CN113054114B

CN113054114B - Solar cell based on D-A type organic micromolecule doped ZnO electron transport layer and preparation method thereof

Info

Publication number: CN113054114B
Application number: CN202110273335.0A
Authority: CN
Inventors: 温善鹏; 王晨; 郭文滨; 沈亮; 董玮; 周敬然; 张歆东; 刘彩霞; 阮圣平
Original assignee: Jilin University
Current assignee: Jilin University
Priority date: 2021-03-15
Filing date: 2021-03-15
Publication date: 2022-03-18
Anticipated expiration: 2041-03-15
Also published as: CN113054114A

Abstract

A solar cell based on a D-A type organic micromolecule doped ZnO electron transport layer and a preparation method thereof belong to the technical field of organic solar cells. The cell structure is a glass/ITO or PET/ITO substrate, a TPTS doped ZnO electronic transmission layer prepared at low temperature, a PBDB-T-2F, an IT-4F active layer, a molybdenum oxide layer and an Ag electrode, and incident light is incident from the direction of the glass/ITO or PET/ITO substrate. In the invention, TPTS doping is utilized to inhibit defect states and carrier recombination in ZnO, so that the electron transmission and extraction capacity of ZnO is improved, and the photovoltaic performance of a polymer solar cell taking ZnO as an electron transmission layer is further improved. The effectiveness of the method is tested by performing a defect fluorescence test and a Hall effect test on a pure ZnO electron transport layer and a TPTS-doped ZnO electron transport layer (TPTS accounts for 1 wt%).

Description

Solar cell based on D-A type organic micromolecule doped ZnO electron transport layer and preparation method thereof

Technical Field

The invention belongs to the technical field of organic solar cells, and particularly relates to a solar cell based on a D-A type organic micromolecule doped ZnO electron transport layer and a preparation method thereof.

Background

Compared with the traditional inorganic solar cell, the organic solar cell has a series of unique advantages of light weight, flexibility, portability, color and the like. In order to improve the energy conversion efficiency of the organic solar cell, on one hand, high-efficiency light absorption donor materials (PffBT4T-2OD, PM6, Y6 and the like) are developed to increase the absorption and utilization of light by an active layer; on the other hand, a novel electron transport material and a hole transport material are designed and synthesized to finely regulate and control an electrode interface. Among many electron transport materials, solution processed ZnO is receiving attention because of its good n-type conductivity, high electron mobility, and excellent transparency. More importantly, the relatively low processing temperature of ZnO makes it particularly attractive for flexible device fabrication. However, ZnO processed at low temperature has numerous problems such as bulk defects, surface defects, extraction barriers, etc., which further results in significant trapping/de-trapping processes of carrier traps and corresponding recombination losses of trap-induced carriers in devices, which severely restricts the improvement of energy conversion efficiency of batteries and also hinders the commercial large-scale use thereof. Therefore, a simple and effective method is found for inhibiting carrier trap capture and recombination loss in the low-temperature ZnO electronic transmission layer, and the method has important significance for developing high-efficiency flexible optoelectronic devices.

Disclosure of Invention

The invention aims to provide a solar cell based on a D-A type organic micromolecule doped ZnO electron transport layer and a preparation method thereof, wherein the electron transport layer can effectively inhibit carrier trap trapping recombination.

In the invention, ITO/TPTS doped ZnO/active layer/MoO is adopted₃The bulk heterojunction polymer solar cell is prepared by the trans-structure of/Ag, and the cell is respectively manufactured on a rigid glass/ITO substrate and a flexible PET/ITO substrate.

The ZnO electron transmission layer is prepared by adopting a low-temperature sol-gel method. The method comprises the following specific steps: weighing 0.22g of zinc acetate dihydrate (Sigma-Aldrich, 99.9%), adding 2mL of dimethoxyethanol (Sigma-Aldrich, 99.9%) and 76.1mg of ethanolamine (Beijing carbofuran), stirring in the air for 10-15 hours, and aging for 10-15 hours to obtain ZnO sol-gel precursor solution; and spin-coating the ZnO sol-gel precursor solution on a clean glass/ITO substrate (Hunan City, Inc. of China) at 2500-3500 rpm for 50-70 s, then transferring the glass/ITO substrate into a muffle furnace to anneal for 0.5-1.5 hours at 120-140 ℃, wherein zinc acetate dihydrate is hydrolyzed and further pyrolyzed in the annealing process to completely convert the zinc acetate into ZnO, so that a ZnO electronic transmission layer is obtained on the glass/ITO substrate.

There are usually a large number of structural defects (typically as uncoordinated Zn) in and on the surface of such low temperature processed ZnO electron transport layers²⁺) Resulting in trap trapping and carrier recombination loss, thereby affecting the electron transport and extraction ability thereof as an electron transport layer. The invention introduces D-A type organic micromolecule TPTS into ZnO, and nitrogen atoms and non-coordinated Zn in the TPTS²⁺The ZnO electron transport layer can generate bonding action to passivate related structural defects, inhibit trap capture and carrier recombination, and improve the electron transport and extraction capability of the ZnO electron transport layer.

In the invention, D-A type organic micromolecule TPTS is doped into ZnO to prepare a TPTS-doped ZnO electron transport layer, so that the trapping recombination of a carrier trap is inhibited. The TPTS doping mode is as follows: weighing 5-15 mg of TPTS solid (independently synthesized in a laboratory, and the structural formula is shown below. the synthesis method refers to Liqiang, Jiayilong, Tianwenjing, and the like. the alkyl chain effect and the photoelectric property [ J ] of D-A-D type organic micromolecules which can be processed by solution are reported in advanced chemical science, 2012,033(001): 182-; adding 4-80 mu L of TPTS solution into 1mL of prepared ZnO sol-gel precursor solution, and stirring for 10-15 hours at room temperature in nitrogen to obtain clear and transparent TPTS doped ZnO (abbreviated as TPTS: ZnO) sol-gel precursor solution, wherein the TPTS doped ZnO sol-gel precursor solution can be stably stored at room temperature for more than 6 months.

Spin-coating TPTS doped ZnO sol-gel precursor liquid for 50-70 s at 2500-3500 rpm on the surface of a clean glass/ITO substrate (Hunan City Co., Ltd.) and transferring the glass/ITO substrate into a muffle furnace to anneal for 0.5-1.5 hours at 120-140 ℃, so that a TPTS doped ZnO electronic transmission layer is obtained on the glass/ITO substrate, wherein the TPTS accounts for 0.1-2 wt% of ZnO in the TPTS doped ZnO electronic transmission layer.

In the invention, TPTS doping is utilized to inhibit defect states and carrier recombination in ZnO, so that the electron transmission and extraction capacity of ZnO is improved, and the photovoltaic performance of a polymer solar cell taking ZnO as an electron transmission layer is further improved. The effectiveness of the method is tested by performing a defect fluorescence test and a Hall effect test on a pure ZnO electron transmission layer and a TPTS-doped ZnO electron transmission layer (the mass fraction of TPTS in ZnO is 1 wt%).

And (2) irradiating the ZnO and TPTS doped ZnO electronic transmission layers by using 350-nanometer exciting light, wherein the defect fluorescence peak of the TPTS doped ZnO electronic transmission layer (the mass fraction of TPTS in ZnO is 1 wt%) in the range of 450-600 nanometers is obviously inhibited, and the defect fluorescence intensity at the 520-nanometer peak is reduced by 20 times. The Hall effect test of ZnO/Al and TPTS is carried out on ZnO/Al by using a Van der Bager four-electrode method, and the result shows that compared with a pure ZnO electron transmission layer, the electron concentration and the Hall mobility of the TPTS doped ZnO electron transmission layer are obviously improved. The electron concentrations in the ZnO and TPTS doped ZnO electron transport layers were 1.0X 10, respectively¹³cm^-3And 2.0X 10¹³cm^-3Hall mobility of 3.16cm respectively²Vs and 10.54cm²/Vs。

In order to test the effectiveness of the TPTS doping strategy on improving the photovoltaic performance of a polymer solar cell taking low-temperature ZnO as an electron transport layer, ZnO and ZnO with different TPTS doping levels are respectively used as electron transport layers to prepare a trans-form bulk heterojunction polymer solar cell and test a current-voltage characteristic curve of the trans-form bulk heterojunction polymer solar cell. The specific method is that a bulk heterojunction light absorption active layer blended with an acceptor is spin-coated on the prepared glass/ITO/ZnO or TPTS (different TPTS doping ratios), PBDB-T-2F is selected as an electron donor, IT-4F is selected as an electron acceptor, and the specific steps are as follows:

1) weighing the components in a mass ratio of 1: 1 PBDB-T-2F and IT-4F (available from Lumteck technologies, Inc.), and then weighing the mixture in a volume ratio of 99.4: 0.6 of chlorobenzene (Beijing carbofuran) and 1, 8-diiodooctane (sigma-aldrich), dissolving PBDB-T-2F and IT-4F in a mixed solvent of the chlorobenzene and the 1, 8-diiodooctane, and stirring for 12-20 hours at room temperature in a nitrogen environment to obtain an active layer solution, wherein the concentration of the PBDB-T-2F is 10 mg/mL;

2) respectively spin-coating the active layer solution obtained in the step 1) on a ZnO electronic transmission layer and a TPTS-doped ZnO electronic transmission layer for 80-100 s under the conditions of nitrogen and 1500-2000 revolutions per minute, and then dropwise adding 180-220 mu L of isopropanol (Beijing lark, purity is 99.9%) on the active layer, and spin-washing for 20-40 s at 2000-3000 revolutions per minute; then placing the mixture on a hot bench at 90-110 ℃ for treatment for 10-20 minutes to obtain an active layer with the thickness of 100-120 nanometers;

3) depositing a molybdenum oxide hole transport layer and a silver electrode on the active layer by using an SD400B multi-source vapor deposition system, wherein the vacuum degree during evaporation is 4 multiplied by 10^-4～8×10^-4The evaporation rate of the molybdenum oxide is 0.1-0.3 angstrom/second, and the thickness is 4-8 nanometers; the evaporation rate of the silver electrode is 0.4-1.2 angstroms/second, and the thickness is 90-100 nanometers; thereby obtaining the organic solar cell based on the ZnO electron transport layer and the TPTS-doped ZnO electron transport layer.

In the invention, the application of the TPTS doped ZnO electron transport layer in the flexible polymer solar cell is also considered. In actual industrial production, the photovoltaic performance of the device is generally required to change as little as possible along with the change of the thickness of the ZnO electron transport layer, so as to improve the repeatability of the device in the actual production process. Therefore, TPTS doping ZnO electronic transmission layers with different thicknesses are coated on a PET/ITO substrate in a spin mode, a flexible battery device is prepared, and the performance of the device is tested to be influenced by the thickness of the hybridization ZnO electronic transmission layer.

Spin-coating TPTS doped ZnO sol-gel precursor liquid for 50-70 s at 1000-4000 rpm on the surface of a clean PET/ITO substrate, and transferring the TPTS doped ZnO sol-gel precursor liquid into a muffle furnace to anneal for 0.5-1.5 hours at 120-140 ℃. The results of the elliptical polarization tests show that the thicknesses of the TPTS doped ZnO electron transport layers prepared at 1000 revolutions per minute, 2000 revolutions per minute, 3000 revolutions per minute and 4000 revolutions per minute are 73-75 nanometers, 58-62 nanometers, 41-44 nanometers and 20-22 nanometers respectively.

The flexible polymer solar cell is prepared on the basis of the TPTS doped ZnO electron transmission layers with different thicknesses, and the light absorption active layer still adopts a bulk heterojunction structure consisting of a PBDB-T-2F electron donor and an IT-4F electron acceptor. Spin coating a PBDB-T-2F (indium tin oxide) IT-4F solution for 80-100 seconds at 1500-2000 rpm in a nitrogen atmosphere, then dropwise adding 180-220 mu L of isopropanol (Beijing carbofuran, purity of 99%) on the active layer, and spin-washing for 20-40 seconds at 2000-3000 rpm. Then, the mixture is placed on a heating table at 90-110 ℃ for treatment for 10-20 minutes. And then evaporating 4-8 nm molybdenum oxide and 90-100 nm silver electrodes in vacuum. The current-voltage characteristic curve of the battery was tested.

In order to test that the TPTS-doped ZnO electronic transmission layer can effectively inhibit carrier trap capture and recombination loss in the device, a step photovoltage response test (shown in figure 6) is carried out on a solar cell based on a ZnO electronic transmission layer base and the TPTS-doped ZnO electronic transmission layer, and a carrier trap capture recombination process in the device is inspected. The test method comprises the following steps: a high-brightness white light LED (Kingbright company) is used as a light source (the wavelength is 400-650 nanometers, the power is 100mW), and a self-programmed singlechip is used as a function generator to control the on and off of the LED so as to ensure that the LED can generate 500 microsecond square wave light pulses. ZnO-based solar cells focus square wave light pulses onto individual pixels of ZnO and TPTS using a set of lenses and varying the pulse intensity using a neutral density filter wheel. The single chip microcomputer outputs signals at the same time to control synchronous triggering of the oscilloscopes. ZnO-based solar cells were recorded by connecting ZnO and TPTS ZnO-based solar cells in series with an Agilent DSO6052A digital oscilloscope with an input impedance of 1M Ω.

Drawings

FIG. 1: the device structure diagram of the rigid (a) and flexible polymer (b) solar cell is that a glass/ITO or PET/ITO substrate 1, a ZnO or TPTS doped ZnO electronic transmission layer 2 prepared at low temperature, a PBDB-T-2F, an IT-4F active layer 3, a molybdenum oxide layer 4 and an Ag electrode 5 are arranged in sequence from 1 to 5, and incident light is incident from the direction of the glass/ITO or PET/ITO substrate 1.

FIG. 2: scanning electron microscopy images of a pure ZnO electron transport layer (a) and a TPTS doped (TPTS at 1 wt% of ZnO mass%) ZnO electron transport layer (b). As can be seen from the figure, the ZnO and TPTS doped ZnO electron transport layers both consist of nanoparticles. But there are significant grain boundaries and gaps between the particles of the pure ZnO electron transport layer. In contrast, the TPTS-doped ZnO electron transport layer shows a uniform and crack-free film, and gaps among ZnO particles are filled with TPTS, so that connectivity among ZnO particles and flatness of the surface of the film are improved.

FIG. 3: a defect fluorescence spectrogram (a) of a pure ZnO electron transmission layer and a TPTS doped ZnO electron transmission layer (the mass fraction of TPTS in the ZnO is 1 wt%), a Hall voltage-working current characteristic curve (b) between 12 electrodes and a Hall voltage-working current characteristic curve (c) between 34 electrodes in a four-electrode Hall effect test. The curve I and the curve II are respectively a pure ZnO electron transmission layer and a TPTS-doped ZnO electron transmission layer. As can be seen from the figure, pure ZnO has obvious fluorescence peak in the range of 450 to 600 nanometers, corresponding to oxygen vacancy and is not coordinated with Zn²⁺And the like. After TPTS doping, the defect fluorescence peak is obviously inhibited, and the intensity at 520 nm of the peak value is reduced by 20 times. From the graphs (b, c), the carrier concentration and the hall mobility can be calculated.

FIG. 4: in the current-voltage characteristic curve of the solar cell assembled by using pure ZnO and ZnO with different TPTS doping levels as the electron transport layer described in embodiment 1 of the present invention. The curves I, II, III, IV and V respectively correspond to the current-voltage characteristic curves of the ZnO-based device, wherein TPTS accounts for 0.1 wt%, 0.5 wt%, 1 wt% and 2 wt% of pure ZnO and TPTS. It can be seen from the figure that the pure ZnO devices processed at low temperature have the worst performance, because of the severe loss of carrier recombination due to the higher defect state density inside the device. The performance of the TPTS-doped device is improved to different degrees, and the increased filling factor shows that the carrier recombination inside the device is reduced. The optimum device performance is obtained at a TPTS doping level of 1 wt%.

FIG. 5: in the embodiment 2 of the invention, the current-voltage characteristic curve of the flexible polymer solar cell prepared by using the TPTS and ZnO with different thicknesses as the electron transport layer is provided. The curves I, II, III and IV in the figure respectively correspond to the thicknesses of the TPTS doped ZnO electron transport layer of 20 nm, 43 nm, 60 nm and 75 nm. As can be seen from the figure, when the ZnO electron transport layer is increased from 20 nanometers to 75 nanometers, the device performance can still be kept above 95% of the optimal value, and the photovoltaic performance is insensitive to the film thickness, so that the application of TPTS (thermoplastic polystyrene) ZnO in the actual roll-to-roll production is facilitated.

FIG. 6: ZnO is used as an electron transport layer to prepare a step photovoltage response transient curve of a polymer solar cell device. The graph (a) and the graph (b) respectively correspond to ZnO-based devices and TPTS-ZnO-based devices, and curves I, II, III, IV and V in the two graphs respectively correspond to pulse light intensities of 3.1, 6.5, 15.3, 44.2 and 80.5mW/cm². As can be seen from the figure, the response starting point of the pure ZnO-based device has obvious overshoot phenomenon along with the increase of the light intensity, and the response closing point has obvious photovoltage tailing phenomenon. The "overshoot" and "tailing" phenomena correspond to the processes of carrier capture by and de-capture from traps, respectively. In contrast, the phenomena of 'overshoot' and 'tailing' in the TPTS and ZnO-based device are not obvious, which shows that the TPTS doping effectively inhibits the process of trapping/de-trapping of carriers in the device by a trap, and is beneficial to reducing the recombination loss of the carriers, thereby improving the photoelectric conversion efficiency of the cell.

Detailed Description

Example 1:

1) 0.22g of zinc acetate dihydrate was weighed, 2mL of dimethoxyethanol and 76.1mg of ethanolamine were added thereto, and the mixture was stirred in a sealed atmosphere for 12 hours and aged for 12 hours to obtain a ZnO sol-gel precursor solution. 10mg of TPTS was weighed out and dissolved in 1mL of anhydrous tetrahydrofuran, and stirred in a nitrogen glove box for 12 hours to obtain a TPTS solution. And respectively adding 4, 20, 40 and 80 mu L of TPTS solution into 1mL of ZnO sol-gel precursor solution, and stirring for 12 hours to obtain TPTS doped ZnO sol-gel with different TPTS doping concentrations. 10mg of PBDB-T-2F and 10mg of IT-4F were weighed, mixed, added with 994. mu.L of chlorobenzene and 6. mu.L of 1, 8-diiodooctane, and stirred in a glove box for 12 hours to obtain an active layer solution.

2) A glass/ITO substrate with the thickness of 15mm multiplied by 20mm is sequentially cleaned by liquid detergent, deionized water and isopropanol for 20 minutes in an ultrasonic mode, the surface of the substrate is dried by nitrogen, and the substrate is placed on a 70 ℃ hot bench for 5 minutes.

3) And (3) spin-coating ZnO sol-gel on a clean glass/ITO substrate at 3000 rpm for 60 seconds, and transferring the substrate into a muffle furnace to anneal for 1 hour at 130 ℃. Immediately taking out and transferring into a nitrogen glove box. The ZnO electron transport layer thus produced was approximately 40 nm thick.

Spin-coating TPTS doped ZnO sol-gel with different TPTS doping concentrations on another clean glass/ITO substrate at 3000 r/min for 60 seconds, and transferring the substrate into a muffle furnace to anneal for 1 hour at 130 ℃. Immediately taking out and transferring into a nitrogen glove box. The thickness of the TPTS-doped ZnO electron transport layer prepared by the method is about 40 nanometers.

4) Respectively dripping 50 mu L of LPBDB-T-2F and IT-4 active layer solution on the surfaces of the ZnO electron transport layer and the TPTS doped ZnO electron transport layer, spin-coating at 1600 rpm for 90 seconds, then dripping 200 mu L of ultra-dry isopropanol on the active layer, and spin-washing at 2500 rpm for 30 seconds; then, the substrate was placed on a hot stage at 100 ℃ for 15 minutes to obtain an active layer having a thickness of 110 nm.

5) Taking out the device, transferring into SD400B multi-source temperature-controlled vapor deposition evaporation apparatus for preparing molybdenum oxide layer and Ag electrode with vacuum degree of 5.1 × 10^-4The evaporation rate of molybdenum oxide was 0.2 angstroms/second and the thickness was 6 nanometers. The evaporation rate of the silver electrode is controlled to be 0.8 angstrom/second, and the thickness is 90 nanometers. The effective area of the battery is 6.4mm²Thereby obtaining the rigid substrate solar cell based on the ZnO electron transport layer and the TPTS-doped ZnO electron transport layer.

Example 2:

1) 0.22g of zinc acetate dihydrate was weighed, 2mL of dimethoxyethanol and 76.1mg of ethanolamine were added thereto, and the mixture was stirred in a sealed atmosphere for 12 hours and aged for 12 hours to obtain a ZnO sol-gel precursor solution. Weighing 10mg of TPTS, dissolving in 1mL of anhydrous tetrahydrofuran, and stirring in a nitrogen glove box for 12 hours to obtain a TPTS solution; and adding 40 microliter of TPTS solution into 1mL of ZnO sol-gel precursor solution, and stirring for 12 hours to obtain the TPTS doped ZnO sol-gel. 10mg of PBDB-T-2F and 10mg of IT-4F were weighed, mixed, added with 994. mu.L of chlorobenzene and 6. mu.L of 1, 8-diiodooctane, and stirred in a glove box for 12 hours to obtain an active layer solution.

2) The PET/ITO substrate with the thickness of 15mm multiplied by 20mm is sequentially cleaned by liquid detergent, deionized water and isopropanol for 20 minutes in an ultrasonic mode, the surface of the PET/ITO substrate is dried by nitrogen, and the PET/ITO substrate is placed on a 70 ℃ hot bench for 5 minutes.

3) Spin coating TPTS doped ZnO precursor solution on a clean PET/ITO substrate at 1000, 2000, 3000 and 4000 rpm for 60 seconds, and transferring the substrate to a muffle furnace for annealing at 130 ℃ for 1 hour. Immediately taking out and transferring into a nitrogen glove box. The thicknesses of the TPTS doped ZnO electron transport layers prepared by the method are respectively 75 nm, 60 nm, 43 nm and 20 nm.

4) 50 mu L of active layer solution of the TPTS doped ZnO electron transport layer (75 nm, 60 nm, 43 nm and 20 nm) is respectively dripped on the surface of the TPTS doped ZnO electron transport layer, 1600 rpm spin-coating is carried out for 90 seconds, and then 200 mu L of ultra-dry isopropanol is dripped on the active layer, and 2500 rpm spin-washing is carried out for 30 seconds. Then placed on a 100 ℃ hot plate for treatment for 15 minutes. The thickness of the obtained active layer was 110 nm.

5) Taking out the device, transferring into SD400B multi-source temperature-controlled vapor deposition evaporation apparatus for preparing molybdenum oxide layer and Ag electrode with vacuum degree of 5.1 × 10^-4The evaporation rate of the molybdenum oxide is controlled to be 0.2 angstrom per second, and the thickness is 6 nanometers. The evaporation rate of the silver electrode is controlled to be 0.8 angstrom/second, and the thickness is 90 nanometers. The effective area of the battery is 6.4mm²And thus obtaining the flexible substrate solar cell based on the TPTS doped ZnO electron transport layer.

Claims

1. A preparation method of a solar cell based on a D-A type organic micromolecule doped ZnO electron transport layer comprises the following steps that the electron transport layer can effectively inhibit carrier trap in a device from trapping and compounding,

(1) preparing ZnO sol-gel precursor solution: weighing 0.22g of zinc acetate dihydrate, adding 2mL of dimethoxy ethanol and 76.1mg of ethanolamine into the zinc acetate dihydrate, stirring the mixture in the air for 10 to 15 hours, and aging the mixture for 10 to 15 hours to obtain ZnO sol-gel precursor solution;

(2) weighing 5-15 mg of D-A type organic micromolecule TPTS solid with the structural formula shown as the following formula, dissolving the D-A type organic micromolecule TPTS solid in 0.5-1.5 mL of tetrahydrofuran, and stirring for 10-15 hours at room temperature under nitrogen to obtain TPTS solution; adding 4-80 mu L of TPTS solution into 1mL of ZnO sol-gel precursor solution obtained in the step (1), and stirring for 10-15 hours at room temperature in nitrogen to obtain clear and transparent TPTS-doped ZnO sol-gel precursor solution;

(3) spin-coating a TPTS-doped ZnO sol-gel precursor solution on the surface of a clean glass/ITO substrate or the surface of a clean PET/ITO substrate, and transferring the substrate into a muffle furnace to anneal for 0.5-1.5 hours at 120-140 ℃, so as to obtain a TPTS-doped ZnO electronic transmission layer on the substrate, wherein the TPTS accounts for 0.1-2 wt% of ZnO;

(4) weighing the components in a mass ratio of 1: 1 of PBDB-T-2F and IT-4F, and then weighing the mixture with the volume ratio of 99.4: 0.6 parts of chlorobenzene and 1, 8-diiodooctane, dissolving PBDB-T-2F and IT-4F in a mixed solvent of the chlorobenzene and the 1, 8-diiodooctane, and stirring for 12-20 hours at room temperature in a nitrogen environment to obtain an active layer solution;

(5) spin-coating the active layer solution obtained in the step (4) on a TPTS-doped ZnO electronic transmission layer, then dropwise adding 180-220 mu L of isopropanol on the active layer, and spin-washing at 2000-3000 rpm for 20-40 seconds; then placing the mixture on a hot bench at 90-110 ℃ for treatment for 10-20 minutes to obtain an active layer with the thickness of 100-120 nanometers;

(6) depositing a molybdenum oxide hole transport layer and a silver electrode on the active layer under a vacuum degree of 4 × 10^-4～8×10^-4And the thickness of the molybdenum oxide is 4-8 nanometers, and the thickness of the silver electrode is 90-100 nanometers, so that the organic solar cell based on the TPTS doped ZnO electron transport layer is obtained.

2. The method for preparing a solar cell based on a D-A type organic small molecule doped ZnO electron transport layer according to claim 1, wherein the method comprises the following steps: in the step (2), 5-15 mg of TPTS solid is firstly dissolved in 0.5-1.5 mL of tetrahydrofuran, the mixture is stirred for 10-15 hours at room temperature under nitrogen to obtain a TPTS solution, 4-80 microliter of TPTS solution is added into 1mLZnO sol-gel precursor solution, and the mixture is stirred for 10-15 hours at room temperature under nitrogen to obtain clear and transparent TPTS doped ZnO sol-gel precursor solution.

3. The method for preparing a solar cell based on a D-A type organic small molecule doped ZnO electron transport layer according to claim 1, wherein the method comprises the following steps: spin-coating TPTS doped ZnO sol-gel precursor liquid on the surface of a clean glass/ITO substrate at 2500-3500 rpm for 50-70 s; or spin-coating the TPTS doped ZnO sol-gel precursor solution on the surface of a clean PET/ITO substrate at 1000-4000 rpm for 50-70 s, transferring the PET doped ZnO sol-gel precursor solution into a muffle furnace, and annealing the PET doped ZnO sol-gel precursor solution for 0.5-1.5 hours at 120-140 ℃ to obtain the TPTS/ZnO hybrid film with low defect density and high mobility.

4. The method for preparing a solar cell based on a D-A type organic small molecule doped ZnO electron transport layer according to claim 1, wherein the method comprises the following steps: and (4) spin-coating the active layer solution obtained in the step (4) on the TPTS-doped ZnO electronic transmission layer obtained in the step (3), dropwise adding 180-220 mu L of isopropanol after the active layer is spin-coated, and spin-washing at 2000-3000 r/min for 20-40 seconds.

5. The method for preparing a solar cell based on a D-A type organic small molecule doped ZnO electron transport layer according to claim 1, wherein the method comprises the following steps: the TPTS doped ZnO is used as an electron transport layer to prepare a solar cell device without an obvious trapping/de-trapping process.

6. A solar cell based on a D-A type organic micromolecule doped ZnO electron transport layer is characterized in that: is prepared by the method of any one of claims 1 to 5.