Device and method for preparing perovskite fiber solar cell

Abstract

The present invention discloses a device and a method for preparing a perovskite fiber solar cell. The present invention utilizes the surface tension between a glass capillary and a precursor solution droplet to achieve the wrapping of a fiber electrode. The combination of a programmable stepper motor lead screw stage and a glass capillary is used to enable adjustable speed and range for the coating application work. An adjustable DC regulated power supply is used to fix the fiber electrode and the annealing of the coating is achieved by using the principle of heat generation based on Joule's law. Meanwhile, the solution of partially evaporating the solvent under thermal assistance conditions can effectively increase the viscosity of the perovskite precursor and enhance the interaction force between it and the electron transport layer, thereby enabling the perovskite to successfully grow on the fiber surface, effectively avoiding the problems of uneven perovskite coating, difficult crystallization, and poor crystallization.

Description

Technical Field

[0001] The present invention relates to a perovskite cell, in particular to a device and method for preparing a perovskite fiber solar cell. Background Art

[0002] Constructing flexible, lightweight and integrable fiber energy devices is the basis for future smart self-powered fabrics. Compared with traditional planar energy devices, fiber energy devices can be integrated into wearable devices on a large scale through weaving technology, just like polymer fibers. Among them, fiber solar cells can directly convert solar energy into electrical energy, and have become a very important development direction in fiber energy devices. Organic hybrid perovskite fiber solar cells based on large-diameter metal wire electrodes have attracted attention due to their fiber morphology, bendability, weavability and other characteristics.

[0003] The means of controlling the growth of perovskite on the surface of curved fibers are relatively limited, and can be divided into solution method and evaporation method. The evaporation method has high requirements for equipment. In comparison, the solution method is more suitable for low-cost preparation and large-scale use. The solution method is mainly divided into two steps: precursor solution dipping and electrochemical deposition of PbI2. At present, it is still very difficult to grow a perovskite active layer on the surface of curved fibers by solution method. This process involves the viscosity of the perovskite precursor liquid and the uneven growth caused by the special-shaped cross-section fibers. The instability of perovskite itself and the difficulty in growing an all-inorganic perovskite active layer with controllable grain size and thickness on the surface of small-diameter fibers while maintaining high flexibility limit its further application, and uneven coating and difficult annealing often occur during preparation. This makes the preparation of fiber perovskite solar cells more difficult. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention utilizes the surface tension of glass capillaries and precursor solution droplets to realize the wrapping of fiber electrodes, adopts a coded stepper motor screw slide combined with a glass capillary to realize the adjustable speed and range of coating, uses an adjustable DC regulated power supply to fix the fiber electrode and utilizes the principle of heating by Joule's law to realize the annealing of the coating. At the same time, the solution of partially evaporating the solvent under heat-assisted conditions can effectively increase the viscosity of the perovskite precursor and increase the interaction between it and the electron transport layer, so that the perovskite can successfully grow on the fiber surface, effectively avoiding the problems of uneven perovskite coating, difficult crystallization, and poor crystallization.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A method for preparing a perovskite fiber solar cell comprises the following steps:

[0007] (1) Pass the fiber through the droplets of the electron transport layer precursor solution, and then use a driving device to perform reciprocating heat-assisted droplet circulation coating of the droplets on the fiber. Then connect both ends of the fiber to a power source for annealing to obtain a fiber coated with an electron transport layer;

[0008] (2) Replace the capillary and the precursor solution droplets in the order of the perovskite layer and the hole transport layer, turn on the power source, and then perform reciprocating heat-assisted droplet circulation coating to successively complete the coating and annealing of the perovskite layer and the hole transport layer on the surface of the fiber coated with the electron transport layer;

[0009] (3) Suspend the counter electrode precursor solution droplets at the end of the capillary, and use a driving device to make the counter electrode precursor solution droplets reciprocate on the fiber obtained in step 2 to form a counter electrode. Then twist another fiber with it to obtain a perovskite fiber solar cell with the fiber, electron transport layer, perovskite layer, hole transport layer, and counter electrode from the inside to the outside in sequence.

[0010] Preferably, the fiber is made of carbon nanotubes or silver and gold fibers, with a diameter of 0.02 mm to 0.05 mm.

[0011] Preferably, the electron transport layer is selected from at least one of ZnO, TiO2, SnO2, Nb2O5, In2O3, Zn2SnO4, SrTiO3, WO3, TaO3, PC 60 BM or C60.

[0012] Preferably, the hole transport layer is selected from one of CuSCN, PEDOT:PSS, Spiro-OMeTAD, P3HT, PTAA, NiO, and MoOx (2.5 ≤ x ≤ 3).

[0013] Preferably, the perovskite is CsPbBr3 or an organic hybrid perovskite, and the organic hybrid perovskite is Cs 0.17 FA 0.83 Pb(I 0.94 Br 0.06 )3, Cs 0.17 FA 0.83 Pb(I 0.95 Cl 0.05 )3, Cs 0.5 FA 0.4 MA 0.1 Pb(I 0.83 Br 0.17 )3.

[0014] Preferably, the thermal-assisted droplet circulation coating operation is specifically as follows: One end of a capillary with a diameter of 0.9 mm is fixed to a sliding table, and the other end is suspended. A precursor solution is dropped at the suspended end. A fiber is passed through the precursor liquid droplet in a direction perpendicular to the capillary, and then fixed and tightened. The sliding table slides along the direction of the fiber driven by a stepping motor, and the liquid droplet circulates and coats on the fiber as the sliding table reciprocates. Both ends of the fiber are connected to a power supply, and annealing is assisted by an electric current during the coating process to complete the thermal-assisted droplet circulation coating of the fiber. The voltage generated by the power supply is less than 25 V, and the current is less than 2 A.

[0015] Preferably, the height at which the capillary is suspended is 3 - 4 cm, and the volume of the precursor liquid droplet is not less than 0.3 mL.

[0016] The present invention also provides a device for preparing a perovskite fiber solar cell. The device includes: a sliding table, a capillary, a platform, an adjustable DC regulated power supply, a power negative terminal connector, a power positive terminal connector, a stepping motor, and an encoder. One end of the capillary is fixedly connected to the sliding table, and the other end is suspended above the platform. A precursor solution is dropped at the suspended end. A fiber is passed through the precursor liquid droplet, and both ends are fixed to the power positive terminal connector and the power negative terminal connector. The encoder is connected to the sliding table through the stepping motor and drives the capillary on the sliding table to reciprocate along the direction of the fiber. The positive and negative poles of the adjustable DC regulated power supply are respectively connected to the power positive terminal connector and the power negative terminal connector through wires.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] The thermal-assisted (resistance heating) droplet circulation coating technology adopted by the present invention can effectively control the temperature of the perovskite precursor liquid droplet. By using the scheme of partially evaporating the solvent under thermal-assisted conditions, the viscosity of the perovskite precursor can be effectively increased, and the interaction force between it and the electron transport layer can be increased, so that perovskite can successfully grow on its surface, effectively avoiding the problems of uneven perovskite coating, difficult crystallization, and poor crystallization.

[0019] The thermal-assisted droplet circulation coating technology of the present invention can adjust the number of circulation coatings according to actual needs, so as to adjust the thickness and length of the coating layer; according to different fiber materials and coating layer materials, the annealing temperature can be accurately controlled by changing the voltage and current, and annealing work can be carried out at the optimal temperature. Whether from the cost of the equipment or the accuracy of the annealing temperature, the thermal-assisted droplet circulation coating technology has greater advantages. Description of the Drawings

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on the provided drawings.

[0021] Figure 1 is a schematic diagram of a device for preparing perovskite fiber solar cells provided by the present invention;

[0022] Figure 2 is a top view of a device for preparing perovskite fiber solar cells provided by the present invention;

[0023] Figure 3 is a front view of a precursor solution suspended on a capillary through which a fiber passes in a device for preparing perovskite fiber solar cells provided by the present invention;

[0024] Figure 4 is an efficiency diagram of a fiber perovskite solar cell prepared in Example 1, where (a) is an SEM diagram of the fiber perovskite solar cell;

[0025] Figures 1-3 in;

[0026] 1. Slide table, 2. Capillary, 3. Platform, 4. Precursor liquid droplet, 5. Fiber, 6. Adjustable DC regulated power supply, 7. Power negative terminal connector, 8. Power positive terminal connector, 9. Stepper motor, 10. Encoder. Detailed implementation manners

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0028] Such as Figures 1-3As shown in the figure, an embodiment of the present invention provides a device for preparing a perovskite fiber solar cell. The device includes: a sliding table 1, a capillary 2, a platform 3, an adjustable DC regulated power supply 6, a power negative terminal connector 7, a power positive terminal connector 8, a stepping motor 9, and an encoder 10. One end of the capillary 2 is fixedly connected to the sliding table 1, and the other end is suspended above the platform 3. A precursor solution 4 is dropped at the suspended end. A fiber 5 is passed through the precursor liquid droplet 4, and both ends are fixed to the power positive terminal connector 7 and the power negative terminal connector 8. The encoder 10 is connected to the sliding table 1 through the stepping motor 9, driving the capillary 2 on the sliding table 1 to reciprocate along the direction of the fiber 5. The positive and negative poles of the adjustable DC regulated power supply 6 are connected to the power positive terminal connector 7 and the power negative terminal connector 8 respectively through wires.

[0029] A method for preparing a perovskite fiber solar cell using the above device includes the following steps:

[0030] Step 1: Drop the electron transport layer precursor solution on the capillary that is fixed to the sliding table and semi-suspended, and the liquid droplet suspended thereon is sufficient to wrap the fiber.

[0031] Step 2: Pass the fiber through the liquid droplet, fix and tighten it. The liquid droplet moves with the movement of the sliding table. With the reciprocating movement of the sliding table, the coating work of the fiber is completed.

[0032] Step 3: Connect the fiber to the power supply, and realize rapid annealing through the heat generation phenomenon of Joule's law to obtain a fiber with an electron transport layer.

[0033] Step 4: Replace the capillary, drop the perovskite precursor solution on the capillary that is fixed to the sliding table and semi-suspended, and the liquid droplet suspended thereon is sufficient to wrap the fiber.

[0034] Step 5: Pass the fiber through the liquid droplet, fix and tighten it. The liquid droplet moves with the movement of the sliding table. With the reciprocating movement of the sliding table, the coating work of the fiber is completed.

[0035] Step 6: Connect the fiber to the power supply before coating. Appropriate voltage and current should be applied at the start of coating. Realize rapid annealing through the heat generation phenomenon of Joule's law to obtain a fiber with a perovskite layer and an electron transport layer.

[0036] Step 7: Complete the coating and annealing work of the hole transport layer CuSCN as in the previous steps 4 - 6 to obtain a fiber with a hole transport layer, a perovskite layer, and an electron transport layer.

[0037] Step 8: Suspend the silver nanowire isopropanol droplet at the end of the capillary tube, and use a motor to drive the capillary tube to reciprocate. In this way, the silver nanowires can be evenly wrapped on the fiber surface to form a counter electrode. Finally, twist another carbon nanotube fiber with it, and control the unit length of the final twisted pair fiber according to different twist numbers to complete the preparation of the fiber battery.

[0038] Example 1

[0039] 1. Add 1000 mg of anhydrous zinc acetate to 15 ml of 2-MA and 250 μL of EA, stir at 60 °C for 2 hours, and then stir at room temperature for 48 hours to obtain the electron transport layer precursor solution. In the laboratory, prepare a 5 ml DMF / DMSO (1 / 1 v / v) solution with a molar ratio of CsI / HPbI3 / PbBr = 2 / 1 / 1, and stir at room temperature for 48 hours to obtain the perovskite precursor solution. Disperse 350 mg of CuSCN (99%) powder in 10 ml of dimethyl sulfide (98%), and stir at room temperature for 1 hour to obtain the hole transport layer precursor solution.

[0040] 2. Use the device for preparing perovskite fiber solar cells described above for preparation, including the following steps:

[0041] (1) Fix one end of a glass capillary tube with a diameter of 0.9 mm on the sliding table and leave the other end suspended. Connect the two ends of a silver fiber with a diameter of 0.02 mm to 0.05 mm to the power supply. Turn on the adjustable DC regulated power supply in advance and set the voltage and current so that the temperature of the silver fiber is stable at the annealing temperature required for each layer. To prevent the fiber electrode from melting, set the voltage to 20 V and the current to 1.5 A. After the voltage and current are stable, drop 0.35 mL of the electron transport layer precursor solution at the suspended end of the glass capillary tube. The silver fiber passes through the precursor liquid droplet perpendicular to the capillary tube, and is fixed and tightened. Use a preset program to control the movement speed of the stepping motor screw sliding table to be 1 cm / s and move within a range of 5 cm to the left and right centered on the origin, and repeat 3 times. The sliding table slides along the direction of the fiber driven by the stepping motor, and the liquid droplet is cyclically coated on the fiber as the sliding table reciprocates;

[0042] (2) Replace the capillary tube and the precursor solution droplet in the order of the perovskite layer and the hole transport layer, connect the power supply, and then perform reciprocating heat-assisted droplet cyclic coating according to the method in step (1) to complete the coating and annealing of the perovskite layer and the hole transport layer on the fiber surface coated with the electron transport layer in turn;

[0043] (3) Suspend a droplet of a silver nanowire isopropanol solution with a mass concentration of 10 mg / ml at the end of a capillary tube. The diameter of the silver nanowires in the silver nanowire isopropanol solution is 70 - 100 nm, and the length is 20 - 60 μm. Use a motor to drive the capillary tube to reciprocate, and the silver nanowires are evenly wrapped on the fiber surface to form a counter electrode. Finally, twist another carbon nanotube fiber with it. According to the different number of twist turns, control the unit length of the final twisted pair fiber to complete the preparation of the perovskite fiber solar cell.

[0044] Example 2

[0045] 1. Add 1000 mg of anhydrous zinc acetate to 15 ml of 2-MA and 250 μL of EA. After stirring at 60 °C for 2 hours, then stir at room temperature for 48 hours to obtain an electron transport layer precursor solution. In the laboratory, prepare a 5 ml DMF / DMSO (8 / 2 v / v) solution with a molar ratio of FAI / PbI3 = 1 / 1, and oscillate it at room temperature for 20 minutes to obtain a perovskite precursor solution. Disperse 350 mg of CuSCN (99%) powder in 10 ml of dimethyl sulfide (98%), and stir it at room temperature for 1 hour to obtain a hole transport layer precursor solution.

[0046] 2. Use the above device for the preparation of perovskite fiber solar cells, including the following steps:

[0047] (1) Fix one end of a glass capillary tube with a diameter of 0.9 mm on a sliding table, and the other end is suspended. Connect both ends of a silver fiber with a diameter of 0.02 mm to 0.05 mm to a power supply. Turn on the adjustable DC regulated power supply in advance and set the voltage and current so that the temperature of the silver fiber is stabilized at the annealing temperature required for each layer. And to prevent the fiber electrode from being melted, the voltage is less than 21 V and the current is 1.2 A. After the voltage and current are stable, drop an electron transport layer precursor solution at the suspended end of the glass capillary tube. The volume of the precursor liquid droplet is 0.35 mL. The silver fiber passes through the precursor liquid droplet perpendicular to the capillary tube, and is fixed and tightened. Use a preset program to control the movement speed of the stepping motor screw sliding table to be 1 cm / s and move within a range of 5 cm to the left and right centered on the origin, and cycle 3 times. The sliding table slides along the direction of the fiber driven by the stepping motor, and the liquid droplet is cyclically coated on the fiber as the sliding table reciprocates;

[0048] (2) Replace the capillary tube and the precursor solution droplet in the order of the perovskite layer and the hole transport layer, connect the power supply, and then perform reciprocating heat-assisted droplet cyclic coating according to the method in step (1) to complete the coating and annealing of the perovskite layer and the hole transport layer on the fiber surface coated with the electron transport layer in turn;

[0049] (3) Suspend a droplet of a 10 mg / ml silver nanowire isopropanol solution at the end of a capillary tube. The diameter of the silver nanowires in the silver nanowire isopropanol solution is 70 - 100 nm, and the length is 20 - 60 μm. Use a motor to drive the capillary tube to reciprocate, and the silver nanowires are evenly wrapped on the fiber surface to form a counter electrode. Finally, twist another carbon nanotube fiber with it, and control the unit length of the final twisted fiber according to the number of twist turns to complete the preparation of the perovskite fiber solar cell.

[0050] Example 3

[0051] 1. Add 1000 mg of anhydrous zinc acetate to 15 ml of 2-MA and 250 μL of EA. After stirring at 60 °C for 2 hours, then stir at room temperature for 48 hours to obtain an electron transport layer precursor solution. In the laboratory, prepare a 5 ml DMF / DMSO (8 / 2 v / v) solution with a molar ratio of PbBr2 / MABr = 1 / 1, and stir at room temperature for 24 hours to obtain a perovskite precursor solution. Disperse 200 mg of PTAA powder in 10 ml of chlorobenzene (98%) and stir at room temperature for 0.5 hours to obtain a hole transport layer precursor solution.

[0052] 2. Use the above device for the preparation of perovskite fiber solar cells, including the following steps:

[0053] (1) Fix one end of a glass capillary tube with a diameter of 0.9 mm on a sliding table, and the other end is suspended. Connect both ends of a silver fiber with a diameter of 0.02 mm to 0.05 mm to a power supply. Turn on the adjustable DC regulated power supply in advance and set the voltage and current so that the temperature of the silver fiber is stabilized at the annealing temperature required for each layer. And to prevent the fiber electrode from melting, the voltage is 24 V and the current is 1.5 A. After the voltage and current are stabilized, drop an electron transport layer precursor solution at the suspended end of the glass capillary tube. The volume of the precursor liquid droplet is 0.35 mL. The silver fiber passes through the precursor liquid droplet perpendicular to the capillary tube, and is fixed and tightened. Use a preset program to control the movement speed of the stepping motor screw sliding table to be 0.5 cm / s and move within a range of 5 cm to the left and right centered on the origin, and cycle 3 times. The sliding table slides along the direction of the fiber driven by the stepping motor, and the liquid droplet is circularly coated on the fiber as the sliding table reciprocates;

[0054] (2) Replace the capillary tube and the precursor solution droplet in the order of the perovskite layer and the hole transport layer, connect the power supply, and then perform reciprocating heat-assisted droplet circular coating according to the method in step (1) to complete the coating and annealing of the perovskite layer and the hole transport layer on the fiber surface coated with the electron transport layer in turn;

[0055] (3) Suspend a droplet of a 10 mg / ml silver nanowire isopropanol solution at the end of a capillary tube. The diameter of the silver nanowires in the silver nanowire isopropanol solution is 70 - 100 nm, and the length is 20 - 60 μm. Suspend it at the end of the capillary tube, and use a motor to drive the capillary tube to reciprocate. The silver nanowires are evenly wrapped on the fiber surface to form a counter electrode. Finally, twist another carbon nanotube fiber with it, and control the unit length of the final twisted fiber according to the number of twist turns to complete the preparation of the perovskite fiber solar cell.

[0056] Example 4

[0057] 1. Add 230 mg of PC 60 BM to 10 ml of chlorobenzene (98%). After stirring at 60 °C for 12 hours, an electron transport layer precursor solution is obtained. In the laboratory, prepare a 5 ml DMF / DMSO (8 / 2 v / v) solution with a molar ratio of FAI / PbI3 = 1 / 1, and oscillate it at room temperature for 20 minutes to obtain a perovskite precursor solution. Disperse 300 mg of NiO powder in 10 ml of chlorobenzene (98%) and ultrasonicate it at room temperature for 20 minutes to obtain a hole transport layer precursor solution.

[0058] 2. Use the above device for the preparation of perovskite fiber solar cells, including the following steps:

[0059] (1) Fix one end of a glass capillary tube with a diameter of 0.9 mm to a sliding table and leave the other end suspended. Connect both ends of a silver fiber with a diameter of 0.02 mm to 0.05 mm to a power supply. Turn on the adjustable DC regulated power supply in advance and set the voltage and current so that the temperature of the silver fiber is stabilized at the annealing temperature required for each layer. To prevent the fiber electrode from melting, the voltage is 21 V and the current is 1.2 A. After the voltage and current are stabilized, drop an electron transport layer precursor solution with a volume of 0.35 mL at the suspended end of the glass capillary tube. The silver fiber passes through the precursor solution droplet perpendicular to the capillary tube, and is fixed and tightened. Use a preset program to control the movement speed of the stepping motor screw sliding table at 0.5 cm / s and move within a range of 5 cm to the left and right centered on the origin for 3 cycles. The sliding table slides along the direction of the fiber driven by the stepping motor, and the droplet is cyclically coated on the fiber as the sliding table reciprocates;

[0060] (2) Replace the capillary tube and the precursor solution droplet in the order of the perovskite layer and the hole transport layer, connect the power supply, and then perform reciprocating heat-assisted droplet cyclic coating according to the method in step (1) to complete the coating and annealing of the perovskite layer and the hole transport layer on the fiber surface coated with the electron transport layer in turn;

[0061] (3) Suspend a droplet of a silver nanowire isopropanol solution with a mass concentration of 10 mg / ml at the end of a capillary. The diameter of the silver nanowires in the silver nanowire isopropanol solution is 70 - 100 nm, and the length is 20 - 60 μm. Suspend it at the end of the capillary, and use a motor to drive the capillary to reciprocate. The silver nanowires are evenly wrapped on the fiber surface to form a counter electrode. Finally, twist another carbon nanotube fiber with it. According to the different number of twist turns, control the unit length of the final twisted pair fiber to complete the preparation of the perovskite fiber solar cell.

[0062] Figure 4 It is the efficiency diagram of the fiber perovskite solar cell prepared in Example 1, where (a) is the SEM diagram of the fiber perovskite solar cell. The twist length of the double-twisted solar cell may also affect the cell performance. A short twist length results in a larger contact area, lower contact resistance but a larger light shadow, while a long twist length results in a smaller contact area, higher contact resistance but a smaller light shadow. Therefore, it is very important to find an appropriate twist length. It can be seen from the figure that when the twist length is about 450 μm, the average PCE is the highest, which is 2.54%. It can be seen from the SEM diagram that the twist length of the fiber perovskite solar cell prepared by the present invention is about 450 μm, and it has the best performance.

[0063] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the description in the method part.

[0064] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a perovskite fiber solar cell, characterized in that, It includes the following steps: (1) Pass the fiber through the droplets of the electron transport layer precursor solution, and then use a driving device to perform reciprocating thermally assisted droplet circulation coating on the fiber with the droplets to obtain a fiber coated with the electron transport layer; The thermally assisted droplet circulation coating is that both ends of the fiber are connected to a power source, and annealing is assisted by current during the coating process to complete the thermally assisted droplet circulation coating work on the fiber. The voltage generated by the power source is less than 25V, and the current is less than 2A; (2) Replace the capillary and the precursor solution droplets in the order of the perovskite layer and the hole transport layer, connect the power source, and then perform reciprocating thermally assisted droplet circulation coating to complete the coating and annealing of the perovskite layer and the hole transport layer on the surface of the fiber coated with the electron transport layer in turn; (3) Suspend the counter electrode precursor solution droplets at the end of the capillary, and use a driving device to make the counter electrode precursor solution droplets reciprocate on the fiber obtained in step 2 to form a counter electrode, and then twist another fiber with it to obtain a perovskite fiber solar cell with a fiber, an electron transport layer, a perovskite layer, a hole transport layer, and a counter electrode from the inside to the outside.

2. A method for preparing a perovskite fiber solar cell according to claim 1, characterized in that The fiber is made of carbon nanotubes or silver or gold fibers, and the diameter is 0.02mm to 0.05mm.

3. A method for preparing a perovskite fiber solar cell according to claim 1, characterized in that, The electron transport layer is selected from at least one of ZnO, TiO2, SnO2, Nb2O5, In2O3, Zn2SnO4, SrTiO3, WO3, TaO3, PC 60 BM or C60.

4. A method for preparing a perovskite fiber solar cell according to claim 1, characterized in that, The hole transport layer is selected from one of CuSCN, PEDOT:PSS, Spiro-OMeTAD, P3HT, PTAA, NiO, and MoOx(2.5≤x≤3).

5. A method for preparing a perovskite fiber solar cell according to claim 1, wherein, The perovskite selects CsPbBr3 or organic hybrid perovskite, and the organic hybrid perovskite is Cs 0.17 FA 0.83 Pb(I 0.94 Br 0.06 )3, Cs 0.17 FA 0.83 Pb(I 0.95 Cl 0.05 )3, Cs 0.5 FA 0.4 MA 0.1 Pb(I 0.83 Br 0.17 )3.

6. A method for preparing a perovskite fiber solar cell according to claim 1, characterized in that, The specific operation of the thermally assisted droplet circulation coating is as follows: Fix one end of a capillary with a diameter of 0.6 - 1.2mm on a sliding table, and the other end is suspended. Drop the precursor solution at the suspended end. Pass the fiber through the precursor solution droplets in a direction perpendicular to the capillary, and fix and tighten it. The sliding table slides along the direction of the fiber under the drive of a stepping motor, and the droplets perform circular coating on the fiber with the reciprocation of the sliding table.

7. A method for preparing a perovskite fiber solar cell according to claim 6, characterized in that, The height of the suspended end of the capillary is 3 - 4 cm, and the volume of the precursor solution droplets is not less than 0.3 mL.

8. A perovskite fiber solar cell prepared by the method for preparing a perovskite fiber solar cell according to any one of claims 1 - 7.

9. Application of a perovskite fiber solar cell according to claim 8 in the field of wearable devices.

10. An apparatus for preparing a perovskite fiber solar cell, characterized in that, The device includes: a sliding table, a capillary, a platform, an adjustable DC regulated power supply, a power negative terminal connector, a power positive terminal connector, a stepping motor, and an encoder. One end of the capillary is fixedly connected to the sliding table, and the other end is suspended above the platform. Drop the precursor solution at the suspended end. Pass the fiber through the precursor solution droplets, and fix both ends to the power positive terminal connector and the power negative terminal connector. The encoder is connected to the sliding table through the stepping motor to drive the capillary on the sliding table to reciprocate along the direction of the fiber. The positive and negative poles of the adjustable DC regulated power supply are connected to the power positive terminal connector and the power negative terminal connector respectively through wires.

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