Purple phosphorus photovoltaic effect photoelectric detector and preparation method thereof

Abstract

The invention relates to the technical field of optoelectronic devices, and discloses a purple phosphorus photovoltaic effect photoelectric detector and a preparation method thereof.The purple phosphorus photovoltaic effect photoelectric detector comprises a substrate, a purple phosphorus active layer and two electrodes, the purple phosphorus active layer is arranged on the top face of the substrate, and the two electrodes are in ohmic contact with the purple phosphorus active layer respectively; the purple phosphorus active layer absorbs incident light and generates photon-generated carriers through a bulk photovoltaic effect, and the photon-generated carriers are directionally separated under the action of an internal electric field of the purple phosphorus active layer and are respectively collected by the two electrodes. Purple phosphorus is selected as a photosensitive material, the photovoltaic effect of the purple phosphorus is used as a core mechanism of photoelectric conversion, self-driven work of the photoelectric detector is achieved, dependence on an external power source is eliminated, the detection signal-to-noise ratio and practicability are improved, and the photoelectric detector can accurately distinguish the polarization state of light and also can accurately distinguish the polarization state of light. And an electric signal which is strong enough can be generated for high-sensitivity detection.

Description

Technical Field

[0001] This application relates to the field of optoelectronic device technology, and in particular to a purple phosphorus photovoltaic effect photodetector and its preparation method. Background Technology

[0002] In recent years, low-dimensional semiconductor materials with intrinsic structural anisotropy, such as black phosphorus, have been used to construct polarization-sensitive optoelectronic devices due to their varying light absorption across different polarization directions. These optoelectronic devices require an external bias voltage to drive the separation and collection of photogenerated carriers during operation. Furthermore, black phosphorus is highly susceptible to oxidative degradation, with amorphous phosphorus oxides rapidly forming on its surface. This leads to a sharp decline in material properties, weakening its electrical and optical anisotropy and severely limiting the long-term operational stability, reliability, and lifespan of optoelectronic devices. Summary of the Invention

[0003] This application aims to address at least one of the technical problems existing in the prior art or related technologies.

[0004] The first aspect of this application proposes a purple phosphorus bulk photovoltaic effect photodetector, which includes a substrate, a purple phosphorus active layer, and two electrodes. The purple phosphorus active layer is disposed on the top surface of the substrate, and the two electrodes are in ohmic contact with the purple phosphorus active layer. The purple phosphorus active layer absorbs incident light and generates photogenerated carriers through the bulk photovoltaic effect. The photogenerated carriers are directionally separated under the action of the internal electric field of the purple phosphorus active layer and are collected by the two electrodes respectively.

[0005] In some of the technical solutions provided in this application, the purple phosphorus active layer is anisotropic, and the anisotropy of the purple phosphorus active layer is higher in the direction of high anisotropy axis than in other directions, and the two electrodes are respectively arranged along the direction of high anisotropy axis.

[0006] In some of the technical solutions provided in this application, the purple phosphorus active layer includes multiple layers of stacked purple phosphorus sheets.

[0007] In some of the technical solutions provided in this application, the purple phosphorus photovoltaic effect photodetector further includes: an anisotropic layer, which is stacked with the purple phosphorus active layer to form a heterojunction, and the material of the anisotropic layer includes ReS2 or GeSe.

[0008] In some of the technical solutions provided in this application, the substrate is transparent.

[0009] In some of the technical solutions provided in this application, the substrate material is a flexible polymer.

[0010] In some of the technical solutions provided in this application, the substrate material includes at least one of polyethylene terephthalate, polyimide, and polyvinyl naphthalene.

[0011] In some of the technical solutions provided in this application, the thickness of the purple phosphorus active layer is 5 nm to 100 nm, and / or the thickness of the substrate is 50 μm to 200 μm.

[0012] In some of the technical solutions provided in this application, the electrode material includes at least one of gold, silver, graphene, or indium tin oxide.

[0013] The second aspect of this application provides a method for fabricating a purple phosphorus photovoltaic effect photodetector, used to fabricate the purple phosphorus photovoltaic effect photodetector provided in any of the above embodiments. The fabrication method includes: cleaning a substrate; transferring a purple phosphorus active layer to the substrate surface using a dry transfer technique, and aligning the highly anisotropic axes of the purple phosphorus active layer; and depositing and patterning two electrodes on the surface of the purple phosphorus active layer using photolithography, electron beam evaporation, and lift-off processes, wherein the electrodes form an ohmic contact with the purple phosphorus active layer.

[0014] Compared with related technologies, the present invention has at least the following beneficial effects: This application selects purple phosphorus as the photosensitive material and utilizes its bulk photovoltaic effect as the core mechanism for photoelectric conversion to achieve self-driven operation of the photodetector, eliminating dependence on external power supply, simplifying the power supply structure, reducing power consumption, and obtaining output photocurrent under zero external bias conditions, thereby improving the detection signal-to-noise ratio and practicality. Furthermore, the inherent crystal anisotropy of purple phosphorus material achieves a high polarization ratio and high photoresponsivity, enabling the photodetector to accurately resolve the polarization state of light and generate a sufficiently strong electrical signal for high-sensitivity detection. Moreover, as an intrinsically stable photosensitive material, purple phosphorus avoids the performance degradation problems caused by the easy oxidation of materials such as black phosphorus, improving the environmental stability and long-term operational reliability of the photodetector. Attached Figure Description

[0015] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of some embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 One of the partial schematic diagrams of a purple phosphorus photovoltaic effect photodetector provided in this application; Figure 2 A second partial schematic diagram of a purple phosphorus photovoltaic effect photodetector according to an embodiment of this application; Figure 3 A schematic diagram of the structure of a purple phosphorus photovoltaic effect photodetector according to an embodiment of this application; Figure 4This is a schematic flowchart illustrating a method for fabricating a purple phosphorus photovoltaic effect photodetector according to an embodiment of this application.

[0016] in, Figures 1 to 3 The correspondence between the reference numerals and component names in the attached drawings is as follows: 100, Substrate; 200, Purple phosphorus active layer; 300, Electrode. Detailed Implementation

[0017] To better understand the above technical solutions, the technical solutions of the embodiments of this application will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of this application and the specific features in the embodiments are detailed descriptions of the technical solutions of the embodiments of this application, rather than limitations on the technical solutions of this application. In the absence of conflict, the embodiments of this application and the technical features in the embodiments can be combined with each other.

[0018] The first aspect of this application provides a purple phosphorus photovoltaic effect photodetector, such as... Figure 1 and Figure 2 As shown, the purple phosphorus bulk photovoltaic photodetector includes a substrate 100, a purple phosphorus active layer 200, and two electrodes 300. The purple phosphorus active layer 200 is disposed on the top surface of the substrate 100. The two electrodes 300 are in ohmic contact with the purple phosphorus active layer 200. The purple phosphorus active layer 200 absorbs incident light and generates photogenerated carriers through the bulk photovoltaic effect. The photogenerated carriers are directionally separated under the action of the internal electric field of the purple phosphorus active layer 200 and are collected by the two electrodes 300 respectively.

[0019] In this embodiment, substrate 100, serving as the support substrate for the photodetector, is located at the bottom layer. Violet phosphorus (VP) active layer 200 is disposed on the upper surface of substrate 100. Violet phosphorus, as a photosensitive material, is a phosphorus allotrope with a unique layered structure and higher stability. The atomic arrangement within violet phosphorus is asymmetrical, and due to the intrinsic anisotropy of its crystal structure, it has different absorption coefficients for incident light with different polarization directions. Under illumination, the violet phosphorus active layer 200 generates photogenerated carriers through the bulk photovoltaic effect (BPVE), producing directional illumination related to the polarization state of the light. A portion of the surface area of ​​the violet phosphorus active layer 200 forms ohmic contact with two electrodes 300. Electrodes 300 are used to collect and output the charge carried by the photogenerated carriers. The two electrodes 300 are connected to an external circuit via leads to extract the photocurrent signal to the external circuit, which can be an ammeter or a signal processing chip. For example, two electrodes 300 are respectively disposed at the left and right ends of the top or bottom surface of the purple phosphorus active layer 200, and the interval between them is 5μm to 50μm.

[0020] When the purple phosphorus active layer 200 absorbs incident linearly polarized light, it is excited by photons to generate photogenerated carriers, including electrons and holes. Under the influence of the internal electric field of the purple phosphorus, the photogenerated carriers undergo directional separation through the bulk photovoltaic effect and are collected by the electrodes 300 at both ends, thus forming a photocurrent with zero external bias voltage. The accuracy of the photocurrent reaches the μA level. The magnitude of the photocurrent is directly related to the polarization state of the incident light, especially the polarization direction. By measuring the magnitude of the photocurrent, the polarization state of the incident light can be detected.

[0021] This application selects purple phosphorus as the photosensitive material and utilizes its bulk photovoltaic effect as the core mechanism for photoelectric conversion to achieve self-driven operation of the photodetector. This eliminates dependence on external power supply, simplifies the power supply structure, reduces power consumption, and obtains output photocurrent under zero external bias conditions, thereby improving the detection signal-to-noise ratio and practicality. Furthermore, the inherent crystal anisotropy of purple phosphorus material achieves a high polarization ratio and high photoresponsivity, enabling the photodetector to accurately resolve the polarization state of light and generate a sufficiently strong electrical signal for high-sensitivity detection. Moreover, as an intrinsically stable photosensitive material, purple phosphorus avoids the performance degradation problem caused by the easy oxidation of materials such as black phosphorus, improving the environmental stability and long-term operational reliability of the photodetector.

[0022] For example, such as Figure 3 As shown, the purple phosphorus active layer 200 and the electrode 300 form a bulk photovoltaic (PV) module, and multiple bulk PV modules are arranged in a matrix on the substrate 100. The two electrodes 300 can be symmetrically arranged to simplify the process and avoid interference variables. Alternatively, the two electrodes 300 can be asymmetrically arranged; for example, the two electrodes 300 can be made of metal materials with different work functions to enhance the built-in electric field.

[0023] In some embodiments provided in this application, the purple phosphorus active layer 200 is anisotropic, and the anisotropy of the purple phosphorus active layer 200 is higher in the direction of high anisotropy axis than in other directions, and the two electrodes 300 are arranged along the direction of high anisotropy axis.

[0024] In this embodiment, an arrangement of electrode 300 relative to the purple phosphorus active layer 200 is provided. Purple phosphorus exhibits significant differences in light absorption and conductivity along different directions, i.e., anisotropy. An anisotropy axis refers to the direction in the crystal exhibiting anisotropy; therefore, the photoelectric properties of purple phosphorus differ significantly along and perpendicular to the anisotropy axis. The high anisotropy axis is the direction with the most significant anisotropy difference among all anisotropy axes of the purple phosphorus crystal; for example, the high anisotropy axis could be the <010> crystal orientation of purple phosphorus. As the direction with the greatest difference in absorption of polarized light, the high anisotropy axis makes purple phosphorus most sensitive to polarization detection. Two electrodes 300 are spaced apart along the high anisotropy axis, with the electrodes 300 located at both ends of the high anisotropy axis. This makes the transport direction of photogenerated carriers consistent with the anisotropy direction most sensitive to purple phosphorus, enhancing the capture and modulation of polarized light by the electrodes 300, optimizing the carrier separation and collection efficiency based on the bulk photovoltaic effect, maximizing the influence of polarization direction on photocurrent, and improving the sensitivity and polarization ratio of polarization detection.

[0025] In one embodiment, the purple phosphorus active layer 200 is a single-layer structure, which reduces the thickness of the purple phosphorus active layer 200 and improves the portability of the photodetector.

[0026] In another embodiment provided in this application, the purple phosphorus active layer 200 comprises multiple stacked purple phosphorus sheets, with the number of purple phosphorus sheets potentially reaching dozens. This increases the overall thickness of the purple phosphorus active layer 200, expands the light absorption area and photon capture capacity, and improves the generation density of photogenerated carriers, thereby enhancing the photoresponsivity of the device. Furthermore, the multilayer structure improves the bonding strength between the purple phosphorus active layer 200 and the substrate 100, reducing the risk of the purple phosphorus active layer 200 detaching during flexible bending or use of the photodetector, and improving the reliability of the photodetector.

[0027] In some embodiments provided in this application, the purple phosphorus photovoltaic effect photodetector further includes: an anisotropic layer, which is stacked with the purple phosphorus active layer 200 to form a heterojunction, and the material of the anisotropic layer includes ReS2 or GeSe.

[0028] In this embodiment, the purple phosphorus active layer 200 is stacked with other anisotropic two-dimensional materials to form a heterojunction. Purple phosphorus focuses on absorbing visible light, ReS2 focuses on absorbing near-infrared light, and GeSe focuses on absorbing near-infrared light while covering a broad spectrum from visible to near-infrared. The light absorption bands of ReS2, GeSe, and purple phosphorus are complementary, enabling the heterojunction to respond to incident light over a wider wavelength range, thus adapting to multispectral detection scenarios. Furthermore, the strong built-in electric field formed at the heterojunction interface due to the band difference between the two materials, combined with the photovoltaic effect of purple phosphorus, further promotes the separation of photogenerated electron and hole pairs, reduces recombination, and increases photocurrent intensity. Moreover, ReS2 and GeSe themselves are anisotropic, and their synergistic effect with the high anisotropy axis of purple phosphorus can further amplify the influence of polarization direction on photocurrent, improving the resolution of polarization detection.

[0029] In some embodiments provided in this application, the substrate 100 is transparent.

[0030] In this embodiment, the light transmittance of the substrate 100 allows light to enter from one side of the substrate 100, enabling the purple phosphorus active layer 200 to absorb incident light from the back side. The purple phosphorus photovoltaic effect photodetector can support multi-directional incident light detection, increasing the flexibility of the photodetector and adapting to different installation and detection scenarios.

[0031] In some embodiments provided in this application, such as Figure 2 and Figure 3 As shown, the substrate 100 is made of a flexible polymer.

[0032] In this embodiment, the photodetector is fabricated on a flexible substrate 100. Compared to a traditional rigid SiO2 / Si substrate 100, the flexible substrate 100 provides flexible mechanical support, enabling the photodetector to be bent and folded for integration into flexible electronic systems. This is suitable for non-planar applications such as wearable devices, flexible displays, and curved surface imaging. Furthermore, the flexible material possesses excellent impact and bending resistance, reducing the risk of damage to the photodetector due to collisions or deformations during transportation or use.

[0033] In some embodiments provided in this application, the material of the substrate 100 includes at least one of polyethylene terephthalate, polyimide, and polyvinyl naphthalene.

[0034] In this embodiment, specific materials for the flexible polymer substrate 100 are provided to adapt to different application scenarios. Specifically, polyethylene terephthalate (PET) is low in cost and easy to process, making it suitable for mass production. Polyimide (PI) is resistant to high temperatures and radiation, making it suitable for detection in extreme environments. Polyvinyl naphthalene (PEN) has excellent barrier properties and balanced mechanical properties, balancing stability and flexibility. All of the above materials have good light transmittance and chemical stability, avoiding reactions with the purple phosphorus active layer 200, and providing stable support for the purple phosphorus active layer 200 and the electrode 300, thus preventing the substrate 100 material from affecting the photoelectric performance of the photodetector.

[0035] In some embodiments provided in this application, the thickness of the purple phosphorus active layer 200 is 5 nm to 100 nm, and / or the thickness of the substrate 100 is 50 μm to 200 μm.

[0036] In this embodiment, the thickness range of the purple phosphorus active layer 200 and the substrate 100 is reasonably defined. This reasonable thickness range makes the photodetector thin and lightweight, facilitating integration with other electronic components and improving system integration. Specifically, a purple phosphorus active layer 200 with a thickness of 5nm to 100nm ensures light absorption efficiency while retaining anisotropy and high carrier mobility. This avoids insufficient light absorption and low carrier generation due to excessive thickness, while preventing the purple phosphorus active layer 200 from being too thin, which would compromise the two-dimensional material properties and increase carrier transport distance and recombination probability. A substrate 100 with a thickness of 50μm to 200μm balances flexibility, support stability, and light transmittance, adapting to different bending radii and application scenarios. This avoids insufficient support for the flexible substrate 100 due to excessive thinness, which could lead to device damage, while preventing the substrate 100 from being too thick, which would negatively impact flexibility and light transmittance.

[0037] In some embodiments provided in this application, the material of electrode 300 includes at least one of gold, silver, graphene, or indium tin oxide.

[0038] In this embodiment, various material choices are limited for electrode 300. The electrode 300 material in this embodiment can ensure ohmic contact and adapt to different needs and application scenarios. Specifically, gold and silver are highly conductive metals with low contact resistance with purple phosphorus, enabling the formation of good ohmic contact and ensuring efficient collection of photogenerated carriers, suitable for high-response-speed scenarios. Graphene and indium tin oxide (ITO) are transparent conductive materials that can reduce the obstruction of incident light by electrode 300, especially suitable for detection scenarios where light is incident from the electrode 300 side. Furthermore, the above-mentioned electrode 300 materials have good compatibility with electron beam evaporation and photolithography lift-off processes, and strong chemical stability, avoiding reactions with purple phosphorus and ensuring the long-term stability of the detector.

[0039] A second aspect of this application provides a method for fabricating a purple phosphorus photovoltaic effect photodetector, used to fabricate the purple phosphorus photovoltaic effect photodetector provided in any of the above embodiments, such as... Figure 4 As shown, the preparation method includes: Step 1, clean the substrate; Step 2: The purple phosphorus active layer is transferred to the substrate surface using a dry transfer technique, and the highly anisotropic axes of the purple phosphorus active layer are aligned. Step 3: Two electrodes are deposited and patterned on the surface of the purple phosphorus active layer through photolithography, electron beam evaporation and stripping processes, and the electrodes form ohmic contacts with the purple phosphorus active layer.

[0040] In this embodiment, the substrate is cleaned to prepare it. After obtaining a thin film of purple phosphorus active layer through chemical vapor deposition and mechanical exfoliation, the thin film is transferred to the substrate surface using dry transfer technology. Optical or Raman spectroscopy is then used to align the high anisotropy axis of the purple phosphorus active layer to a predetermined direction, ensuring the accuracy of the polarization-sensitive direction and avoiding a decrease in polarization detection performance due to crystal orientation misalignment. Electrodes are then deposited and patterned using photolithography, electron beam evaporation, and exfoliation processes to fabricate electrodes. This ensures good ohmic contact between the electrodes and the purple phosphorus active layer. Electrode preparation by electron beam evaporation results in high purity and excellent conductivity, improving the quality of the ohmic contact and preventing short circuits or poor contact. The fabrication process is simple, reducing process complexity and production costs.

[0041] Purple phosphorus, as a photosensitive material, utilizes its bulk photovoltaic effect as the core mechanism for photoelectric conversion, enabling self-driven operation of the photodetector. This eliminates dependence on external power supplies, simplifies the power supply structure, reduces power consumption, and generates output photocurrent under zero external bias conditions, improving the detection signal-to-noise ratio and practicality. Furthermore, the inherent crystal anisotropy of purple phosphorus achieves a high polarization ratio and high photoresponsivity, allowing the photodetector to accurately resolve the polarization state of light and generate a sufficiently strong electrical signal for high-sensitivity detection. Moreover, as an intrinsically stable photosensitive material, purple phosphorus avoids the performance degradation problems caused by the easy oxidation of materials such as black phosphorus, improving the environmental stability and long-term operational reliability of the photodetector.

[0042] In this invention, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0043] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0044] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0045] The above are merely some embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A purple phosphorus photovoltaic effect photodetector, characterized in that, include: Substrate; A purple phosphorus active layer is disposed on the top surface of the substrate; Two electrodes are respectively in ohmic contact with the purple phosphorus active layer. The purple phosphorus active layer absorbs incident light and generates photogenerated carriers through the bulk photovoltaic effect. The photogenerated carriers are directionally separated under the action of the internal electric field of the purple phosphorus active layer and collected by the two electrodes respectively.

2. The purple phosphorus photovoltaic effect photodetector according to claim 1, characterized in that, The purple phosphorus active layer is anisotropic, and the anisotropy of the purple phosphorus active layer is higher in the direction of high anisotropy axis than in other directions. The two electrodes are arranged along the direction of high anisotropy axis.

3. The purple phosphorus photovoltaic effect photodetector according to claim 1 or 2, characterized in that, The purple phosphorus active layer comprises multiple layers of stacked purple phosphorus sheets.

4. The purple phosphorus photovoltaic effect photodetector according to claim 1 or 2, characterized in that, Also includes: An anisotropic layer is stacked with the purple phosphorus active layer to form a heterojunction, wherein the material of the anisotropic layer includes ReS2 or GeSe.

5. The purple phosphorus photovoltaic effect photodetector according to claim 1 or 2, characterized in that, The substrate is transparent.

6. The purple phosphorus photovoltaic effect photodetector according to claim 1 or 2, characterized in that, The substrate is made of a flexible polymer.

7. The purple phosphorus photovoltaic effect photodetector according to claim 1 or 2, characterized in that, The substrate material includes at least one of polyethylene terephthalate, polyimide, and polyvinyl naphthalene.

8. The purple phosphorus photovoltaic effect photodetector according to claim 1 or 2, characterized in that, The thickness of the purple phosphorus active layer is 5 nm to 100 nm; and / or The thickness of the substrate is from 50 μm to 200 μm.

9. The purple phosphorus photovoltaic effect photodetector according to claim 1 or 2, characterized in that, The electrode material includes at least one of gold, silver, graphene, or indium tin oxide.

10. A method for fabricating a purple phosphorus photovoltaic effect photodetector, characterized in that, The method for preparing a purple phosphorus photovoltaic effect photodetector as described in any one of claims 1 to 9 comprises: Clean the substrate; The purple phosphorus active layer is transferred to the substrate surface using a dry transfer technique, and the highly anisotropic axes of the purple phosphorus active layer are aligned. Two electrodes are deposited and patterned on the surface of the purple phosphorus active layer using photolithography, electron beam evaporation, and stripping processes. The electrodes form an ohmic contact with the purple phosphorus active layer.

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