Organic-inorganic heterojunction photovoltaic device with nanosheet microstructure and method of making

Abstract

The application discloses an organic-inorganic heterojunction photoelectric device with a nanosheet microstructure and a preparation method. 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 self-assembled by nanosheets grown vertically or at a high inclination. The organic semiconductor layer is prepared by an evaporation method, and the inorganic semiconductor layer is prepared by a physical vapor deposition method. The method realizes preparation of a large-area two-dimensional material film, and a high-performance heterojunction photoelectric detector is constructed, the heterojunction photoelectric detector has good responsivity, normalized detectivity and response speed in a visible light band, and has potential application value.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic materials technology, specifically relating to an organic-inorganic heterojunction optoelectronic device with a nanosheet microstructure and its preparation method. Background Technology

[0002] Light and electricity are among the most common elements in daily life. Photodetectors can convert light signals into electrical signals using the photoelectric effect and are applied in fields such as photovoltaics and photoelectric detection. Therefore, optoelectronic devices have become one of the hot research directions. Among optoelectronic devices, organic-inorganic hybrid devices have attracted widespread attention due to their advantages such as high performance, broad corresponding spectrum, and the combination of characteristics of both organic and inorganic materials. The continuous development of technology has placed higher demands on the performance of photodetectors, so new materials and novel devices have always been hot issues in the field of optoelectronic materials technology.

[0003] In recent years, with breakthroughs in graphene research, two-dimensional materials have become one of the most popular new optoelectronic materials due to their superior properties such as ultra-high mobility and broadband photoelectric response, and have broad application prospects in optoelectronic devices, photovoltaic devices, and flexible devices. For this reason, current research on organic-inorganic hybrid devices mainly focuses on two-dimensional inorganic / organic heterojunctions. Based on different material selections for two-dimensional inorganic / organic frameworks, high-performance heterojunction optoelectronic devices can cover multiple wavelengths from ultraviolet to far-infrared light, and can be applied to several fields such as optical biomimetic transistors, multifunctional photodetectors, and perovskite solar cells (Han J, Wang F, Han S, Recent Progress in 2D Inorganic / Organic Charge Transfer Heterojunction Photodetectors. Adv. Funct. Mater. 2022, 32, 2205150). Furthermore, with further research on two-dimensional materials and heterojunction mechanisms, the performance and applications of two-dimensional inorganic / organic heterojunction devices still have significant room for development.

[0004] Applying these devices to practical commercial applications often requires large-area, high-performance thin films as a foundation. However, while current two-dimensional inorganic / organic heterojunction devices offer superior performance, the small size of two-dimensional materials and the high difficulty of fabrication often limit the production of large-area films. While common methods such as liquid-phase synthesis can achieve large-area film fabrication, the damage to the two-dimensional materials and residual solvents can severely impact film performance. Therefore, it is essential to actively seek novel materials, device structures, and fabrication methods to obtain heterojunction optoelectronic devices based on large-area, high-performance thin films. Summary of the Invention

[0005] To address the problems of the prior art, this invention proposes an organic-inorganic heterojunction optoelectronic device with a nanosheet microstructure, thereby utilizing two-dimensional materials to fabricate a large-area thin film and realizing a high-performance heterojunction optoelectronic device. Another objective of this invention is to provide a method for fabricating the aforementioned device.

[0006] The technical solution adopted in this invention is as follows:

[0007] An organic-inorganic heterojunction optoelectronic device with a nanosheet microstructure includes an organic-inorganic heterojunction composed of an organic semiconductor layer and an inorganic semiconductor layer, wherein the inorganic semiconductor layer is self-assembled from nanosheets grown vertically or at a high angle.

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

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

[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 vapor deposition; Step 3, growing an inorganic semiconductor layer with a nanosheet microstructure on the organic semiconductor layer by physical vapor deposition; 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 vapor deposition; Step 2, growing an inorganic semiconductor layer with a nanosheet microstructure on the organic semiconductor layer by physical vapor deposition; Step 3, growing a top electrode on the inorganic semiconductor layer by magnetron sputtering.

[0012] The organic-inorganic heterojunction prepared by this invention can be used to fabricate optoelectronic devices such as photodetectors. Compared with the prior art, this 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 are toxic due to their lead content, while the two-dimensional material in this invention uses bismuth iodide, which has lower toxicity.

[0015] 3) The fabrication process is simple, and based on the obtained large-area thin film, arrayed devices can be realized with an area of ​​centimeters or even larger. Compared with traditional small-sized two-dimensional materials (micrometer scale), this invention has greater commercial application potential. Attached Figure Description

[0016] Figure 1 The present invention includes: (a) a schematic diagram of the device structure of Embodiment 1, and (b) a schematic diagram of the device structure of Embodiment 2;

[0017] Figure 2 This is a side view of the device according to Embodiment 1 of the present invention;

[0018] Figure 3 This is a front view of the fourth layer of nanosheet microstructure in the device of Embodiment 1 of the present invention;

[0019] Figure 4 The following are test results of the photoelectric performance of the device in Embodiment 1 of the present invention, with a 635nm laser as the test light source: (a) IV (current-voltage) curve of the device near 0V; (b) responsivity and normalized detectivity of the device at 0V and different light intensities.

[0020] Figure 5 This is a graph showing the rise and fall times of the device in Embodiment 1 of the present invention at 0V.

[0021] Figure 6 The following are test results of the photoelectric performance of the device in Embodiment 2 of the present invention, with a 635nm laser as the test light source: (a) IV curve of the device; (b) rise and fall time curve of the device at 5V.

[0022] Figure 7 This is a performance comparison chart between the device of Embodiment 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 Embodiment 2 of the present invention and existing devices of the same type. Detailed Implementation

[0024] The organic-inorganic heterojunction optoelectronic device with a nanosheet microstructure provided by this invention has the following bottom-up structure: 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; and the fifth layer is a metal or metal oxide, used as a top electrode. This is a common vertical structure device (such as a photovoltaic device, a photodiode device, or a self-powered photodetector). If a lateral structure device is considered, only the second bottom electrode layer needs to be removed, and the subsequent layer structures can be directly fabricated on the substrate.

[0025] Preferably, the first layer is a silicon substrate or a flexible PET 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 nanosheet microstructures, such as BiI3 (bismuth iodide), with a thickness on the order of micrometers. The microstructures are self-assembled from vertically or highly inclined nanosheets, with a thickness on the order of hundreds of nanometers. The fifth layer is ITO or gold.

[0026] The method for preparing the above-mentioned organic-inorganic heterojunction optoelectronic device with nanosheet microstructure according to the present invention specifically includes the following steps:

[0027] Step 1: Grow a bottom electrode on the substrate by magnetron sputtering (this step is not required if it is the aforementioned lateral structure device). The thickness of the bottom electrode is 300-500 nm.

[0028] Step 2: Grow p-type organic semiconductors by vapor deposition at a growth rate of [missing information]. The thickness is approximately 30-50 nm;

[0029] Step 3: An n-type inorganic semiconductor with a nanosheet microstructure is grown on a p-type organic semiconductor by physical vapor deposition; wherein the argon flow rate is 5-6 sccm, the distance between the substrate and the material source is 12-14 cm, the source temperature is 270-320℃, and the temperature holding time is 30-60 min.

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

[0031] Example 1

[0032] This embodiment fabricates 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 285 nm layer of silicon dioxide on its surface. The second layer is an ITO bottom electrode, prepared by magnetron sputtering at a sputtering pressure of 0.5 Pa for 6 min, with a thickness of approximately 300 nm. The third layer is a p-type organic semiconductor pentacene, prepared by vapor deposition at a growth rate of [missing information]. The thickness is approximately 40 nm. The fourth layer is an n-type inorganic semiconductor, bismuth iodide, which has the following properties: Figure 2 , 3 The nanosheet microstructure shown consists of vertically or highly inclined nanosheets, prepared by physical vapor deposition in a tube furnace at an argon flow rate of 6 sccm, a substrate-to-source distance of 12 cm, a maximum source temperature of 270 °C, and a holding time of 30 min. The nanosheet thickness is in the hundreds of nanometers. The fifth layer is an ITO top electrode, prepared by magnetron sputtering at a sputtering pressure of 0.5 Pa and a growth time of 4 min, with a thickness of approximately 200 nm. Its transparent electrode facilitates the testing of the device's optoelectronic performance. Testing was performed using a laser, probe station, and a 4200 semiconductor analyzer.

[0033] Figure 4 (a) shows the IV characteristic curve of the fabricated device near 0V, indicating that the open-circuit voltage of the device is close to 0.3V and the short-circuit current is around 10V. -7 A-level. Figure 4 (b) shows the responsivity and normalized detectivity of the device at 0V and different light intensities. The maximum responsivity is close to 1 A / W, and the normalized detectivity is close to 10. 13 The Jones-level light exhibits excellent photoresponse characteristics in the visible light band. Furthermore, Figure 5 This shows the rise and fall time curves of the device at 0V, with a rise time of approximately 357μs and a fall time of approximately 543μs. Performance comparisons with existing devices of the same type are provided. Figure 7 As shown, compared with existing achievements, this device not only has higher responsivity and normalized detectivity, 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 second bottom electrode is removed, a heterojunction is directly fabricated on the silicon substrate, and a photoconductive photodetector with a lateral structure is formed between the top electrodes, such as... Figure 1 (b) Its specific structure from bottom to top is as follows: The first layer is a silicon substrate with a 285nm silicon dioxide layer on its surface. The second layer is a p-type organic semiconductor pentacene, prepared by vapor deposition at a growth rate of [missing information]. The thickness is approximately 40 nm. The third layer is an n-type inorganic semiconductor bismuth iodide with a nanosheet microstructure, prepared by physical vapor deposition at an argon flow rate of 6 sccm, a substrate-to-source distance of 12 cm, a maximum source temperature of 270 °C, and a maximum temperature holding time of 30 min. The fourth layer is a gold electrode, prepared by magnetron sputtering at a sputtering pressure of 2 Pa and a growth time of 10 min, with a thickness of approximately 100 nm. The channel length formed between the two gold electrodes is approximately 50 μm.

[0036] Figure 6 (a) shows the IV characteristic curves of the fabricated device. Under a 5V bias, the device's responsivity can reach up to 85A / W, and the normalized detectivity can reach 3.55×10⁻⁶. 12 Jones indicates 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) shows the rise and fall time curves of the device at 5V, with a rise time of approximately 1.38ms and a fall time of approximately 4.50ms. Performance comparison with existing devices of the same type is provided. Figure 8 As shown, compared with existing achievements, this device simultaneously achieves 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, the inorganic semiconductor layer is self-assembled by nanosheets grown vertically or at a high inclination; the material of the organic semiconductor layer is p-type organic semiconductor pentacene; and the material of the inorganic semiconductor layer is bismuth iodide.

2. The organic-inorganic heterojunction photovoltaic device with nanoplatelets microstructure according to claim 1, wherein, The photoelectric device has a structure from bottom to top: the first layer is a substrate; the second layer is a metal or metal oxide used as a bottom electrode; the third layer is the organic semiconductor layer; the fourth layer is the inorganic semiconductor layer; and the fifth layer is a metal or metal oxide used as a top electrode.

3. The organic-inorganic heterojunction photovoltaic device with nanoplatelets microstructure according to claim 1, wherein, The photoelectric device has a structure from bottom to top: the first layer is a substrate; the second layer is the organic semiconductor layer; the third layer is the inorganic semiconductor layer; and the fourth layer is a metal or metal oxide used as a top electrode, the top electrode including two electrodes with a spacing.

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

5. The method of claim 2, wherein the inorganic nanosheet microstructure is formed by a chemical vapor deposition method. The method comprises 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.

6. The method of claim 3, wherein the inorganic nanosheet microstructure is formed by a chemical vapor deposition method. 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 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.

7. The production method according to claim 5 or 6, characterized by, The growth rate of the evaporation method is about 0.2-0.5 Å / s.

8. The production method according to claim 5 or 6, characterized by, In the physical vapor deposition method, the argon flow rate is 5-6 sccm, the distance between the substrate and the material source is 12-14 cm, the source zone temperature is 270-320 ℃, and the temperature holding time is 30-60 min.

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