Flexible silicon-based photoelectric device, receiving end and visible light communication system

Abstract

The invention belongs to the technical field of optical communication, and relates to a flexible silicon-based photoelectric device, a receiving end and a visible light communication system. The flexible silicon-based photoelectric device comprises a back electrode layer, a hole transport layer, a P-type silicon light absorption layer, an electron transport layer and a front electrode layer. The valence band side energy difference between the electron transport layer and the P-type silicon light absorption layer is greater than the conduction band side energy difference; the conduction band side energy difference between the P-type silicon light absorption layer and the hole transport layer is greater than the valence band side energy difference; the forbidden bandwidth of the electron transport layer is greater than 3.0 eV. The front electrode layer comprises a plurality of grid electrodes which are separately arranged on the surface of the electron transport layer. According to the scheme provided by the invention, the heterojunction is formed on the surfaces of the two sides of the P-type silicon light absorption layer, so that the intensity of a built-in electric field is effectively enhanced, and the flowing speed of photo-generated electrons and photo-generated holes in the device is accelerated, thereby improving the response speed of the device; and meanwhile, the collection efficiency of electrons and holes is improved, so that the photoelectric conversion efficiency of a photoelectric device is improved.

Description

Technical Field

[0001] The present invention relates to the field of optical communication technology, and in particular to a flexible silicon-based optoelectronic device, a receiving end and a visible light communication system. Background Art

[0002] A photodetector is a device that can directly convert optical signals into electrical signals. It is widely used in civil and military fields such as optical sensing, optical communications, lidar, spectral detection, and infrared guidance. It converts incident photons into movable and collectible carriers through the internal photoelectric effect of semiconductor materials, thereby forming a photocurrent or photovoltage related to the wavelength and intensity of the incident light.

[0003] In the prior art, common photodetection devices (such as solar cells and commercial photodetectors) are usually used to detect visible light and collect energy. Solar cells use the photovoltaic effect to make photons in sunlight excite electrons in semiconductor materials, generate current or voltage that can be used by external circuits, and thus realize the direct conversion of light energy into electrical energy. At present, they have been widely used in fields such as homes, industries, and transportation. However, solar cells have problems such as slow response speed and large noise interference, which makes the detection accuracy of solar cells for visible light low and cannot be used in visible light communication systems. In order to meet the needs of visible light communication systems, the spectral response of commercial photodetectors usually focuses on the wavelength range used for communication, such as the near-infrared band, while the indoor environment is mainly visible light and part of the near-infrared light. This mismatch in spectral response makes it impossible to efficiently convert limited visible light energy into electrical energy under low light intensity indoors. At the same time, commercial photodetectors usually require external bias when in use, which causes the internal electric field of the semiconductor material in the photodetector to change, thereby increasing the dark current and generating additional power consumption.

[0004] In order to solve the above problems, PN junction silicon-based optoelectronic devices and Schottky structure silicon-based optoelectronic devices have been proposed. PN junction silicon-based optoelectronic devices form a PN junction on the surface of a silicon substrate. When photons irradiate the silicon-based PN junction, silicon atoms absorb the photon energy and generate electron-hole pairs. Under the action of the built-in electric field of the PN junction, the photogenerated holes drift to the P region, and the photogenerated electrons drift to the N region, thereby forming a photocurrent; Schottky structure silicon-based optoelectronic devices set a metal layer on the surface of the silicon substrate, the metal layer forms a Schottky contact with the silicon substrate, and a Schottky barrier is formed on the contact surface. After the silicon atoms absorb the photon energy and generate electron-hole pairs, when the energy of the electrons is higher than the height of the Schottky barrier, the electrons cross the barrier and enter the metal layer, while the holes remain in the silicon substrate, forming a potential difference between the metal layer and the silicon substrate, thereby forming a photocurrent. These two types of silicon-based optoelectronic devices utilize the energy band structure of silicon-based materials and the efficient carrier separation mechanism to improve the photoelectric conversion efficiency, and do not require external bias to drive, so the dark current is small and no additional power consumption is generated. However, the response speed of existing silicon-based optoelectronic devices is slow, and their response time is mostly in the order of tens of μs or ms, which cannot meet the needs of high-speed visible light communication systems; although silicon-based avalanche detectors have a high response speed, their operating bias and operating temperature need to be precisely controlled, and the preparation process is relatively complex and the production cost is high. They are not suitable for visible light communication self-powered systems with high integration, small size and low power consumption.

[0005] In summary, how to design a silicon-based optoelectronic device that has a fast response speed to visible light, high photoelectric conversion efficiency, simple preparation process and low cost is a problem that needs to be solved at present. Summary of the invention

[0006] To this end, the technical problem to be solved by the present invention is to overcome the problems of low light response and long response time of silicon-based optoelectronic devices in the prior art, which result in the inability to meet the requirements of high-speed visible light communication systems or have strict requirements on working conditions, complex preparation processes and high production costs.

[0007] In order to solve the above technical problems, the present invention provides a flexible silicon-based optoelectronic device, comprising: A back electrode layer, a hole transport layer, a P-type silicon light absorption layer, an electron transport layer and a front electrode layer are stacked in sequence from bottom to top; Wherein, the valence band edge energy difference between the electron transport layer and the P-type silicon light absorption layer is greater than the conduction band edge energy difference between the electron transport layer and the P-type silicon light absorption layer; The conduction band edge energy difference between the P-type silicon light absorption layer and the hole transport layer is greater than the valence band edge energy difference between the P-type silicon light absorption layer and the hole transport layer; The band gap width of the electron transport layer is greater than 3.0 eV; the front electrode layer includes a plurality of grid electrodes discretely arranged on the surface of the electron transport layer.

[0008] Preferably, the thickness of the P-type silicon light absorption layer is 3 μm to 25 μm; The doping concentration of the P-type silicon light absorbing layer is .

[0009] Preferably, a plurality of nano-protrusion structures are arranged on the surface of the P-type silicon light absorption layer close to the electron transport layer.

[0010] Preferably, the plurality of nano-protrusion structures are periodically arranged on the surface of the P-type silicon light absorbing layer; and / or The shapes of the nano-protrusion structures include pyramid, nano-rod and nano-hole.

[0011] Preferably, the size of the nano-protrusion structure is 100nm~1300nm, and the thickness is 100nm~920nm.

[0012] The material of the hole transport layer includes molybdenum oxide, nickel oxide, tungsten oxide, and vanadium oxide; and / or The material of the electron transport layer includes tin oxide, titanium oxide, zinc oxide, niobium oxide, and tantalum oxide.

[0013] Preferably, the thickness of the hole transport layer is 40 nm to 400 nm; and / or The thickness of the electron transport layer is 30nm~300nm.

[0014] The present invention also provides a receiving end, comprising the above-mentioned flexible silicon-based optoelectronic device, wherein the flexible silicon-based optoelectronic device is used to receive visible light signals and convert the visible light signals into electrical signals.

[0015] Preferably, it also includes: A decoupling circuit is connected to the flexible silicon-based optoelectronic device and is used to decouple the electrical signal and output a direct current component and an alternating current component.

[0016] The present invention also provides a visible light communication system, comprising: A transmitting end, used for transmitting a visible light signal; The receiving end mentioned above.

[0017] The flexible silicon-based optoelectronic device provided in this application has the following beneficial effects: 1. The electron transport layer contacts the P-type silicon light absorption layer to form a first heterojunction, and the energy difference between the valence band edge of the electron transport layer and the P-type silicon light absorption layer is greater than the energy difference between the conduction band edge, thereby forming an energy slope in the direction of electron movement, making it easier for electrons to be injected from the conduction band of the P-type silicon light absorption layer to the conduction band of the electron transport layer; the P-type silicon light absorption layer contacts the hole transport layer to form a second heterojunction, and the energy difference between the conduction band edge of the P-type silicon light absorption layer and the hole transport layer is greater than the energy difference between the valence band edge, thereby forming an energy slope in the direction of hole movement, making it easier for holes to be injected from the valence band of the P-type silicon light absorption layer to the valence band of the hole transport layer. When the incident light is absorbed by the P-type silicon light absorption layer and generates photogenerated electron-hole pairs, the photogenerated electrons are transferred to the electron transport layer and the photogenerated holes are transferred to the hole transport layer under the driving of the built-in electric field formed by the first heterojunction and the second heterojunction, thereby forming a photocurrent. Since the P-type silicon light absorption layer has heterojunctions on both the upper and lower sides, space charges are formed on the upper and lower surfaces of the P-type silicon light absorption layer at the same time, thereby expanding the spatial action range of the built-in electric field, accelerating the flow speed of photogenerated electrons and photogenerated holes between the two heterojunctions, and improving the response speed of the device; at the same time, the driving effect of the two heterojunctions on the carriers enables the photogenerated electrons and photogenerated holes to be effectively separated before reaching the heterojunction interface, inhibiting the recombination of photogenerated electrons and photogenerated holes, and improving the collection efficiency of electrons and holes, thereby improving the photoelectric conversion efficiency and light responsiveness of the optoelectronic device; in addition, the flexible silicon-based optoelectronic device provided in the present application has a simple preparation process and a low production cost, and can achieve a high response speed without the need to precisely control the bias voltage and temperature during use.

[0018] 2. By limiting the thickness and doping concentration of the P-type silicon light absorption layer, the built-in electric field strength formed by the first heterojunction and the second heterojunction can be further enhanced. At the same time, the photogenerated electron-hole pairs formed in the P-type silicon light absorption layer only need to diffuse a short distance to enter the space charge region (i.e., the depletion region) generated by the heterojunction. The electric field inside the depletion region and the band deviation at the heterojunction interface cause electrons and holes to be selectively transferred to the electron transport layer and the hole transport layer, respectively, shortening the diffusion distance of photogenerated carriers in the P-type silicon light absorption layer and improving the response speed of the device. In addition, the shortening of the diffusion distance can also reduce the bulk recombination of carriers, thereby increasing the photoelectric conversion efficiency and light responsiveness of the device. In addition, the micron-level thick P-type silicon light absorption layer also has the characteristics of self-supporting flexibility, which allows the device to be used in wearable devices and robotics in complex / harsh environments.

[0019] 3. By constructing a nano-protrusion structure on the surface of a P-type silicon light absorption layer with a thickness of several microns, the reflectivity of the device to the visible light band can be reduced, avoiding the problem of insufficient absorption of visible light by the silicon light absorption layer with limited thickness. This allows the device to have a faster response speed while having excellent light absorption efficiency and photogenerated carrier collection efficiency in the entire visible light band, thereby allowing the device to take into account both light response speed and energy collection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein: Figure 1 A schematic diagram of the structure of a flexible silicon-based optoelectronic device provided in this application; Figure 2 The energy band diagram and carrier transport schematic diagram of the flexible silicon-based optoelectronic device provided in this application under zero bias; Figure 3 A schematic diagram of the structure of the visible light communication system provided for this application; Figure 4 The flexible silicon-based optoelectronic devices provided in Example 3, Example 4 and the comparative example are subjected to the following conditions when the wavelength of the incident light is 467 nm and the power density of the incident light is 0.3 mW cm -2 Schematic diagram of the current density-voltage curve; Figure 5 The flexible silicon-based optoelectronic devices provided in Example 3, Example 4 and the comparative example are subjected to an incident light power density of 0.3 mW cm -2 Responsivity spectrum under ; Figure 6 The flexible silicon-based optoelectronic devices provided in Example 3, Example 4 and the comparative example are subjected to an incident light power density of 0.3 mW cm -2 External quantum efficiency curve under Figure 7 The flexible silicon-based optoelectronic devices provided in Example 3, Example 4 and the comparative example are subjected to an incident light power density of 0.3 mW cm -2 Internal quantum efficiency curve under Figure 8 The flexible silicon-based optoelectronic devices provided in Example 3, Example 4 and the comparative example are subjected to an incident light power density of 0.3 mW cm -2 The specific detectivity curve below; Fig. 9 The flexible silicon-based optoelectronic device provided in Example 4 is zero bias, the wavelength of the incident light is 467nm, and the incident light power density is 0.3mWcm -2 Transient photocurrent response curve under ; Fig.10The flexible silicon-based optoelectronic devices provided in Example 3, Example 4 and the comparative example are -2 Current density-voltage curve under white light LED irradiation; Fig.11 The incident light power density is 0.3 mW cm -2 Schematic diagram of the spectrum of white light LED; Fig.12 Light absorption rate curves of the flexible silicon-based optoelectronic devices provided in Example 3 and Example 4; Description of the accompanying drawings: 11, back electrode layer; 12, hole transport layer; 13, P-type silicon light absorption layer; 131, nano-protrusion structure; 14, electron transport layer; 15, front electrode layer; 151, grid electrode; 21. Transmitter; 211. Coupling circuit; 212. LED component; 22. Receiving end; 221. Flexible silicon-based optoelectronic device; 222. Decoupling circuit. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0022] See also Figure 1 , Figure 1 The flexible silicon-based photoelectric device provided by the present application is shown, and the flexible silicon-based photoelectric device includes a back electrode layer 11, a hole transport layer 12, a P-type silicon light absorption layer 13, an electron transport layer 14 and a front electrode layer 15 which are stacked in sequence from bottom to top.

[0023] The valence band edge energy difference between the electron transport layer 14 and the P-type silicon light absorbing layer 13 is greater than the conduction band edge energy difference between the electron transport layer 14 and the P-type silicon light absorbing layer 13 .

[0024] Further, in some embodiments, the material of the electron transport layer 14 includes tin oxide, titanium oxide, zinc oxide, niobium oxide, tantalum oxide, etc.; the thickness of the electron transport layer 14 is 30nm~300nm, for example, the thickness of the electron transport layer 14 can be 30nm, 50nm, 100nm, 150nm, 200nm, 250nm or 300nm.

[0025] The conduction band edge energy difference between the P-type silicon light absorption layer 13 and the hole transport layer 12 is greater than the valence band edge energy difference between the P-type silicon light absorption layer 13 and the hole transport layer 12 .

[0026] Further, in some embodiments, the material of the hole transport layer 12 includes molybdenum oxide, nickel oxide, copper oxide, tungsten oxide, vanadium oxide, etc.; the thickness of the hole transport layer 12 is 40nm~400nm, for example, the thickness of the hole transport layer 12 can be 40nm, 100nm, 160nm, 220nm, 280nm, 340nm or 400nm.

[0027] The band gap of the electron transport layer 14 is greater than 3.0 eV.

[0028] By limiting the bandgap width of the electron transport layer 14 , it is ensured that the electron transport layer 14 is transparent to visible light, and it is ensured that visible light can pass through the electron transport layer 14 into the P-type silicon light absorption layer 13 .

[0029] The front electrode layer 15 includes a plurality of grid electrodes 151 discretely arranged on the surface of the electron transport layer 14 .

[0030] Specifically, considering the opacity of the electrode, in the present application, multiple gate electrodes 151 are separately arranged on the surface of the electron transport layer 14 so that the incident light is incident between adjacent gate electrodes 151. It is particularly noted that when the optoelectronic device is in use, multiple gate electrodes 151 are interconnected.

[0031] When the electron transport layer 14 contacts the P-type silicon light absorption layer 13 to form a first heterojunction, since the energy difference between the valence band edge of the electron transport layer 14 and the P-type silicon light absorption layer 13 is greater than the energy difference between the conduction band edge, an energy slope is formed in the direction of electron movement, making it easier for electrons to be injected from the conduction band of the P-type silicon light absorption layer 13 to the conduction band of the electron transport layer 14; similarly, when the P-type silicon light absorption layer 13 contacts the hole transport layer 12 to form a second heterojunction, since the energy difference between the conduction band edge of the P-type silicon light absorption layer 13 and the hole transport layer 12 is greater than the energy difference between the valence band edge, an energy slope is formed in the direction of hole movement, making it easier for holes to be injected from the valence band of the P-type silicon light absorption layer 13 to the valence band of the hole transport layer 12; therefore , the present application forms heterojunctions on both the upper and lower sides of the P-type silicon light absorption layer 13, so that space charge regions are formed on the upper and lower surfaces of the P-type silicon light absorption layer 13 at the same time, thereby increasing the width of the depletion region of the P-type silicon light absorption layer and reducing the width of the neutral region of the P-type silicon light absorption layer, thereby expanding the spatial action range of the built-in electric field, accelerating the flow speed of photogenerated electrons and photogenerated holes between the two heterojunctions, and improving the response speed of the device; at the same time, the built-in electric field formed by the first heterojunction and the second heterojunction enables holes and electrons to quickly leave the P-type silicon light absorption layer 13, thereby reducing the combination of holes and electrons, allowing more carriers to participate in the current formation process, thereby improving the photoelectric conversion efficiency and light responsiveness of the device. In addition, the flexible silicon-based optoelectronic device provided by the present application is simple to prepare and has a low manufacturing cost, and there is no need to strictly control the reverse bias and operating temperature of the device when in use.

[0032] Furthermore, in order to improve the energy collection efficiency, silicon-based optoelectronic devices in the prior art usually use a silicon substrate with a thickness of hundreds of microns or more. However, if the thickness of the silicon substrate is too large, the diffusion distance of the carriers in the silicon substrate will be too large, thereby reducing the response speed of the device. In addition, an overly thick silicon substrate is a rigid substrate and often does not have the self-supporting flexible characteristics, which makes the device unable to be used in scenarios such as wearable devices that require device flexibility, limiting the application scenarios of the device.

[0033] Based on this, in some embodiments of the present application, the thickness of the P-type silicon light absorption layer 13 is 3 μm to 25 μm; the doping concentration of the P-type silicon light absorption layer 13 is For example, the thickness of the P-type silicon light absorption layer 13 may be 3 μm, 6 μm, 9 μm, 12 μm, 15 μm, 18 μm, 21 μm or 25 μm; the doping concentration of the P-type silicon light absorption layer 13 may be , , or .

[0034] By limiting the thickness and doping concentration of the P-type silicon light absorption layer 13, the built-in electric field strength formed by the first heterojunction and the second heterojunction can be further enhanced. At the same time, the photogenerated electron-hole pairs formed in the p-type silicon light absorption layer 13 only need to diffuse a short distance to enter the depletion region generated by the heterojunction. The electric field inside the depletion region and the band deviation at the heterojunction interface cause the electrons and holes to be selectively transferred to the electron transport layer 14 and the hole transport layer 12, respectively, thereby shortening the diffusion distance of the photogenerated carriers in the P-type silicon light absorption layer 13 and improving the response speed of the device. In addition, the shortening of the diffusion distance can also reduce the bulk recombination of the carriers, thereby increasing the photoelectric conversion efficiency and light responsiveness of the device. In addition, according to the mechanical properties of silicon materials and existing research, the micron-thick P-type silicon light absorption layer 13 also has a self-supporting flexible feature, so that the device can be used in wearable devices and robotics in complex / harsh environments.

[0035] Furthermore, in order to improve the device response speed while taking into account the photogenerated carrier collection efficiency of the device, the present application further improves the P-type silicon light absorption layer 13.

[0036] Specifically, Figure 1 As shown, in some embodiments of the present application, a plurality of nano-protrusion structures 131 are further provided on the surface of the P-type silicon light absorption layer 13 close to the electron transport layer 14 .

[0037] Furthermore, a plurality of nano-protrusion structures 131 are periodically arranged on the surface of the P-type silicon light absorbing layer 13 .

[0038] Furthermore, the shape of the nano-protrusion structure 131 includes a pyramid shape, a nano-rod shape, a nano-hole shape, and the like.

[0039] Further, the size of the nano-protrusion structure 131 is 100 nm to 1300 nm, and the thickness is 100 nm to 920 nm. For example, the size of the nano-protrusion structure 131 can be 100 nm, 250 nm, 500 nm, 750 nm, 1000 nm, or 1300 nm; the thickness of the nano-protrusion structure 131 can be 100 nm, 300 nm, 500 nm, 800 nm, or 920 nm.

[0040] It is worth noting that the size of the nano-protrusion structure 131 refers to the bottom diameter or side length of the nano-protrusion structure 131 , that is, the diameter or side length of the surface of the nano-protrusion structure 131 in contact with the P-type silicon light absorbing layer 13 .

[0041] By constructing a nano-protrusion structure 131 on the surface of the P-type silicon light absorption layer 13 with a thickness of several microns, the reflectivity of the device to the visible light band can be reduced, avoiding the problem of insufficient absorption of visible light by the P-type silicon light absorption layer 13 with limited thickness. This allows the device to have a faster response speed while having excellent photogenerated carrier collection efficiency in the entire visible light band, while taking into account the device's light response speed and energy collection efficiency.

[0042] like Figure 2 The figure shows the energy band diagram and carrier transport schematic diagram of the flexible silicon-based optoelectronic device provided by the present application under zero bias; it can be seen from the figure that after the incident light is absorbed by the P-type silicon light absorption layer 13, photogenerated electron-hole pairs are generated in the P-type silicon light absorption layer 13. Driven by the built-in electric field formed by the two heterojunctions, the photogenerated electrons are transferred to the electron transport layer 14, and the photogenerated holes are transferred to the hole transport layer 12, thereby forming a macroscopic photocurrent. When the incident light is modulated, the photocurrent generated by the flexible silicon-based optoelectronic device is an alternating current that varies with time, that is, an electrical signal; when the incident light is steady, the photocurrent generated by the flexible silicon-based optoelectronic device is a direct current that does not vary with time, that is, electrical energy.

[0043] Based on the flexible silicon-based optoelectronic device provided in the above embodiment, the embodiment of the present application also provides a receiving end, which includes the flexible silicon-based optoelectronic device provided in the above embodiment, and the flexible silicon-based optoelectronic device is used to receive visible light signals and convert the visible light signals into electrical signals.

[0044] Furthermore, the receiving end also includes a decoupling circuit, which is connected to the flexible silicon-based optoelectronic device and is used to decouple the electrical signal and output a DC component and an AC component.

[0045] Based on the receiving end provided in the above embodiment, an embodiment of the present application further provides a visible light communication system, which includes a transmitting end and the receiving end provided in the above embodiment.

[0046] For example, Figure 3 The figure shows a visible light communication system provided by a specific example of the present application, which includes a transmitting end 21 and a receiving end 22 .

[0047] The transmitting end 21 specifically includes a coupling circuit 211 and an LED component 212 .

[0048] The coupling circuit 211 is used to couple the AC electric signal carrying information and the DC electric signal carrying energy, and output a coupled electric signal.

[0049] The LED assembly 212 is connected to the output end of the coupling circuit 211 and is used to convert the coupled electrical signal into a visible light signal and emit it.

[0050] The receiving end 22 specifically includes a flexible silicon-based optoelectronic device 221 and a decoupling circuit 222 .

[0051] The flexible silicon-based optoelectronic device 221 is used to receive the visible light signal emitted by the LED assembly 212 and convert the visible light signal into an electrical signal.

[0052] The decoupling circuit 222 is connected to the flexible silicon-based optoelectronic device 221 and is used to decouple the electrical signal and output a DC component and an AC component.

[0053] Specifically, the subsequent processing of the AC component needs to consume electric energy, and the DC component is electric energy. Therefore, the DC component can be stored to be provided to the processing module of the AC component.

[0054] The technical solution of the present application is described in more detail below in conjunction with a plurality of embodiments, but it should be understood that the following embodiments are only for explaining and illustrating the technical solution and do not limit the scope of the present application. Example 1

[0055] The present embodiment provides a flexible silicon-based photoelectric device, which includes a back electrode layer, a hole transport layer, a P-type silicon light absorption layer, an electron transport layer and a front electrode layer stacked in sequence from bottom to top.

[0056] The hole transport layer is made of molybdenum oxide (MoO 3-x ), with a thickness of 40nm.

[0057] The thickness of the P-type silicon light absorption layer is 3 μm and the doping concentration is .

[0058] The electron transport layer is made of tin oxide (SnO2 ), with a thickness of 30nm. Example 2

[0059] The present embodiment provides a flexible silicon-based photoelectric device, which includes a back electrode layer, a hole transport layer, a P-type silicon light absorption layer, an electron transport layer and a front electrode layer stacked in sequence from bottom to top.

[0060] The hole transport layer is made of molybdenum oxide (MoO 3-x ), with a thickness of 400nm.

[0061] The thickness of the P-type silicon light absorption layer is 25 μm and the doping concentration is .

[0062] The electron transport layer is made of tin oxide (SnO 2 ), with a thickness of 300nm. Example 3

[0063] The present embodiment provides a flexible silicon-based photoelectric device, which includes a back electrode layer, a hole transport layer, a P-type silicon light absorption layer, an electron transport layer and a front electrode layer stacked in sequence from bottom to top.

[0064] The hole transport layer is made of molybdenum oxide (MoO 3-x ), with a thickness of 60nm.

[0065] The thickness of the P-type silicon light absorption layer is 6 μm and the doping concentration is .

[0066] The electron transport layer is made of tin oxide (SnO 2 ), with a thickness of 60nm. Example 4

[0067] The present embodiment provides a flexible silicon-based photoelectric device, which includes a back electrode layer, a hole transport layer, a P-type silicon light absorption layer, an electron transport layer and a front electrode layer stacked in sequence from bottom to top; wherein a plurality of pyramid-shaped nano-protrusion structures are arranged on the surface of the P-type silicon light absorption layer close to the electron transport layer.

[0068] The hole transport layer is made of molybdenum oxide (MoO 3-x ), with a thickness of 60nm.

[0069] The thickness of the P-type silicon light absorption layer is 6 μm and the doping concentration is .

[0070] A plurality of nano-protrusion structures are periodically and uniformly arranged on the surface of the P-type silicon light absorption layer, and the arrangement period is 1300nm.

[0071] The size of the nano-protrusion structure is 1300nm and the thickness is 920nm.

[0072] The electron transport layer is made of tin oxide (SnO 2 ), with a thickness of 60nm.

[0073] Comparative Example This comparative example provides a flexible silicon-based photoelectric device, which includes a back electrode layer, a P-type silicon light absorption layer, an electron transport layer and a front electrode layer stacked in sequence from bottom to top.

[0074] The thickness of the P-type silicon light absorption layer is 6 μm and the doping concentration is .

[0075] The electron transport layer is made of tin oxide (SnO 2 ), with a thickness of 60nm.

[0076] like Figure 4 As shown, by solving Maxwell's equations, carrier transport equations and Poisson's equations, the present application obtains the flexible silicon-based optoelectronic devices provided in Example 3, Example 4 and the comparative example when the wavelength of the incident light is 467nm and the incident light power density is 0.3mWcm -2 41 is the light-state current density-voltage curve of the flexible silicon-based photoelectric device provided in Example 4, and 42 is the dark-state current density-voltage curve of the flexible silicon-based photoelectric device provided in Example 4; 43 is the light-state current density-voltage curve of the flexible silicon-based photoelectric device provided in Example 3, and 44 is the dark-state current density-voltage curve of the flexible silicon-based photoelectric device provided in Example 3; 45 is the light-state current density-voltage curve of the flexible silicon-based photoelectric device provided in the comparative example, and 46 is the dark-state current density-voltage curve of the flexible silicon-based photoelectric device provided in the comparative example.

[0077] from Figure 4 It can be seen that the open circuit voltage of the flexible silicon-based photoelectric device provided in Example 3 and Example 4 is greater than the open circuit voltage of the flexible silicon-based photoelectric device provided in the comparative example, and the dark state current of the flexible silicon-based photoelectric device provided in Example 3 and Example 4 under reverse bias is less than the dark state current of the flexible silicon-based photoelectric device provided in the comparative example under reverse bias, indicating that the flexible silicon-based photoelectric device provided in the present application can effectively improve the response speed of the device by designing a double heterojunction, and at the same time has a higher photoelectric conversion efficiency.

[0078] At the same time, from Figure 4It can also be seen that the flexible silicon-based optoelectronic devices provided in Examples 3 and 4 can both operate under zero bias, but the open circuit voltage of the flexible silicon-based optoelectronic device provided in Example 3 is lower than the open circuit voltage of the flexible silicon-based optoelectronic device with a nano-protrusion structure provided in Example 4, and the dark state current of the flexible silicon-based optoelectronic device provided in Example 3 under reverse bias is greater than the dark state current of the flexible silicon-based optoelectronic device with a nano-protrusion structure provided in Example 4 under reverse bias, indicating that by designing a nano-protrusion structure on the P-type silicon light absorption layer, the response speed and photoelectric conversion efficiency of the device can be further improved, thereby enhancing the device performance.

[0079] The present application also obtains through simulation calculation that the flexible silicon-based optoelectronic devices provided in Example 3, Example 4 and the comparative example have an incident light power density of 0.3 mW cm -2 The responsivity, external quantum efficiency (EQE), internal quantum efficiency (IQE) and specific detectivity vary with wavelength under different conditions.

[0080] Figure 5 The flexible silicon-based optoelectronic devices provided in Example 3, Example 4 and the comparative example are shown in Figure 3 at an incident light power density of 0.3 mW cm -2 In the figure, 51 is the responsivity spectrum of the flexible silicon-based optoelectronic device provided in Example 4, 52 is the responsivity spectrum of the flexible silicon-based optoelectronic device provided in Example 3, and 53 is the responsivity spectrum of the flexible silicon-based optoelectronic device provided in the comparative example.

[0081] from Figure 5 It can be seen that the flexible silicon-based optoelectronic devices provided in Examples 3 and 4 have an incident light wavelength of 467 nm and an incident light power density of 0.3 mW cm -2 The response is 0.339AW -1 , and its responsiveness is better than that of the flexible silicon-based optoelectronic device provided in the comparative example, indicating that the flexible silicon-based optoelectronic device with double heterojunction provided in the present application has a higher light responsiveness and a wider spectral response range.

[0082] Figure 6 The flexible silicon-based optoelectronic devices provided in Example 3, Example 4 and the comparative example are shown in Figure 3 at an incident light power density of 0.3 mW cm -2 The external quantum efficiency curves are as follows. In the figure, 61 is the external quantum efficiency curve of the flexible silicon-based optoelectronic device provided in Example 4, 62 is the external quantum efficiency curve of the flexible silicon-based optoelectronic device provided in Example 3, and 63 is the external quantum efficiency curve of the flexible silicon-based optoelectronic device provided in the comparative example.

[0083] from Figure 6It can be seen that the external quantum efficiency of the flexible silicon-based optoelectronic devices provided in Examples 3 and 4 is better than that of the flexible silicon-based optoelectronic device provided in the comparative example, indicating that the flexible silicon-based optoelectronic device with double heterojunction provided in the present application has a stronger ability to convert incident photons into actual collectible carriers, that is, the actual efficiency of photoelectric conversion is higher, and has better light collection efficiency. At the same time, the external quantum efficiency of the flexible silicon-based optoelectronic device provided in Example 4 is better than that of the flexible silicon-based optoelectronic device provided in Example 3, which also shows that setting a nano-protrusion structure on the surface of the P-type silicon light absorption layer can further improve the light collection efficiency of the device while improving the photoelectric conversion efficiency of the device.

[0084] Figure 7 The flexible silicon-based optoelectronic devices provided in Example 3, Example 4 and the comparative example are shown in Figure 3 at an incident light power density of 0.3 mW cm -2 In the internal quantum efficiency curves, 71 is the internal quantum efficiency curve of the flexible silicon-based optoelectronic device provided in Example 4, 72 is the internal quantum efficiency curve of the flexible silicon-based optoelectronic device provided in Example 3, and 73 is the internal quantum efficiency curve of the flexible silicon-based optoelectronic device provided in the comparative example.

[0085] from Figure 7 It can be seen that the internal quantum efficiency curves of the flexible silicon-based optoelectronic devices provided by Example 3 and Example 4 are basically overlapped, and are both better than the internal quantum efficiency curve of the flexible silicon-based optoelectronic devices provided by the comparative example, indicating that the present application improves the photoelectric conversion performance of the device by forming a heterojunction on both sides of the P-type silicon light absorption layer, which can not only more effectively generate electron-hole pairs, but also effectively suppress the recombination loss of photogenerated carriers inside the device, thereby improving the device's efficiency in utilizing photon energy.

[0086] Figure 8 The flexible silicon-based optoelectronic devices provided in Example 3, Example 4 and the comparative example are shown in Figure 3 at an incident light power density of 0.3 mW cm -2 In the figure, 81 is the specific detection rate curve of the flexible silicon-based optoelectronic device provided in Example 4, 82 is the specific detection rate curve of the flexible silicon-based optoelectronic device provided in Example 3, and 83 is the specific detection rate curve of the flexible silicon-based optoelectronic device provided in the comparative example.

[0087] from Figure 8It can be seen that the specific detection rate of the flexible silicon-based optoelectronic devices provided in Examples 3 and 4 is much higher than the specific detection rate of the flexible silicon-based optoelectronic devices provided in the comparative example, indicating that the flexible silicon-based optoelectronic devices with double heterojunctions provided in the present application have higher detection sensitivity and can detect weak light signals more keenly. At the same time, the response uniformity in the entire spectral range is better and has lower noise equivalent power. At the same time, by comparing the specific detection rate curves of the flexible silicon-based optoelectronic devices provided in Examples 3 and 4, it can be seen that the setting of the nano-protrusion structure effectively improves the detection sensitivity of the device for weak light signals and optimizes the performance of the device.

[0088] like Fig. 9 As shown, the present application also provides the flexible silicon-based optoelectronic device provided in Example 4 under zero bias, incident light wavelength of 467nm, and incident light power density of 0.3mWcm -2 The transient photocurrent response curve under Fig. 9 It can be seen that the rise time of the transient photocurrent response of the flexible silicon-based optoelectronic device provided in Example 4 is 20ns and the fall time is 18.6ns.

[0089] like Fig.10 The flexible silicon-based optoelectronic devices provided in Example 3, Example 4 and the comparative example provided in this application are shown in FIG. Fig.11 The incident light power density shown is 0.3 mW cm -2 The current density-voltage curve under the irradiation of the white light LED is shown in FIG. 101 , which is the current density-voltage curve of the flexible silicon-based optoelectronic device provided in Example 4, 102 is the current density-voltage curve of the flexible silicon-based optoelectronic device provided in Example 3, and 103 is the current density-voltage curve of the flexible silicon-based optoelectronic device provided in the comparative example. Fig.10 It can be seen that the photoelectric conversion efficiency of the flexible silicon-based photoelectric device with a double heterojunction provided in the present application is significantly better than the photoelectric conversion efficiency of the flexible silicon-based photoelectric device with a single heterojunction provided in the comparative example.

[0090] Table 1 shows the visible light energy collection and detection performance data of the flexible silicon-based optoelectronic devices provided in Example 3, Example 4 and the comparative example: Table 1 Device structure Conversion efficiency of white light LED spectrum (%) <![CDATA[Specific detectivity @ 467nm 0.3mWcm -2 (Jones)]]> Planar morphology single heterojunction 6.5 <![CDATA[7.71×10 11 ]]> Double heterojunction 19.8 <![CDATA[2.84×10 12 ]]> Nano-protrusion structure double heterojunction 22.64 <![CDATA[1.58×10 13 ]]> It can also be seen from the data in Table 1 that the flexible silicon-based optoelectronic devices with double heterojunctions of nano-protrusion structures are superior to those with double heterojunctions of planar morphology in terms of visible light energy collection (photoelectric conversion efficiency) and visible light detection (specific detection rate). This is because the nano-protrusion structure has a stronger absorption capacity for the visible light band; and the visible light energy collection and visible light detection performance of flexible silicon-based optoelectronic devices with double heterojunctions are better than those with single heterojunctions. This is because the separation and transfer efficiency of double heterojunctions for photogenerated electrons and photogenerated holes is higher than that of single heterojunctions.

[0091] Fig.12 The light absorption rate curves of the flexible silicon-based optoelectronic devices provided in Examples 3 and 4 of the present application are shown. In the figure, 121 is the light absorption rate curve of the flexible silicon-based optoelectronic device provided in Example 4, and 122 is the light absorption rate curve of the flexible silicon-based optoelectronic device provided in Example 3. It can be seen from the figure that by providing a plurality of nano-protrusion structures on the surface of the P-type silicon light absorption layer, the absorption capacity of the device in the visible light band can be effectively improved, and the light absorption rate of the device can be improved.

[0092] In addition, combined Figure 5~Figure 10 It can be seen that the flexible silicon-based optoelectronic device provided in Example 4 has an incident light wavelength of 467 nm and an incident light power density of 0.3 mW cm -2 The response is 0.339AW -1 The external quantum efficiency is 89.8%, the internal quantum efficiency is 91.26%, and the specific detection rate is The rise time of the transient photocurrent response is 20ns, the fall time is 18.6ns, and the corresponding photoelectric conversion efficiency is 22.64%. The flexible silicon-based photoelectric device provided in Example 3 has an incident light wavelength of 467nm and an incident light power density of 0.3mWcm -2 The response is 0.339AW -1 The external quantum efficiency is 89.81%, the internal quantum efficiency is 90.46%, and the specific detection rate is , the corresponding photoelectric conversion efficiency is 19.8%; it shows that the flexible silicon-based optoelectronic device with nano-protrusion structure and double heterojunction has better photoelectric conversion performance, faster response speed and higher energy collection efficiency, and can also show excellent detection performance for the blue light band commonly used in visible light communication.

[0093] Obviously, the above embodiments are merely examples for the purpose of clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A flexible silicon-based optoelectronic device, characterized in that: include: A back electrode layer, a hole transport layer, a P-type silicon light absorption layer, an electron transport layer and a front electrode layer are stacked in sequence from bottom to top; Wherein, the valence band edge energy difference between the electron transport layer and the P-type silicon light absorption layer is greater than the conduction band edge energy difference between the electron transport layer and the P-type silicon light absorption layer; The conduction band edge energy difference between the P-type silicon light absorption layer and the hole transport layer is greater than the valence band edge energy difference between the P-type silicon light absorption layer and the hole transport layer; The band gap width of the electron transport layer is greater than 3.0 eV; the front electrode layer includes a plurality of grid electrodes discretely arranged on the surface of the electron transport layer.

2. The flexible silicon-based optoelectronic device according to claim 1, characterized in that: The thickness of the P-type silicon light absorption layer is 3 μm to 25 μm; The doping concentration of the P-type silicon light absorbing layer is .

3. The flexible silicon-based optoelectronic device according to claim 2, characterized in that: A plurality of nano-protrusion structures are arranged on the surface of the P-type silicon light absorption layer close to the electron transport layer.

4. The flexible silicon-based optoelectronic device according to claim 3, characterized in that: The plurality of nano-protrusion structures are periodically arranged on the surface of the P-type silicon light absorbing layer; and / or The shapes of the nano-protrusion structures include pyramid, nano-rod and nano-hole.

5. The flexible silicon-based optoelectronic device according to claim 4, characterized in that: The size of the nano-protrusion structure is 100nm~1300nm, and the thickness is 100nm~920nm.

6. The flexible silicon-based optoelectronic device according to claim 1, characterized in that: The material of the hole transport layer includes molybdenum oxide, nickel oxide, tungsten oxide, and vanadium oxide; and / or The material of the electron transport layer includes tin oxide, titanium oxide, zinc oxide, niobium oxide, and tantalum oxide.

7. The flexible silicon-based optoelectronic device according to claim 1, characterized in that: The thickness of the hole transport layer is 40nm to 400nm; and / or The thickness of the electron transport layer is 30nm~300nm.

8. A receiving end, characterized in that: It comprises a flexible silicon-based optoelectronic device as described in any one of claims 1 to 7, wherein the flexible silicon-based optoelectronic device is used to receive visible light signals and convert the visible light signals into electrical signals.

9. The receiving end according to claim 8, characterized in that: Also includes: A decoupling circuit is connected to the flexible silicon-based optoelectronic device and is used to decouple the electrical signal and output a direct current component and an alternating current component.

10. A visible light communication system, characterized in that: include: A transmitting end, used for transmitting a visible light signal; The receiving end as claimed in claim 8 or 9.

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