阅读说明：本技术 基于层状过渡金属硫化物的柔性光电探测器及其制备方法 (Flexible photoelectric detector based on layered transition metal sulfide and preparation method thereof ) 是由 坚佳莹 董芃凡 常洪龙 坚增运 于 2019-09-12 设计创作，主要内容包括：本发明涉及微电子技术领域,具体涉及一种基于层状过渡金属硫化物的柔性光电探测器及其制备方法。本发明光电探测器由柔性衬底、过渡金属硫化物薄膜和金属电极由下而上依次叠加组成；其制备方法为：过渡金属硫化物是通过低成本、可大批量生产的水热法或物理气相沉积法制备而成,在过渡金属硫化物加入分散剂和增稠剂,采用球磨法分散材料形成过渡金属硫化物分散液,并采用旋涂法在柔性衬底上形成一层过渡金属硫化物纳米薄膜,最后以铜网为硬质掩膜版,采用真空镀膜法制备金属电极。本发明的柔性光电探测器制备工艺简单、产量高、成本低、柔性好。(The invention relates to the technical field of microelectronics, in particular to a flexible photoelectric detector based on a layered transition metal sulfide and a preparation method thereof. The photoelectric detector is formed by sequentially superposing a flexible substrate, a transition metal sulfide thin film and a metal electrode from bottom to top; the preparation method comprises the following steps: the transition metal sulfide is prepared by a hydrothermal method or a physical vapor deposition method which is low in cost and capable of being produced in large scale, a dispersing agent and a thickening agent are added into the transition metal sulfide, a ball milling method is adopted to disperse materials to form a transition metal sulfide dispersion liquid, a layer of transition metal sulfide nano film is formed on a flexible substrate by a spin-coating method, and finally a copper mesh is used as a hard mask to prepare a metal electrode by a vacuum coating method. The flexible photoelectric detector has the advantages of simple preparation process, high yield, low cost and good flexibility.)

1. The flexible photoelectric detector based on the layered transition metal sulfide is characterized in that: the detector structure consists of a flexible substrate, a transition metal sulfide thin film layer and a metal electrode which are sequentially stacked from bottom to top;

the flexible substrate is a polyethylene terephthalate (PET), polyvinyl chloride (PVC) or Polyimide (PI) film;

the transition metal sulfide is MoS prepared by a hydrothermal method or a supersonic speed jet milling method₂Or WS₂A nanomaterial;

the metal electrode is Ti/Au or Cr/Au.

2. The method of claim 1, wherein the flexible photodetector comprises a layered transition metal sulfide-based material, and the method comprises:

step 1) preparing transition metal sulfide, a dispersing agent and a thickening agent in a polytetrafluoroethylene planetary ball-milling tank with the volume of 100 ml;

step 2) adding agate grinding balls with diameters of 10mm and 5mm respectively according to the quantity proportion of 1/5-1/10, and performing sealed ball milling in a planetary ball mill tank for 3-96 hours at the rotating speed of 150-450 r/min to obtain a transition metal sulfide suspension;

step 3) cutting the flexible material into a square with the size of 1cm multiplied by 1cm, respectively ultrasonically cleaning the flexible material for 5-20 min by using absolute ethyl alcohol and deionized water, and blow-drying the flexible material by using a nitrogen gun to obtain a flexible substrate;

step 4) preparing a transition metal sulfide film on the surface of the flexible substrate by adopting a spin-coating method;

step 5) cutting the single-sided polyimide high-temperature adhesive tape into a rectangle with the width less than or equal to 200 mu m and the length of 5-10 mm, and fixing square-hole copper nets with different specifications on the upper surface of the transition metal sulfide film by using the cut single-sided polyimide high-temperature adhesive tape;

step 6) taking a square-hole copper mesh as a hard mask, firstly evaporating a Cr or Ti metal electrode with the thickness of 3-10 nm on the surface of the transition metal sulfide film by adopting a vacuum evaporation coating method, and then evaporating an Au metal electrode with the thickness of 20-80 nm;

step 7) taking down the square hole copper mesh on the surface of the transition metal sulfide and the polyimide high-temperature adhesive tape by using pointed tweezers to prepare a photoelectric detector;

and 8) carrying out photosensitive characteristic test on the light detector by adopting a semiconductor analyzer.

3. The method of claim 2, wherein the flexible photodetector is made of a layered transition metal sulfide, and the method comprises the following steps: the dispersing agent in the step 1) is isopropanol.

4. A method of making a layered transition metal sulfide based flexible photodetector according to claim 2 or 3, wherein: the thickening agent in the step 1) is ethyl cellulose.

5. The method of claim 4, wherein the flexible photodetector is made of a layered transition metal sulfide, and the method comprises the following steps: the ball milling mode in the step 2) is as follows: and rotating forwards for 20-30 min, stopping for 3-10 min, rotating backwards for 20-30 min, stopping for 3-10 min, and operating periodically.

6. The method of claim 5, wherein the flexible photodetector comprises a layered transition metal sulfide-based material, and the method comprises: the spin coating method in the step 4) comprises the following specific steps:

1) vacuum adsorbing the flexible substrate at the central position of the spin coater;

2) the rotating speed of the spin coater is set to be 1000-5000 r/min; setting the time to be 30-80 s;

3) absorbing 0.3-0.8 ml of transition metal sulfide suspension by using 1ml of disposable drop irrigation, and dripping a drop of suspension at the center of the flexible substrate after the rotating speed of the spin coater is stable;

4) and after the spin coater stops running, obtaining the transition metal sulfide film on the upper surface of the flexible substrate.

7. The method of claim 6, wherein the flexible photodetector comprises a layered transition metal sulfide-based material, and the method comprises: and 5), the square-hole copper meshes with different specifications in the step 5) are transmission electron microscope copper meshes.

8. The method of claim 7, wherein the flexible photodetector comprises a layered transition metal sulfide-based material, and the method comprises: the specific method for fixing the square-hole copper mesh in the step 5) comprises the following steps: two cut rectangular single-sided polyimide high-temperature adhesive tapes are taken and crossed and stuck to the center of the copper mesh in a cross shape and stuck to the surface of the transition metal sulfide film.

9. The method of claim 8, wherein the flexible photodetector comprises a layered transition metal sulfide: the vacuum evaporation conditions in the step 6) are as follows: vacuum degree of 5X 10 or less^-4Pa, metal Cr or Ti evaporation rate is

Technical Field

The invention relates to the technical field of microelectronics, in particular to a flexible photoelectric detector based on a layered transition metal sulfide and a preparation method thereof.

Background

The layered transition metal sulfide is a planar two-dimensional material with a graphene-like structure, layers are bonded together by weak van der waals force, and each monomolecular layer is formed by strong covalent bonding. MX2(M ═ Mo, W, Nb, Ti, etc.; X ═ S, Se, Te) type transition metal chalcogenides have a graphite-like layered hexagonal close-packed structure and a narrow band gap, and thus exhibit excellent performance in the fields of light, electricity, lubrication, catalysis, and the like. Wherein, molybdenum disulfide (MoS)₂) And tungsten disulfide (WS)₂) Are the most typical representatives of transition metal disulfides.

With the development of science and technology, people continuously pursue portable wearable electronic equipment, and the corresponding flexible sensing device is promoted to develop towards the directions of high efficiency, low cost, large-area manufacturing and the like. In recent years, in order to realize portability of the photodetector, design and preparation of the flexible photodetector have received extensive attention from researchers.

SnS adopted by Tao Y, Wu X et al₂Is made of photosensitive material and polyvinyl chloride (PVC) as flexible substrate, sticking one side of double-sided adhesive tape on the flexible substrate, and dripping SnS₂A photosensitive film was formed on the other side of the double-sided tape, and finally a photo detector with a 65 μm wide channel was fabricated using a 70 μm wide copper wire as a mask for patterning the electrode, as described in (Tao Y, Wu X, Wang W, et₂nanosheet microsphere film[J]Journal of Materials Chemistry C,2014,3(6): 1347-; however, the photosensitive film prepared by the method is not uniform, and the metal electrode pattern which is patterned by taking a copper wire as a mask is irregular.

The method for preparing the metal electrode by manually coating silver paste by using PET as a flexible substrate by Xinhang Chen, Zongyu Huang and the like prepares the SnS₂And a photodetector using a graphene mixture as a photosensitive material, see (photodythophores based on SnS)₂/Graphene Heterostructure on Rigid and Flexible Substrates[J].ChemNanoMat,2018, 4.); however, the error of the electrode channel distance prepared by manually coating silver paste is large, the channel distance is not easy to control, and the preparation of the photoelectric detector with the micro channel distance is not easy to realize. The thin film prepared by the spin coating method is relatively uniform, but the viscosity of the transition metal sulfide dispersion liquid prepared by the dispersing agent such as ethanol or isopropanol is low, and the dispersion liquid is thrown away by the spin coating method and is not easy to form a film.

Disclosure of Invention

In view of the above, the present invention provides a flexible photodetector based on a layered transition metal sulfide and a method for manufacturing the same, which solves the problems of non-uniform thickness of a photosensitive thin film, irregular pattern of a patterned metal electrode, and difficulty in controlling a channel distance between metal electrodes in the prior art.

In order to solve the problems in the prior art, the technical scheme of the invention is as follows: the flexible photoelectric detector based on the layered transition metal sulfide is characterized in that: the detector structure consists of a flexible substrate, a transition metal sulfide thin film layer and a metal electrode which are sequentially stacked from bottom to top;

the flexible substrate is a polyethylene terephthalate (PET), polyvinyl chloride (PVC) or Polyimide (PI) film;

the transition metal sulfide is MoS prepared by a hydrothermal method or a supersonic speed jet milling method₂Or WS₂A nanomaterial;

the metal electrode is Ti/Au or Cr/Au.

A method for preparing a flexible photoelectric detector based on a layered transition metal sulfide is characterized by comprising the following steps:

step 1) preparing transition metal sulfide, a dispersing agent and a thickening agent in a polytetrafluoroethylene planetary ball-milling tank with the volume of 100 ml;

step 2) adding agate grinding balls with diameters of 10mm and 5mm respectively according to the quantity proportion of 1/5-1/10, and performing sealed ball milling in a planetary ball mill tank for 3-96 hours at the rotating speed of 150-450 r/min to obtain a transition metal sulfide suspension;

step 3) cutting the flexible material into a square with the size of 1cm multiplied by 1cm, respectively ultrasonically cleaning the flexible material for 5-20 min by using absolute ethyl alcohol and deionized water, and blow-drying the flexible material by using a nitrogen gun to obtain a flexible substrate;

step 4) preparing a transition metal sulfide film on the surface of the flexible substrate by adopting a spin-coating method;

step 5) cutting the single-sided polyimide high-temperature adhesive tape into a rectangle with the width less than or equal to 200 mu m and the length of 5-10 mm, and fixing square-hole copper nets with different specifications on the upper surface of the transition metal sulfide film by using the cut single-sided polyimide high-temperature adhesive tape;

step 6) taking a square-hole copper mesh as a hard mask, firstly evaporating a Cr or Ti metal electrode with the thickness of 3-10 nm on the surface of the transition metal sulfide film by adopting a vacuum evaporation coating method, and then evaporating an Au metal electrode with the thickness of 20-80 nm;

step 7) taking down the square hole copper mesh on the surface of the transition metal sulfide and the polyimide high-temperature adhesive tape by using pointed tweezers to prepare a photoelectric detector;

and 8) carrying out photosensitive characteristic test on the light detector by adopting a semiconductor analyzer.

The dispersing agent in the step 1) is isopropanol.

The thickening agent in the step 1) is ethyl cellulose.

The ball milling mode in the step 2) is as follows: and rotating forwards for 20-30 min, stopping for 3-10 min, rotating backwards for 20-30 min, stopping for 3-10 min, and operating periodically.

The spin coating method in the step 4) comprises the following specific steps:

1) vacuum adsorbing the flexible substrate at the central position of the spin coater;

2) the rotating speed of the spin coater is set to be 1000-5000 r/min; setting the time to be 30-80 s;

3) absorbing 0.3-0.8 ml of transition metal sulfide suspension by using 1ml of disposable drop irrigation, and dripping a drop of suspension at the center of the flexible substrate after the rotating speed of the spin coater is stable;

4) and after the spin coater stops running, obtaining the transition metal sulfide film on the upper surface of the flexible substrate.

And 5), the square-hole copper meshes with different specifications in the step 5) are transmission electron microscope copper meshes.

The specific method for fixing the square-hole copper mesh in the step 5) comprises the following steps: two cut rectangular single-sided polyimide high-temperature adhesive tapes are taken and crossed and stuck to the center of the copper mesh in a cross shape and stuck to the surface of the transition metal sulfide film.

The vacuum evaporation conditions in the step 6) are as follows: vacuum degree of 5X 10 or less^-4Pa, metal Cr or Ti evaporation rate is

The evaporation rate of metal Au is

The purity of the Cr, Ti and Au metal is more than or equal to 5N.

Compared with the prior art, the invention has the following advantages:

1. the photosensitive materials used in the invention are all transition metal sulfides which have low cost and can be produced in large batch;

2. in the invention, the thickening agent is added in the process of preparing the transition metal sulfide photosensitive film to improve the viscosity of the transition metal sulfide suspension, so that the film prepared by adopting a spin-coating method has uniform thickness;

3. the invention takes copper nets with different specifications as hard mask plates, the patterned metal electrode patterns are regular, and the channel distance between the electrodes is controllable;

4. according to the invention, the flexible transparent material is used as the substrate, so that the prepared photoelectric detector can be bent at will;

5. the photoelectric detector produced by the method has the characteristics of simple preparation process, high yield, low cost and good flexibility.

Description of the drawings:

FIG. 1 is a schematic structural diagram of a flexible photoelectric detection device based on a layered transition metal sulfide;

FIG. 2 is a photograph of a test of a flexible photodetector device based on a layered transition metal sulfide;

FIG. 3-1, example 1 physical vapor deposition prepared MoS₂TEM photograph before ball milling;

FIG. 3-2, example 1 physical vapor deposition prepared MoS₂TEM photograph after ball milling;

FIGS. 3-3 MoS prepared in example 1₂I-V curve graphs of the flexible photoelectric detector under different illumination intensities under 405nm point laser;

FIGS. 3-4 MoS prepared in example 1₂A cycle I-T curve graph of the flexible photoelectric detector under 405nm point laser and different illumination intensities;

FIGS. 3-5 MoS prepared in example 1₂An I-T curve graph of a period of the flexible photoelectric detector under 405nm point laser; the optical power is: 0.285mW/cm²；

FIG. 4-1, WS prepared by physical vapor deposition of example 2₂TEM photograph before ball milling;

FIG. 4-2, WS prepared by physical vapor deposition of example 2₂TEM photograph after ball milling;

WS prepared in FIGS. 4-3, example 2₂The flexible photoelectric detector is under the condition of 405nm point laser, and the I-V curve is under different illumination intensities;

WS prepared in example 2, FIGS. 4-4₂A cycle I-T curve graph of the flexible photoelectric detector under 405nm point laser and different illumination intensities;

FIGS. 4-5 MoS prepared in example 2₂An I-T curve graph of a period of the flexible photoelectric detector under 405nm point laser; the optical power is: 0.285mW/cm²；

FIG. 5-1, example 3 hydrothermal preparation of MoS₂TEM photograph before ball milling;

FIG. 5-2, example 3 hydrothermal preparation of MoS₂TEM photograph after ball milling;

FIGS. 5-3 MoS prepared in example 3₂I-V curve graphs of the flexible photoelectric detector under different illumination intensities under 405nm point laser;

FIGS. 5-4 MoS prepared in example 3₂A cycle I-T curve graph of the flexible photoelectric detector under 405nm point laser and different illumination intensities;

FIGS. 5-5 MoS prepared in example 3₂Under the condition of 405nm point laser, the I-T curve chart of one period of the flexible photoelectric detector shows that the optical power is as follows: 0.285mW/cm²。

Detailed Description

The structure of the flexible photoelectric detector based on the layered transition metal sulfide is formed by a flexible substrate, a transition metal sulfide thin film layer and a metal electrode which are sequentially overlapped from bottom to top, as shown in figure 1;

the flexible substrate is a polyethylene terephthalate (PET), polyvinyl chloride (PVC) or Polyimide (PI) film;

the transition metal sulfide is a nano material which can be produced in large scale and is prepared by a hydrothermal method or a supersonic speed airflow pulverization method; the transition metal sulfide material prepared by a hydrothermal method is serious in agglomeration, the layered transition metal sulfide prepared by a supersonic airflow pulverization method is more in layers and difficult to form a film, so a dispersing agent is required to be added, the material is dispersed by a ball milling method, and a thickening agent is required to be added for facilitating spin coating and film forming due to the fact that the viscosity of a solution after the dispersing agent is added and ball milling is low.

The metal electrode is Ti/Au or Cr/Au.

The method for preparing the layered transition metal sulfide-based flexible photoelectric detector comprises the following steps:

1. preparing transition metal sulfide, a dispersing agent and a thickening agent in a polytetrafluoroethylene planetary ball milling tank with the volume of 100 ml;

the dispersant is isopropanol; the thickening agent is ethyl cellulose.

2. Adding agate grinding balls with the diameters of 10mm and 5mm according to the quantity proportion of 1/5-1/10, and performing sealed ball milling in a planetary ball milling tank for 3-96 h at the rotating speed of 150-450 r/min to obtain a transition metal sulfide suspension;

the ball milling mode is as follows: rotating forwards for 20-30 min, stopping for 3-10 min, rotating backwards for 20-30 min, stopping for 3-10 min, and operating periodically;

3. cutting the flexible material into a square with the size of 1cm multiplied by 1cm, respectively ultrasonically cleaning the flexible material for 5-20 min by using absolute ethyl alcohol and deionized water, and drying the flexible material by using a nitrogen gun to obtain a flexible substrate;

4. preparing a transition metal sulfide film on the surface of the flexible substrate by adopting a spin-coating method;

the spin coating method comprises the following specific steps:

1) vacuum adsorbing the flexible substrate at the central position of the spin coater;

2) the rotating speed of the spin coater is set to be 1000-5000 r/min; setting the time to be 30-80 s;

3) absorbing 0.3-0.8 ml of transition metal sulfide suspension by using 1ml of disposable drop irrigation, and dripping a drop of suspension at the center of the flexible substrate after the rotating speed of the spin coater is stable;

4) after the spin coater stops running, obtaining a transition metal sulfide film on the upper surface of the flexible substrate;

5. cutting the single-sided polyimide high-temperature adhesive tape into a rectangle with the width of less than or equal to 200 mu m and the length of 5-10 mm, and fixing a square-hole copper mesh on the upper surface of the transition metal sulfide film by using the cut single-sided polyimide high-temperature adhesive tape;

the square-hole copper mesh with different specifications is a transmission electron microscope copper mesh available in the market. The channel spacing between the detector electrodes can be adjusted by selecting square-hole copper meshes with different rib widths;

the concrete method for fixing the copper mesh comprises the following steps: taking two cut rectangular single-sided polyimide high-temperature adhesive tapes, crosswise sticking the two cut rectangular single-sided polyimide high-temperature adhesive tapes to the center of the copper mesh, and sticking the two cut rectangular single-sided polyimide high-temperature adhesive tapes to the surface of the transition metal sulfide film;

6. taking square-hole copper nets with different specifications as hard mask plates, firstly evaporating Cr or Ti metal electrodes with the thickness of 3-10 nm on the surface of the transition metal sulfide film by adopting a vacuum evaporation coating method, and then evaporating Au metal electrodes with the thickness of 20-80 nm;

the vacuum evaporation conditions were: vacuum degree of 5X 10 or less^-4Pa, metal Cr or Ti evaporation rate is

The evaporation rate of metal Au is

The purity of the Cr, Ti and Au metal is more than or equal to 5N;

7. taking down the square hole copper mesh on the surface of the transition metal sulfide and the polyimide high-temperature adhesive tape by using pointed tweezers to prepare a photoelectric detector;

8. the light sensor was tested for light sensitivity using a semiconductor analyzer, as shown in fig. 2.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.