Method for regulating and controlling polarity transport of two-dimensional WSe2 by using PEDOT: PSS electrode with adjustable work function to prepare optoelectronic device

Abstract

The invention discloses a method for regulating and controlling polarity transport of two-dimensional WSe2 by a PEDOT: PSS electrode with an adjustable work function to prepare an optoelectronic device. The organic PEDOT: PSS electrode is prepared by adopting a solution method, the work function regulation can be realized by adjusting the component ratio of PEDOT to PSS, then the PEDOT: PSS electrode and two-dimensional WSe2 are assembled through a mechanical transfer method, the work function change of the PEDOT: PSS electrode can realize the controllable adjustment of the Schottky barrier height of a WSe2 contact interface, further the polarity transport characteristic of a WSe2 carrier is changed, and the performance of the WSe2 is improved. And the photoelectric property of the WSe2 is improved. The preparation method of the organic PEDOT: PSS electrode is simple, the work function can be adjusted in a large range, polarity transport regulation and control of two-dimensional WSe2 can be achieved, and the organic PEDOT: PSS electrode is suitable for various optoelectronic devices and logic electronic circuits and has huge potential application value.

Description

Technical Field

[0001] The present invention belongs to the field of optoelectronic devices, and particularly relates to a method for regulating the polar transport of two-dimensional WSe2 by an organic PEDOT:PSS electrode with adjustable work function to prepare optoelectronic devices. Background Art

[0002] The polar regulation of two-dimensional materials has been an important research direction in the fields of materials science and nanotechnology in recent years, with profound and extensive background significance. Two-dimensional materials, such as graphene, transition metal dichalcogenides (TMDs), and black phosphorus, etc., due to their unique atomic layer structure, excellent electrical, optical, and mechanical properties, show great application potential in the fields of electronic devices, optoelectronic devices, catalysis, energy storage and conversion, etc. [Adv. Funct. Mater. 2023, 33, 2210619].

[0003] Among them, WSe2 used in this patent belongs to transition metal dichalcogenides (TMDs). WSe2 (tungsten diselenide) has significant advantages in the field of optoelectronic devices, especially outstanding in the aspect of carrier type regulation. It is a common means in this field to regulate the properties of carriers through external electric fields, chemical modifications, and strain engineering, and then improve the properties of WSe2 optoelectronic devices [ACS Nano 2019, 13, 11613 - 11622]. In WSe2-based field-effect transistors, by applying an external electric field or chemical doping, its conduction type (n-type or p-type) can be adjusted, and the switching characteristics of the device can be optimized [ACS Nano 2024, 18, 4180 - 4188]. In addition, polar regulation can also be used to realize reconfigurable logic circuits [ACS Appl. Mater. Interfaces 2023, 15, 45116 - 45], providing technical support for the development of future flexible electronics and wearable devices.

[0004] In the field of optoelectronic devices, polar regulation can effectively improve the light absorption and carrier separation efficiency of two-dimensional materials, thereby enhancing the performance of photodetectors and solar cells. For example, by regulating the polarity of TMDs materials, their band structures can be optimized to make them more suitable for light absorption at specific wavelengths, and at the same time, improve the separation and collection efficiency of photo-generated carriers. In addition, polar regulation can also be used to realize efficient optical modulators and light-emitting devices, providing new solutions for optical communication and display technologies.

[0005] In addition, polar regulation also provides a research platform for exploring novel physical phenomena of two-dimensional materials. For example, by regulating the polarity of two-dimensional materials, the research of quantum phenomena such as topological phase transitions, superconductivity, and magnetism can be realized, providing new perspectives and experimental bases for the development of condensed matter physics and quantum materials science.

[0006] External doping and strain engineering provide important ways to regulate the carrier properties of WSe2, but there are still many limitations. In terms of doping, common methods such as chemical modification and plasma treatment not only require additional post-treatment steps, increasing the preparation complexity and cost, but also may introduce impurities or defects, affecting the material properties. In addition, external doping is difficult to achieve uniform distribution of carriers, and the doping effect may degrade over time or with changes in the environment, limiting the long-term stability of devices. Although strain engineering can adjust the band structure and carrier properties of WSe2, it is difficult to ensure precise control and uniformity of the applied strain, resulting in inconsistent material properties. The carrier properties of WSe2 are sensitive to the number of layers, and the regulation mechanisms of single-layer and few-layer materials are different, increasing the difficulty of experimental design and device optimization. Although theoretical design provides various regulation strategies, experimental verification is limited by preparation techniques and characterization methods, making it difficult to fully achieve the performance predicted by theory. In summary, although certain progress has been made in external doping and strain engineering, further optimization of methods is still needed to achieve more efficient, stable, and controllable device applications. Summary of the Invention

[0007] The prior art for the polarity regulation of WSe2 relies on external electric fields, chemical modification, and strain engineering. The purpose of the present invention is to provide a method for regulating the polar transport of two-dimensional WSe2 using a work function-tunable poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) electrode. Specifically, it is a solution-prepared and work function-adjustable electrode - PEDOT:PSS. By adjusting the work function of PEDOT:PSS, the Schottky barrier height at the contact between PEDOT:PSS and WSe2 is further adjusted to achieve the regulation of the polarity of WSe2.

[0008] The present invention utilizes the characteristic that the PEDOT:PSS electrode is convenient for regulating the work function, changes the work function of PEDOT:PSS by solution method. After the PEDOT:PSS electrode contacts the WSe2 material, the formed Schottky barrier changes, thereby regulating the polarity of WSe2, and then improving the carrier transport, light absorption, and carrier separation efficiency of the photodetector. Furthermore, the performance of the photodetector and the field effect transistor is improved.

[0009] To achieve the purpose of the present invention, the following technical solutions are adopted.

[0010] A method for regulating the polar transport of two-dimensional WSe2 using a work function-tunable PEDOT:PSS electrode to prepare optoelectronic devices, characterized in that the polar transport of WSe2 is regulated using a poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) electrode, including the following steps:

[0011] (1) Prepare thin-layer WSe2 nanosheets;

[0012] (2) Prepare a poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) electrode;

[0013] (3) Adjust the component ratio in the poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) electrode by solution method to change the work function of the PEDOT:PSS electrode;

[0014] (4) Bring the obtained poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) into surface contact with WSe2 to form a well-contact electrode-semiconductor interface, and then construct a PEDOT:PSS-WSe2 optoelectronic device.

[0015] The PEDOT:PSS electrode described in the present invention is prepared by solution method, annealed to form a film, and then the components of the organic electrode PEDOT:PSS are regulated by the post-film treatment process, and further the work function of the PEDOT:PSS electrode is accurately regulated.

[0016] Preferably, the WSe2 nanosheets and the PEDOT:PSS electrode are sequentially transferred onto a target substrate, such as a SiO2 gate dielectric substrate, a PET substrate, a PI substrate, and a PEN substrate.

[0017] Further, in step (1), the WSe2 nanosheets are thin-layer 2H semiconductor phase WSe2 nanosheets with 1 to 4 layers prepared by chemical vapor deposition (CVD) growth or mechanical exfoliation.

[0018] Further, in step (2), the electrode preparation methods include: spin coating, drop coating, blade coating, screen printing, and inkjet printing to prepare an organic electrode PEDOT:PSS thin film with a thickness of 0.2 to 2 μm. The post-film treatment process methods include: annealing, vacuum drying, nitrogen-assisted annealing, and laser-assisted annealing to dry the organic electrode PEDOT:PSS thin film and form a conductive network of PEDOT:PSS. Preferably, the PEDOT:PSS thin film is prepared by spin coating, the spin coating speed is selected in the range of 800 rpms to 4000 rpms, preferably 1000 rpms, the spin coating time is selected in the range of 30 s to 5 min, preferably 60 s, the annealing temperature is selected in the range of 80 °C to 180 °C, preferably 120 °C, and the annealing time is selected in the range of 30 s to 40 min, preferably 20 min.

[0019] Further, in step (2), the preparation ratio of the PEDOT:PSS solution is as follows: the content range of ethylene glycol (EG) is 0.5 wt% to 10 wt%, the content range of FS3100 is 0.05 wt% to 1 wt%, and the balance is PEDOT:PSS. Preferably, the content of ethylene glycol (EG) is 6 wt%, the content of FS3100 is 0.05 wt%, and the content of PEDOT:PSS is 93.95 wt%.

[0020] Further, in step (3), the solution method is adjusted to use acids, bases, and organic solvents to adjust the components of the organic electrode PEDOT:PSS. According to the etching time, the ratio of PEDOT:PSS can be precisely controlled, and thus the work function of the electrode can be adjusted.

[0021] The adjustment relationship of the work function of the electrode is as follows:

[0022] The work function of the PEDOT:PSS electrode without any treatment is 5.04 eV;

[0023] The work function of the PEDOT:PSS electrode obtained by etching with 70 - 75 wt% HNO3 solution for 25 - 30 s, 65 - 69 wt% HNO3 solution for 30 - 35 s, 60 - 65 wt% HNO3 solution for 35 - 40 s, and 55 - 60 wt% HNO3 solution for 40 - 45 s is 4.1 - 4.8 eV;

[0024] The work function of the PEDOT:PSS electrode obtained by etching with 70 - 75 wt% HNO3 solution for 55 - 60 s, 65 - 69 wt% HNO3 solution for 60 - 65 s, 60 - 65 wt% HNO3, 55 - 60 wt% HNO3 solution for 75 s - 80 s, and 70 - 75 s is 3.0 - 3.5 eV;

[0025] The work function of the PEDOT:PSS electrode obtained by etching with 90 - 95 wt% H2SO4 solution for 20 - 25 s, 85 - 90 wt% H2SO4 solution for 25 - 30 s, 80 - 85 wt% H2SO4 solution for 30 - 33 s, and 75 - 80 wt% H2SO4 solution for 33 - 35 s is 4.0 - 4.7 eV;

[0026] The work function of the PEDOT:PSS electrode obtained by etching with 90 - 95 wt% H2SO4 solution for 45 - 55 s, 85 - 90 wt% H2SO4 solution for 55 - 60 s, 80 - 85 wt% H2SO4 solution for 60 - 65 s, and 75 - 80 wt% H2SO4 solution for 65 - 70 s is 3.1 - 3.6 eV;

[0027] Etch with a 30 - 35 wt% HCl solution for 100 - 110 s, a 25 - 30 wt% HCl solution for 110 - 120 s, and a 20 - 25 wt% HCl solution for 120 - 130 s to obtain a PEDOT:PSS electrode with a work function of 3.1 - 3.6 eV;

[0028] Etch with a 30 - 35 wt% HCl solution for 30 - 40 s, a 25 - 30 wt% HCl solution for 40 - 50 s, and a 20 - 25 wt% HCl solution for 50 - 60 s to obtain a PEDOT:PSS electrode with a work function of 4.2 - 4.5 eV.

[0029] Further preferably, the adjustment relationship of the work function of the electrode is as follows:

[0030] The work function of a PEDOT:PSS electrode without any treatment is 5.04 eV.

[0031] Etch with a 70 - 75 wt% HNO3 solution for 25 - 30 s to obtain a PEDOT:PSS electrode with a work function of 4.43 eV;

[0032] Etch with a 65 - 69 wt% HNO3 solution for 30 - 35 s to obtain a PEDOT:PSS electrode with a work function of 4.43 eV;

[0033] Etch with a 60 - 65 wt% HNO3 solution for 35 - 40 s to obtain a PEDOT:PSS electrode with a work function of 4.43 eV;

[0034] Etch with a 55 - 60 wt% HNO3 solution for 40 - 45 s to obtain a PEDOT:PSS electrode with a work function of 4.43 eV;

[0035] Etch with a 70 - 75 wt% HNO3 solution for 55 - 60 s to obtain a PEDOT:PSS electrode with a work function of 3.2 eV;

[0036] Etch with a 65 - 69 wt% HNO3 solution for 60 - 65 s to obtain a PEDOT:PSS electrode with a work function of 3.2 eV;

[0037] Etch with a 60 - 65 wt% HNO3 solution for 70 - 75 s to obtain a PEDOT:PSS electrode with a work function of 3.2 eV;

[0038] Etch with a 55 - 60 wt% HNO3 solution for 75 - 80 s to obtain a PEDOT:PSS electrode with a work function of 3.2 eV;

[0039] Etch with a 90 - 95 wt% H2SO4 solution for 20 - 25 s to obtain a PEDOT:PSS electrode with a work function of 4.43 eV;

[0040] Etching with an 85 - 90 wt% H2SO4 solution for 25 - 30 s results in a PEDOT:PSS electrode work function of 4.43 eV;

[0041] Etching with an 80 - 85 wt% H2SO4 solution for 30 - 33 s results in a PEDOT:PSS electrode work function of 4.43 eV;

[0042] Etching with a 75 - 80 wt% H2SO4 solution for 33 - 35 s results in a PEDOT:PSS electrode work function of 4.43 eV;

[0043] Etching with a 90 - 95 wt% H2SO4 solution for 45 - 55 s results in a PEDOT:PSS electrode work function of 3.2 eV;

[0044] Etching with an 85 - 90 wt% H2SO4 solution for 55 - 60 s results in a PEDOT:PSS electrode work function of 3.2 eV;

[0045] Etching with an 80 - 85 wt% H2SO4 solution for 60 - 65 s results in a PEDOT:PSS electrode work function of 3.2 eV;

[0046] Etching with a 75 - 80 wt% H2SO4 solution for 65 - 70 s results in a PEDOT:PSS electrode work function of 3.2 eV;

[0047] Etching with a 30 - 35 wt% HCl solution for 30 - 40 s results in a PEDOT:PSS electrode work function of 4.43 eV;

[0048] Etching with a 25 - 30 wt% HCl solution for 40 - 50 s results in a PEDOT:PSS electrode work function of 4.43 eV;

[0049] Etching with a 20 - 25 wt% HCl solution for 50 - 60 s results in a PEDOT:PSS electrode work function of 4.43 eV;

[0050] Etching with a 30 - 35 wt% HCl solution for 100 - 110 s results in a PEDOT:PSS electrode work function of 3.2 eV;

[0051] Etching with a 25 - 30 wt% HCl solution for 110 - 120 s results in a PEDOT:PSS electrode work function of 3.2 eV;

[0052] Etching with a 20 - 25 wt% HCl solution for 120 - 130 s results in a PEDOT:PSS electrode work function of 3.2 eV.

[0053] Further, step (4) is specifically as follows: dry transfer, wet transfer, and hybrid stamp transfer are adopted to enable the poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) and WSe2 to form a high-quality electrode-semiconductor interface through good interfacial contact.

[0054] Further, in the present invention, the optional temperature range for electrode drying is 80°C to 150°C, preferably 120°C, and the drying time is 20 min.

[0055] The device structure involved in the present invention includes the following parts: 1. Organic PEDOT:PSS electrode; 2. Two-dimensional semiconductor WSe2; 3. Gate dielectric layer / substrate. The present invention discloses an optoelectronic device including two structures: WSe2 / PEDOT:PSS / substrate and PEDOT:PSS / WSe2 / substrate, having a high-quality electrode-semiconductor interface between PEDOT:PSS and WSe2; the optoelectronic device has a high-quality electrode-semiconductor interface between PEDOT:PSS and WSe2.

[0056] The present invention provides a PEDOT:PSS electrode prepared by the above preparation method. That is, the organic electrode in the present invention uses a polypropylene carbonate (PPC) / polydimethylsiloxane (PDMS) layer to transfer the PEDOT:PSS electrode from an OTS / Si substrate to a thin-layer WSe2 single crystal to form a good physical contact point.

[0057] A parallel-structured WSe2 device provided by the present invention can be used as a device field-effect transistor and a photodetector (attached Figure 1 ) and includes a gate dielectric layer, WSe2, and transparent electrodes at both ends stacked in sequence, and the transparent electrodes are prepared by the above acid solution etching method.

[0058] In the method for fabricating an optoelectronic device by regulating the polar transport of two-dimensional WSe2 using the above-mentioned work function-adjustable PEDOT:PSS electrode, the following steps are further included: the prepared electrode is subjected to plasma etching with a mask by oxygen plasma etching for patterning.

[0059] Further, solution etching is adopted, and the available solutions include strong acids (sulfuric acid, nitric acid, hydrochloric acid). Preferably, an acidic solution with strong oxidizing properties is used to adjust the component ratio of PEDOT:PSS, and the acid used can be 55 wt% to 75 wt% concentrated nitric acid, 75 wt% to 95 wt% concentrated nitric acid, preferably 75 wt% concentrated nitric acid.

[0060] A van der Waals transfer method for an organic electrode and a thin-layer two-dimensional material provided by the present invention includes the following steps:

[0061] (1) Prepare a polydimethylsiloxane (PDMS) layer by crosslinking method;

[0062] (2) Dissolve poly(propylene carbonate) (PPC) in anisole and mix well. The ratio of poly(propylene carbonate) (PPC) to anisole is preferably 1 g of poly(propylene carbonate) (PPC) dissolved in 10 ml of anisole;

[0063] (3) Spin-coat poly(propylene carbonate) (PPC) on the prepared polydimethylsiloxane (PDMS) layer and then heat it. The heating temperature is preferably 120 °C;

[0064] (4) Grasp and release the target electrode and two-dimensional material on the transfer stage.

[0065] Further, in the polydimethylsiloxane (PDMS) layer in step (1), the mass ratio of the curing agent to polydimethylsiloxane (PDMS)

[0066] can be in the range of 1:5 to 1:20, preferably 1:10;

[0067] Further, the spin-coating speed in step (3) can be in the range of 500 rpms to 3000 rpms

[0068] Further preferably, in step (4), the grasping and releasing of the target electrode and two-dimensional material are achieved by relying on the change in the viscosity of poly(propylene carbonate) (PPC) on the surface of polydimethylsiloxane (PDMS) due to temperature change. The grasping temperature is 38 °C to 45 °C, and the releasing temperature is 65 °C to 80 °C

[0069] A method for regulating the work function of an electrode for the polarity of WSe2 provided by the present invention

[0070] (1) Electrodes of 5.04 eV, 4.43 eV, and 3.20 eV prepared by the above acid etching method

[0071] (2) Transfer the target two-dimensional material and organic electrode to the target substrate by the above van der Waals transfer method

[0072] (3) Obtain devices with different carrier transport types;

[0073] A method for constructing a broadband and high-speed response photodetector by combining PEDOT:PSS and WSe2 provided by the present invention

[0074] (1) An electrode of 4.43 eV prepared by the above acid etching method

[0075] (2) Transfer the target two-dimensional material and organic electrode to the target substrate by the above van der Waals transfer method

[0076] (3) Achieving the improvement of the device responsivity by regulating the work function of the electrodes;

[0077] The present invention discloses a two-dimensional material field-effect transistor (which can also be used as a photodetector) based on a tunable work function electrode and its preparation method, specifically relating to a technical solution for constructing a WSe2-based field-effect transistor (which can also be used as a photodetector) using a poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) heterojunction electrode. It is characterized in that: by selecting PEDOT:PSS electrodes with different work functions and combining the van der Waals force transfer process to achieve non-destructive interfacial contact, and at the same time using the adjustable work function characteristics of the electrodes to dynamically control the carrier transport mechanism of the device.

[0078] The preparation method includes the following steps: prefabricating a patterned PEDOT:PSS electrode array on a target substrate, regulating the surface chemical state of the electrode by a solution method to obtain the target electrode work function; preparing a single-layer or multi-layer WSe2 thin film by mechanical exfoliation or chemical vapor deposition method, and using the van der Waals transfer technology to accurately cover the two-dimensional material on the electrode gap region to form a physical contact interface without dangling bonds. Among them, the contact interface between the electrode and WSe2 is only combined by intermolecular forces, avoiding the lattice damage caused by high-energy particle bombardment in the traditional metal deposition process, thereby maintaining the intrinsic electrical properties of the semiconductor material.

[0079] The core innovation of this solution is that: by adjusting the soaking time of the electrode in an acidic solution, the electrode work function can be continuously regulated, and then the Schottky barrier height between WSe2 and the electrode can be changed. Through the change of the electrode work function, the device can be induced to change from hole-dominated transport to electron and hole co-dominated transport (the ratio of μ p and μ n changes significantly). By selectively enhancing the electron or hole injection efficiency, the carrier transport characteristics can be significantly improved. This regulation method does not require changing the physical structure or doping process of the device, and the device performance can be directionally optimized only through a post-treatment process.

[0080] In addition, the transparent characteristics of the PEDOT:PSS electrode make it compatible with a transmissive photodetection architecture, and large-area array preparation can be realized by combining a solution processing technology. Compared with vacuum-evaporated metal electrodes, this solution avoids the performance degradation of two-dimensional materials caused by high-temperature processes, and at the same time simplifies the micro-nano processing process, providing a feasible technical path for the large-scale integration of short-channel two-dimensional devices. Experiments show that this device structure can effectively suppress the interfacial recombination current, improve the carrier migration efficiency, and exhibit excellent photodetection performance in a wide spectral range.

[0081] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0082] (1) The poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) provided by the present invention has the advantages of being easy to process in solution and having a work function that can be regulated between 3.2 eV and 5.04 eV.

[0083] (2) For the organic electrode poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) provided by the present invention, the process from hot pressing to acid soaking only takes 40 minutes, which significantly shortens the electrode preparation time compared with traditional evaporation electrodes, and is conducive to the continuous and rapid production of two-dimensional material optoelectronic devices.

[0084] (3) In the organic electrode poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) electrode and its preparation method provided by the present invention, the electrode preparation temperature is low (<150 °C), and no precision equipment is required, which is suitable for large-scale production by all solution methods, such as spraying, doctor blading, spin coating, and screen printing. Compared with traditional thermal evaporation electrodes of high melting point metals (Ag, Au), the equipment cost and energy cost of two-dimensional material optoelectronic devices can be significantly reduced.

[0085] (4) In the method for polar regulation of few-layer WSe2 by the organic electrode poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) provided by the present invention, the effective regulation of carrier properties can be achieved by changing the work function of the organic electrode poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS), overcoming the problems of different uniformity and poor repeatability of traditional external doping methods.

[0086] (5) The process method provided by the present invention is simple, has good repeatability, and low cost, providing a new feasibility for the preparation of two-dimensional material photodetectors. The work function tunable organic electrode poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) of the present invention has broad application prospects in many fields such as other photodetectors and wearable flexible electronic devices. Description of the Drawings

[0087] Figure 1 It is a schematic structural diagram of the present invention using the organic electrode poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) and WSe2.

[0088] Figure 2 It is the transfer characteristic curve of the transistor made of the organic electrode poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) with a work function of 5.04 eV and WSe2 in Example 1.

[0089] Figure 3It is the output characteristic curve of the transistor fabricated in Example 1 using the organic electrode poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) with a work function of 5.04 eV and WSe2.

[0090] Figure 4 It is the transfer characteristic curve of the transistor fabricated in Example 2 using the organic electrode poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) with a work function of 4.43 eV and WSe2.

[0091] Figure 5 It is the output characteristic curve of the transistor fabricated in Example 2 using the organic electrode poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) with a work function of 4.43 eV and WSe2.

[0092] Figure 6 It is the transfer characteristic curve of the transistor fabricated in Example 3 using the organic electrode poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) with a work function of 3.2 eV and WSe2.

[0093] Figure 7 It is the output characteristic curve of the transistor fabricated in Example 3 using the organic electrode poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) with a work function of 3.2 eV and WSe2.

[0094] Figure 8 It is the relationship diagram between the ratio of carrier mobilities (μ p / μ n ) of the transistor device fabricated in the present invention using the organic electrode poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) and WSe2 and the work function of the electrode.

[0095] Figure 9 It is the volt-ampere characteristic curve of the photodetector fabricated in Example 4 using the organic electrode poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) with a work function of 4.43 eV and WSe2.

[0096] Figure 10 It is the current-time curve of the photodetector fabricated in Example 4 using the organic electrode poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) with a work function of 4.43 eV and WSe2. Specific implementation method

[0098] The following further describes the specific implementation of the present invention in conjunction with embodiments and drawings, but the implementation and protection of the present invention are not limited thereto. It should be noted that for the processes not specifically described in detail below, those skilled in the art can implement or understand them with reference to the prior art. Reagents or instruments without indicating the manufacturer are regarded as conventional products that can be obtained through commercial purchase.

[0099] Example 1

[0100] (1) Cleaning of the SiO2 substrate:

[0101] The SiO2 substrate was ultrasonically cleaned with dishwashing liquid solution, deionized water, acetone, isopropanol, and deionized water in sequence for 20 minutes, and finally the cleaned SiO2 substrate was stored in an ethanol solution for standby. Before use, it was dried with nitrogen.

[0102] (2) Preparation of an organic electrode (PEDOT:PSS) with an adjustable work function:

[0103] The PEDOT:PSS solution containing 6 vol% ethylene glycol (EG) and 0.1% FS3100 was spin-coated onto an octadecyltrichlorosilane (OTS)-modified silicon substrate at a speed of 1000 rpm, and then annealed on a hot plate at 120 °C for 30 minutes. In this example, the work function of 5.04 eV was adopted, and the electrode did not require acid solution immersion. Lithography and O2 plasma etching techniques were used for PEDOT:PSS patterning.

[0104] (3) Preparation of a van der Waals assisted transfer tool:

[0105] In this example, a two-component dimethylsiloxane (PDMS) was used. Component A was the PDMS raw material, and component B was phenyltrichlorosilane. After mixing in a volume ratio of A:B = 10:1, it was left to stand for degassing and then heated and cured with a mold. After demolding, it was adhered to a plasma-treated glass sheet. Then, polycarbonate propylene carbonate (PPC) fully dissolved in anisole was spin-coated on the dimethylsiloxane (PDMS), annealed at 120 °C for 2 minutes, and then cooled for standby.

[0106] (4) Mechanical exfoliation of WSe2 nanosheets:

[0107] In this example, WSe2 bulk materials prepared by chemical vapor deposition were used. The WSe2 bulk materials were thinned by mechanical exfoliation to obtain thinner nanosheets (with a thickness of 3 - 5 nm). A fully cooled polycarbonate propylene carbonate (PPC) / dimethylsiloxane (PDMS) assisted transfer tool was used to grab the preferably WSe2 thin sheets at 43 °C and release them onto a clean SiO2 substrate at 75 °C. The residual polycarbonate propylene carbonate (PPC) on the material was washed off with acetone.

[0108] (5) Transfer of the organic electrode (PEDOT:PSS) with adjustable work function:

[0109] In this embodiment, the organic electrode poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) with a work function of 5.04 eV is selected, and the electrode thickness is 50 nm. The patterned organic electrode (PEDOT:PSS) is grasped at 43 °C using a fully cooled polycarbonate propylene carbonate (PPC) / dimethyl silicone (PDMS) assisted transfer tool and released onto the cleaned WSe2 flake at 75 °C. The residual polycarbonate propylene carbonate (PPC) on the device is washed off with acetone.

[0110] (6) Testing:

[0111] When using a semiconductor analyzer to test the output curve and transfer curve of the field-effect transistor (FET), first connect the source, drain, and gate of the device to the corresponding ports of the analyzer respectively to ensure good contact to avoid the influence of contact resistance. When testing the output curve, fix the gate voltage (V GS ), gradually increase it from 10 V to 40 V, and scan the drain voltage (V GS , from 0 V to 2 V) at each V DS , record the drain current (I DS ), and obtain the I DS -V DS curve for analyzing the characteristics of the linear region and saturation region of the device. When testing the transfer curve, fix the drain voltage (V DS , such as 0.01 V, 0.1 V, 0.5 V, 1 V), scan the gate voltage (V GS , from -60 V to 60 V), record I DS , and obtain the I DS -V GS curve for extracting key parameters such as the threshold voltage (V th ), subthreshold swing (SS), and on / off ratio (I on / I off ) to observe the types of carriers in the device and the transport properties of carriers. The testing process needs to be carried out in a shielded environment to avoid electromagnetic interference, and the equipment needs to be calibrated to ensure data accuracy. By analyzing the output curve and transfer curve, the electrical performance of the FET can be comprehensively evaluated, providing a reliable basis for device optimization.

[0112] The transfer characteristic curve of the device is shown by Figure 2 ; as shown in the figure, the hole mobility of the device is 79 cm 2 V -1 s -1 , and the electron mobility of the device is 4 cm 2 V -1 s-1 As Figure 3 shown, V G = -60V, V DS = 2V, the I of the device DS = 50 μA, V G = 60V, V DS = 2V, the I of the device DS = 17.5 μA.

[0113] Example 2

[0114] (1) Cleaning of the SiO2 substrate: The same as in Example 1.

[0115] (2) Preparation of the organic electrode with adjustable work function (PEDOT:PSS):

[0116] The PEDOT:PSS solution containing 6 vol% ethylene glycol (EG) and 0.1% FS3100 was spin-coated onto the octadecyltrichlorosilane (OTS)-modified silicon substrate at a speed of 1000 rpm, and then annealed on a hot plate at 120 °C for 30 minutes. The work function adopted in this example is 4.43 eV, and the electrode needs to be soaked in 75 wt% concentrated HNO3 solution for 30 s. Lithography and O2 plasma etching techniques were used for PEDOT:PSS patterning.

[0117] (3) Preparation of the van der Waals assisted transfer tool: The same as in Example 1.

[0118] (4) Mechanical exfoliation of WSe2 nanosheets: The same as in Example 1.

[0119] (5) Transfer of the organic electrode with adjustable work function (PEDOT:PSS): The same as in Example 1

[0120] (6) Testing:

[0121] The testing conditions are the same as in Example 1. The obtained results are as Figure 4 , Figure 5 shown. The transfer characteristic curve of the device is shown by Figure 4 As shown, the hole mobility of the device is 41 cm 2 V -1 s -1 , and the electron mobility of the device is 5.8 cm 2 V -1 s -1 . The output characteristic curve of the device is shown by Figure 5 As shown, V G = -40V, V DS = 2V, the I of the device DS = 43.3 μA, V G = 40V, V DS = 2V, the I of the deviceDS = 1.61 μA

[0122] Example 3

[0123] (1) Cleaning of the SiO2 substrate: The same as in Example 1.

[0124] (2) Preparation of the organic electrode with adjustable work function (PEDOT:PSS):

[0125] The PEDOT:PSS solution containing 6 vol% ethylene glycol (EG) and 0.1% FS3100 was spin-coated onto the octadecyltrichlorosilane (OTS)-modified silicon substrate at a speed of 1000 rpm, and then annealed on a hot plate at 120 °C for 30 minutes. In this example, the electrode with a work function of 3.2 eV was immersed in 75 wt% concentrated HNO3 solution for 60 s. Lithography and O2 plasma etching techniques were used for PEDOT:PSS patterning.

[0126] (3) Preparation of the van der Waals assisted transfer tool: The same as in Example 1.

[0127] (4) Mechanical exfoliation of WSe2 nanosheets: The same as in Example 1.

[0128] (5) Transfer of the organic electrode with adjustable work function (PEDOT:PSS): The same as in Example 1

[0129] (6) Testing:

[0130] The testing conditions were the same as in Example 1. The obtained results are as Figure 6 , Figure 7 shown. The transfer characteristic curve of the device is shown by Figure 8 . As shown, the hole mobility of the device is 36 cm 2 V -1 s -1 , and the electron mobility of the device is 16 cm 2 V -1 s -1 . The output characteristic curve of the device is shown by Figure 9 . As shown, at V G = -60 V and V DS = 2 V, the I DS of the device is 60 μA. At V G = 40 V and V DS = 2 V, the I DS of the device is 40 μA.

[0131] As Figure 8 shown, the relationship between the ratio of the hole mobility and the electron mobility of the device and the work function of the PEDOT:PSS electrode. The ratio of the hole mobility and the electron mobility is described by Example 1, Example 2, and Example 3.

[0132] Example 4

[0133] (1) Cleaning of the SiO2 substrate: The same as in Example 1.

[0134] (2) Preparation of the organic electrode with tunable work function (PEDOT:PSS): The same as in Example 1.

[0135] (3) Preparation of the auxiliary transfer tool: The same as in Example 1.

[0136] (4) Mechanical exfoliation of WSe2 nanosheets: The same as in Example 1, except that the selected WSe2 is thicker than that in Example 1 (with a thickness of 35 nm).

[0137] In this example, WSe2 bulk materials prepared by chemical vapor deposition are used. The WSe2 bulk materials are thinned by mechanical exfoliation to obtain nanosheets with a thickness of 35 nm. A fully cooled polycarbonate propylene carbonate (PPC) / dimethylsiloxane (PDMS) auxiliary transfer tool is used to grab preferably the WSe2 thin sheets at 43 °C and release them onto a clean SiO2 substrate at 75 °C. The residual polycarbonate propylene carbonate (PPC) on the material is washed off with acetone.

[0138] (5) Transfer of the organic electrode with tunable work function (PEDOT:PSS): The same as in Example 1

[0139] (6) Testing:

[0140] Prepare a tunable laser as the light source to ensure that it can stably output lasers in three bands of 405 nm, 520 nm, 638 nm, and 1550 nm. Connect the laser to the photodetector through an optical fiber, and install a precision optical power meter in front of the detector to calibrate the incident optical power. Before the experiment starts, place the photodetector on the optical platform to ensure that its photosensitive surface is perpendicularly aligned with the laser beam. First, test the 405 nm band. Adjust the output wavelength of the laser to 405 nm and adjust the optical power to the set value (such as 1 mW), and record the output current or voltage signal of the photodetector. After completing the 405 nm test, turn off the laser and wait for the detector to cool to room temperature, and then successively conduct tests on the 520 nm, 638 nm, and 1550 nm bands, repeating the above steps. When testing each band, ensure that the ambient light interference is minimized and conduct the test in a dark room or under light-shielding conditions. After the test is completed, organize the data, plot the response curve of the photodetector at different wavelengths, and analyze its spectral response characteristics. During the experiment, pay attention to laser safety protection, avoid direct viewing of the laser beam, and ensure that the equipment is well grounded to prevent electrostatic interference.

[0141] As Figure 9As shown, the volt-ampere characteristic curves of the device at a laser power of 10 μW in the wavelength bands of 405 nm, 520 nm, 638 nm, and 1550 nm.

[0142] As Figure 10 As shown, the current-time images of the device at a laser power of 10 μW in the wavelength bands of 405 nm, 520 nm, 638 nm, and 1550 nm reflect that the device can detect pulsed light in the bands of 405 nm, 520 nm, 638 nm, and 1550 nm without applying an additional bias.

Claims

1. A method for fabricating optoelectronic devices by regulating the polar transport of two-dimensional WSe2 using a work function-adjustable PEDOT:PSS electrode pair, characterized in that, The regulation of the polar transport of WSe2 using a poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) electrode includes the following steps: (1) Prepare thin-layer WSe2 nanosheets; (2) Prepare a poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate PEDOT:PSS electrode; (3) Adjust the component ratio in the poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate PEDOT:PSS electrode by solution method to change the work function of the poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate PEDOT:PSS electrode; (4) Bring the obtained poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate PEDOT:PSS into surface contact with WSe2 to form a well-contact electrode-semiconductor interface, and then construct a PEDOT:PSS-WSe2 optoelectronic device.

2. The method for regulating the polarity of WSe2 with an organic electrode (PEDOT:PSS) having an adjustable work function according to claim 1, wherein In step (1), the WSe2 nanosheets are thin-layer 2H semiconductor phase WSe2 nanosheets with 1 - 4 layers prepared by chemical vapor deposition growth CVD and mechanical exfoliation.

3. The method for regulating the polarity of WSe2 by an organic electrode (PEDOT:PSS) with an adjustable work function according to claim 1, characterized in that, In step (2), the electrode preparation method includes: drop coating, spin coating, blade coating, screen printing and inkjet printing to prepare an organic electrode PEDOT:PSS thin film with a thickness of 0.2 - 2 μm.

4. The method for regulating the polarity of WSe2 by an organic electrode (PEDOT:PSS) with an adjustable work function according to claim 3, wherein, The process methods for post-treatment of the thin film include: annealing, vacuum drying, nitrogen-assisted annealing and laser-assisted annealing to dry the organic electrode PEDOT:PSS thin film and form a conductive network of PEDOT:PSS.

5. The method for regulating the polarity of WSe2 by an organic electrode (PEDOT:PSS) with adjustable work function according to claim 1, characterized in that, In step (3), the solution method is adjusted to use acids, bases and organic solvents to adjust the components of the organic electrode PEDOT:PSS, and precisely control the ratio of PEDOT:PSS according to the etching time, so as to adjust the work function of the electrode.

6. The method for regulating the polarity of WSe2 by an organic electrode (PEDOT:PSS) with an adjustable work function according to claim 5, characterized in that, The adjustment relationship of the work function of the electrode is as follows: The work function of the PEDOT:PSS electrode without any treatment is 5.04 eV; The work function of the PEDOT:PSS electrode obtained by etching with 70 - 75 wt% HNO3 solution for 25 - 30 s, 65 - 69 wt% HNO3 solution for 30 - 35 s, 60 - 65 wt% HNO3 solution for 35 - 40 s, 55 - 60 wt% HNO3 solution for 40 - 45 s is 4.1 - 4.8 eV; The work function of the PEDOT:PSS electrode obtained by etching with 70 - 75 wt% HNO3 solution for 55 - 60 s, 65 - 69 wt% HNO3 solution for 60 - 65 s, 60 - 65 wt% HNO3, 55 - 60 wt% HNO3 solution for 75 s - 80 s solution for 70 - 75 s is 3.0 - 3.5 eV; The work function of the PEDOT:PSS electrode obtained by etching with 90 - 95 wt% H2SO4 solution for 20 - 25 s, 85 - 90 wt% H2SO4 solution for 25 - 30 s, 80 - 85 wt% H2SO4 solution for 30 - 33 s, 75 - 80 wt% H2SO4 solution for 33 - 35 s is 4.0 - 4.7 eV; Etch with a 90 - 95 wt% H2SO4 solution for 45 - 55 s, an 85 - 90 wt% H2SO4 solution for 55 - 60 s, an 80 - 85 wt% H2SO4 solution for 60 - 65 s, and a 75 - 80 wt% H2SO4 solution for 65 - 70 s to obtain a PEDOT:PSS electrode with a work function of 3.1 - 3.6 eV; Etch with a 30 - 35 wt% HCl solution for 100 - 110 s, a 25 - 30 wt% HCl solution for 110 - 120 s, and a 20 - 25 wt% HCl solution for 120 - 130 s to obtain a PEDOT:PSS electrode with a work function of 3.1 - 3.6 eV; Etch with a 30 - 35 wt% HCl solution for 30 - 40 s, a 25 - 30 wt% HCl solution for 40 - 50 s, and a 20 - 25 wt% HCl solution for 50 - 60 s to obtain a PEDOT:PSS electrode with a work function of 4.2 - 4.5 eV.

7. Method for regulating the polarity of WSe2 by an organic electrode (PEDOT:PSS) with adjustable work function according to claim 5, characterized in that, The adjustment relationship of the work function of the said electrode is as follows: The work function of a PEDOT:PSS electrode without any treatment is 5.04 eV; Etch with a 70 - 75 wt% HNO3 solution for 25 - 30 s to obtain a PEDOT:PSS electrode with a work function of 4.43 eV; Etch with a 65 - 69 wt% HNO3 solution for 30 - 35 s to obtain a PEDOT:PSS electrode with a work function of 4.43 eV; Etch with a 60 - 65 wt% HNO3 solution for 35 - 40 s to obtain a PEDOT:PSS electrode with a work function of 4.43 eV; Etch with a 55 - 60 wt% HNO3 solution for 40 - 45 s to obtain a PEDOT:PSS electrode with a work function of 4.43 eV; Etch with a 70 - 75 wt% HNO3 solution for 55 - 60 s to obtain a PEDOT:PSS electrode with a work function of 3.2 eV; Etch with a 65 - 69 wt% HNO3 solution for 60 - 65 s to obtain a PEDOT:PSS electrode with a work function of 3.2 eV; Etch with a 60 - 65 wt% HNO3 solution for 70 - 75 s to obtain a PEDOT:PSS electrode with a work function of 3.2 eV; Etch with a 55 - 60 wt% HNO3 solution for 75 - 80 s to obtain a PEDOT:PSS electrode with a work function of 3.2 eV; Etch with a 90 - 95 wt% H2SO4 solution for 20 - 25 s to obtain a PEDOT:PSS electrode with a work function of 4.43 eV; Etch with an 85 - 90 wt% H2SO4 solution for 25 - 30 s to obtain a PEDOT:PSS electrode with a work function of 4.43 eV; Etch with an 80 - 85 wt% H2SO4 solution for 30 - 33 s to obtain a PEDOT:PSS electrode with a work function of 4.43 eV; Etch with a 75 - 80 wt% H2SO4 solution for 33 - 35 s to obtain a PEDOT:PSS electrode with a work function of 4.43 eV; Etch with a 90 - 95 wt% H2SO4 solution for 45 - 55 s to obtain a PEDOT:PSS electrode with a work function of 3.2 eV; Etching with an 85 - 90 wt% H2SO4 solution for 55 - 60 s results in a PEDOT:PSS electrode with a work function of 3.2 eV; Etching with an 80 - 85 wt% H2SO4 solution for 60 - 65 s results in a PEDOT:PSS electrode with a work function of 3.2 eV; Etching with a 75 - 80 wt% H2SO4 solution for 65 - 70 s results in a PEDOT:PSS electrode with a work function of 3.2 eV; Etching with a 30 - 35 wt% HCl solution for 30 - 40 s results in a PEDOT:PSS electrode with a work function of 4.43 eV; Etching with a 25 - 30 wt% HCl solution for 40 - 50 s results in a PEDOT:PSS electrode with a work function of 4.43 eV; Etching with a 20 - 25 wt% HCl solution for 50 - 60 s results in a PEDOT:PSS electrode with a work function of 4.43 eV; Etching with a 30 - 35 wt% HCl solution for 100 - 110 s results in a PEDOT:PSS electrode with a work function of 4.43 eV; Etching with a 25 - 30 wt% HCl solution for 110 - 120 s results in a PEDOT:PSS electrode with a work function of 4.43 eV; Etching with a 20 - 25 wt% HCl solution for 120 - 130 s results in a PEDOT:PSS electrode with a work function of 4.43 eV.

8. The method for regulating the polarity of WSe2 by using an organic electrode (PEDOT:PSS) with an adjustable work function according to claim 1, wherein Step (4) specifically is: adopting dry transfer, wet transfer, and hybrid stamp transfer to enable the poly(3,4 - ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) and WSe2 to form a good interfacial contact, thereby forming a high - quality electrode - semiconductor interface.

9. An optoelectronic device prepared by the method according to any one of claims 1 to 8, comprising: Both the WSe2 / PEDOT:PSS / substrate and PEDOT:PSS / WSe2 / substrate structures have a high - quality electrode - semiconductor interface between PEDOT:PSS and WSe2.

10. The optoelectronic device according to claim 9, wherein, The optoelectronic device has a high - quality electrode - semiconductor interface between PEDOT:PSS and WSe2.

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