A stretchable organic phototransistor based on stable bulk heterojunction and a preparation method thereof

Abstract

This invention discloses a stretchable organic phototransistor based on a stable bulk heterojunction and its fabrication method. The transistor has a bottom-gate-top-contact top electrode structure and, from bottom to top, comprises a stretchable substrate, a stretchable gate electrode, a stretchable insulating layer, a stretchable organic active layer, coplanar stretchable source / drain electrodes, and a stretchable encapsulation layer. This invention uses a mixture of semiconductor polymers and elastomer polymers as the stretchable electron donor and highly photosensitive organic small molecules as the electron acceptor. An organic heterojunction is formed through solution blending to serve as the stretchable organic active layer. All functional layers are fabricated using stretchable materials, and the device is assembled using a thermal bonding transfer method. This phototransistor achieves a balance between stretchability and photoelectric performance, exhibiting not only high carrier mobility and high photoresponse sensitivity but also maintaining stable photoelectric performance under high mechanical stretching deformation.

Description

Technical Field

[0001] This application relates to the field of semiconductor device technology, specifically to a stretchable organic phototransistor based on a stable bulk heterojunction and its fabrication method. Background Technology

[0002] Stretchable electronic devices possess excellent mechanical bending, foldability, and stretchability, enabling seamless attachment to irregular, curved, and moving objects. Therefore, stretchable electronic devices show great potential in fields such as physiological monitoring, medical diagnostics, medical implantation, human-computer interaction, flexible robotics, and augmented reality. The realization of stretchable electronic devices mainly involves sacrificing electronic device density and electrical performance to achieve stretchability, and preparing elastic semiconductor thin films by blending conjugated polymers with elastomeric polymers. The Zhenan Bao research group at Stanford University prepared elastic semiconductor thin films by blending conjugated polymers with elastomeric polymers. This method fully utilizes the flexibility, controllable molecular structure, solution processability, and mobility comparable to amorphous Si of polymer semiconductors, while achieving a balance between the mechanical and electrical properties of semiconductor thin films. Based on this strategy, they successfully fabricated intrinsically stretchable organic field-effect transistors. Organic phototransistors possess characteristics such as high sensitivity, low noise, integrated light detection and signal amplification functions, and convenient circuit integration. They can be used as prototype devices for studying the optoelectronic properties of specific materials and hold promise for realizing photoelectric sensors.

[0003] However, in the existing technology, research on stretchable organic phototransistors is very limited. In particular, the technical solution of applying bulk heterojunction structure to stretchable organic phototransistors has not been fully developed, which makes it difficult for stretchable organic phototransistors to maintain stable optoelectronic performance under high mechanical stretching deformation. Summary of the Invention

[0004] Based on previous research and existing problems, this invention provides a stretchable organic phototransistor based on a stable bulk heterojunction and its fabrication method, which can solve the technical problem that stretchable organic phototransistors are difficult to maintain stable photoelectric performance under high mechanical stretching deformation.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A stretchable organic phototransistor based on a stable heterojunction comprises, from bottom to top, a stretchable substrate, a stretchable gate electrode, a stretchable insulating layer, a stretchable organic active layer, a stretchable source electrode and a stretchable drain electrode located on the same plane, and a stretchable encapsulation layer. The stretchable organic phototransistor has a bottom gate top contact upper electrode structure.

[0006] Preferably, the stretchable organic active layer is made of a stretchable organic active material with a thickness of 50-300 nm; Stretchable organic active materials are mixtures of stretchable electron donor materials and non-stretchable electron acceptor materials in a mass ratio of 1~9:1~9.

[0007] Preferably, the stretchable electron donor material is a mixture of semiconductor polymer and elastomer polymer in a mass ratio of 1~9:1~9; The semiconductor polymer is any one of poly(2,5-bis(2-octyldodecyl)-3,6-bis(thiophen-2-yl)dionepyrrole[3,4-c]pyrrole-1,4-dione-alt-thiophene[3,2-b]thiophene), poly((2,5-bis(5-decyl-1-pentyl)–3,6-bis(thiophen-2-yl)pyrrole[3,4-c]pyrrole-1,4(2H,5H)-dione)-alt-((E)–1,2-bis(thiophen-2-yl)ethane), poly(2,5-bis(3-alkylthiophen-2-yl)thiophene[3,2-b]thiophene), poly(tetrathiopheneacetic acid dionepyrrole), polyisoindigo dithiophene, and poly(3-hexylthiophene); The elastomer polymer is any one of hydrogenated styrene-butadiene block copolymer, polydimethylsiloxane, natural rubber, styrene-butadiene rubber, ethylene propylene rubber, butyl rubber, and polyurethane elastomer.

[0008] Preferably, the non-stretchable electron acceptor material is any one of fullerene C61, fullerene derivative PC61BM, perylene diimide (PDI) derivative, and fused ring electron acceptor Y6.

[0009] Preferably, the stretchable substrate, the stretchable insulating layer, and the stretchable encapsulation layer are all made of elastomeric polymers with thicknesses of 200µm-3mm, 500nm-2µm, and 10-1000µm, respectively. The elastomer polymer is any one of styrene-butadiene rubber, hydrogenated styrene-butadiene block copolymer, polydimethylsiloxane, natural rubber, ethylene propylene rubber, butyl rubber, and polyurethane elastomer.

[0010] Preferably, the stretchable gate electrode, stretchable source electrode, and stretchable drain electrode are all made of single-walled carbon nanotube material, and the single-walled carbon nanotube is any one of P2-SWNT, P3-SWNT, P5-SWNT, P8-SWNT, and P9-SWNT.

[0011] In addition, this invention also proposes a method for fabricating a stretchable organic phototransistor based on a stable bulk heterojunction as mentioned above, comprising the following steps: S1. A stretchable substrate, a stretchable gate electrode, a stretchable insulating layer, a stretchable organic active layer, a stretchable source electrode, a stretchable drain electrode, and a stretchable encapsulation layer are respectively fabricated on a substrate with a self-assembled molecular layer. S2. The stretchable substrate is transferred from the substrate with the self-assembled molecular layer. The stretchable gate electrode is transferred to the surface of the stretchable substrate by thermal bonding. Then, the stretchable insulating layer, stretchable organic active layer, stretchable source electrode and stretchable drain electrode, and stretchable encapsulation layer are transferred to the corresponding upper structure surface by thermal bonding in sequence to obtain a stretchable organic phototransistor based on a stable body heterojunction.

[0012] Preferably, in S1, the substrate is any one of silicon wafer, glass, ceramic, metal, quartz, and hard alloy; The preparation process of the substrate with the self-assembled molecular layer is as follows: the substrate is ultrasonically cleaned sequentially with detergent, deionized water, acetone and ethanol, dried with a nitrogen gun and then subjected to ultraviolet peroxidation treatment to obtain a clean substrate; the clean substrate is subjected to vacuum heating treatment or solution immersion treatment with any one of octadecyltrimethoxysilane, octadecyltrichlorosilane, octadecyltrichlorosilane and phenyltrichlorosilane to obtain the substrate with the self-assembled molecular layer.

[0013] Preferably, the stretchable gate electrode, stretchable source electrode, and stretchable drain electrode are all prepared by spraying, and the solvent used for spraying is water, ethanol, isopropanol, or any mixture thereof. The spraying conditions are as follows: substrate temperature 40-200°C, distance between spray gun nozzle and substrate 3-20mm, spraying rate 0.5-5mL / min, and spraying amount 0.5~5mL.

[0014] Preferably, in S2, the heat bonding process is carried out in a vacuum drying oven; The heat bonding conditions are: vacuum degree 0.1~10 Pascal, heating temperature 50~150°C, and heat treatment time 0.5~5 hours.

[0015] Compared with the prior art, the present invention provides a stretchable organic phototransistor based on a stable bulk heterojunction and its fabrication method, which has the following beneficial effects: This invention achieves intrinsic stretchability of the entire device through a fully stretchable stacked structure design, comprising, from bottom to top, a stretchable substrate, a stretchable gate electrode, a stretchable insulating layer, a stretchable organic active layer, stretchable source electrodes and stretchable drain electrodes located on the same plane, and a stretchable encapsulation layer. By designing the stretchable organic phototransistor as a top electrode structure, light can be effectively incident on the organic active layer from the top, improving light absorption efficiency. Simultaneously, it ensures good ohmic contact between the source / drain electrodes and the active layer, optimizing the carrier injection and extraction process. Based on this, a bulk heterojunction formed by solution blending of stretchable electron donor material (a mixture of semiconductor polymer and elastomeric polymer) and non-stretchable electron acceptor material (highly photosensitive organic small molecules) is used as the stretchable organic active layer. The semiconductor polymer provides the charge transport framework, and the elastomeric polymer forms a continuous flexible network. The two are blended to form an interpenetrating network structure. During stretching, the elastomeric network can buffer stress, inhibit semiconductor phase breakage, and maintain the charge transport pathway, while the acceptor small molecules are uniformly dispersed in the donor network to form an efficient exciton separation interface, thereby achieving synergistic optimization of carrier mobility and stretchability.

[0016] By limiting the stretchable substrate, insulating layer, and encapsulation layer to be made of elastomeric polymers, it is ensured that the dielectric / support / protective layers other than the active layer are also stretchable, thus avoiding delamination, wrinkling, or failure of the overall device during stretching due to interlayer modulus mismatch.

[0017] Furthermore, by employing single-walled carbon nanotubes as stretchable gate, source, and drain electrodes, the one-dimensional network structure can dissipate energy through slip and rearrangement during stretching, thus maintaining the conductive path, ensuring effective gate control, and efficient source / drain carrier injection / extraction, thereby maintaining the transistor on / off ratio and photoresponse linearity.

[0018] Ultimately, the stretchable organic phototransistor provided in this application can maintain stable photoelectric performance under high mechanical stretching deformation, solving the problem that stretchable organic phototransistors in the prior art are difficult to maintain stable photoelectric performance under high mechanical stretching deformation, and achieving the technical effects of high carrier mobility, fast photoresponse speed and high photoresponse sensitivity. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the stretchable organic phototransistor based on a stable heterojunction disclosed in this invention.

[0020] Figure 2 The figures show the transfer characteristic curves of the stretchable organic phototransistor based on a stable heterojunction prepared in Example 1 of this invention under conditions of no light and low-energy white light (1.0 mW / cm²). Figure 2 (a) represents the unstretched condition; Figure 2 (b) Under the condition of 50% elongation; Figure 2 (c) is under the condition of 100% elongation.

[0021] Figure 3 The image shows the change in the light-dark current ratio with gate voltage for the stretchable organic phototransistor based on a stable heterojunction prepared in Example 1 of this invention under the conditions of no stretching, stretching ratio of 50%, and stretching ratio of 100%.

[0022] Figure 4 The photoresponse sensitivity of the stretchable organic phototransistor based on a stable heterojunction prepared in Example 1 of the present invention varies with gate voltage under the conditions of no stretching, stretching ratio of 50%, and stretching ratio of 100%.

[0023] Figure 5 The figures show the transfer characteristic curves of the stretchable organic phototransistor based on a stable heterojunction prepared in Example 2 of this invention under conditions of no light and low-energy white light (1.0 mW / cm²). Figure 5 (a) represents the unstretched condition; Figure 5 (b) is the condition of 50% elongation.

[0024] Figure 6 The figures show the transfer characteristic curves of the stretchable organic phototransistor based on a stable heterojunction prepared in Example 3 of this invention under conditions of no light and low-energy white light (1.0 mW / cm²). Figure 6 (a) represents the unstretched condition; Figure 6 (b) is the condition of 50% elongation. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] like Figure 1 As shown, the stretchable organic phototransistor based on a stable bulk heterojunction provided by this invention has a bottom-gate top-contact structure. Its structure, from bottom to top, consists of a stretchable substrate, a stretchable gate electrode, a stretchable insulating layer, a stretchable organic active layer, a stretchable source electrode and a stretchable drain electrode located on the same plane, and a stretchable encapsulation layer. The stretchable organic active layer is made of an organic heterojunction material formed by solution blending a stretchable electron donor material and a non-stretchable electron acceptor material.

[0027] This application utilizes a stretchable organic active layer formed from stretchable electron donor (N-type semiconductor) material and non-stretchable electron acceptor (P-type semiconductor) material in a stretchable organic phototransistor, which can significantly improve the carrier mobility, photoresponse speed, photoresponse sensitivity, and photoelectric performance stability of the prepared organic phototransistor under high mechanical stretching deformation.

[0028] The mass ratio of the stretchable electron donor material to the non-stretchable electron acceptor material is 1~9:1~9, preferably 3~6:6~3; in the stretchable electron donor material, the mass ratio of the elastomeric polymer to the semiconductor polymer is 1~9:1~9, preferably 5~9:1~5; the thickness of the stretchable organic active layer is 50-300 nm, preferably 100-150 nm; the thickness of the stretchable substrate is 200 µm-3 mm, preferably 500 µm-1.5 mm; the thickness of the stretchable insulating layer is 500-2000 nm, preferably 1000-1500 nm; and the thickness of the stretchable encapsulation layer is 10-1000 µm, preferably 200-500 µm.

[0029] The following steps are used to fabricate the above-mentioned stretchable organic phototransistor based on a bulk heterojunction: Step 1: Fabrication of the stretchable substrate Stretchable substrates are prepared on substrates with self-assembled molecular layers by drop coating, spin coating, blade coating and roll coating.

[0030] Step 2: Fabrication of the stretchable gate electrode A stretchable gate electrode is fabricated on a substrate with a self-assembled molecular layer by spraying.

[0031] Step 3: Preparation of the stretchable insulating layer Stretchable insulating layers are prepared on substrates with self-assembled molecular layers by spin coating, blade coating, roller coating, brush coating, and stretch coating.

[0032] Step 4: Preparation of the stretchable organic active layer Stretchable organic active layers are prepared on substrates with self-assembled molecular layers by spin coating, blade coating, roller coating, brush coating, and stretching.

[0033] Step 5: Fabrication of stretchable source electrode and stretchable drain electrode Stretchable source electrodes and stretchable drain electrodes are fabricated by spraying on a substrate with a self-assembled molecular layer.

[0034] Step 6: Fabrication of the stretchable encapsulation layer Stretchable encapsulation layers are prepared on substrates with self-assembled molecular layers by drop coating, spin coating, blade coating, and roll coating.

[0035] Step 7: Fabrication of Stretchable Optotransistors Based on Bulk Heterojunctions Using pointed tweezers, the stretchable substrate is transferred from the substrate with the self-assembled molecular layer, and then gently placed over the stretchable gate electrode from one side. The stretchable gate electrode is then transferred onto the stretchable substrate using a thermal bonding method. Following the same method and steps, the stretchable insulating layer, the stretchable organic active layer, the stretchable source electrode, and the stretchable drain electrode are sequentially transferred onto the stretchable gate electrode. Finally, the stretchable encapsulation layer is transferred onto the stretchable source and gate electrodes, thus fabricating a stretchable organic phototransistor based on a stable heterojunction.

[0036] To make the technical solution and effects of this application clearer and more explicit, basic transfer characteristics of the stretchable phototransistor based on a stable heterojunction were first tested under dark conditions to obtain electrical parameters such as carrier mobility in the saturation region. Then, its transfer characteristics were tested under low-energy white light conditions to compare the differences in electrical performance under dark and low-energy white light conditions. Calculations were performed according to the following formula: Light sensitivity = (Current under illumination - Current under darkness) / Incident light power sensed in the transistor channel Photocurrent / Dark current = (Transistor current under illumination - Transistor current under darkness) / Transistor current under darkness Example 1 The steps for fabricating a stretchable organic phototransistor based on a stable bulk heterojunction in this embodiment are as follows: 1) Using a silicon wafer as a substrate, ultrasonically clean the silicon wafer for 5 minutes at a power of 30 watts and a frequency of 40 kHz with detergent, deionized water, acetone and ethanol in sequence. After drying with a nitrogen gun, treat the cleaned silicon wafer with ultraviolet ozone for 20 minutes. Then place the silicon wafer and octadecyltrimethoxysilane in the same petri dish and place the petri dish in a vacuum drying oven at a vacuum degree of 0.1 Pa and a temperature of 120°C for 3 hours. After the vacuum drying oven cools down to room temperature, remove the petri dish to obtain a silicon wafer with a self-assembled molecular layer.

[0037] 2) Place the silicon wafer with the self-assembled molecular layer on a hot plate. Slowly draw 0.8 ml of SEBS toluene solution (concentration 180 mg / mL) using a 1 mL syringe and uniformly drop it onto the silicon wafer with the self-assembled molecular layer. Then, maintain the temperature at 50°C for 3 hours, followed by 90°C for 1 hour to obtain a stretchable substrate with a thickness of 1.2 nm. (Note: To ensure that no air bubbles appear in the prepared stretchable substrate, the drop-coating rate should be as slow as possible, and the last two drops of SEBS toluene solution should not be dropped onto the silicon wafer with the self-assembled molecular layer.)

[0038] 3) Place the silicon wafer with the self-assembled molecular layer on a hot stage at 50°C and keep it for 5 minutes. Use a 5mL pipette to transfer 1.5mL of carbon nanotube P3-SWNT isopropanol solution (0.2mg / mL) into the volume chamber of the spray gun. Then, spray it evenly onto the silicon wafer with the self-assembled molecular layer at a rate of 1.5mL / min (where the distance between the spray gun nozzle and the silicon wafer is 6mm) to obtain the stretchable gate electrode.

[0039] 4) Place the silicon wafer with the self-assembled molecular layer at the center of the spin coater rotor. Use a 1mL pipette to draw 200mL of SEBS cyclohexane solution (concentration 80mg / mL), then evenly drop 160mL of the SEBS cyclohexane solution onto the silicon wafer with the self-assembled molecular layer. Start the spin coater and maintain a speed of 1000 rpm for 1 minute. Finally, remove the silicon wafer and anneal it on a hot plate at 80°C for 1 hour to obtain the stretchable insulating layer.

[0040] 5) Place the silicon wafer with the self-assembled molecular layer at the center of the spin coater rotor. Use a 100µL pipette to draw 50µL of a chlorobenzene solution of (2,5-bis(2-octyldodecyl)-3,6-di(thiophene-2-yl)dione-pyrrolo[3,4-c]pyrrolo-1,4-dione-3-thiophenolo[3,2-b]thiophene) / hydrogenated styrene-butadiene block copolymer / fullerene C61 (wherein the mass ratio of the three substances is 4:5:1 and the concentration is 20mg / ml). Then, uniformly drop 35µL of this solution onto the silicon wafer. Start the spin coater and maintain a speed of 2000 rpm for 1 minute. Finally, remove the silicon wafer and place it on a hot plate at 180°C for 20 minutes to obtain the stretchable organic active layer.

[0041] 6) Place the silicon wafer with the self-assembled molecular layer on a magnet, and then place the mask on the silicon wafer to tightly adhere the mask to the silicon wafer with the self-assembled molecular layer. Gently place the magnet and silicon wafer on a hot stage at 110°C for 15 minutes. Then, use a 1mL pipette to draw 1mL of isopropanol solution of carbon nanotube P3-SWNT (concentration of 0.15mg / mL) and spray it uniformly onto the silicon wafer with the self-assembled molecular layer at a rate of 3mL / min (wherein, the distance between the nozzle of the spray gun and the silicon wafer is 9mm). This will give you a patterned stretchable source electrode and a stretchable drain electrode.

[0042] 7) Place the silicon wafer with the self-assembled molecular layer on a hot plate. Slowly draw 0.6 ml of SEBS toluene solution (concentration 110 mg / mL) with a 1 mL syringe and uniformly drop it onto the silicon wafer with the self-assembled molecular layer. Then, maintain the temperature at 60°C for 1 hour, and then at 90°C for 1 hour to obtain a stretchable encapsulation layer with a thickness of 500 µm. (Note: To ensure that no air bubbles appear in the prepared stretchable encapsulation layer, the drop-coating rate should be as slow as possible, and the last two drops of SEBS toluene solution should not be dropped onto the silicon wafer with the self-assembled molecular layer.)

[0043] 8) Gently transfer the stretchable substrate from the substrate with the self-assembled molecular layer using pointed tweezers. Then, gently cover the stretchable gate electrode from one side with the stretchable substrate and place it in a vacuum drying oven with a vacuum degree of 0.1 Pascals at 60°C for 20 minutes. After the temperature drops to room temperature, gently transfer the stretchable substrate off with pointed tweezers. This process transfers the stretchable gate electrode onto the stretchable substrate. Then, using the same method and steps, sequentially transfer the stretchable insulating layer, the stretchable organic active layer, and the stretchable source electrode and stretchable drain electrode located on the same plane onto the stretchable gate electrode. Finally, transfer the stretchable encapsulation layer onto the stretchable source and drain electrodes to obtain a stretchable organic phototransistor based on a stable heterojunction, as shown in the figure. Figure 1 As shown.

[0044] Figure 2 The graphs show the transfer characteristics of the stretchable organic phototransistor based on a stable heterojunction prepared in Example 1 under different stretching rates and under light and dark conditions. Figure 2 Analysis shows that the on-state current, off-state current, and threshold voltage of the phototransistor remain relatively stable under different tensile deformation rates, indicating that the phototransistor maintains stable electrical performance even under 50% and 100% tensile deformation. Furthermore, the phototransistor also exhibits significant differences in transfer characteristics under both light-free and light-bearing conditions. Figure 3 and Figure 4 It can be seen that the stretchable organic phototransistor based on a stable heterojunction prepared in Example 1 exhibits high photoresponse sensitivity and photocurrent-to-dark-current ratio, and the phototransistor still maintains a certain photoresponse sensitivity and photocurrent-to-dark-current ratio under different stretching deformation rates. These results all indicate that the stretchable organic phototransistor based on a stable heterojunction prepared in Example 1 can be used under conditions of large stretching deformation.

[0045] Example 2 This embodiment uses the same preparation method as Example 1, except that the stretchable organic active layer material in step 5) is replaced with a mixture of (2,5-bis(2-octyldodecyl)-3,6-di(thiophene-2-yl)dionepyrrolo[3,4-c]pyrrolo-1,4-dione-3-thiophenolo[3,2-b]thiophene) / hydrogenated styrene-butadiene block copolymer / fullerene C61 (wherein the mass ratio of the three substances is 3:4:3 and the concentration is 20 mg / ml), to prepare a stretchable organic phototransistor based on a stable heterojunction.

[0046] Figure 5 (a) The transfer characteristic curves of the stretchable organic phototransistor based on a stable heterojunction prepared in Example 2 under both illuminated and dark conditions. Figure 5 (a) Analysis shows that the phototransistor exhibits ideal transfer characteristic curves under both light-free and light-bearing conditions. Furthermore, the transfer characteristic curves of the phototransistor show significant differences under light-free and light-bearing conditions, indicating that the stretchable organic phototransistor based on a stable bulk heterojunction prepared in Example 2 has a significant photoresponse and can maintain stable photoresponse capability even under large tensile strain (e.g., ...). Figure 5 (b) shown).

[0047] Example 3 This embodiment uses the same preparation method as Example 1, except that the stretchable organic active layer material in step 5) is replaced with a mixture of poly(2,5-bis(3-alkylthiophen-2-yl)thiophene[3,2-b]thiophene / hydrogenated styrene-butadiene block copolymer / fullerene C61 (wherein the mass ratio of the three substances is 3:4:3 and the concentration is 20 mg / ml), and a stretchable organic phototransistor based on a stable heterojunction is prepared.

[0048] Figure 6 The graphs show the transfer characteristics of the stretchable organic phototransistor based on a stable heterojunction prepared in Example 3 under light and dark conditions and under different stretching deformation rates. Figure 6 (a) and Figure 6 (b) Analysis shows that the phototransistor exhibits significant differences in transfer characteristics under both illuminated and dark conditions, and this difference is unaffected by the 50% stretching deformation. These results demonstrate that the stretchable organic phototransistor based on a stable bulk heterojunction prepared in Example 3 can maintain relatively stable photoresponse capability even under large tensile strain. Moreover, the method for preparing a stretchable organic phototransistor based on a stable bulk heterojunction provided by this invention is applicable to a variety of semiconductor polymer materials, greatly broadening the application prospects of stretchable organic phototransistors in the field of ultrathin, lightweight, and flexible photosensitive semiconductor devices.

[0049] In summary, this invention successfully fabricated a stretchable organic phototransistor based on a stable bulk heterojunction by employing an organic heterojunction formed from an electron donor stretchable organic semiconductor material and an electron acceptor organic small molecule material as the stretchable organic active layer material system. The fabricated stretchable organic phototransistor exhibits significant photoresponse under conditions of no light and low-energy white light, and this photoresponse maintains relative stability under different stretching deformations. These results all indicate that the stretchable organic phototransistor based on a stable bulk heterojunction prepared in this invention can be used in environments with high mechanical deformation.

[0050] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions claimed by the present invention.

Claims

1. A stretchable organic phototransistor based on a stable body heterojunction, characterized in that, From bottom to top, it includes a stretchable substrate, a stretchable gate electrode, a stretchable insulating layer, a stretchable organic active layer, a stretchable source electrode and a stretchable drain electrode located on the same plane, and a stretchable encapsulation layer. The stretchable organic phototransistor has a bottom gate top contact upper electrode structure.

2. The stretchable organic phototransistor based on stable body heterojunction according to claim 1, wherein, The stretchable organic active layer is made of stretchable organic active material with a thickness of 50-300 nm; Stretchable organic active materials are mixtures of stretchable electron donor materials and non-stretchable electron acceptor materials in a mass ratio of 1~9:1~9.

3. The stretchable organic phototransistor based on stable body heterojunction according to claim 2, wherein, The stretchable electron donor material is a mixture of semiconductor polymer and elastomer polymer in a mass ratio of 1~9:1~9; The semiconductor polymer is any one of poly(2,5-bis(2-octyldodecyl)-3,6-bis(thiophen-2-yl)dionepyrrole[3,4-c]pyrrole-1,4-dione-alt-thiophene[3,2-b]thiophene), poly((2,5-bis(5-decyl-1-pentyl)–3,6-bis(thiophen-2-yl)pyrrole[3,4-c]pyrrole-1,4(2H,5H)-dione)-alt-((E)–1,2-bis(thiophen-2-yl)ethane), poly(2,5-bis(3-alkylthiophen-2-yl)thiophene[3,2-b]thiophene), poly(tetrathiopheneacetic acid dionepyrrole), polyisoindigo dithiophene, and poly(3-hexylthiophene); The elastomer polymer is any one of hydrogenated styrene-butadiene block copolymer, polydimethylsiloxane, natural rubber, styrene-butadiene rubber, ethylene propylene rubber, butyl rubber, and polyurethane elastomer.

4. A stretchable organic phototransistor based on a stable bulk heterojunction according to claim 2, characterized in that, The non-stretchable electron acceptor material is any one of fullerene C61, fullerene derivative PC61BM, perylene diimide (PDI) derivative, or fused ring electron acceptor Y6.

5. A stretchable organic phototransistor based on a stable bulk heterojunction according to claim 1, characterized in that, The stretchable substrate, stretchable insulating layer, and stretchable encapsulation layer are all made of elastomeric polymers with thicknesses of 200µm-3mm, 500nm-2µm, and 10-1000µm, respectively. The elastomer polymer is any one of styrene-butadiene rubber, hydrogenated styrene-butadiene block copolymer, polydimethylsiloxane, natural rubber, ethylene propylene rubber, butyl rubber, and polyurethane elastomer.

6. A stretchable organic phototransistor based on a stable bulk heterojunction according to claim 1, characterized in that, The stretchable gate electrode, stretchable source electrode, and stretchable drain electrode are all made of single-walled carbon nanotube material, which can be any one of P2-SWNT, P3-SWNT, P5-SWNT, P8-SWNT, and P9-SWNT.

7. A method for fabricating a stretchable organic phototransistor based on a stable bulk heterojunction as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1. A stretchable substrate, a stretchable gate electrode, a stretchable insulating layer, a stretchable organic active layer, a stretchable source electrode, a stretchable drain electrode, and a stretchable encapsulation layer are respectively fabricated on a substrate with a self-assembled molecular layer. S2. The stretchable substrate is transferred from the substrate with the self-assembled molecular layer. The stretchable gate electrode is transferred to the surface of the stretchable substrate by thermal bonding. Then, the stretchable insulating layer, stretchable organic active layer, stretchable source electrode and stretchable drain electrode, and stretchable encapsulation layer are transferred to the corresponding upper structure surface by thermal bonding in sequence to obtain a stretchable organic phototransistor based on a stable body heterojunction.

8. The method for fabricating a stretchable organic phototransistor based on a stable heterojunction according to claim 7, characterized in that, In S1, the substrate can be any one of silicon wafer, glass, ceramic, metal, quartz, or cemented carbide; The preparation process of the substrate with the self-assembled molecular layer is as follows: the substrate is ultrasonically cleaned sequentially with detergent, deionized water, acetone and ethanol, dried with a nitrogen gun and then subjected to ultraviolet peroxidation treatment to obtain a clean substrate; the clean substrate is subjected to vacuum heating treatment or solution immersion treatment with any one of octadecyltrimethoxysilane, octadecyltrichlorosilane, octadecyltrichlorosilane and phenyltrichlorosilane to obtain the substrate with the self-assembled molecular layer.

9. The method for fabricating a stretchable organic phototransistor based on a stable bulk heterojunction according to claim 7, characterized in that, The stretchable gate electrode, stretchable source electrode, and stretchable drain electrode are all prepared by spraying. The solvent used for spraying is water, ethanol, isopropanol, or any mixture thereof. The spraying conditions are as follows: substrate temperature 40-200°C, distance between spray gun nozzle and substrate 3-20mm, spraying rate 0.5-5mL / min, and spraying amount 0.5~5mL.

10. The method for fabricating a stretchable organic phototransistor based on a stable bulk heterojunction according to claim 7, characterized in that, In S2, the heat bonding process is carried out in a vacuum drying oven; The heat bonding conditions are: vacuum degree 0.1~10 Pascal, heating temperature 50~150°C, and heat treatment time 0.5~5 hours.

Images