An ultra-flexible all-organic bipolar wearable photodetector and its preparation method

Abstract

The present invention belongs to the technical field of semiconductor optoelectronic devices, specifically an ultra-flexible all-organic bipolar wearable photodetector and a method for preparing the same. The ultra-flexible all-organic bipolar wearable photodetector has a stacked structure, which comprises, from bottom to top, an ultra-flexible organic substrate, a first flexible organic electrode, a first flexible organic interface layer, an organic semiconductor mixture, a second flexible organic interface layer, and a second flexible organic electrode. The present invention realizes an all-organic photodetector with intrinsic flexibility, which can fit human skin and can operate in scenarios of multiple bending, folding, and twisting; the polarity conversion of the current signal can be achieved by bending or flipping the device, simplifying the structure and mechanism of the traditional bipolar photocurrent output device; the preparation process of the device only involves a solution method, with simple processes and equipment and a short production cycle, which can reduce the preparation cost of the detector and facilitate large-scale production.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor optoelectronic devices, and in particular relates to an all-organic bipolar wearable photodetector and a preparation method thereof. Background Art

[0002] Imparting mechanical flexibility and practical functionality to photodetectors is a hot topic in current optoelectronic device research. Currently, commercial photodetectors are still primarily based on inorganic materials, which are inherently rigid and therefore difficult to meet the requirements of next-generation wearable and flexible electronics. Compared to inorganic semiconductors, organic semiconductors offer unique advantages in the field of flexible electronics due to their intrinsic flexibility and ease of processing. Organic photodetectors using organic semiconductors as the photosensitive layer rival low-noise silicon photodetectors in nearly all performance metrics. Bipolar photocurrent output characteristics can imbue photodetectors with practical functionality and offer new avenues for addressing traditional challenges. Traditional pn junction photodiodes adhere to the physical principle of unidirectional current flow and rely on the combined effects of the photovoltaic, photoelectrochemical, and photothermoelectric effects to achieve bipolar photocurrent output. This places high demands on the selection of photosensitive materials and device fabrication. Furthermore, metal or metal oxide electrodes still dominate the field of organic photodetectors, hindering the realization of intrinsically flexible devices. Furthermore, the complex process of fabricating these metal or metal oxide electrodes, requiring thermal or electron beam deposition, significantly increases production costs and cycle times. Summary of the Invention

[0003] In view of the above technical status quo, the purpose of the present invention is to provide an ultra-flexible all-organic bipolar wearable photodetector and a preparation method thereof.

[0004] The ultra-flexible all-organic bipolar wearable photodetector provided by the present invention has a layered stacked structure, which comprises, from bottom to top, an ultra-flexible organic substrate, a first flexible organic electrode, a first flexible organic interface layer, an organic semiconductor mixture, a second flexible organic interface layer, and a second flexible organic electrode; wherein:

[0005] The ultra-flexible organic substrate material is any one of PET, TPU, and SEBS;

[0006] The material of the first flexible organic interface layer is PEDOT:PSS (Clevios P ​​VP 4083), and the model number represents the ratio of the two; 4083 can be used as a substitute;

[0007] The organic semiconductor mixture is P3HT:PC71BM, with a mass ratio of 1:1.2-1.6; the preferred mass ratio is 1:1.5;

[0008] The second flexible organic interface layer is PEIE;

[0009] The first flexible organic electrode and the second flexible organic electrode are made of the same material PH1000;

[0010] P3HT is a polymer of 3-hexylthiophene;

[0011] PH1000 is a type of PEDOT:PSS; the model is Clevios PH1000, so it is also called PH1000;

[0012] PC71BM (Phenyl-C71-butyric-acid-methyl ester), a fullerene derivative,

[0013] CAS:609771-63-3;

[0014] PEIE (polyethylenimineethoxylated), ethoxylated polyethyleneimine.

[0015] In the present invention, it is preferred that:

[0016] The thickness of the first flexible organic electrode is 200-400 nm;

[0017] The thickness of the first flexible organic interface layer is 10-30 nm;

[0018] The thickness of the organic semiconductor mixture is 400-800 nm;

[0019] The thickness of the second flexible organic interface layer is 10-30 nm;

[0020] The thickness of the second flexible organic electrode is 200-400 nm.

[0021] In the present invention, in the organic semiconductor mixture, P3HT and PC71BM are mixed to form a bulk heterojunction, photodetection is achieved through the formed bulk heterojunction, and collection of photogenerated carriers is achieved through the first electrode layer PH1000 and the second electrode layer PH1000.

[0022] The present invention also provides a method for preparing an ultra-flexible all-organic bipolar wearable photodetector, the specific steps of which are as follows:

[0023] (1) Cleaning ultra-soft organic substrates;

[0024] (2) Ultraviolet ozone (UVO) pretreatment of ultra-soft organic substrates, the treatment time is 15-25 minutes;

[0025] (3) Spraying the first organic electrode layer PH1000 on the ultra-flexible organic substrate using a spraying process, and immediately annealing at 100-120 degrees Celsius for 10-20 minutes after spraying to obtain a smooth and uniform film;

[0026] (4) Spraying the first organic interface layer 4083 on the first organic electrode layer PH1000 by a spraying process, and annealing at 100-120 degrees Celsius for 20-30 minutes after spraying to obtain a smooth and uniform film;

[0027] (5) Spin coating an organic photosensitive active layer P3HT:PC71BM on the first organic interface layer 4083 by a spin coating process, and annealing at 100-120 degrees Celsius for 20-40 minutes after the spin coating is completed to obtain a smooth and uniform film;

[0028] (6) Spraying a second flexible organic interface layer PEIE on the organic photosensitive active layer P3HT:PC71BM by a spraying process to obtain a smooth and uniform film;

[0029] (7) The second organic electrode layer PH1000 is sprayed on the second flexible organic interface layer PEIE by a spraying process to obtain a smooth and uniform film.

[0030] The ultra-flexible all-organic bipolar wearable photodetector described in the present invention has the following characteristics and advantages compared with the existing technology:

[0031] (1) Realize an all-organic photodetector with intrinsic flexibility that can conform to human skin and operate under multiple bending, flexing, and twisting scenarios;

[0032] (2) The polarity of the current signal can be converted by bending or flipping the device, which simplifies the structure and mechanism of the traditional bipolar photocurrent output device;

[0033] (3) The preparation process of the device only involves the solution method, which has simple technology and equipment and a short production cycle. It can greatly reduce the preparation cost of the detector and is conducive to large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a physical picture of the ultra-flexible all-organic bipolar wearable photodetector in an embodiment of the present invention.

[0035] Figure 2 This is a diagram of the structure of the ultra-flexible, all-organic bipolar wearable photodetector of the present invention.

[0036] Figure 3The photoelectric test results of the ultra-flexible all-organic bipolar wearable photodetector in Example 1 of the present invention are as follows: the output curve of current over time when flipped at different angles, simulating sunlight on and off, and without bias; the device can stably output current when simulating sunlight on-off switching.

[0037] Figure 4 These are the photoelectric test results of the ultra-flexible all-organic bipolar wearable photodetector in Example 1 of the present invention: output curves of current over time when folded at different angles, simulating sunlight on and off, and without bias; the device can stably output current when simulating sunlight on-off switching.

[0038] Figure 5 These are the photoelectric test results of the ultra-flexible all-organic bipolar wearable photodetector in Example 2 of the present invention: output curves of current over time when flipped at different angles, simulating sunlight on and off, and without bias; the device can stably output current when simulating sunlight on-off switching.

[0039] The numbers in the figure are: 1 is the ultra-flexible organic substrate; 2 is the first flexible organic electrode; 3 is the first flexible organic interface layer; 4 is the organic semiconductor mixture; 5 is the second flexible organic interface layer; 6 is the second flexible organic electrode. DETAILED DESCRIPTION

[0040] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be noted that the embodiments described below are intended to facilitate understanding of the present invention and do not have any limiting effect on the present invention.

[0041] Example 1, the preparation steps are:

[0042] (1) Cleaning ultra-soft organic substrate PET;

[0043] (2) Ultraviolet ozone (UVO) pretreatment of ultra-flexible organic substrate PET, the treatment time is 25 minutes;

[0044] (3) The first organic electrode layer PH1000 was sprayed on the ultra-flexible organic substrate by a spraying process. After the spraying was completed, it was immediately annealed at 100 degrees Celsius for 15 minutes to obtain a smooth and uniform film;

[0045] (4) Spraying the first organic interface layer 4083 on the first organic electrode layer PH1000 by a spraying process, and annealing at 150 degrees Celsius for 30 minutes after spraying to obtain a smooth and uniform film;

[0046] (5) Spin coating an organic photosensitive active layer P3HT:PC71BM on the first organic interface layer 4083 by a spin coating process. After the spin coating is completed, the organic photosensitive active layer is annealed at 100 degrees Celsius for 30 minutes to obtain a smooth and uniform film with a thickness of about 600 nm.

[0047] (6) Spraying a second flexible organic interface layer PEIE on the organic photosensitive active layer P3HT:PC71BM by a spraying process to obtain a smooth and uniform film;

[0048] (7) The second organic electrode layer PH1000 is sprayed on the second flexible organic interface layer PEIE by a spraying process to obtain a smooth and uniform film. At this point, the preparation of the ultra-flexible all-organic bipolar wearable photodetector is completed.

[0049] The ultra-flexible all-organic bipolar wearable photodetector prepared, when irradiated with simulated sunlight and without external bias, outputs forward photocurrent when flipped 0°, 45°, and 90°, and gradually reaches the minimum. After the flip angle exceeds 90°, the polarity of the device photocurrent reverses, and the maximum reverse current is reached at 180°.

[0050] The ultra-flexible all-organic bipolar wearable photodetector prepared outputs a forward photocurrent when exposed to simulated sunlight and without an external bias when unfolded. After being folded 90°, the photocurrent reaches a minimum. When further folded to 180°, the device outputs a photocurrent of opposite polarity.

[0051] Example 2, the preparation steps are as follows (changing the thickness and annealing time of the organic photosensitive active layer P3HT:PC71BM):

[0052] (1) Cleaning ultra-soft organic substrate PET;

[0053] (2) Ultraviolet ozone (UVO) pretreatment of ultra-flexible organic substrate PET, the treatment time is 25 minutes;

[0054] (3) The first organic electrode layer PH1000 was sprayed on the ultra-flexible organic substrate by a spraying process. After the spraying was completed, it was immediately annealed at 100 degrees Celsius for 15 minutes to obtain a smooth and uniform film;

[0055] (4) Spraying the first organic interface layer 4083 on the first organic electrode layer PH1000 by a spraying process, and annealing at 150 degrees Celsius for 30 minutes after spraying to obtain a smooth and uniform film;

[0056] (5) Spin coating an organic photosensitive active layer P3HT:PC71BM on the first organic interface layer 4083 by a spin coating process. After the spin coating is completed, the organic photosensitive active layer is annealed at 100 degrees Celsius for 15 minutes to obtain a smooth and uniform film with a thickness of about 400 nm.

[0057] (6) Spraying a second flexible organic interface layer PEIE on the organic photosensitive active layer P3HT:PC71BM by a spraying process to obtain a smooth and uniform film;

[0058] (7) The second organic electrode layer PH1000 is sprayed on the second flexible organic interface layer PEIE by a spraying process to obtain a smooth and uniform film. At this point, the preparation of the ultra-flexible all-organic bipolar wearable photodetector is completed.

[0059] The ultra-flexible all-organic bipolar wearable photodetector prepared was flipped 0°, 90°, and 180° under simulated sunlight without an external bias. When no flipping occurred, the device output a forward photocurrent. When flipped 90°, the photocurrent output by the device dropped to the minimum. After the flipping angle exceeded 90°, the polarity of the device photocurrent reversed, reaching the maximum reverse photocurrent at 180°.

Claims

1. An ultra-flexible all-organic bipolar wearable photodetector, characterized in that: It has a layered stacking structure, which includes, from bottom to top, an ultra-flexible organic substrate, a first flexible organic electrode, a first flexible organic interface layer, an organic semiconductor mixture, a second flexible organic interface layer, and a second flexible organic electrode; wherein: The ultra-flexible organic substrate material is any one of PET, TPU, and SEBS; The material of the first flexible organic interface layer is PEDOT:PSS (Clevios P ​​VP 4083); The organic semiconductor mixture is P3HT:PC71BM, and the mass ratio of the two is 1:1.2-1.6; The second flexible organic interface layer is PEIE; The first flexible organic electrode and the second flexible organic electrode are made of the same material PH1000; P3HT is a polymer of 3-hexylthiophene; PH1000 is a type of PEDOT:PSS; the model is Clevios PH1000; PC71BM is a type of fullerene derivative; PEIE is ethoxylated polyethyleneimine.

2. The ultra-flexible all-organic bipolar wearable photodetector according to claim 1, characterized in that: The thickness of the first flexible organic electrode is 200-400 nm.

3. The ultra-flexible all-organic bipolar wearable photodetector according to claim 1, characterized in that: The thickness of the first flexible organic interface layer is 10-30 nm.

4. The ultra-flexible all-organic bipolar wearable photodetector according to claim 1, characterized in that: The thickness of the organic semiconductor mixture is 400-800 nm.

5. The ultra-flexible all-organic bipolar wearable photodetector according to claim 1, characterized in that: The thickness of the second flexible organic interface layer is 10-30 nm.

6. The ultra-flexible all-organic bipolar wearable photodetector according to claim 1, characterized in that: The thickness of the second flexible organic electrode is 200-400 nm.

7. The ultra-flexible all-organic bipolar wearable photodetector according to claim 1, characterized in that: In the organic semiconductor mixture, P3HT and PC71BM are mixed to form a bulk heterojunction, photodetection is achieved through the formed bulk heterojunction, and collection of photogenerated carriers is achieved through the first electrode layer PH1000 and the second electrode layer PH1000.

8. The method for preparing the ultra-flexible all-organic bipolar wearable photodetector according to any one of claims 1 to 7, characterized in that: The specific steps are as follows: (1) Cleaning ultra-soft organic substrates; (2) Ultra-soft organic substrate pretreatment with UV-ozone, the treatment time is 15-25 minutes; (3) Spraying the first organic electrode layer PH1000 on the ultra-flexible organic substrate using a spraying process, and immediately annealing at 100-120 degrees Celsius for 10-20 minutes after spraying to obtain a smooth and uniform film; (4) Spraying the first organic interface layer 4083 on the first organic electrode layer PH1000 by a spraying process, and annealing at 100-120 degrees Celsius for 20-30 minutes after spraying to obtain a smooth and uniform film; (5) Spin coating an organic photosensitive active layer P3HT:PC71BM on the first organic interface layer 4083 by a spin coating process, and annealing at 100-120 degrees Celsius for 20-40 minutes after the spin coating is completed to obtain a smooth and uniform film; (6) Spraying a second flexible organic interface layer PEIE on the organic photosensitive active layer P3HT:PC71BM by a spraying process to obtain a smooth and uniform film; (7) The second organic electrode layer PH1000 is sprayed on the second flexible organic interface layer PEIE by a spraying process to obtain a smooth and uniform film.

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