of the crystalline silicon APD layer was fabricated via reactive ion etching (RIE). The nanopillars have diameters of 80-350 nm, heights of 300-700 nm, periods of 150-600 nm, and wall roughness ≤10 nm. Smaller diameters and appropriate periods enhance light scattering and trapping, reducing reflection losses. The height of the nanopillars determines the path length of light propagation within the structure; taller nanopillars increase the light absorption path, thereby improving light absorption efficiency. Controlling the sidewall roughness helps reduce light scattering losses, ensuring efficient light propagation within the nanopillar array.

[0069] The light absorption process in the active layer follows the Lambert-Beer law, where the exciton generation rate is:

[0070]

[0071] Where α is the absorption coefficient of the organic material (unit: cm). -1 I0 is the incident light intensity (unit: W / cm). 2 x represents the penetration depth (in cm). The light trapping effect enhancement factor η trap The geometric parameters and material optical constants (refractive index n) of the micro / nano structure (nanopillar array, period P, diameter D, height H) are used. si n org Extinction coefficient k Si k org The optical field distribution was obtained by quantitatively simulating the optical field using the finite-difference time-domain (FDTD) method.

[0072] This formula guides material selection and thickness design: high-absorption-coefficient organic materials are chosen to enhance near-infrared absorption; the organic layer thickness is optimized to ensure most light is absorbed while avoiding excessive thickness that would prevent excitons from diffusing to the interface. This patent selects an active layer thickness of 500-1000 nm, covering the absorption depth requirements of typical organic materials while avoiding excessive thickness that would reduce transmittance.

[0073] Exciton concentration evolution: The spatiotemporal variation of exciton concentration n(x,t) is described by the diffusion equation, which is:

[0074]

[0075] Where τ is the exciton lifetime (in seconds) and the effective diffusion coefficient (D) is the effective diffusion coefficient. eff = D·η trap Units: cm² / s, D is the exciton diffusion coefficient. The steady-state solution of this equation is:

[0076]

[0077] This formula guides diffusion length matching: ensuring that the organic layer thickness d ≤ L d This allows excitons to diffuse to the transport interface, and interface engineering: increasing the interface contact area through microstructures such as nanopillar arrays to improve the probability of exciton dissociation.

[0078] The crystalline silicon APD has N ++ The doped electrode region serves as the main electrode; this region is relatively narrow and can generate a strong electric field; P + The surface of the region has periodically arranged micro- and nano-structures to enhance light absorption and capture; the organic semiconductor active layer is composed of a mixture of donor and acceptor materials, forming a heterojunction in close contact with the crystalline silicon layer, and also with N... ++ The doped electrode region has multiple contact sites, which can enhance charge transport;

[0079] Dual-reflector resonant cavity: The dual-reflector resonant cavity consists of N ++ The region (crystalline silicon APD layer) and the Ag / TeO2 reflective layer together form a synergistic resonance mode of Ag-Ag metal cavity and TeO2-Ag dielectric cavity.

[0080] The synergistic mechanism between the dual-reflector resonant cavity and the nanopillar array includes:

[0081] Standing wave resonance enhancement: The incident light forms a standing wave between the double reflection interfaces, which localizes the light field energy in the active layer of the organic semiconductor through the interference effect;

[0082] Localized surface plasmon resonance: Nanopillars excite transverse and longitudinal plasmon modes in the near-infrared band. The spacing between the nanopillars (10-50 nm) forms a subwavelength gap, which excites localized surface plasmon resonance.

[0083] Photonic crystal scattering: Periodic nanopillars extend the optical path through multiple scattering paths, forming photonic crystal scattering, which significantly improves light capture efficiency.

[0084] like Figure 2 The image shows the light field distribution from the FDTD simulation (see the published journal *Energy Environ. Sci.*, 2021). Figure 2 (a) is a traditional planar device. Figure 2 (b) is a micro / nano structure device of the present invention. Based on the above-mentioned light field enhancement principle, the photoelectric field intensity (|E|²) of the organic semiconductor active layer region near the nanopillar array is enhanced by 2-3 times compared with traditional planar devices.

[0085] In crystalline silicon-organic heterojunction photodetectors, the exciton dissociation efficiency (η) diss The energy level is closely related to the interfacial electric field strength (E), energy level matching degree (ΔE), and material properties. This relationship can be quantitatively described by the following formula:

[0086]

[0087] k diss : Exciton dissociation rate constant, which is related to the interfacial energy level difference (ΔE) and the material band structure matching.

[0088] k rec : Exciton recombination rate constant, which is related to the interface defect state density.

[0089] E: Interface electric field strength;

[0090] μ: Carrier mobility;

[0091] τ drift : Electric field driving time;

[0092] d: Interface thickness;

[0093] ΔE: Energy level difference between the organic semiconductor active layer and the crystalline silicon APD layer (unit: eV);

[0094] k B Boltzmann constant;

[0095] T: Absolute temperature.

[0096] The first term is the kinetic competition term, which, in a crystalline silicon-organic heterojunction photodetector, represents the exciton dissociation efficiency (η). diss ) and recombination rate (k recThe exciton dissociation rate constant can be quantitatively described using Marcus charge transfer theory. According to Marcus theory, the exciton dissociation rate constant can be expressed as:

[0097]

[0098] in:

[0099] ΔE: Interfacial energy level difference, i.e., the conduction band shift between organic materials and crystalline silicon (unit: eV).

[0100] λ: Recombination energy, reflecting the energy required for molecular geometric transformation (unit: eV);

[0101] V: Electronic coupling matrix element, describing the interaction strength of interfacial charge transfer (unit: eV).

[0102] k B Boltzmann constant (8.617 × 10⁻⁶) -5 eV / K);

[0103] T: Temperature (unit: K);

[0104] ℏ: Reduced Planck constant (6.582 × 10⁻⁶) -16 eV·s).

[0105] When ΔE+λ=0, k diss The interface energy level reaches its maximum value, at which point the interface energy level matching is optimal; a small change in ΔE (e.g., from 0.5 eV to 0.2 eV) can make k... diss Increase by 2-3 orders of magnitude.

[0106] Exciton recombination rate and interfacial defect state density (N t ) and activation energy (E) b Related:

[0107]

[0108] in:

[0109] σ: Carrier trapping cross section (unit: cm²);

[0110] v th : Thermal velocity of charge carriers (unit: cm / s);

[0111] N t Volumetric defect state density (unit: cm³) -3 );

[0112] E b : Recombination activation energy, which is related to the depth of the defect state (unit: eV).

[0113] The kinetic competition term for exciton dissociation efficiency can be expressed as:

[0114]

[0115] When k diss >> k rec At this point, the dissociation efficiency approaches 100%. This patent optimizes this through energy level matching: APTES is used to modify the silicon surface, resulting in ΔE = 0.1 eV, k diss Upgraded to 10 12 s -1 Passivation effect: Defect state density N t From 10 13 cm -3 Reduced to 10 10 cm -3 k rec Reduced to 10 11 s -1 Dissociation efficiency: η diss ≥ 90%.

[0116] The second term is the electric field driving term:

[0117] E: Interface electric field strength, determined by the reverse bias voltage (-V) of the crystalline silicon APD layer. bias ) and doping concentration (N) d )Decide.

[0118] According to Poisson's equation, the electric field in the depletion region is:

[0119]

[0120] Where V bi This is the built-in potential. In this invention, the optimization of the electric field distribution through the micro / nano structure is achieved by introducing a structure enhancement factor η. struct The revised formula is:

[0121]

[0122] Where, η struct Related to the geometric parameters (diameter D, period P, height H) and material properties of the nanopillar, it is defined as:

[0123]

[0124] λ: Incident light wavelength, matched with the absorption band;

[0125] ΔR: Actual sidewall roughness (unit: nm);

[0126] ΔR0: Reference roughness (e.g., 10 nm).

[0127] Nanopillar period P: The smaller the period, the more significant the multiple scattering of light between the nanopillars, which enhances the light capture efficiency and indirectly improves the electric field utilization rate.

[0128] Diameter D and height H: The ratio of diameter to height optimizes the light propagation path, reduces reflection loss, and increases the contact area of ​​the depletion region, thereby improving carrier separation efficiency.

[0129] Roughness compensation term (1-ΔR / ΔR0): The lower the sidewall roughness (ΔR ≤ 5nm), the higher the carrier mobility and the stronger the electric field driving efficiency.

[0130] This patent optimizes the doping concentration (N) of the APD layer. d = 1×10 17 cm -3 A reverse bias (-10 V) and a reverse bias (-10 V) make E≥10 5 V / cm, by optimizing the micro / nano structure (e.g., D = 200nm, P = 300nm, H = 500nm), η struct ≥ 1.3, making the actual electric field strength E eff It increases by 30%, significantly enhancing avalanche gain and exciton dissociation efficiency.

[0131] In summary, substituting the formulas for the exciton dissociation rate, recombination rate, and interfacial electric field into the final exciton dissociation efficiency:

[0132]

[0133] The first term of the numerator and denominator of the formula are exactly the same, so they can be directly simplified to obtain the simplified form:

[0134]

[0135] The ratio in the denominator can be further simplified:

[0136]

[0137] make:

[0138]

[0139] The formula then simplifies to:

[0140]

[0141] Where A is a coefficient related to material parameters (such as carrier mobility, trap concentration, etc.), and Γ is the activation energy difference parameter.

[0142] The exponential terms within parentheses can be combined with constants and parameterized:

[0143]

[0144] The exponent term can then be rewritten as:

[0145]

[0146] After further simplification, the final formula is:

[0147]

[0148] Simplified physical meaning:

[0149] 1. Competition Mechanism: The first term is 1 / (1+A·exp(Γ / (k)). B ·T) describes the competition between two carrier dynamic processes:

[0150] Transition-dominated: When the temperature is low or the activation energy difference Γ is large, the second term in the denominator dominates, and the efficiency is dominated by exponential decay.

[0151] Trapping recombination dominates: When the temperature is high or the activation energy difference is small, trap recombination (represented by coefficient A) dominates.

[0152] 2. Space charge effect: The second term 1-exp(-βγ / d) reflects the transport efficiency of charge carriers under the electric field gradient, which is related to the depletion layer width, mobility and lifetime.

[0153] This invention achieves efficient exciton dissociation and carrier extraction by synergistically optimizing the energy level matching, interface characteristics, and electric field distribution of crystalline silicon-organic heterojunctions. Specifically, it reduces the defect state density to N0.05 by passivating interface defects in the crystalline silicon nanopillar array using a self-assembled monolayer (such as APTES). t ≤ 10 10 ~cm -3 Furthermore, by modulating the work function shift by 0.1-0.5 eV through the molecular dipole effect, the organic layer achieves optimal type II band alignment with crystalline silicon (ΔE+λ≈0), significantly enhancing the exciton dissociation rate to k. diss ≥ 10 12 ~s -1 At the same time, reverse bias (V bias = -10 ~ V) works synergistically with the geometric parameters of the nanopillar (diameter D = 200 ~ nm, period P = 300 ~ nm, height H = 500 ~ nm) to introduce a structure enhancement factor η. struct ≥ 1.3, so that the effective electric field strength E at the interface eff Increased to 1.56×10 5~V / cm, accelerating carrier drift after exciton separation. Quantum doping (e.g., 3% PbS) extends light absorption to the near-infrared band through localized plasmon resonance, and, combined with a charge-blocking layer (e.g., C60 / MoO3 / BCP), suppresses interfacial recombination to kJ / cm². rec ≤4×10 11 s -1 Ultimately, the exciton dissociation efficiency exceeded 90%. Through the above synergistic optimization, efficient exciton dissociation and carrier extraction can be achieved, ultimately achieving wide-spectrum, high-sensitivity detection.

[0154] The donor materials of the organic semiconductor active layer include, but are not limited to, PTB7-Th, PM6, PBDB-T, DIP, CuPc, or their derivatives, and the acceptor materials include, but are not limited to, Y6, PC71BM, ITIC, N2200, COi8DFIC, or combinations thereof. The donor-to-acceptor mass ratio is 1:0.8 to 1:3.5, the band gap is 0.7-1.2 eV, and the thickness is 500-1000 nm. A thinner organic layer ensures efficient light absorption within the organic layer while allowing unabsorbed light to enter the crystalline silicon APD layer for further absorption. This design enables the device to simultaneously utilize the efficient absorption of near-infrared light by the organic layer and the absorption of visible light by the crystalline silicon, thereby achieving a broad-spectrum response.

[0155] The sidewalls of the nanopillar array are modified with self-assembled monolayers (SAMs). The SAM molecules include functionalized materials containing anchoring groups such as phosphate groups, thiol groups, or silane groups, including but not limited to APTES, PFDT, 2PACz, MeO-2PACz, MPA, or their derivatives. These SAMs passivate silicon interface defects through chemical bonding and modulate the work function shift by 0.1-0.5 eV. The phosphate groups form stable Si-OP covalent bonds with silicon surface hydroxyl groups (-OH), passivating interface defect states; or the anchoring groups coordinate with silicon dangling bonds (such as Si-), suppressing deep-level traps, reducing interfacial recombination losses, and regulating the surface work function through molecular dipole effects, optimizing energy level matching with the organic layer.

[0156] The organic active layer is doped with 0.1%-5% by mass of quantum dot materials, including but not limited to PbS, CdSe, CsPbBr3, and InAs quantum dots, with a particle size of 3-5 nm, to enhance absorption and carrier multiplication in the 300-1500 nm spectral range. Quantum doping enhances light absorption through localized plasmon resonance. The band gap of the quantum dots is tunable, enabling them to absorb light of different wavelengths and generate additional carriers. This localized plasmon resonance not only enhances light absorption but also significantly improves the efficiency of photogenerated carrier generation through carrier multiplication (i.e., one photon generates multiple carrier pairs).

[0157] The planar electrode includes, but is not limited to, ITO, AZO, IZO, and PEDOT:PSS, with a thickness of 20-100 nm. The reflective layer includes, but is not limited to, a high-reflectivity metal layer selected from Al, Ag, or their alloys, with a thickness of 20-50 nm; or a metal oxide layer selected from TiO2, ZnO, or their alternating layers, with a single layer thickness of 0.1-5 nm, a total thickness of 10-50 nm, and a reflectivity ≥90%@300-1600 nm.

[0158] The charge blocking layer includes, but is not limited to, C60-C60:MoO3-BCP, TiO2 / BCP / Alq3, and ZnO / Bphen / Ag stacks, with each layer having a thickness of 5-50 nm. These layers are used to suppress hole injection and reduce the interfacial recombination rate by ≥50%. The selection of these materials and the optimization of their thickness ensure effective carrier separation and transport, thereby improving the device's response speed and stability.

[0159] Secondly, the method for preparing the detector includes the following steps:

[0160] a. Fabrication of pn junctions and etching of nanopillar arrays on crystalline silicon substrates: n+ doped regions are formed on p-type crystalline silicon substrates by ion implantation or diffusion processes to form pn junctions; a periodic nanopillar array is formed by reactive ion etching (RIE) with SF6 / C4F8 mixed gas (volume ratio 1:3) as etchant at RF power of 200 W and pressure of 10 mTorr, with a diameter of 80-350 nm, a height of 300-700 nm, a period of 150-600 nm, and a sidewall roughness ≤10 nm; a 0.1-1 mM SAM solution is prepared, and a monomolecular passivation layer with a thickness of 1-10 nm is prepared by spin coating, dip coating, or blade coating.

[0161] b. Dissolve the donor and acceptor materials in a chlorobenzene solution (concentration 20 mg / mL) at a mass ratio of 1:0.8 to 1:3.5, and dop with 3% PbS quantum dots (particle size 3-5 nm) and ultrasonically disperse for 30 minutes; form a film on the surface of the nanopillar array by spin coating, slit coating, or blade coating, and then anneal at 150°C for 20 minutes in a nitrogen atmosphere to optimize the phase separation morphology and form an organic active layer with a thickness of 500-1000 nm.

[0162] c. Prepare a multilayer charge blocking layer on the surface of the organic active layer by means of vapor deposition or other methods, including but not limited to C60-C60:MoO3-BCP, TiO2 / BCP / Alq3, ZnO / Bphen / Ag stacks, with each layer having a thickness of 5-50 nm, to suppress hole injection and reduce the interfacial recombination rate by ≥50%.

[0163] d. Spin-coat a PEDOT:PSS solution (50 nm thick) onto the surface of the charge barrier layer at 3000 rpm for 30 seconds, and anneal at 150°C for 10 minutes to form a planar electrode;

[0164] e. An Ag layer (20-50 nm thick) is deposited on the surface of the flat electrode by magnetron sputtering to form a reflective layer.

[0165] Working Principle: This invention provides a broadband photodetector based on a crystalline silicon-organic composite heterojunction and its fabrication method. When photons irradiate the detector surface, due to the type II band alignment formed between the crystalline silicon APD layer and the organic layer, excitons separate at the interface. Electrons are guided to the crystalline silicon APD layer, while holes remain in the organic layer. The high electric field of the crystalline silicon APD layer triggers an avalanche multiplication effect, significantly improving carrier gain and enhancing detection sensitivity. Simultaneously, the nanopillar array structure enhances light capture efficiency, and quantum doping further improves light absorption and carrier generation efficiency through localized plasmon resonance. The planar electrode and reflective layer enhance secondary light absorption. Finally, the optical signal is efficiently converted into an electrical signal and output through the above mechanism, achieving high-sensitivity detection over a wide spectral range.

[0166] The present invention will be further explained below through specific embodiments:

[0167] Example 1

[0168] A broadband photodetector based on a crystalline silicon-organic composite heterojunction is fabricated as follows:

[0169] a. On a p-type crystalline silicon substrate (doping concentration 1×10⁻⁶) 16 (cm⁻³) N is formed through phosphorus ion implantation. ++ A pn junction was constructed in the region, and a nanopillar array with a diameter of 200 nm, a height of 500 nm, and a period of 300 nm was prepared by reactive ion etching (SF6 / C4F8 volume ratio 1:3, power 200 W). A 2 nm thick octadecylphosphonic acid (ODPA) self-assembled monolayer was formed on the surface by dip coating, with a work function shift of 0.3 eV, which improved the interface energy level matching.

[0170] b. PTB7-Th:Y6 (mass ratio 1:1.2) was dissolved in chlorobenzene (20 mg / mL), doped with 3% PbS quantum dots (4 nm particle size), ultrasonically dispersed for 40 minutes, and then spin-coated at 2000 rpm to form a 500 nm thick active layer; annealed in nitrogen at 150°C for 20 minutes to form a bicontinuous interpenetrating network structure with an exciton dissociation efficiency of 95%.

[0171] c. Vacuum evaporation of a charge barrier layer consisting of C60 (20 nm), MoO3 (5 nm), and BCP (10 nm).

[0172] d. A 10 nm silver layer was deposited by magnetron sputtering (Ar gas pressure 3 mTorr), and PEDOT:PSS was spin-coated (3000 rpm, 50 nm thickness) to form a composite planar electrode.

[0173] e. An aluminum oxide layer with a total thickness of 10-50 nm is formed by ALD deposition on the surface of the flat electrode.

[0174] Example 2 (modified from Example 1)

[0175] a. The diameter of the nanopillars was adjusted to 250 nm and the period to 400 nm to improve near-infrared light capture;

[0176] b. The active layer was replaced with PM6:Y6 (1:1.5) and coated with a doctor blade to form a 700 nm thick film;

[0177] c. Evaporation of a TiO2 (15 nm) / BCP (8 nm) / Alq3 (5 nm) stacked barrier layer;

[0178] d. Magnetron sputtering of 100nm ITO as a planar electrode;

[0179] e. Alternating deposition of zinc oxide and aluminum oxide by ALD forms a reflective layer with a total thickness of 10-50 nm.

[0180] Figure 3 The image shows a comparison of the EQE of a silicon-based APD and a broadband photodetector based on a crystalline silicon-organic composite heterojunction provided in this embodiment of the invention. Compared with the traditional silicon-based APD, this patent improves photoelectric conversion and EQE by using SAM passivation of surface dangling bonds and the insertion of charge blocking layers, especially in the 1000-1600nm range where it is stable at over 20%, while the silicon-based APD is cut off due to its band gap.

[0181] Example 3 (modified from Example 1)

[0182] a. Nanopillars with a diameter of 300 nm, surface-modified with MeO-2PACz SAM, and a work function shift of 0.5 eV;

[0183] b. The active layer is made of D18:L8-BO (1:2), spin-coated to a thickness of 800 nm, with a gradient phase separation structure;

[0184] c. Sol-gel deposition of ZnO (10 nm), followed by vapor deposition of Bphen (5 nm) / Ag (15 nm) barrier layer;

[0185] d. Magnetron sputtering of 100nm IZO as a planar electrode;

[0186] e. Al2O3 / SiNx (50 nm total thickness) is alternately deposited in Al2O3 / SiNx layer to form a reflective layer.

[0187] Figure 4 The image shows a comparison of the responsivity of a silicon-based APD and a broadband photodetector based on a crystalline silicon-organic composite heterojunction provided in this embodiment of the invention. By doping the active layer with quantum dots and utilizing the thiol ligands on the quantum dot surface to construct a fast carrier transport channel, the responsivity is approximately 22.5 A / W in the 500-750 nm range, which is 12.5% ​​higher than that of the silicon-based APD. Furthermore, thanks to the absorption characteristics of organic materials, the responsivity is approximately 5 A / W in the 1200-1600 nm range, which is much higher than that of the silicon-based APD.

[0188] Example 4 (modified from Example 1)

[0189] a. On a p-type crystalline silicon substrate (doping concentration 1×10⁻⁶) 16 cm -3 A tapered nanopillar array was prepared by dynamic plasma etching (SF6 / C4F8 volume ratio 1:2→1:4, power 200 W). The substrate diameter was 300 nm, the tip was 80 nm, the height was 600 nm, and the period was 450 nm. MeO-2PACz and PFDT bilayer self-assembled monolayer (SAM) were dip-coated. After each dip-coating, nitrogen was purged for 10 seconds and annealed at 150°C for 30 minutes.

[0190] b. Dissolve PM6:Y6:IT-4F (mass ratio 1:1:0.5) and 5% CsPbBr3 quantum dots (particle size 3 nm) in a chlorobenzene / o-xylene mixed solvent (7:3 volume ratio, total concentration 25 mg / mL), ultrasonically disperse for 60 minutes, deposit an 800 nm thick active layer on a substrate at 40°C using a slot coating process at a speed of 5 mm / s, and perform gradient annealing with dichloromethane vapor (5°C / min to 180°C).

[0191] c. Magnetron sputtering of SnO2 electron transport layer (10 nm, O2 / Ar flow ratio 1:10), ALD deposition of ZnO layer (5 nm, 120°C), evaporation of MoO3 (3 nm) to form charge blocking layer.

[0192] d. Magnetron sputtering of 100nm IZO as a planar electrode;

[0193] e. Al2O3 / HfO2 (1 nm / 0.5 nm, 20 cycles, 200°C) were alternately deposited by ALD to form a reflective layer.

[0194] Figure 5 The graph shows the specific detectivity performance under different operating modes. At low bias (-5 V), the crystalline silicon APD and the organic semiconductor active layer work together to achieve high-sensitivity detection over a wide spectrum of 300–1600 nm, and the specific detectivity D in the visible light band (300–1100 nm) is [not specified]. * Rise to 10 12 Jones's gain stems from the complementary relationship between the avalanche gain of the crystalline silicon APD and the light absorption of the organic layer; the near-infrared (300–1100 nm) gain decreases slowly but remains at 10 nm. 11 Jones-level performance is achieved through localized plasmon resonance of organic layer quantum dots and optical field enhancement via a dual-reflective microcavity, supporting near-infrared light absorption. At high bias (-15 V), electric field modulation separates the response bands of the two components, meeting the needs of multi-scenario detection. Specifically, under high reverse bias, the strong electric field of the crystalline silicon APD forms a "barrier effect," suppressing the response of the organic layer in the visible light region, limiting the response band to only 300–1000 nm, essentially cutting off at 1000 nm. In the near-infrared band, the broad absorption of the organic material and quantum dots, combined with the light scattering of the nanopillar array and the optical field enhancement of the microcavity resonance, enables D... * Maintain 10 10 Jones-level. In summary, this invention provides a broadband photodetector based on a crystalline silicon-organic composite heterojunction and its fabrication method. This detector achieves broadband and efficient detection from the visible to near-infrared bands through a composite structure of a crystalline silicon APD layer and an organic semiconductor active layer, combined with innovative technologies such as nanopillar arrays and quantum doping.

[0195] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A broadband photodetector based on a crystalline silicon-organic composite heterojunction, comprising: Crystalline silicon avalanche photodiode (APD) layer, including P ++ District, primary district, N ++ District, P + District, of which P + The surface of the region has a periodic array of nanopillars; Organic semiconductor active layer: covering the nanopillar array, composed of a blend of donor and acceptor materials; Charge blocking layer: covering the surface of the organic semiconductor active layer, composed of a composite of a sub-transport material and a hole blocking material; Plate electrode: composed of a continuous conductive layer, covering the surface of the charge blocking layer; Reflective layer: composed of highly reflective metal or metal oxide, located above the planar electrode; Three-terminal stacked structure: the N ++ The region serves as a common electrode, connecting the crystalline silicon APD subunit and the organic active layer subunit in series.

2. The detector according to claim 1, characterized in that: The crystalline silicon APD subunit responds to the visible light band of 300 nm to 1100 nm; the organic active layer subunit responds to the near-infrared band of 1100 nm to 1600 nm. The detector has two operating modes by adjusting the bias voltage: First operating mode: Under reverse bias voltage of -1 V to -5 V, the crystalline silicon APD subunit and the organic active layer subunit work together to achieve broadband detection in the 300 nm to 1600 nm band. Second operating mode: Under reverse bias voltage of -5 V to -15 V, spectral selectivity detection in the visible and near-infrared bands is achieved through voltage regulation.

3. The detector according to claim 1, characterized in that, The nanopillar array of the crystalline silicon APD layer was prepared by reactive ion etching (RIE), and the geometric parameters met the following conditions: The nanopillars have a diameter of 80-350 nm, a height of 300-700 nm, a period of 150-600 nm, and a sidewall roughness of ≤10 nm. The ratio of the period to the incident light wavelength of 300 nm to 1600 nm is 0.3 to 2.

0.

4. The detector according to claim 1, characterized in that, The donor material of the organic semiconductor active layer includes, but is not limited to, PTB7-Th, PM6, PBDB-T, DIP, CuPc or their derivatives, and the acceptor material includes, but is not limited to, Y6, PC71BM, ITIC, N2200, COi8DFIC or combinations thereof. The donor to acceptor mass ratio is 1:0.8 to 1:3.5, the band gap is 0.7-1.2 eV, and the thickness is 500-1000 nm.

5. The detector according to claim 1, characterized in that, The organic active layer is doped with 0.1%-5% quantum dot material by mass fraction, including but not limited to PbS, CdSe, CsPbBr3, and InAs quantum dots, with a quantum dot particle size of 3-5 nm.

6. The detector according to claim 1, characterized in that, The sidewalls of the nanopillar array are modified with self-assembled monolayers (SAMs). The SAM molecules include functionalized materials with phosphate groups, thiol groups, or silane groups, including but not limited to APTES, PFDT, 2PACz, MeO-2PACz, MPA, or their derivatives, with a thickness of 1-10 nm and a work function shift of 0.1-0.5 eV.

7. The detector according to claim 1, characterized in that, The planar electrode includes, but is not limited to, ITO, AZO, IZO, and PEDOT:PSS, with a thickness of 20-100 nm; the reflective layer includes, but is not limited to, a high-reflectivity metal layer selected from Al, Ag, or their alloys, with a thickness of 20-50 nm; or a metal oxide layer selected from TiO2, ZnO, or their alternating layers, with a single layer thickness of 0.1-5 nm, a total thickness of 10-50 nm, and a reflectivity ≥90%@300-1600 nm.

8. The detector according to claim 1, characterized in that, The charge blocking layer includes, but is not limited to, C60-C60:MoO3-BCP, TiO2 / BCP / Alq3, and ZnO / Bphen / Ag stacks, with each layer having a thickness of 5-50 nm.

9. The detector according to claim 1, characterized in that, The exciton dissociation efficiency of the broadband photodetector satisfies the following formula. in, The exciton dissociation efficiency satisfies the following condition: The activation energy difference Γ is 0.1-0.5 eV; reverse bias V bias -5 V to -15 V; The composite competition coefficient A satisfies A ≤ 10 -2 Where the defect state density N t ≤ 1×10 10 cm -3 The electronic coupling matrix element |V| ≥ 0.3 eV; The interface electric field enhancement factor βγ / d ≥ 0.

5.

10. A method for manufacturing the detector according to any one of claims 1-9, comprising the following steps: Fabrication of pn junctions and etching of nanopillar arrays on crystalline silicon substrates; An organic active layer was prepared on the surface of the nanopillars and then annealed. A charge-blocking layer is prepared on the surface of the organic active layer; A planar electrode is fabricated on the surface of a charge barrier layer; A reflective layer is prepared on the surface of a flat electrode.

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