Perovskite solar cell and preparation method thereof

Abstract

The invention relates to a perovskite solar cell and a preparation method thereof.The internal structure of the perovskite solar cell sequentially comprises a transparent conductive substrate, an electron transport layer, a cadmium sulfide thin film layer, a carbon quantum dot layer, a perovskite light absorption layer, a hole transport layer and a top electrode from top to bottom, the thickness of the cadmium sulfide thin film layer is 5-20 nm, and the thickness of the hole transport layer is 5-20 nm. The film thickness of the carbon quantum dot layer is 5-20 nm, and the particle size of a material for preparing the carbon quantum dot layer is 3-15 nm. The cadmium sulfide thin film layer and the carbon quantum dot layer are sequentially prepared on the surface of the electron transport layer of the metal oxide, the defect of a contact interface with the perovskite light absorption layer is passivated, incident light of ultraviolet-blue light bands is reduced, and the photoelectric conversion efficiency and stability of the perovskite solar cell are both improved.

Description

Technical Field

[0001] This invention belongs to the field of perovskite solar cell technology, and specifically relates to a perovskite solar cell and its preparation method. Background Technology

[0002] The application of organic-inorganic hybrid perovskite materials in solar cells began in 2009 with Miyasaka's team, initially achieving a photoelectric conversion efficiency of less than 4%. Recent reports indicate that small-area perovskite solar cells fabricated using solution methods have achieved photoelectric conversion efficiencies exceeding 25%, demonstrating the ultra-high photoelectric performance of perovskite solar cells. However, stability is increasingly becoming a significant obstacle to the commercialization of perovskite solar cells.

[0003] Generally, perovskite solar cells consist of electrodes, a transport layer, and a perovskite photoactive layer. Studies have shown that the transport layer plays a crucial role in the performance of perovskite solar cells. Common electron transport layer materials are mainly titanium dioxide, zinc oxide, and tin dioxide. However, titanium dioxide exhibits a significant photocatalytic effect under illumination, leading to rapid degradation of the perovskite material and limiting the long-term use of perovskite solar cells. Zinc oxide readily removes protons from the perovskite components, inducing degradation. Tin dioxide is relatively more stable, but defects inevitably exist on the oxide surface, leading to a large amount of non-radiative recombination, which restricts the improvement of the photoelectric conversion efficiency of perovskite solar cells. Therefore, interface modification is commonly used, depositing a very thin passivation layer on the surface of these metal oxides to avoid direct contact with the perovskite layer and improve cell performance. On the other hand, the low bond energy of perovskite materials means that prolonged exposure to high-energy incident light, especially in the ultraviolet band, will break these chemical bonds, generating mobile anions and reducing metal cations. These defects accelerate the deterioration of perovskite solar cell performance. Additives are typically introduced into perovskite thin films to improve the stability of chemical bonds and suppress redox reactions; or an ultraviolet light filter layer is set on the incident light side to reduce the incident intensity of high-energy photons, thereby improving the stability of perovskite solar cells. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a perovskite solar cell and its preparation method. A bifunctional layer of cadmium sulfide thin film and carbon quantum dot layer is sequentially prepared on the surface of the electron transport layer of metal oxide. This not only passivates the interface defects at the contact with the perovskite light-absorbing layer, but also reduces the incident light in the ultraviolet to blue light band, thereby improving both the photoelectric conversion efficiency and stability of the perovskite solar cell.

[0005] This invention is implemented as follows: a perovskite solar cell is provided, wherein the internal structure of the perovskite solar cell, from top to bottom, includes a transparent conductive substrate, an electron transport layer, a cadmium sulfide thin film layer, a carbon quantum dot layer, a perovskite light-absorbing layer, a hole transport layer, and a top electrode. The thickness of the cadmium sulfide thin film layer is 5 nm to 20 nm, the thickness of the carbon quantum dot layer is 5 nm to 20 nm, and the particle size of the material used to prepare the carbon quantum dot layer is 3 nm to 15 nm.

[0006] Furthermore, the transparent conductive substrate is composed of a support layer and a conductive material layer. The support layer is made of any one of glass, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyimide (PI). The conductive material layer is made of any one of indium tin oxide (ITO), fluorine-doped tin oxide (FTO), and aluminum-doped zinc oxide (AZO).

[0007] Furthermore, the electron transport layer is prepared using any one of titanium dioxide, zinc oxide, and tin dioxide.

[0008] Furthermore, the perovskite light-absorbing layer is prepared from a material with an ABX3 structure, wherein A is a methylamino group (CH3NH3). + ), formamidinyl (CH(NH2)2 + Any monovalent organic cation in ), or K + 、Rb + Cs + Given any monovalent inorganic cation, B is a divalent lead ion (Pb). 2+ ) or tin ions (Sn 2+ X is Cl- or Br-. - I - Thiocyanate (SCN) - ) and acetate ions (CH3COO - Any monovalent anion in ().

[0009] Furthermore, the perovskite light-absorbing layer is also doped with metal ions, including at least one of boron, silicon, germanium, arsenic, antimony, beryllium, magnesium, calcium, strontium, barium, aluminum, indium, gallium, thallium, bismuth, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, silver, cadmium, hafnium, tantalum, tungsten, rhenium, osmium, iridium, platinum, and gold. The doped metal ions are compatible with Pb. 2+ or Sn 2+ The percentage of moles does not exceed 5%.

[0010] Furthermore, the hole transport layer is prepared from any one of nickel oxide, vanadium oxide, molybdenum oxide, tungsten oxide, copper sulfide, cuprous thiocyanate, copper oxide, cuprous oxide, cobalt oxide, PTAA, PEDOT, and Spiro-MeOTAD, and the thickness of the hole transport layer is 5 nm to 200 nm.

[0011] Furthermore, the material used to prepare the top electrode is any one of copper, silver, aluminum, gold, ITO, or carbon.

[0012] This invention is achieved by providing a method for fabricating a perovskite solar cell as described above, comprising the following steps:

[0013] Step 1: Prepare a metal oxide electron transport layer on the surface of a transparent conductive substrate;

[0014] Step 2: Prepare a cadmium sulfide thin film layer and a carbon quantum dot layer sequentially on the surface of the electron transport layer;

[0015] Step 3: Sequentially fabricate a perovskite light-absorbing layer, a hole transport layer, and a top electrode on the carbon quantum dot layer until the fabrication of the perovskite solar cell is complete.

[0016] Furthermore, in step one, the material of the transparent conductive substrate has a light transmittance of not less than 80% in the wavelength range of 350nm to 800nm.

[0017] Furthermore, in step two, the fluorescence emission peak range of the carbon quantum dot layer preparation material is 400 nm to 500 nm wavelength.

[0018] Compared with existing technologies, the perovskite solar cell and its fabrication method of the present invention, wherein the internal structure of the perovskite solar cell, from top to bottom, includes a transparent conductive substrate, an electron transport layer, a cadmium sulfide thin film layer, a carbon quantum dot layer, a perovskite light-absorbing layer, a hole transport layer, and a top electrode. By sequentially fabricating a bifunctional layer of cadmium sulfide thin film and carbon quantum dot layer on the surface of the electron transport layer, and then fabricating the perovskite light-absorbing layer, not only are interface defects at the contact layer with the perovskite light-absorbing layer passivated, but incident light in the ultraviolet to blue light band is also reduced, thereby improving the photoelectric performance and long-term stability of the perovskite solar cell. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the internal structure of a preferred embodiment of the perovskite solar cell of the present invention;

[0020] Figure 2 The graphs show the continuous illumination stability curves of Examples 1 to 3 and the control group of the present invention. Detailed Implementation

[0021] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0022] Please refer to Figure 1 As shown in the preferred embodiment of the perovskite solar cell of the present invention, the internal structure of the perovskite solar cell, from top to bottom, includes a transparent conductive substrate 1, an electron transport layer 2, a cadmium sulfide thin film layer 3, a carbon quantum dot layer 4, a perovskite light-absorbing layer 5, a hole transport layer 6, and a top electrode 7. The thickness of the cadmium sulfide thin film layer 3 is 5 nm to 20 nm, the thickness of the carbon quantum dot layer 4 is 5 nm to 20 nm, and the particle size of the material used to prepare the carbon quantum dot layer 4 is 3 nm to 15 nm.

[0023] Cadmium sulfide possesses a suitable optical bandgap, effectively absorbing incident light in the ultraviolet to blue light bands and passivating defect sites on the surface of metal oxides, thus suppressing carrier recombination at the interface. However, cadmium sulfide reacts with the organic components of perovskite to form an insulating layer, inhibiting electron transport and exhibiting significant series resistance. Carbon quantum dots possess excellent electron transport properties, and their abundant surface functional groups, when combined with perovskite, greatly enhance interface stability. This invention fabricates a bifunctional layer of cadmium sulfide thin film layer 3 and carbon quantum dot layer 4 between the electron transport layer 2 and the perovskite light-absorbing layer 5. This not only passivates interface defects at the contact with the perovskite light-absorbing layer but also reduces incident light in the ultraviolet to blue light bands, resulting in a dual improvement in the photoelectric conversion efficiency and stability of the perovskite solar cell.

[0024] Specifically, the transparent conductive substrate 1 is composed of a support layer 8 and a conductive material layer 9. The support layer 8 is made of any one of glass, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyimide (PI). The conductive material layer 9 is made of any one of indium tin oxide (ITO), fluorine-doped tin oxide (FTO), and aluminum-doped zinc oxide (AZO).

[0025] Specifically, the electron transport layer 2 is prepared using any one of titanium dioxide, zinc oxide, and tin dioxide.

[0026] Specifically, the perovskite light-absorbing layer 5 is prepared from a material with an ABX3 structure, wherein A is a methylamino group (CH3NH3). + ), formamidinyl (CH(NH2)2 + Any monovalent organic cation in ), or K + 、Rb + Cs + Given any monovalent inorganic cation, B is a divalent lead ion (Pb).2+ ) or tin ions (Sn 2+ ), X is Cl - ,Br - I - Thiocyanate (SCN) - ) and acetate ions (CH3COO - Any monovalent anion in ().

[0027] Specifically, the perovskite light-absorbing layer 5 is further doped with metal ions, including at least one of boron, silicon, germanium, arsenic, antimony, beryllium, magnesium, calcium, strontium, barium, aluminum, indium, gallium, thallium, bismuth, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, silver, cadmium, hafnium, tantalum, tungsten, rhenium, osmium, iridium, platinum, and gold. The doped metal ions are similar to Pb. 2+ or Sn 2+ The percentage of moles does not exceed 5%.

[0028] Specifically, the hole transport layer 6 is made of any one of nickel oxide, vanadium oxide, molybdenum oxide, tungsten oxide, copper sulfide, cuprous thiocyanate, copper oxide, cuprous oxide, cobalt oxide, PTAA, PEDOT, and Spiro-MeOTAD, and the thickness of the hole transport layer 6 is 5 nm to 200 nm.

[0029] Specifically, the material used to prepare the top electrode 7 is any one of copper, silver, aluminum, gold, ITO, or carbon.

[0030] This invention also discloses a method for fabricating a perovskite solar cell as described above, comprising the following steps:

[0031] Step 1: Prepare a metal oxide electron transport layer 2 on the surface of a transparent conductive substrate 1;

[0032] Step 2: Prepare a cadmium sulfide thin film layer 3 and a carbon quantum dot layer 4 sequentially on the surface of electron transport layer 2;

[0033] Step 3: Sequentially prepare the perovskite light-absorbing layer 5, hole transport layer 6, and top electrode 7 on the carbon quantum dot layer 4 until the perovskite solar cell is fabricated.

[0034] In step one, the material of the transparent conductive substrate 1 has a light transmittance of not less than 80% in the wavelength range of 350nm to 800nm.

[0035] In step two, the fluorescence emission peak of the carbon quantum dot layer 4 is in the range of 400 nm to 500 nm wavelength.

[0036] The perovskite solar cell and its preparation method of the present invention are further illustrated below through specific embodiments.

[0037] Example 1

[0038] The first embodiment of the present invention for preparing perovskite solar cells specifically includes the following steps:

[0039] Step 11: Use cleaning agent, purified water, acetone and isopropanol in sequence to ultrasonically clean the ITO conductive glass substrate, and treat it with UV / O3 for 15 minutes.

[0040] Step 12: Spin-coat a 2.5wt% tin dioxide nano-aqueous dispersion onto a clean ITO surface, anneal at 150°C for 30 minutes, and deposit electron transport layer 2.

[0041] Step 13: Prepare cadmium sulfide thin film layer 3 on tin dioxide surface: Add 2 mmol thiourea and 1 mmol cadmium chloride to 1L deionized water, then add ammonia to adjust the pH value to 10. Tilt the substrate treated in step 12 into the solution and react at 85℃ for 10 minutes. After taking it out, rinse with water, sonicate, blow dry with nitrogen, and heat at 300℃ for 30 minutes.

[0042] Step 14: In-situ growth of carbon quantum dot layer 4 on the surface of cadmium sulfide thin film layer 3: Dissolve 1g of sodium hydroxide in 1L of acetone, place it in the substrate treated in step 13, react for 24h, rinse the surface with water, and dry at 80℃.

[0043] Step 15: Prepare perovskite Cs 0.05 (FA 0.9 MA 0.1 ) 0.95 Pb(I 0.97 br 0.03 The precursor solution for step 3 was prepared by using a DMF:DMSO mixture with a volume ratio of 4:1 and a concentration of 1.2 mol / L. The perovskite precursor solution was dropped onto the substrate surface treated in step 14, and the substrate was spin-coated at 5000 rpm for 10 s. Then, 200 μL of chlorobenzene was rapidly added, followed by another spin-coating for 20 s. The substrate was then removed and annealed at 100 °C for 30 minutes to complete the preparation of the perovskite light-absorbing layer 5.

[0044] Step 16: Add N,N-dimethylphenylammonium tetra(pentafluorophenyl)borate to a 70 mg / ml Spiro chlorobenzene solution, with a molar ratio of 10% of Spiro. After stirring thoroughly overnight, filter and spin-coat at 3000 rpm onto the surface of the perovskite light-absorbing layer 5 to form a hole transport layer 6.

[0045] Step 17: Deposit a 60-nanometer-thick layer of gold on the surface of hole transport layer 6 to obtain top electrode 7, until the fabrication of perovskite solar cell is completed.

[0046] The perovskite solar cells prepared in this embodiment were subjected to performance testing, and the photoelectric conversion efficiency data are shown in Table 1 and the data are shown in Table 2. Figure 2 The continuous illumination stability curve. Figure 2 The control group in the study consists of perovskite solar cells prepared without steps 13 and 14.

[0047] Table 1. Photovoltaic conversion efficiency data of perovskite solar cells prepared in Example 1

[0048]

[0049] Example 2

[0050] The first embodiment of the present invention for preparing perovskite solar cells specifically includes the following steps:

[0051] Step 21: Use cleaning agent, purified water, acetone and isopropanol in sequence to ultrasonically clean the ITO conductive glass substrate, and treat it with UV / O3 for 15 minutes.

[0052] Step 22: Prepare a 40mM titanium tetrachloride ice-water solution, place it on a clean ITO glass substrate, react at 70°C for 30 minutes, rinse the surface with water, dry with nitrogen, and anneal at 200°C for 30 minutes to prepare a 40nm titanium dioxide electron transport layer 2 thin film.

[0053] Step 23: Prepare a cadmium sulfide thin film layer 3 on the titanium dioxide surface: Heat the ITO glass to 300°C, use a cadmium sulfide target with 99.999% purity, and use magnetron sputtering at a rate of 4 nm / min to deposit a total thickness of 10 nm, then heat at 300°C for 60 minutes.

[0054] Step 24: In-situ growth of carbon quantum dot layer 4 on the surface of cadmium sulfide thin film layer 3: Dissolve 0.1g of sodium hydroxide in 1L of acetone, place it in the substrate treated in step 23, react for 100h, rinse the surface with water, and dry at 80℃.

[0055] Step 25: Prepare perovskite FA 0.6 MA 0.4 The PbI3 precursor solution was prepared by using a DMF:DMSO mixture with a volume ratio of 4:1 and a concentration of 1.5 mol / L. The perovskite precursor solution was dropped onto the substrate surface treated in step 24, spin-coated at 6000 rpm for 10 s, followed by rapid addition of 1 mL of diethyl ether, and then spin-coated and annealed at 100 °C for 10 minutes to complete the preparation of the perovskite light-absorbing layer 5.

[0056] Step 26: Add the additives tetra-tert-butylpyridine and lithium bis(trifluoromethanesulfonylimide) to a Spiro chlorobenzene solution with a concentration of 90 mg / ml, and spin-coat the solution at 5000 rpm to form a hole transport layer 6 on the surface of the perovskite light-absorbing layer 5.

[0057] Step 27: Sequentially deposit 5 nm of molybdenum oxide and 100 nm of silver on the surface of hole transport layer 6 to obtain top electrode 7, until the fabrication of perovskite solar cell is completed.

[0058] The perovskite solar cells prepared in this embodiment were subjected to performance testing, and the photoelectric conversion efficiency data are shown in Table 1 and the data are shown in Table 2. Figure 2 The continuous illumination stability curve.

[0059] Example 3

[0060] The first embodiment of the present invention for preparing perovskite solar cells specifically includes the following steps:

[0061] Step 31: Use cleaning agent, purified water, acetone and isopropanol in sequence to ultrasonically clean the FTO conductive glass substrate, and treat it with UV / O3 for 15 minutes.

[0062] Step 32: Prepare a 40mM titanium tetrachloride ice-water solution, place it in a clean FTO glass, react at 70°C for 40 minutes, rinse the surface with water, dry with nitrogen, and anneal at 200°C for 30 minutes to prepare a 50 nm titanium dioxide electron transport layer 2 thin film.

[0063] Step 33: Prepare a cadmium sulfide thin film layer 3 on the titanium dioxide surface: Prepare a 10 mM solution of thiourea and cadmium chloride, with a molar ratio of cadmium chloride / thiourea of ​​1:2. Use nitrogen as the carrier gas and a flow rate of 8 L / min. Spray the solution onto the substrate surface at 400℃ at a flow rate of 2.5 ml / min, with the nozzle 20 cm away from the substrate surface. After spraying, continue heating for 30 minutes.

[0064] Step 34: In-situ growth of carbon quantum dot layer 4 on the surface of cadmium sulfide thin film layer 3: Dissolve 10g of sodium hydroxide in 1L of acetone, place it in the substrate treated in step 33, react for 5h, rinse the surface with water, and dry at 80℃.

[0065] Step 35: Prepare perovskite Cs 0.1 FA 0.9 Pb(I 0.9 br 0.1 The precursor solution of step 3 was prepared by using a DMF:DMSO mixture with a volume ratio of 4:1 and a concentration of 2 mol / L. The perovskite precursor solution was dropped onto the substrate surface treated in step 34, spin-coated at 6000 rpm for 10 s, 100 mL of anisole was quickly added, and then spin-coated and annealed at 100 °C for 30 minutes to complete the preparation of the perovskite light-absorbing layer 5.

[0066] Step 36: Add the additives tetra-tert-butylpyridine and lithium bis(trifluoromethanesulfonylimide) to a Spiro chlorobenzene solution with a concentration of 90 mg / ml, and spin-coat the solution at 5000 rpm to form a hole transport layer 6 on the surface of the perovskite light-absorbing layer 5.

[0067] Step 37: Sequentially deposit 5 nm of molybdenum oxide and 100 nm of silver on the surface of hole transport layer 6 to obtain top electrode 7, until the fabrication of perovskite solar cell is completed.

[0068] The perovskite solar cells prepared in this embodiment were subjected to performance testing, and the photoelectric conversion efficiency data are shown in Table 1 and the data are shown in Table 2. Figure 2 The continuous illumination stability curve.

[0069] pass Figure 2 The comparison shows that the normalized photoelectric conversion efficiency of the perovskite solar cells prepared by the method of the present invention in Examples 1 to 3 decreases significantly with time compared to the control group, achieving the expected results.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A perovskite solar cell, characterized by, The internal structure of the perovskite solar cell comprises, from top to bottom, a transparent conductive substrate, an electron transport layer, a cadmium sulfide film layer, a carbon quantum dot layer, a perovskite light-absorbing layer, a hole transport layer and a top electrode, wherein the thickness of the cadmium sulfide film layer is 5-20 nm, the film thickness of the carbon quantum dot layer is 5-20 nm, and the particle size of the material for preparing the carbon quantum dot layer is 3-15 nm.

2. The perovskite solar cell of claim 1, wherein the perovskite layer is formed by a two-step method. The transparent conductive substrate is composed of a support layer and a conductive material layer, wherein the support layer is made of any one of glass, polyethylene terephthalate (PET), polyethylene naphthalate (PEN) and polyimide (PI), and the conductive material layer is made of any one of indium tin oxide (ITO), fluorine-doped tin oxide (FTO) and aluminum-doped zinc oxide (AZO). 3.The perovskite solar cell of claim 1, wherein, The electron transport layer is made of any one of titanium dioxide, zinc oxide and tin dioxide. 4.The perovskite solar cell of claim 1, wherein, The preparation material of the perovskite light-absorbing layer is a material of ABX3 structural formula, wherein A is any one of monovalent organic cations of methylamine group (CH3NH3 + ), formamidine group (CH(NH2)2 + ), or any one of monovalent inorganic cations of K + , Rb + , Cs + , B is divalent lead ion (Pb 2+ ) or stannous ion (Sn 2+ ), and X is any one of monovalent anions of Cl - , Br - , I - , thiocyanate (SCN-) and acetate ion (CH3COO - ).

5. The perovskite solar cell of claim 4, wherein the perovskite layer is formed by a two-step method. The metal ions include at least one of boron, silicon, germanium, arsenic, antimony, beryllium, magnesium, calcium, strontium, barium, aluminum, indium, gallium, thallium, bismuth, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, silver, cadmium, hafnium, tantalum, tungsten, rhenium, osmium, iridium, platinum, gold, and the molar percentage ratio of the doped metal ions to Pb 2+ or Sn 2+ is not more than 5%.

6. The perovskite solar cell of claim 1, wherein the perovskite layer is formed by a one-step solution process. The hole transport layer is made of any one of nickel oxide, vanadium oxide, molybdenum oxide, tungsten oxide, copper sulfide, cuprous thiocyanate, copper oxide, cuprous oxide, cobalt oxide, PTAA, PEDOT and Spiro-MeOTAD, and the thickness of the hole transport layer is 5-200 nm.

7. The perovskite solar cell of claim 1, wherein the perovskite layer is formed by a one-step solution process. The top electrode is made of any one of copper, silver, aluminum, gold, ITO and carbon material.

8. A method of producing a perovskite solar cell according to any one of claims 1 to 7, characterized by, The method comprises the following steps: Step one: preparing a metal oxide electron transport layer on the surface of the transparent conductive substrate; Step two: sequentially preparing a cadmium sulfide film layer and a carbon quantum dot layer on the surface of the electron transport layer; Step three: sequentially preparing a perovskite light-absorbing layer, a hole transport layer and a top electrode on the carbon quantum dot layer until the preparation of the perovskite solar cell is completed.

9. The method for preparing a perovskite solar cell as described in claim 8, characterized in that, In step one, the material of the transparent conductive substrate has a light transmittance of not less than 80% in the wavelength range of 350-800 nm.

10. The method for preparing a perovskite solar cell as described in claim 8, characterized in that, In step two, the fluorescence emission peak of the carbon quantum dot layer is in the wavelength range of 400-500 nm.

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