Organic-inorganic heterojunction photoelectric device with nanosheet microstructure and preparation method of organic-inorganic heterojunction photoelectric device

Abstract

The invention discloses an organic-inorganic heterojunction photoelectric device with a nanosheet microstructure and a preparation method of the organic-inorganic heterojunction photoelectric device. The photoelectric device comprises an organic-inorganic heterojunction, the organic-inorganic heterojunction is composed of an organic semiconductor layer and an inorganic semiconductor layer, and the inorganic semiconductor layer is formed by self-assembly of nanosheets growing vertically or at a high gradient. Wherein the organic semiconductor layer is prepared by an evaporation method, and the inorganic semiconductor layer is prepared by a physical vapor deposition method. According to the method, preparation of the large-area two-dimensional material film is achieved, a high-performance heterojunction photoelectric detector is constructed, and the heterojunction photoelectric detector has good responsivity, normalized detectivity and response speed in the visible light wave band and has potential application value.

Description

Technical Field

[0001] The invention belongs to the technical field of optoelectronic materials, and in particular relates to an organic-inorganic heterojunction optoelectronic device with a nanosheet microstructure and a preparation method thereof. Background Art

[0002] Light and electricity are the most common elements in daily life. Photodetectors can use the photoelectric effect to convert light signals into electrical signals and are applied to fields such as photovoltaics and photoelectric detection. Therefore, optoelectronic devices have become one of the hottest research directions. Among optoelectronic devices, organic-inorganic hybrid devices have received extensive attention due to their high performance, wide corresponding spectrum, and the characteristics of both organic and inorganic materials. The continuous development of the times has put forward higher requirements on the performance of photodetectors, so new materials and new devices have always been hot issues in the field of optoelectronic material technology.

[0003] In recent years, with the breakthrough of graphene-related research, two-dimensional materials have become one of the hottest new optoelectronic materials with their excellent properties such as ultra-high mobility and broadband photoelectric response, and have broad application prospects in optoelectronic devices, photovoltaic devices, flexible devices and other fields. For this reason, the current research on organic-inorganic hybrid devices is mainly focused on the direction of two-dimensional inorganic / organic heterojunctions. Based on the different material selections of two-dimensional inorganic / organic frameworks, high-performance heterojunction optoelectronic devices can cover multiple bands from ultraviolet to far-infrared light, which can be specifically applied to optical bionic transistors, multifunctional photodetectors, perovskite solar cells and other fields (Han J, Wang F, Han S, Recent Progress in 2D Inorganic / Organic Charge Transfer Heterojunction Photodetectors. Adv. Funct. Mater. 2022, 32, 2205150). And with the further study of two-dimensional materials and heterojunction mechanisms, the performance and application of two-dimensional inorganic / organic heterojunction devices still have a lot of room for development.

[0004] Putting devices into actual commercial applications often requires large-area, high-performance thin films as a basis. However, although today's two-dimensional inorganic / organic heterojunction devices have superior performance, they are often difficult to obtain large-area thin films due to the small size and high difficulty of preparation of two-dimensional materials. Although the current common liquid phase synthesis method and other methods can achieve large-area thin film preparation, the damage to the two-dimensional material and the residual solvent will seriously affect the performance of the film. Therefore, it is necessary to actively seek new materials, device structures and preparation methods to obtain heterojunction optoelectronic devices based on large-area, high-performance thin films. Summary of the invention

[0005] In view of the above problems of the prior art, the present invention proposes an organic-inorganic heterojunction optoelectronic device with a nanosheet microstructure, thereby using two-dimensional materials to prepare a large-area thin film and realize a high-performance heterojunction optoelectronic device. Another object of the present invention is to provide a method for preparing the above device.

[0006] The technical solution adopted by the present invention is as follows:

[0007] An organic-inorganic heterojunction optoelectronic device with a nanosheet microstructure comprises an organic-inorganic heterojunction, wherein the organic-inorganic heterojunction is composed of an organic semiconductor layer and an inorganic semiconductor layer, and the inorganic semiconductor layer is self-assembled by vertically or highly inclined nanosheets.

[0008] Furthermore, the structure of the optoelectronic device of the present invention from bottom to top is: the first layer is the substrate; the second layer is metal or metal oxide, used as the bottom electrode; the third layer is the organic semiconductor layer; the fourth layer is the inorganic semiconductor layer; the fifth layer is metal or metal oxide, used as the top electrode.

[0009] Furthermore, the structure of the optoelectronic device of the present invention from bottom to top is: the first layer is the substrate; the second layer is the organic semiconductor layer; the third layer is the inorganic semiconductor layer; the fourth layer is metal or metal oxide, used as the top electrode, and the top electrode includes two electrodes with a gap.

[0010] The present invention also provides a method for preparing an organic-inorganic heterojunction optoelectronic device with a nanosheet microstructure, comprising the following steps: step 1, growing a bottom electrode on a substrate by magnetron sputtering; step 2, growing an organic semiconductor layer on the bottom electrode by an evaporation method; step 3, growing an inorganic semiconductor layer with a nanosheet microstructure on the organic semiconductor layer by a physical vapor deposition method; step 4, growing a top electrode on the inorganic semiconductor layer by magnetron sputtering.

[0011] The present invention also provides another method for preparing an organic-inorganic heterojunction optoelectronic device with a nanosheet microstructure, comprising the following steps: step 1, growing an organic semiconductor layer on a substrate by an evaporation method; step 2, growing an inorganic semiconductor layer with a nanosheet microstructure on the organic semiconductor layer by a physical vapor deposition method; step 3, growing a top electrode on the inorganic semiconductor layer by magnetron sputtering.

[0012] The organic-inorganic heterojunction prepared by the present invention can be used to prepare photoelectric devices such as photodetectors. Compared with the prior art, the present invention has the following advantages:

[0013] 1) Based on the principle of self-assembly, vertically grown two-dimensional materials are designed into nanosheet microstructures. After light enters, it can be reflected and refracted multiple times and fully absorbed by the material, thereby enhancing the light absorption effect. When applied to large-area thin films and combined with organic materials, high-performance heterojunction devices can be obtained;

[0014] 2) Environmentally friendly. Traditional two-dimensional materials such as lead iodide have certain toxicity due to the lead content, while the two-dimensional material in the present invention uses bismuth iodide, which has lower toxicity;

[0015] 3) The preparation process is simple, and arrayed devices can be realized based on the obtained large-area thin film, with an area of ​​centimeters or even larger. Compared with traditional small-size two-dimensional materials (micrometer level), the present invention has greater commercial application potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 1 is a schematic diagram of the device structure of (a) Embodiment 1, and (b) Embodiment 2;

[0017] Figure 2 is a side profile diagram of the device of Example 1 of the present invention;

[0018] Figure 3 is a front morphology image of the fourth layer of nanosheet microstructure in the device of Example 1 of the present invention;

[0019] Figure 4 These are test diagrams of the optoelectronic performance of the device of Example 1 of the present invention, where the test light source is a 635nm laser: (a) IV (current-voltage) curve of the device near 0V; (b) responsiveness and normalized detection of the device at 0V and different light intensities.

[0020] Figure 5 It is a rise and fall time curve diagram of the device of Example 1 of the present invention at 0V.

[0021] Figure 6 These are test diagrams of the optoelectronic performance of the device of Example 2 of the present invention, where the test light source is a 635nm laser: (a) IV curve of the device; (b) rise and fall time curves of the device at 5V.

[0022] Figure 7 This is a performance comparison chart between the device of Example 1 of the present invention and existing devices of the same type.

[0023] Figure 8 This is a performance comparison chart between the device of Example 2 of the present invention and existing devices of the same type. DETAILED DESCRIPTION

[0024] The organic-inorganic heterojunction optoelectronic device with nanosheet microstructure provided by the present invention has a structure from bottom to top as follows: the first layer is a substrate; the second layer is a metal or metal oxide, used as a bottom electrode; the third layer is an organic semiconductor; the fourth layer is an inorganic semiconductor; the fifth layer is a metal or metal oxide, used as a top electrode. The above is a common vertical structure device (such as a photovoltaic device or a photodiode device or a self-powered photodetector). If a lateral structure device is considered, it is only necessary to remove the second bottom electrode and directly prepare the subsequent layer structure on the substrate.

[0025] Wherein, preferably, the first layer is a silicon substrate or a PET flexible substrate. The second layer is ITO (indium tin oxide) or gold. The third layer is a p-type organic semiconductor, such as pentacene. The fourth layer is an n-type inorganic semiconductor with a nanosheet microstructure, such as BiI3 (bismuth iodide), with a thickness in the micrometer range. The microstructure is self-assembled by nanosheets grown vertically or at a high angle, and the thickness of the nanosheets is in the hundreds of nanometers. The fifth layer is ITO or gold.

[0026] The method for preparing the organic-inorganic heterojunction optoelectronic device having a nanosheet microstructure according to the present invention specifically comprises the following steps:

[0027] Step 1, growing a bottom electrode layer on the substrate by magnetron sputtering (this step is omitted if it is the aforementioned lateral structure device), the thickness of the bottom electrode is 300-500nm;

[0028] Step 2, growing a p-type organic semiconductor by evaporation at a growth rate of Thickness is about 30-50nm;

[0029] Step 3, growing an n-type inorganic semiconductor having a nanosheet microstructure on a p-type organic semiconductor by a physical vapor deposition method; wherein the argon gas flow rate is 5-6 sccm, the distance between the substrate and the material source is 12-14 cm, the source region temperature is 270-320° C., and the temperature holding time is 30-60 min;

[0030] Step 4, growing a top electrode on the n-type inorganic semiconductor by magnetron sputtering, with a thickness of 100-200 nm.

[0031] Example 1

[0032] This embodiment prepares a vertical structure device: a self-powered photodetector, whose specific structure from bottom to top is as follows Figure 1 (a): The first layer is a silicon substrate with a 285nm layer of silicon dioxide on its surface. The second layer is an ITO bottom electrode, prepared by magnetron sputtering, with a sputtering pressure of 0.5Pa, a growth time of 6min, and a thickness of about 300nm. The third layer is a p-type organic semiconductor pentacene, prepared by evaporation, with a growth rate of The thickness is about 40nm. The fourth layer is an n-type inorganic semiconductor bismuth iodide, which has Figure 2 , 3 The nanosheet microstructure shown is composed of vertically or highly inclined nanosheets, which are prepared by physical vapor deposition in a tube furnace, with an argon gas flow rate of 6 sccm, a distance of 12 cm between the substrate and the material source, a maximum source temperature of 270 ° C, a maximum temperature holding time of 30 min, and a thickness of the nanosheet of hundreds of nanometers. The fifth layer is an ITO top electrode, which is prepared by magnetron sputtering, with a sputtering pressure of 0.5 Pa, a growth time of 4 min, and a thickness of about 200 nm. As a transparent electrode, it is conducive to testing the optoelectronic performance of the device. The test is carried out by lasers, probe stations, 4200 semiconductor analyzers and other instruments.

[0033] Figure 4 (a) is the IV characteristic curve of the prepared device near 0V, indicating that the open circuit voltage of the device is close to 0.3V and the short circuit current is 10 -7 A-level. Figure 4 (b) is the device's responsivity and normalized detection at 0V and different light intensities. The maximum responsivity is close to 1A / W, and the normalized detection is close to 10 13 Jones magnitude, showing good photoresponse characteristics in the visible light band. Figure 5 This is the rise and fall time curve of the device at 0V. The rise time is about 357μs and the fall time is about 543μs. Compared with the performance of existing similar devices, Figure 7 As shown, compared with existing achievements, this device not only has higher responsivity and normalized detection, as well as good photovoltaic performance (short-circuit current, open-circuit voltage), but also has a faster response speed.

[0034] Example 2

[0035] The difference between Example 2 and Example 1 is that the bottom electrode of the second layer is removed, a heterojunction is directly prepared on the silicon substrate, and a photoconductive photodetector device with a lateral structure is formed between the top electrodes, such as Figure 1 (b), its specific structure from bottom to top is: the first layer is a silicon substrate with a 285nm layer of silicon dioxide on its surface. The second layer is a p-type organic semiconductor pentacene, prepared by evaporation, with a growth rate of The thickness is about 40nm. The third layer is an n-type inorganic semiconductor bismuth iodide with a nanosheet microstructure, prepared by physical vapor deposition, with an argon gas flow rate of 6sccm, a distance between the substrate and the material source of 12cm, a maximum source temperature of 270°C, and a maximum temperature holding time of 30min. The fourth layer is a gold electrode, prepared by magnetron sputtering, with a sputtering pressure of 2Pa, a growth time of 10min, a thickness of about 100nm, and a channel length of about 50μm formed between the two gold electrodes.

[0036] Figure 6 (a) is the IV characteristic curve of the prepared device. Under 5V bias, the device's responsivity can reach up to 85A / W, and the normalized detection can reach 3.55×10 12 Jones, indicating that it has good photoresponse characteristics in the visible light band, and the linearity and symmetry of the curve indicate that the device has good electrode contact and uniformity. Figure 6 (b) is the rise and fall time curve of the device at 5V, the rise time is about 1.38ms, and the fall time is about 4.50ms. Figure 8 As shown, compared with existing achievements, this device achieves both better photoelectric response and faster response speed.

Claims

1. An organic-inorganic heterojunction optoelectronic device having a nanosheet microstructure, comprising an organic-inorganic heterojunction, characterized in that: The organic-inorganic heterojunction is composed of an organic semiconductor layer and an inorganic semiconductor layer, and the inorganic semiconductor layer is self-assembled by vertically or highly inclined nanosheets.

2. The organic-inorganic heterojunction optoelectronic device with a nanosheet microstructure according to claim 1, characterized in that: The structure of the photoelectric device from bottom to top is: the first layer is the substrate; the second layer is metal or metal oxide, used as the bottom electrode; the third layer is the organic semiconductor layer; the fourth layer is the inorganic semiconductor layer; the fifth layer is metal or metal oxide, used as the top electrode.

3. The organic-inorganic heterojunction optoelectronic device with a nanosheet microstructure according to claim 1, characterized in that: The structure of the photoelectric device from bottom to top is: the first layer is the substrate; the second layer is the organic semiconductor layer; the third layer is the inorganic semiconductor layer; the fourth layer is metal or metal oxide, used as the top electrode, and the top electrode includes two electrodes with a gap.

4. The organic-inorganic heterojunction optoelectronic device with a nanosheet microstructure according to any one of claims 1 to 3, characterized in that: The material of the organic semiconductor layer is p-type organic semiconductor pentacene.

5. The organic-inorganic heterojunction optoelectronic device with a nanosheet microstructure according to any one of claims 1 to 3, characterized in that: The material of the inorganic semiconductor layer is bismuth iodide.

6. The organic-inorganic heterojunction optoelectronic device with a nanosheet microstructure according to any one of claims 1 to 3, characterized in that: The thickness of the nanosheet is on the order of hundreds of nanometers.

7. The method for preparing an organic-inorganic heterojunction optoelectronic device having a nanosheet microstructure according to claim 2, characterized in that: The method comprises the following steps: Step 1, growing a bottom electrode layer on a substrate by magnetron sputtering; Step 2, growing an organic semiconductor layer on the bottom electrode by an evaporation method; Step 3, growing an inorganic semiconductor layer having a nanosheet microstructure on the organic semiconductor layer by a physical vapor deposition method; Step 4: growing a top electrode on the inorganic semiconductor layer by magnetron sputtering.

8. The method for preparing an organic-inorganic heterojunction optoelectronic device having a nanosheet microstructure according to claim 3, characterized in that: The method comprises the following steps: Step 1, growing an organic semiconductor layer on a substrate by an evaporation method; Step 2, growing an inorganic semiconductor layer having a nanosheet microstructure on the organic semiconductor layer by a physical vapor deposition method; Step 3: growing a top electrode on the inorganic semiconductor layer by magnetron sputtering.

9. The preparation method according to claim 7 or 8, characterized in that: The growth rate of the evaporation method is about 10. The preparation method according to claim 7 or 8, characterized in that: In the physical vapor deposition method, the argon gas flow rate is 5-6 sccm, the distance from the substrate to the material source is 12-14 cm, the source region temperature is 270-320° C., and the temperature holding time is 30-60 min.

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