P-n heterojunction thin film with excellent photo-thermoelectric performance and preparation method of p-n heterojunction thin film

Abstract

The invention discloses a p-n heterojunction film with excellent photo-thermoelectric performance and a preparation method thereof, and belongs to the technical field of material preparation. The p-n heterojunction thin film is composed of n-type poly (benzodifuran diketone) (PBFDO) and p-type poly (3, 4-ethylenedioxythiophene: polystyrene sulfonate) (PEDOT: PSS), and the p-n heterojunction thin film is prepared by using a method of vacuum filtration and mask combination after dispersion by using a certain polar solvent. The p-n heterojunction thin film provided by the invention has good photo-thermal electric conversion capability, and shows the potential of wide application in the fields of energy conversion and flexible electronic devices.

Description

Technical Field

[0001] The present invention relates to the technical field of material preparation, and in particular to a pn heterojunction film with excellent photothermal and electric properties and a preparation method thereof. Background Art

[0002] Photothermoelectric materials are green and environmentally friendly clean energy materials that can convert the temperature difference caused by absorbed light into electrical energy. The essence of the photothermoelectric effect is a combination of the Seebeck effect and the photothermal effect. It refers to the process in which the material generates heat energy after being illuminated by light, and the temperature difference (ΔT) generated by the heat energy drives the movement of internal carriers, and finally realizes the conversion to electrical energy. Photothermoelectrics can be used as an ideal candidate for solar energy conversion and utilization in the near-infrared region, thereby realizing multi-energy conversion and collection.

[0003] Traditional inorganic photothermoelectric materials are mainly prepared by growing them on wafers through high-temperature epitaxial growth methods. Photothermoelectric devices made from these materials have complex preparation processes and high costs. Compared with inorganic materials, organic photothermoelectric materials have the advantages of good flexibility, easy processing, and low cost. They can be used in wearable devices, electronic skin, smart textiles and other fields. Therefore, making various organic photothermoelectric materials into flexible photothermoelectric detectors has gradually become a research hotspot.

[0004] Compared with single materials, constructing composite materials is beneficial to give full play to the advantages of each component material to synergistically improve the photothermal efficiency of the material. Among the many composite strategies proposed, constructing a semiconductor-based heterojunction is one of the most widely used strategies, because it can not only achieve effective spatial separation of electron-hole pairs, but also effectively broaden the response range of the material in the solar spectrum. The so-called heterojunction is the interface area formed by the contact of two different semiconductors. According to the different conductivity types of the two materials, heterojunctions can be divided into homogeneous heterojunctions (pp junctions or nn junctions) and heterogeneous heterojunctions (pn). Heterojunctions usually have excellent optoelectronic properties that cannot be achieved by the junctions of the two semiconductors themselves. For this reason, the construction of heterojunctions is currently widely used in the manufacture of ultra-high-speed switching devices, solar cells, photodetectors, and semiconductor optoelectronic devices.

[0005] In the prior art, the preparation of pn heterojunctions usually involves compounding carbon nanotubes or layered materials with polymers to prepare thin films or fiber materials, which is costly and complex. Summary of the invention

[0006] In order to solve the technical problems existing in the prior art, the present invention provides a pn heterojunction film with excellent photothermoelectric performance and a preparation method thereof. The film of the present invention is composed of PBFDO and PEDOT:PSS and is prepared by a vacuum filtration method; the preparation method has the characteristics of being simple and easy to operate, safe and environmentally friendly. The PEDOT:PSS / PBFDO heterojunction film exhibits excellent photothermoelectric performance in air, showing the potential for wide application in the fields of energy conversion and optoelectronic devices.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0008] In one aspect, the present invention provides a method for preparing a pn heterojunction thin film having excellent photothermoelectric properties, comprising:

[0009] Step 1: Add the PEDOT:PSS aqueous solution into the solvent and ultrasonically prepare a uniformly dispersed solution, which is recorded as PP solution;

[0010] Step 2: Add the PBFDO solution to the solvent and ultrasonically prepare a uniformly dispersed solution, which is referred to as PB solution;

[0011] Step 3: Mask the filter membrane with a plastic wrap, add one of the solutions prepared in step 1 or step 2 to the unmasked position, and perform suction filtration. After the suction filtration is completed, remove the plastic wrap, and then perform vacuum drying; the width of the mask is 0-2.5 mm from the center line of the filter membrane;

[0012] Step 4: Take another plastic wrap mask and place it on the unmasked position of step 3, then add the other solution prepared in step 1 or step 2 to the unmasked position, and filter it. After the filtration is completed, tear off the plastic wrap, and then vacuum dry to obtain a pn heterojunction film with excellent photothermal and electric properties; the PP film on the pn heterojunction film is in direct contact with the PB film, and the width of the intermediate layer is 0-5mm.

[0013] Furthermore, in step 1, the concentration of the PP solution is 0.2-5 mg / ml; in step 2, the concentration of the PB solution is 0.2-5 mg / ml; in step 3, the filter membrane is a polyvinylidene fluoride filter membrane with a pore size of 0.45 μm.

[0014] Preferably, the ultrasonic time in step 1 and step 2 is 0.5 to 2 hours.

[0015] Preferably, in step 3, the filter membrane is first wetted with a solvent.

[0016] On the other hand, the present invention also provides a pn heterojunction film with excellent photothermoelectric properties prepared by the above method, wherein the thickness of the PP film and the PB film is not less than 0.1 μm (excluding the filter membrane).

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention relates to the preparation of a pn heterojunction film composed of poly(3,4-ethylenedioxythiophene:polystyrene sulfonate) (PEDOT:PSS) and poly(benzodifurandione) (PBFDO); the film is composed of PBFDO and PEDOT:PSS, ethanol is used as a dispersant, and is prepared by a vacuum filtration method. The preparation method has the characteristics of being simple and easy to operate, safe and environmentally friendly. The PEDOT:PSS / PBFDO heterojunction film exhibits excellent photothermoelectric properties in the air, showing the potential for wide application in the fields of energy conversion and optoelectronic devices. The film of the present invention not only exhibits excellent stability in the air, but also has excellent photothermoelectric properties. These characteristics make the technology have broad application prospects in the fields of energy conversion, green energy and optoelectronic devices, and open up a new direction for the development of photothermoelectric materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the chemical structure of PEDOT:PSS and PBFDO;

[0020] Figure 2 The present invention is a process flow chart for preparing a pn heterojunction thin film;

[0021] Figure 3 This is a diagram showing the photothermoelectric performance of EtOH on a pn heterojunction film in Example 1 of the present invention;

[0022] Figure 4 This is a diagram showing the photothermoelectric performance of DMSO on a pn heterojunction film in Example 2 of the present invention;

[0023] Figure 5 This is a diagram showing the photothermoelectric performance of 3H2O on a pn heterojunction film according to Example 3 of the present invention;

[0024] Figure 6 This is a photothermal and electrical performance diagram of a P-type and N-type thin film connected by applying silver paste in Example 4 of the present invention. DETAILED DESCRIPTION

[0025] In order to make the technical problems to be solved, technical solutions and advantages of the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0026] In the present invention, the materials used are all commercially available unless otherwise specified. Among them, the original mass concentration of PEDOT:PSS is 13.55 mg / ml, and the chemical structure is shown in Figure 1 ; The original mass concentration of PBFDO is 10 mg / ml, and the chemical structure is shown in Figure 1.

[0027] The present invention provides a pn heterojunction film with excellent photothermal and electrical properties and a preparation method thereof. The preparation process schematic diagram is shown in Figure 2 ;include:

[0028] Step 1: Take a PEDOT:PSS aqueous solution (mass concentration of 13.55 mg / ml) and add it to a solvent to prepare a solution with a mass concentration of 0.5-5 mg / ml, and ultrasonicate for 0.5-2h, which is recorded as PP solution;

[0029] Step 2: Take a PBFDO (mass concentration of 10 mg / ml) aqueous solution and add it to the solvent to prepare a solution with a mass concentration of 0.5-5 mg / ml, and ultrasonicate for 0.5-2h, which is recorded as PB solution;

[0030] Step 3: Cut a piece of plastic wrap with a length of 15 cm and a width of 15 cm, mask it on the PVDF filter membrane moistened with the solvent, add 1.5 to 5 ml of PP solution, and then vacuum dry it after filtration at a temperature of 40 to 90 ° C for 1 to 60 minutes;

[0031] Step 4: Take out the dried film, take another piece of cling film of the same size, mask it on the PP film, add 1.5-5 ml of PB solution, tear off the cling film after filtration, and then vacuum dry it at a temperature of 40-90°C for 1-12 hours. The PP film and PB film prepared by the present invention each account for about half of the filter membrane, and the preparation order of the two has little effect on the performance of the prepared film, and the two need to be in direct contact, and the two are stacked in the middle with a width of 0-5 mm. The specific embodiments are as follows.

[0032] Example 1

[0033] A method for preparing a pn heterojunction thin film with excellent photothermoelectric properties, comprising:

[0034] Step 1: 0.093 ml of PEDOT:PSS (mass concentration of 13.55 mg / ml) aqueous solution was added to 2.407 ml of anhydrous ethanol (EtOH), and ultrasonicated for 30 min to prepare 2.5 ml of a solution with a mass concentration of 0.5 mg / ml, which was recorded as PP solution;

[0035] Step 2: Take 0.125 ml of PBFDO (mass concentration is 10 mg / ml) aqueous solution and add it to 2.375 ml of EtOH, and ultrasonicate for 30 min to prepare a solution with a mass concentration of 0.5 mg / ml, which is recorded as PB solution;

[0036] Step 3: Wet the PVDF filter membrane with EtOH, and then use a 15 cm long and 15 cm wide plastic wrap to mask half of the filter membrane, and add 2.5 ml of PP solution to the unmasked position of the other half. After the filtration is completed, gently tear off the plastic wrap, and then put the PP film with the filter membrane into a 60 ° C vacuum oven to dry for 10 minutes;

[0037] Step 4: Take another piece of plastic wrap of the same size (15 cm long and 15 cm wide), mask it on the PP film, and add 2.5 ml of PB solution to the other unmasked part. After the solution is drained, tear off the plastic wrap, put the pn heterojunction film with the filter membrane into a 60°C vacuum oven and dry it for 10 minutes to obtain a pn heterojunction film with excellent photothermal and electrical properties.

[0038] In this example, anhydrous ethanol was used as a solvent to disperse the PEDOT:PSS and PBFDO solutions, and the photothermoelectric performance diagram of the laminated pn heterojunction film obtained by filtration showed that the induced output voltage generated by light was 5 times that generated by heating. Figure 3 .

[0039] Example 2

[0040] A method for preparing a pn heterojunction thin film with excellent photothermoelectric properties, comprising:

[0041] Step 1: 0.922 ml of PEDOT:PSS (mass concentration of 13.55 mg / ml) aqueous solution was added to 1.578 ml of anhydrous ethanol (EtOH), and ultrasonicated for 120 min to prepare 2.5 ml of a solution with a mass concentration of 5 mg / ml, which was recorded as PP solution;

[0042] Step 2: 1.25 ml of PBFDO (mass concentration of 10 mg / ml) aqueous solution was added to 1.25 ml of EtOH, and ultrasonicated for 120 min to prepare 2.5 ml of solution with a mass concentration of 5 mg / ml, which was recorded as PB solution;

[0043] Step 3: Wet the PVDF filter membrane with EtOH, then use a 15 cm long and 15 cm wide plastic wrap, with the width of the mask being 1 mm away from the center line of the filter membrane, and add 2.5 ml of PB solution to the other half of the unmasked position. After the filtration is completed, gently tear off the plastic wrap, and then put the PP film with the filter membrane into a 60 ° C vacuum oven and dry it for 10 min;

[0044] Step 4: Take another piece of plastic wrap of the same size (15 cm long and 15 cm wide), mask it on the PB film, and the width of the mask is 1 mm away from the center line of the filter membrane. Add 2.5 ml of PP solution to the other unmasked part. After the solution is drained, tear off the plastic wrap, put the pn heterojunction film with the filter membrane into a 60°C vacuum oven and dry it for 10 minutes. You can get a pn heterojunction film with an intermediate stack width of 2 mm and excellent photothermal and electrical properties.

[0045] Example 3

[0046] A method for preparing a pn heterojunction thin film with excellent photothermoelectric properties, comprising:

[0047] Step 1: 0.461 ml of PEDOT:PSS (mass concentration of 13.55 mg / ml) aqueous solution was added to 2.039 ml of anhydrous ethanol (EtOH), and ultrasonicated for 60 min to prepare 2.5 ml of a solution with a mass concentration of 2.5 mg / ml, which was recorded as PP solution;

[0048] Step 2: Take 0.5 ml of PBFDO (mass concentration is 10 mg / ml) aqueous solution and add it to 2 ml of EtOH, and ultrasonicate for 60 min to prepare 2.5 ml of solution with mass concentration of 2 mg / ml, which is recorded as PB solution;

[0049] Step 3: Wet the PVDF filter membrane with EtOH, then use a 15 cm long and 15 cm wide plastic wrap, with the width of the mask being 2.5 mm from the center line of the filter membrane, and add 2.5 ml of PP solution to the other half of the unmasked position. After the filtration is completed, gently tear off the plastic wrap, and then put the PP film with the filter membrane into a 60 ° C vacuum oven and dry it for 10 min;

[0050] Step 4: Take another piece of plastic wrap of the same size (15 cm long and 15 cm wide), mask it on the PP film, and the width of the mask is 2.5 mm away from the center line of the filter membrane. Add 2.5 ml of PB solution to the other unmasked part. After the solution is drained, tear off the plastic wrap, put the pn heterojunction film with the filter membrane into a 60°C vacuum oven and dry it for 10 minutes. You can get a pn heterojunction film with an intermediate stack width of 5 mm and excellent photothermal and electrical properties.

[0051] Example 4

[0052] In this embodiment, the concentration of the PP solution is 0.2 mg / ml; the concentration of the PB solution is 0.2 mg / ml; and the other conditions are the same as those in Embodiment 1.

[0053] In order to further illustrate the beneficial effects of the present invention, the following comparative example was constructed.

[0054] Comparative Example 1

[0055] In this comparative example, the concentration of the PP solution is 8 mg / ml; the concentration of the PB solution is 8 mg / ml; and the other conditions are the same as those in Example 1.

[0056] Comparative Example 2

[0057] In this comparative example, anhydrous ethanol was replaced by an equal volume of dimethyl sulfoxide (DMSO), and the other conditions were the same as in Example 1.

[0058] In this comparative example, DMSO was used as a solvent to disperse the PEDOT:PSS and PBFDO solutions, and the photothermoelectric performance diagram of the laminated pn heterojunction film obtained by filtration showed that the induced output voltage generated by light was 3 times that generated by heating. Figure 4 .

[0059] Comparative Example 3

[0060] In this comparative example, anhydrous ethanol was replaced with an equal volume of water, and the other conditions were the same as in Example 1.

[0061] In this comparative example, water was used as a solvent to disperse the PEDOT:PSS and PBFDO solutions, and the photothermoelectric performance diagram of the laminated pn heterojunction film obtained by filtration showed that the induced output voltage generated by light was twice the voltage generated by heating. Figure 5 .

[0062] Comparative Example 4

[0063] A method for preparing a pn heterojunction thin film with excellent photothermoelectric properties, comprising:

[0064] Steps 1-2 are the same as in Example 1;

[0065] Step 3: Use a 15 cm long and 15 cm wide plastic wrap to mask the PVDF filter membrane moistened with EtOH. The width of the mask should be 1 mm wider than the center line of the filter membrane. Then add 2.5 ml of PP solution. After filtration, put the PP film with the filter membrane into a 60 ° C vacuum oven and dry it for 10 minutes.

[0066] Step 4: Take another piece of plastic wrap of the same size and mask it on the PP film. The width of the mask should be 1mm above the center line of the filtration membrane. Then add 2.5ml of PB solution. After the solution is drained, tear off the plastic wrap. At this time, there is a 2mm blank area in the middle. Apply silver paste (purchased from SPI (supplies)) to make it fully contact with the two materials. Finally, put the obtained film into a 60℃ vacuum oven and dry it for 10 minutes.

[0067] In this comparative example, the PEDOT:PSS and PBFDO solution dispersed in EtOH was filtered to obtain a conductive silver paste to connect the p-type and n-type thin films. The results showed that the induced output voltage generated by light was 4 times that generated by heating. Figure 6 .

[0068] Comparative Example 5

[0069] In this comparative example, steps 1-2 are the same as in Example 1;

[0070] In steps 3 and 4, the width of the mask is 3 mm from the center line of the filter membrane, the width of the middle layer is 6 mm, and the other conditions are the same as in Example 1.

[0071] The optical, thermal and electrical properties of the films prepared in the above examples and comparative examples were tested. The specific method was as follows: the prepared sample films were cut into 10×45 mm 2 The film was then fixed on a sample stage with temperature sensors at both ends using silver paste. Copper electrodes were connected to both ends for testing. The distance between the copper electrode at the illumination end and the sample end was 10 mm, and the illumination area was 5×5 mm 2 , place the sample on a 5×5 mm 2 The light source is a xenon lamp with an irradiation power of 249.3 nW. The distance between the light source and the sample is 50 cm. The Keithley 2700 system is used to collect data during the test. The test results are shown in Table 1.

[0072] Table 1

[0073]

[0074] As can be seen from Table 1, the pn heterojunction film prepared by the specific solvent type and solution concentration and the specific filtration method of the present invention has a higher induced output voltage generated by light, and the induced output voltage generated by light is more than 3 times the voltage generated by heating. The preparation method of the present invention is simple and easy to operate, and exhibits excellent photothermal performance in air.

[0075] When the solution concentration is high (Comparative Example 1), the photothermoelectric properties of the prepared film are generally poor; when the solvent type is replaced by DMSO (Comparative Example 2) or water (Comparative Example 3), the induced output voltage generated by light is lower, and the ratio to the voltage generated by heating is also smaller; during the masking process, there is a gap between the two films, and after filling with conductive silver paste, the photothermoelectric properties of the prepared film (Comparative Example 4) are also poor; when the width of the intermediate stack of the two materials is too high (Comparative Example 5), the hotspot performance of the prepared film is poor.

[0076] In summary, the present invention uses PBFDO and PEDOT:PSS at specific concentrations and ethanol as a dispersant to successfully prepare a pn heterojunction film with good photothermal performance by vacuum filtration through a mask, opening up a new direction for the development of photothermal electric materials.

[0077] The above is a preferred embodiment of the present invention. For ordinary technicians in this technical field, making several improvements and modifications without departing from the principles of the present invention should also be regarded as within the protection scope of the present invention.

Claims

1. A method for preparing a pn heterojunction thin film with excellent photothermoelectric properties, characterized in that: include: Step 1: Add the PEDOT:PSS aqueous solution into ethanol and ultrasonically prepare a uniformly dispersed solution, which is recorded as PP solution; Step 2: Add the PBFDO solution into ethanol and ultrasonically prepare a uniformly dispersed solution, which is recorded as PB solution; Step 3: Mask the filter membrane with a plastic wrap, add one of the solutions prepared in step 1 or step 2 to the unmasked position, and perform suction filtration. After the suction filtration is completed, remove the plastic wrap, and then perform vacuum drying; the width of the mask is 0-2.5 mm from the center line of the filter membrane; Step 4: Place another plastic wrap mask on the unmasked position in step 3, then add another solution prepared in step 1 or step 2 to the unmasked position and perform suction filtration. After the filtration is completed, tear off the plastic wrap, and then vacuum dry to obtain a pn heterojunction film with excellent photothermoelectric properties.

2. The method according to claim 1, characterized in that In the step 1, the concentration of the PP solution is 0.2-5 mg / ml.

3. The method according to claim 2, characterized in that In the step 1, the concentration of the PP solution is 0.2-5 mg / ml; in the step 2, the concentration of the PB solution is 0.2-5 mg / ml; in the step 3, the filter membrane is a polyvinylidene fluoride filter membrane with a pore size of 0.45 μm.

4. The method according to claim 3, characterized in that The ultrasonic time in step 1 and step 2 is 0.5 to 2 hours.

5. The method according to claim 4, characterized in that In step 3, the filter membrane is first wetted with a solvent.

6. A pn ​​heterojunction thin film with excellent photothermoelectric properties, characterized in that: It is prepared by the method according to any one of claims 1 to 5.

7. The pn heterojunction thin film with excellent photothermoelectric performance according to claim 6, characterized in that: The thickness of the film is not less than 0.1 μm.

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