阅读说明：本技术 一种基于薄膜晶体管的柔性透明浮栅存储器及其制备方法 (Flexible transparent floating gate memory based on thin film transistor and preparation method thereof ) 是由 张国成 马超 邢俊杰 秦世贤 陈惠鹏 郭太良 于 2021-09-26 设计创作，主要内容包括：本发明涉及一种基于薄膜晶体管的柔性透明浮栅存储器及其制备方法,该存储器采用底栅顶接触的晶体管结构,器件自下而上依次是透明衬底和透明栅极,绝缘层、浮栅层、隧穿层、有机半导体层及透明源漏电极。透明聚合物绝缘薄膜或金属氧化物绝缘薄膜,电荷捕获层和薄的聚合物绝缘薄膜(隧穿层)以及有机半导体聚合物薄膜,最后采用喷涂的方法制备碳纳米管电极。本发明制作的柔性透明存储器件通过利用材料自身特性以及工艺改善,在实现了器件高透明率和柔性的同时,还获得了很高的存储性能；本发明制备的柔性透明浮栅存储器制备工艺简单,易操作,投入成本低,且得到的存储器性能优异,具有成为柔性透明、高性能有机电子的潜力。(The invention relates to a flexible transparent floating gate memory based on a thin film transistor and a preparation method thereof. Transparent polymer insulating film or metal oxide insulating film, charge trapping layer, thin polymer insulating film (tunneling layer) and organic semiconductor polymer film, and finally preparing the carbon nanotube electrode by spraying. The flexible transparent memory device manufactured by the invention utilizes the characteristics of the material and the improvement of the process, and obtains high memory performance while realizing high transparency and flexibility of the device; the flexible transparent floating gate memory prepared by the invention has the advantages of simple preparation process, easy operation and low investment cost, and the obtained memory has excellent performance and has the potential of becoming flexible transparent high-performance organic electrons.)

1. A flexible transparent floating gate memory based on a thin film transistor is characterized in that the floating gate memory is of a bottom gate top contact structure and comprises a flexible transparent substrate, a flexible transparent charge trapping layer, a flexible transparent active layer and a flexible transparent electrode which are sequentially stacked;

the flexible transparent substrate comprises a substrate, a gate electrode and an insulating layer which are sequentially stacked;

the flexible transparent charge trapping layer includes a floating gate layer and a tunneling layer, which are sequentially stacked.

2. The flexible transparent floating gate memory based on thin film transistor according to claim 1, wherein the substrate is a transparent insulating material or a hybrid substrate is formed by inserting a thermosetting substrate into a flexible material; alternative transparent insulating materials include, but are not limited to, PET, PI.

3. The thin film transistor-based flexible transparent floating gate memory according to claim 1, wherein the gate electrode layer is made of a transparent conductive material, and the optional transparent conductive material includes but is not limited to a conductive conjugated polymer, a carbon-based material and a metal nano-material.

4. The thin film transistor-based flexible transparent floating gate memory according to claim 1, wherein the material of the insulating layer is made of transparent metal oxide insulating material or transparent polymer material, wherein the transparent polymer material can be selected from PVP, PVA and PMMA.

5. The thin film transistor-based flexible transparent floating gate memory according to claim 4, wherein the floating gate layer is composed of one-dimensional nanowire material, nano-metal particles, matrix-forming quantum dots, or matrix-forming polymer nanoparticle material.

6. The thin film transistor-based flexible transparent floating gate memory according to claim 1, wherein the tunneling layer is made of a transparent polymer material, and the transparent polymer material is selected from PVP, PVA and PMMA.

7. The thin film transistor-based flexible transparent floating gate memory according to claim 1, wherein the flexible transparent active layer is composed of an organic small molecule material, an organic conjugated polymer material or a mixture of one or two conjugated polymer materials.

8. The thin film transistor-based flexible transparent floating gate memory according to claim 1, wherein the flexible transparent electrode is composed of a mixture of one-dimensional conductive materials, conductive polymer materials, or ionic gel materials.

9. A preparation method of a flexible transparent floating gate memory based on a thin film transistor is characterized by comprising the following steps:

1) cleaning the transparent substrate with a cleaning solution, washing with deionized water for multiple times, and drying;

2) preparing a gate electrode on a transparent substrate;

3) dissolving a transparent polymer material in an organic solvent, coating the material on a gate electrode after the material is completely dissolved, and annealing to prepare an insulating layer; or depositing a transparent metal oxide insulating material on the gate electrode by adopting an ALD (atomic layer deposition) mode to prepare an insulating layer;

4) dissolving the material for the floating gate layer in an organic solvent, coating the material on the insulating layer after the material is completely dissolved, and annealing to obtain the floating gate layer;

5) dissolving a material for the tunneling layer in an organic solvent, coating the material on the floating gate layer after the material is completely dissolved, and annealing to obtain the tunneling layer;

6) dissolving the material for the flexible transparent active layer in an organic solvent, coating the material on the tunneling layer after the material is completely dissolved, and annealing to prepare the active layer;

7) and finally, preparing a transparent electrode on the tunneling layer to prepare the flexible transparent floating gate memory based on the thin film transistor.

10. The method for preparing the flexible transparent floating gate memory based on the thin film transistor according to claim 9, wherein the coating manner includes but is not limited to spin coating/doctor blading/printing.

Technical Field

The invention belongs to the field of organic photoelectric materials, and particularly relates to a flexible transparent floating gate memory based on a thin film transistor and a preparation method thereof.

Background

Over the past decade, efforts have been made to develop stretchable and transparent electronic products. The emergence of a new generation of flexible transparent electronic products represented by smart displays, artificial skins, wearable sensors, and the like, is incomparable with traditional electronic products. This puts new demands on memory technology, and the current mainstream MOSFET flash memory technology has not been able to meet the demand of new products well. 2017 technology and marketing reports of Yole definition have emphasized the growing importance of emerging NVM technologies.

Floating gate memories based on organic thin film transistors are an important direction to solve the new memory types. The organic thin film transistor memory has attracted the attention of international researchers due to the advantages of low manufacturing cost, low-temperature preparation, flexibility and large-area production, and the organic thin film transistor memory can be better produced and used in practical application due to the characteristics of non-destructive reading and manufacturing advantages (the structure of the organic thin film transistor memory can be compatible with an integrated circuit).

Many challenges remain in the processability and performance of flexible materials, most of which suffer from drawbacks such as limited conductivity or mechanical instability. There are also applications where structural engineering can be used to make up for the inherent deficiencies of materials. Furthermore, transparent semiconductors still represent a small part of all known organic semiconductors, and fewer transparent low-cost semiconductors can be used. Therefore, the invention aims to provide a floating gate memory with flexibility and high transparency.

Disclosure of Invention

The invention aims to solve the problems and provides a flexible transparent floating gate memory based on a thin film transistor.

In order to achieve the purpose, the invention adopts the technical scheme that:

a flexible transparent floating gate memory based on a thin film transistor is of a bottom gate top contact structure and comprises a flexible transparent substrate, a flexible transparent charge trapping layer, a flexible transparent active layer and a flexible transparent electrode which are sequentially stacked;

the flexible transparent substrate comprises a substrate, a gate electrode and an insulating layer which are sequentially stacked;

the flexible transparent charge trapping layer includes a floating gate layer and a tunneling layer, which are sequentially stacked.

Further, the substrate is made of a transparent insulating material or a thermosetting substrate is inserted into a flexible material to form a mixed substrate; alternative transparent insulating materials include, but are not limited to, PET, PI.

Further, the gate electrode layer is made of a transparent conductive material, and the transparent conductive material can be selected from a group consisting of a conductive conjugated polymer, a carbon-based material and a metal nano material.

Further, the material used for the insulating layer is made of transparent metal oxide insulating material or transparent polymer material, wherein the transparent polymer material can be selected from PVP, PVA, PMMA.

Further, the floating gate layer is made of one-dimensional nanowire material, nano-metal particles, quantum dots forming a matrix or polymer nano-particle material forming a matrix.

Further, the tunneling layer is made of a transparent polymer material, and the transparent polymer material can be selected from PVP, PVA, and PMMA.

Further, the flexible transparent active layer is made of an organic small molecule material, an organic conjugated polymer material or a mixture of one or two conjugated polymer materials.

Further, the flexible transparent electrode is made of a mixture of one-dimensional conductive materials, conductive polymer materials or ionic gel materials.

The invention further provides a preparation method of the flexible transparent floating gate memory based on the thin film transistor, which comprises the following steps:

1) cleaning the transparent substrate with a cleaning solution, washing with deionized water for multiple times, and drying; wherein the washing solution can be methanol, acetone or anhydrous ethanol.

2) Preparing a gate electrode on a transparent substrate; specifically, a gate electrode is prepared on the substrate in the step 1) by spin coating, evaporation, atomic layer deposition and other modes; the specific preparation method is selected according to materials.

3) Dissolving a transparent polymer material in an organic solvent, coating the material on a gate electrode after the material is completely dissolved, and annealing to prepare an insulating layer, wherein the organic solvent can be PGMEA, chloroform and other materials; or depositing transparent metal oxide insulating material such as Al on the gate electrode by ALD method₂O₃And preparing the insulating layer.

4) And dissolving the material for the floating gate layer in an organic solvent, coating the material on the insulating layer after the material is completely dissolved, and annealing to obtain the floating gate layer.

5) Dissolving a material for the tunneling layer in an organic solvent, coating the material on the floating gate layer after the material is completely dissolved, and annealing to obtain the tunneling layer; wherein, the organic solvent can be PGMEA, chloroform, etc.

6) Dissolving the material for the flexible transparent active layer in an organic solvent, coating the material on the tunneling layer after the material is completely dissolved, and annealing to prepare the active layer; wherein, the organic solvent can be chlorobenzene, chloroform and other materials.

7) And finally, preparing a transparent electrode on the tunneling layer to prepare the flexible transparent floating gate memory based on the thin film transistor. The transparent electrode is prepared by mixing a one-dimensional conductive material, a conductive polymer material or an ionic gel material on an active layer in a mode of evaporation coating, spraying, screen printing, printing and the like.

Further, the coating method includes, but is not limited to, spin coating/doctor blading/printing.

The invention has the following advantages:

the memory manufactured by the invention achieves high transparency and flexibility of the device and also obtains higher storage performance through reasonable arrangement of the structure, the material and the process. The preparation method of the flexible transparent memory is simple, easy to operate, low in investment cost and suitable for further popularization and application.

Drawings

FIG. 1 is a schematic structural diagram of a flexible transparent floating gate memory based on a thin film transistor;

FIG. 2 is a schematic structural diagram of a flexible transparent floating gate memory based on a thin film transistor prepared in example 1;

FIG. 3 is a graph of device memory characteristics of a thin film transistor-based flexible transparent floating gate memory prepared in example 1;

FIG. 4 is a schematic diagram of the transparency of the device of the thin film transistor-based flexible transparent floating gate memory prepared in example 1;

fig. 5 is a device flexibility performance detection graph of the flexible transparent floating gate memory based on the thin film transistor prepared in example 1.

The designations in the drawings are as follows:

110-transparent electrode, 120-semiconductor layer, 130-tunneling layer, 140-floating gate layer, 150-polymer insulating layer, 160-transparent substrate and gate electrode.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, the flexible transparent floating gate memory based on the thin film transistor comprises a flexible transparent substrate, a flexible transparent charge trapping layer, a flexible transparent active layer (organic semiconductor layer), and flexible transparent source and drain electrodes (transparent electrode source and drain electrodes), wherein the flexible transparent substrate comprises a substrate, a gate electrode and an insulating layer which are sequentially stacked, and the flexible transparent charge trapping layer comprises a floating gate layer and a tunneling layer which are sequentially stacked. The flexible transparent floating gate memory is characterized in that a transparent substrate is selected, a transparent gate electrode is prepared on the transparent substrate in a spraying/screen printing/printing mode, and then a polymer solution or metal oxide with high transparency is prepared into a transparent insulating layer in a spin coating/blade coating/printing mode. The floating gate layer is prepared by dissolving PVP quantum dot blend, a one-dimensional nanowire material, nano metal particles and the like in an organic solvent with a certain proportion in a spin coating/blade coating/printing mode and the like. These materials have a large gap or high transparency, and therefore, a floating gate layer having high transparency is obtained. The tunneling layer plays a role in blocking charges on one hand, and on the other hand, the tunneling of the charges is ensured to be carried out under a certain voltage, and the tunneling layer is prepared by selecting a low-concentration insulating layer material through spin coating, blade coating, printing and other modes. The organic micromolecule material or the organic conjugated polymer material or the mixture of one or two conjugated polymer materials is dissolved in organic solvent with a certain proportion to form the active layer material, and the active layer material is prepared by spin coating, blade coating, printing and other modes. Higher transparency is achieved by controlling the thickness. And finally, preparing the transparent electrode on the active layer by using a mixture of a one-dimensional conductive material, a conductive polymer material or an ionic gel material in modes of evaporation plating, spraying, screen printing, printing and the like.

Example 1

1) The ITO-PET conductive film with the size of 1.5cm multiplied by 0.05mm is cleaned in methanol, acetone and absolute ethyl alcohol, washed with deionized water for three times and dried by nitrogen to be used as a substrate.

2) Depositing aluminum oxide on the substrate in the step 1) by adopting an ALD mode, wherein the thickness of the aluminum oxide is 100 nm.

3) Diluting 5mg/ml silver nanowire stock solution to 0.05mg/ml, coating the solution on the alumina deposition layer obtained in the step 2) by taking the solution as a material in a spin coating mode, rotating at the spin coating speed of 2000rpm/min for 60s, and then annealing at 120 ℃ for 5 min.

4) Dissolving 150mg of PVP and 15mg of HAD cross-linking agent in PGMEA and stirring for 24 h; diluting 150mg/ml PVP to 15mg/ml, coating the solution on the silver nanowire coating obtained in the step 3) by using the solution as a material in a spin coating mode, firstly spin-coating at 600rpm/min for 5s, then spin-coating at 2000rpm/min for 30s, and then annealing at 120 ℃ in a glove box for 2 h.

5) The semiconductor polymer PDVT-10 is dissolved in chlorobenzene solvent in the proportion of 5mg/ml and heated at 80 ℃ for 1 hour to be completely dissolved. And (3) coating the solution on the PVP coating obtained in the step 4) by using the solution as an active layer material in a spin coating mode, spin-coating at 2000rpm/min for 60s, and annealing at 120 ℃ for 10 min.

6) And (3) spraying the carbon nano tube on the coating obtained in the step 5) by using a special mask plate in a spraying mode to form a source-drain electrode with the width of 1mm and the thickness of 30 um.

Fig. 3 is a schematic view of a storage window curve of the flexible transparent memory prepared in this embodiment. As can be seen from FIG. 3, the duration memory window is 52V, and the memory ratio is about 10³-10⁴. The main reason is that besides the properties of the material, the thickness of the semiconductor layer is reduced by spin coating, so that the transparency is improved, and the integral transparency of the device is improved.

Fig. 4 is a schematic transparency diagram of the flexible transparent memory prepared in this embodiment, and it can be seen that the flexible transparent memory has higher transmittance for light with wavelength of 350-800 nm.

Fig. 5 is a flexible performance test chart of the flexible transparent memory prepared in this example, and it can be seen that the device can maintain the on-off ratio of about 3 orders of magnitude after 500 bends with a radius of 27 mm.

The above-mentioned embodiments, which further illustrate the objects, technical solutions and advantages of the present invention, should be understood that the above-mentioned embodiments are only preferred embodiments of the present invention, and should not be construed as limiting the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.