Perovskite solar cell doped with graphite carbon nitride g-c3n5 and preparation method thereof

Abstract

This invention discloses a perovskite solar cell with a graphitic carbon nitride (g-C3N5) doped active layer and its fabrication method. The device comprises an anode layer, a hole transport layer, an active layer, an electron transport layer, and a cathode substrate, sequentially stacked. The active layer is a perovskite layer doped with graphitic carbon nitride (g-C3N5). The incorporated graphitic carbon nitride (g-C3N5) can passivate bulk and interface defects in the active layer, effectively reducing charge recombination and improving charge transport and collection. It can also promote perovskite film crystallization, increasing carrier concentration and improving photoelectric performance; and enhance the hydrophobicity of the perovskite film, thereby strengthening device stability. This invention involves blending a graphitic carbon nitride (g-C3N5) solution with a perovskite precursor solution, followed by spin-coating to form a film. The process is simple, low-cost, and can be directly mass-produced, showing great application potential.

Description

Technical Field

[0001] This invention relates to the field of solar cells, and more particularly to a perovskite solar cell with a graphitic carbon nitride g-C3N5 doped active layer and its preparation method. Background Technology

[0002] Over the past few decades, halide perovskite solar cells have gradually taken a dominant position in the photovoltaic field due to their ultra-high power conversion efficiency (certified to be over 25%) and simple manufacturing process, demonstrating enormous commercial potential.

[0003] The superior performance of perovskite solar cells is attributed to their inherent advantages, the most significant of which are their tunable bandgap, small exciton binding energy, high absorption coefficient, and long carrier diffusion distance. However, perovskite films inevitably contain numerous defects during fabrication. These defects typically act as interfacial nonradiative recombination centers, hindering charge transport and leading to reduced performance and stability of perovskite solar cells.

[0004] International scientists, including Minjin Kim, reported recent advancements in interface engineering for perovskite solar cells in the prestigious journal Science, achieving a certified conversion efficiency of 25.4% (Minjin Kim, Jaeki Jeong, Haizhou Lu et al, Conformal quantum dot–SnO2 layers as electron transporters for efficient perovskite solar cells, Science 2022, 375, 302). However, quantum dot-based interface engineering is not only complex but also costly, hindering large-scale commercial applications.

[0005] Therefore, in order to further improve the film formation quality of perovskite thin films and enhance their photoelectric conversion efficiency and stability, existing technologies need to be further improved and perfected. Summary of the Invention

[0006] The purpose of this invention is to address the inherent defects of current perovskite solar cells by using low-cost, clean, and pollution-free graphitic carbon nitride (g-C3N5) as an additive for perovskite solar cells. This improves the crystal quality of the perovskite film, promotes electron-hole separation, and ultimately enhances the photoelectric conversion efficiency and stability of perovskite solar cells.

[0007] This invention is achieved through the following technical solution:

[0008] A perovskite solar cell with a graphitic carbon nitride g-C3N5 doped active layer has a device structure comprising an anode layer, a hole transport layer, an active layer, an electron transport layer, and a cathode substrate stacked sequentially, wherein the active layer is a perovskite layer doped with graphitic carbon nitride g-C3N5.

[0009] Furthermore, the cathode substrate is selected from conductive glass with indium tin oxide (ITO), fluorine-doped SnO2 (FTO), or Al-doped zinc oxide (AZO) as the conductive layer.

[0010] Furthermore, the electron transport layer is a TiO2 or SnO2 thin film, and the thickness of the electron transport layer is 30-50 nm.

[0011] Furthermore, the active layer has ABX m Y 3-m The material has a crystal structure, wherein A is CH3NH3 or C4H9NH3; B is Pb or Sn; X and Y are Cl, Br, or I; and m is 1, 2, or 3. The thickness of the active layer is 150–300 nm.

[0012] Furthermore, the hole transport layer is one or a mixture of two or more of the following in any proportion: NiO, CuO, CuSCN, CuI, tungsten trioxide, molybdenum trioxide, vanadium pentoxide, 2,2',7,7'-tetratetra[N,N-diamino]-9,9'-spirodifluorene (Spiro-OMeTAD), poly-3-hexylthiophene (P3HT), polybis(4-phenyl)(2,4,6-trimethylphenyl)amine (PTAA), N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB), and N,N'-di(3-methylphenyl-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (TPD). The thickness of the hole transport layer is 100–200 nm.

[0013] Furthermore, the anode layer is Ag, and its thickness is [missing information].

[0014] This invention provides a method for fabricating a perovskite solar cell with a graphitic carbon nitride g-C3N5 doped active layer, comprising the following steps:

[0015] (1) Clean the cathode substrate and perform surface oxygen Plasma treatment on the surface of the cathode substrate.

[0016] (2) Spin-coating an electron transport layer onto the surface of the cathode layer that has undergone surface treatment in step (1);

[0017] (3) Prepare an active layer of doped graphitic carbon nitride g-C3N5 by spin coating on the surface of the electron transport layer in step (2);

[0018] (4) Prepare a hole transport layer by spin coating on the surface of the active layer in step (3);

[0019] (5) Vacuum evaporation of an anode layer on the surface of the hole transport layer in step (4);

[0020] After the above process steps are completed, the perovskite solar cell with graphite carbon nitride g-C3N5 doped active layer is obtained.

[0021] Furthermore, in step (1), the cathode substrate is preferably ITO. The cathode substrate treatment includes:

[0022] First, the cathode substrate is ultrasonically cleaned sequentially with dish soap, deionized water, acetone, anhydrous ethanol, and isopropanol for 15–20 minutes each; then dried in a vacuum drying oven at 80–90°C; finally, the cleaned and dried cathode substrate surface is subjected to plasma surface treatment for 13–15 minutes.

[0023] Furthermore, in step (2), the preferred electron transport layer is SnO2. The preparation steps of the electron transport layer include:

[0024] An electron transport layer material solution was coated onto the surface of a cathode substrate that had been treated with ultraviolet light, and then spin-coated at 3000–4000 rpm for 30–40 s. Subsequently, the substrate was annealed at 160–180 °C for 30–50 min to form an electron transport layer on the cathode substrate surface.

[0025] Furthermore, in step (3), the active layer is preferably MaPbI3 doped with graphitic carbon nitride g-C3N5, i.e., CH3NH3PbI3. The preparation steps of the active layer include:

[0026] (1) Preparation of perovskite precursor solution: The compound raw material of the active layer material is dissolved in a mixed organic solution. The mixed organic solution is composed of N,N-dimethylformamide and dimethyl sulfoxide (volume ratio 9:1).

[0027] (2) Preparation of C3N5 solution: 3-amino-1,2,4-triazole powder was placed in an Al2O3 crucible and covered with an Al2O3 lid to maintain a semi-covered state. The crucible was then heated to 500-550℃ in a muffle furnace and kept at that temperature for 3-5 hours. After cooling to room temperature, the obtained brown sample was ground into powder. The prepared C3N5 powder was dispersed in a mixed organic solution composed of N,N-dimethylformamide and dimethyl sulfoxide and stirred overnight.

[0028] (3) C3N5 solutions of different concentrations were mixed with perovskite precursor solutions and magnetically stirred for 8-10 hours. The mixed solution was then spin-coated onto the surface of the electron transport layer. First, the spin coating was carried out at 1000-1500 rpm for 5-10 seconds, and then at 4000-5000 rpm for 30-40 seconds. At 8-15 seconds, chlorobenzene was dropped onto the rotating perovskite film. The spin-coated film substrate was then annealed at 100-150℃ for 15-30 minutes.

[0029] Furthermore, in step (4), the hole transport layer is preferably Spiro-OMeTAD. The preparation steps of the hole transport layer include:

[0030] (1) Solution preparation: Dissolve hole transport layer material powder in chlorobenzene, add 4-tert-butylpyridine and lithium bis(trifluoromethanesulfonyl)imide, and stir overnight;

[0031] (2) Preparation of hole transport layer: The prepared solution is spin-coated onto the thin film substrate with the active layer spin-coated above, spin-coated at 4000-5000 rpm for 30-40 s, and oxidized overnight in atmospheric environment.

[0032] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0033] (1) The graphite carbon nitride g-C3N5 doped into the perovskite active layer of the present invention can passivate the bulk defects and interface defects of the active layer, effectively reduce charge recombination, enhance charge transport and collection, and thus improve the photoelectric conversion efficiency of perovskite solar cells.

[0034] (2) The incorporation of graphitic carbon nitride g-C3N5 can promote the crystallization of perovskite films, increase the carrier concentration, and improve the photoelectric properties of the films. Moreover, the incorporation of graphitic carbon nitride g-C3N5 can also enhance the hydrophobicity of perovskite films, thereby improving the stability of devices.

[0035] (3) The present invention blends graphite carbon nitride g-C3N5 solution with perovskite precursor solution and then spin-coates it into a film. The process is simple and low cost, and can be directly mass-produced, with good application prospects. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of a perovskite solar cell device with a graphitic carbon nitride g-C3N5 doped active layer according to the present invention.

[0037] Figure 2 This is a simplified process flow diagram of the fabrication process of a perovskite solar cell device with a graphitic carbon nitride g-C3N5 doped active layer according to the present invention.

[0038] Figure 3 The graph shows the relationship between current density and voltage for the perovskite solar cell devices prepared in Example 1 and Comparative Example 1. Detailed Implementation

[0039] The technical solution of the present invention will be further described below with reference to specific embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0040] A perovskite solar cell with a graphitic carbon nitride g-C3N5 doped active layer according to the present invention is shown in the schematic diagram of the device structure. Figure 1 As shown, from bottom to top, the layers are: cathode substrate 01, electron transport layer 02, active layer 03, hole transport layer 04, and anode layer 05. The thickness of the electron transport layer is 30–50 nm, the thickness of the active layer is 150–300 nm, the thickness of the hole transport layer is 100–200 nm, and the thickness of the anode layer is…

[0041] The fabrication process of the above-mentioned perovskite solar cell with a graphitic carbon nitride g-C3N5 doped active layer is as follows: Figure 2 As shown, it includes the following steps:

[0042] Step 1: Clean the cathode substrate;

[0043] Step 2: Perform surface oxygen plasma treatment on the cleaned and dried cathode substrate surface;

[0044] Step 3: Spin-coating an electron transport layer onto the treated cathode substrate surface;

[0045] Step 4: Spin-coating an active layer doped with graphitic carbon nitride g-C3N5 onto the surface of the electron transport layer;

[0046] Step 5: Spin-coating a hole transport layer onto the surface of the active layer;

[0047] Step 6: Vacuum vapor deposit an anode layer on the surface of the hole transport layer;

[0048] After the above steps are completed, the perovskite solar cell with graphite carbon nitride g-C3N5 doped active layer is obtained.

[0049] Example 1

[0050] The perovskite solar cell with a graphitic carbon nitride (g-C3N5) doped active layer fabricated in this embodiment has the following device structure: ITO / SnO2 / MaPbI3:C3N5 / Spiro-OMeTAD / Ag. The fabrication process is as follows:

[0051] Step 1: Clean the ITO glass substrate electrode sequentially with dish soap, deionized water, acetone, anhydrous ethanol, and isopropanol, each for 20 minutes; then dry it in a vacuum drying oven at 80°C.

[0052] Step 2: Perform a 13-minute plasma surface treatment on the cleaned and dried cathode substrate (ITO) surface. This treatment method uses the strong oxidizing properties of ozone generated under microwaves to clean residual organic matter on the ITO surface. At the same time, it can increase the oxygen vacancies on the ITO surface, thereby increasing the work function of the ITO surface.

[0053] Step 3: Coat the SnO2 colloid onto the UV-treated ITO substrate surface and spin coat at 3600 rpm for 30 s; then anneal at 180°C for 30 min to form a SnO2 layer (electron transport layer) on the ITO substrate surface.

[0054] Step 4: Spin-coating a perovskite active layer doped with graphitic carbon nitride g-C3N5 onto the surface of the substrate treated above:

[0055] (1) Preparation of perovskite precursor solution: 580.9 mg of MAI and 190.8 mg of PbI2 were dissolved in 1 mL of mixed organic solution, which consisted of N,N-dimethylformamide and dimethyl sulfoxide (volume ratio 9:1).

[0056] (2) Preparation of C3N5 solution: 4.0 g of 3-amino-1,2,4-triazole powder was placed in an Al2O3 crucible, and the crucible was partially covered with an Al2O3 lid. The crucible was then heated to 500 °C in a muffle furnace and held at that temperature for 3 h. After cooling to room temperature, the obtained brown sample was ground into powder. The obtained brown sample was ground into powder for further use. The prepared C3N5 powder was then used in a solution of 0.03 mg·mL⁻¹. -1 The concentration of the substance was dispersed in a mixed organic solution of N,N-dimethylformamide and dimethyl sulfoxide (volume ratio 9:1) and stirred for 24 h.

[0057] (3) The C3N5 solution was mixed with the perovskite precursor solution and magnetically stirred for 8 hours. The mixed solution was spin-coated onto the surface of the electron transport layer. First, it was spin-coated at 1000 rpm for 6 seconds, and then at 4000 rpm for 30 seconds. At the 8th second, 100 μL of chlorobenzene was dropped onto the rotating perovskite film. The spin-coated film substrate was then annealed at 100℃ for 30 minutes.

[0058] Step 5, Preparation of Spiro-OMeTAD solution: Dissolve 72.3 mg Spiro-OMeTAD powder in 1 mL of chlorobenzene, and add 29 μL of 4-tert-butylpyridine and 17.5 μL of lithium bis(trifluoromethanesulfonyl)imide (520 mg·mL⁻¹). -1 In acetonitrile, the mixture was stirred for 10 h. Then, under anhydrous conditions (or relative humidity less than 25 wt%), the Spiro-OMeTAD hole transport layer was prepared by spin-coating at 4000 rpm for 30 s on the surface of the above active layer.

[0059] Step 6: In a vacuum environment (1×10 -5 A layer of Ag electrode is deposited by vapor deposition, with a thickness of pa)

[0060] After the above steps are completed, the product with 0.03 mg·mL⁻¹ doping is obtained. -1 A perovskite solar cell with MaPbI3 as the active layer of graphitic carbon nitride g-C3N5.

[0061] Comparative Example 1

[0062] The preparation conditions for Comparative Example 1 were basically the same as those for Example 1, except that the active layer was an undoped graphitic carbon nitride g-C3N5 perovskite layer. The device structure of the prepared perovskite solar cell was: ITO / SnO2 / MaPbI3 / Spiro-OMeTAD / Ag.

[0063] Figure 3 Example 1 uses 0.03 mg·mL as the dopant. -1 The current density versus voltage curves of a perovskite solar cell with a graphitic carbon nitride (g-C3N5) active layer (MaPbI3) and a comparative example (1) perovskite solar cell with an undoped graphitic carbon nitride (g-C3N5) active layer (MaPbI3) are shown. Figure 3 It can be seen that the open-circuit voltage V of the perovskite solar cell with MaPbI3 as the active layer in Comparative Example 1 is... oc The voltage is 1.01V, and the short-circuit current density is J. sc 16.52 mA / cm 2 Example 1: Doping with 0.03 mg / mL -1 The open-circuit voltage V of a perovskite solar cell with graphitic carbon nitride g-C3N5 as the active layer and MaPbI3 as the active layer is... oc The voltage is 1.04V, and the short-circuit current density is J. sc 19.12 mA / cm 2 This indicates that using MaPbI3 doped with graphitic carbon nitride g-C3N5 as the active layer can effectively improve charge transport efficiency, thereby increasing short-circuit current density.

[0064] Example 2

[0065] The perovskite solar cell with a graphitic carbon nitride (g-C3N5) doped active layer fabricated in this embodiment has the following device structure: ITO / SnO2 / MaPbI3:C3N5 / Spiro-OMeTAD / Ag. The fabrication process is as follows:

[0066] Step 1: Clean the ITO glass substrate electrode sequentially with dish soap, deionized water, acetone, anhydrous ethanol, and isopropanol, each for 20 minutes; then dry it in a vacuum drying oven at 80°C.

[0067] Step 2: Perform a 13-minute plasma surface treatment on the cleaned and dried cathode substrate (ITO). This treatment method utilizes the strong oxidizing properties of ozone generated under microwaves to clean residual organic matter on the ITO surface. At the same time, it can increase the oxygen vacancies on the ITO surface, thereby increasing the work function of the ITO surface.

[0068] Step 3: Coat the SnO2 colloid onto the UV-treated ITO substrate surface and spin coat at 3800 rpm for 35 s; then anneal at 170°C for 40 min to form a SnO2 layer (electron transport layer) on the ITO substrate surface.

[0069] Step 4: Spin-coating a perovskite active layer doped with graphitic carbon nitride g-C3N5 onto the surface of the substrate treated above:

[0070] (1) Preparation of perovskite precursor solution: 580.9 mg of MAI and 190.8 mg of PbI2 were dissolved in 1 mL of mixed organic solution, which consisted of N,N-dimethylformamide and dimethyl sulfoxide (volume ratio 9:1).

[0071] (2) Preparation of C3N5 solution: 4.0 g of 3-amino-1,2,4-triazole powder was placed in an Al2O3 crucible, and the crucible was partially covered with an Al2O3 lid. The crucible was then heated to 500 °C in a muffle furnace and held at that temperature for 3 h. After cooling to room temperature, the obtained brown sample was ground into powder. The obtained brown sample was ground into powder for further use. The prepared C3N5 powder was then used in a solution of 0.05 mg·mL⁻¹. -1 The concentration of the substance was dispersed in a mixed organic solution of N,N-dimethylformamide and dimethyl sulfoxide (volume ratio 9:1) and stirred for 24 h.

[0072] (3) The C3N5 solution was mixed with the perovskite precursor solution and magnetically stirred for 8 hours. The mixed solution was spin-coated onto the surface of the electron transport layer, first at 1500 rpm for 7 seconds, then at 4500 rpm for 30 seconds, and at the 8th second, 100 μL of chlorobenzene was dropped onto the spinning perovskite film. The spin-coated film substrate was then annealed at 120 °C for 20 minutes.

[0073] Step 5, Preparation of Spiro-OMeTAD solution: Dissolve 72.3 mg Spiro-OMeTAD powder in 1 mL of chlorobenzene, and add 29 μL of 4-tert-butylpyridine and 17.5 μL of lithium bis(trifluoromethanesulfonyl)imide (520 mg·mL⁻¹). -1 In acetonitrile, the mixture was stirred for 10 h. Then, under anhydrous conditions (or relative humidity less than 25 wt%), the Spiro-OMeTAD hole transport layer was prepared by spin-coating at 4200 rpm for 40 s on the surface of the above active layer.

[0074] Step 6: In a vacuum environment (1×10 -5 A layer of Ag electrode is deposited by vapor deposition, with a thickness of pa)

[0075] After the above steps are completed, a product with a doping concentration of 0.05 mg·mL is obtained. -1 A perovskite solar cell with MaPbI3 as the active layer of graphitic carbon nitride g-C3N5.

[0076] Example 3

[0077] The perovskite solar cell with a graphitic carbon nitride g-C3N5 doped active layer fabricated in this embodiment has the following device structure: FTO / SnO2 / MaPbI3:C3N5 / Spiro-OMeTAD / Ag. The fabrication process is as follows:

[0078] Step 1: Clean the FTO glass substrate electrode sequentially with dish soap, deionized water, acetone, anhydrous ethanol, and isopropanol, each for 20 minutes; then dry it in an 80°C vacuum drying oven.

[0079] Step 2: Perform a 15-minute plasma surface treatment on the cleaned and dried cathode substrate (FTO). This treatment method utilizes the strong oxidizing properties of ozone generated under microwaves to clean residual organic matter on the FTO surface. At the same time, it can increase the oxygen vacancies on the FTO surface, thereby increasing the work function of the FTO surface.

[0080] Step 3: Coat the SnO2 colloid onto the UV-treated FTO substrate surface and spin coat at 4000 rpm for 30 seconds; then anneal at 160°C for 40 minutes to form a SnO2 layer (electron transport layer) on the FTO substrate surface.

[0081] Step 4: Spin-coating a perovskite active layer doped with graphitic carbon nitride g-C3N5 onto the pretreated substrate surface:

[0082] (1) Preparation of perovskite precursor solution: 580.9 mg of MAI and 190.8 mg of PbI2 were dissolved in 1 mL of mixed organic solution, which consisted of N,N-dimethylformamide and dimethyl sulfoxide (volume ratio 9:1).

[0083] (2) Preparation of C3N5 solution: 4.0 g of 3-amino-1,2,4-triazole powder was placed in an Al2O3 crucible, and the crucible was partially covered with an Al2O3 lid. The crucible was then heated to 500 °C in a muffle furnace and held at that temperature for 3 h. After cooling to room temperature, the obtained brown sample was ground into powder. The obtained brown sample was ground into powder for further use. The prepared C3N5 powder was then used at a concentration of 0.08 mg·mL⁻¹. -1 The concentration of the substance was dispersed in a mixed organic solution of N,N-dimethylformamide and dimethyl sulfoxide (volume ratio 9:1) and stirred for 24 h.

[0084] (3) The C3N5 solution was mixed with the perovskite precursor solution and magnetically stirred for 8 hours. The mixed solution was spin-coated onto the surface of the electron transport layer, first at 1500 rpm for 8 seconds, then at 5000 rpm for 30 seconds, and at the 10th second, 100 μL of chlorobenzene was dropped onto the spinning perovskite film. The spin-coated film substrate was then annealed at 150 °C for 15 minutes.

[0085] Step 5, Preparation of Spiro-OMeTAD solution: Dissolve 72.3 mg Spiro-OMeTAD powder in 1 mL of chlorobenzene, and add 29 μL of 4-tert-butylpyridine and 17.5 μL of lithium bis(trifluoromethanesulfonyl)imide (520 mg·mL⁻¹). -1 In acetonitrile, the mixture was stirred for 10 h. Then, under anhydrous conditions (or relative humidity less than 25 wt%), the Spiro-OMeTAD hole transport layer was prepared by spin-coating at 4500 rpm for 30 s on the surface of the above active layer.

[0086] Step 6: In a vacuum environment (1×10 -5 A layer of Ag electrode is deposited by vapor deposition, with a thickness of pa)

[0087] After the above steps are completed, the product with 0.08 mg·mL⁻¹ doping is obtained. -1 A perovskite solar cell with MaPbI3 as the active layer of graphitic carbon nitride g-C3N5.

[0088] Example 4

[0089] The perovskite solar cell with a graphitic carbon nitride g-C3N5 doped active layer fabricated in this embodiment has the following device structure: FTO / SnO2 / MaPbI3:C3N5 / Spiro-OMeTAD / Ag. The fabrication process is as follows:

[0090] Step 1: Clean the FTO glass substrate electrode sequentially with dish soap, deionized water, acetone, anhydrous ethanol, and isopropanol, each ultrasonically for 20 minutes; then dry it in an 80°C vacuum drying oven.

[0091] Step 2: Perform a plasma surface treatment on the cleaned and dried anode substrate (FTO) surface for 13 minutes. This treatment method uses the strong oxidizing properties of ozone generated under microwaves to clean residual organic matter on the FTO surface. At the same time, it can increase the oxygen vacancies on the FTO surface, thereby increasing the work function of the FTO surface.

[0092] Step 3: Coat the SnO2 colloid onto the UV-treated FTO substrate surface and spin coat at 3000 rpm for 30 seconds; then anneal at 180°C for 30 minutes to form a SnO2 layer (electron transport layer) on the FTO substrate surface.

[0093] Step 4: Spin-coating a perovskite active layer doped with graphitic carbon nitride g-C3N5 onto the pretreated substrate surface:

[0094] (1) Preparation of perovskite precursor solution: 580.9 mg of MAI and 190.8 mg of PbI2 were dissolved in 1 mL of mixed organic solution, which consisted of N,N-dimethylformamide and dimethyl sulfoxide (volume ratio 9:1).

[0095] (2) Preparation of C3N5 solution: 4.0 g of 3-amino-1,2,4-triazole powder was placed in an Al2O3 crucible, and the crucible was partially covered with an Al2O3 lid. The crucible was then heated to 550 °C in a muffle furnace and held at that temperature for 3 h. After cooling to room temperature, the obtained brown sample was ground into powder. The obtained brown sample was ground into powder for further use. The prepared C3N5 powder was then mixed with 0.1 mg·mL⁻¹ -1 The concentration of the substance was dispersed in a mixed organic solution of N,N-dimethylformamide and dimethyl sulfoxide (volume ratio 9:1) and stirred for 24 h.

[0096] (3) The C3N5 solution was mixed with the perovskite precursor solution and magnetically stirred for 10 h. The mixed solution was spin-coated onto the surface of the electron transport layer, first at 1000 rpm for 6 s, then at 4000 rpm for 30 s, and at the 8th s, 100 μL of chlorobenzene was dropped onto the spinning perovskite film. The spin-coated film substrate was then annealed at 100 °C for 30 min.

[0097] Step 5, Preparation of Spiro-OMeTAD solution: Dissolve 72.3 mg Spiro-OMeTAD powder in 1 mL of chlorobenzene, and add 29 μL of 4-tert-butylpyridine and 17.5 μL of lithium bis(trifluoromethanesulfonyl)imide (520 mg·mL⁻¹). -1 In acetonitrile, the mixture was stirred for 10 h. Then, under anhydrous conditions (or relative humidity less than 25 wt%), the Spiro-OMeTAD hole transport layer was prepared by spin-coating at 5000 rpm for 30 s on the surface of the above active layer.

[0098] Step 6: In a vacuum environment (1×10 -5 A layer of Ag electrode is deposited by vapor deposition, with a thickness of pa)

[0099] After the above steps are completed, the product is obtained with 0.1 mg·mL⁻¹ doping. -1 A perovskite solar cell with MaPbI3 as the active layer of graphitic carbon nitride g-C3N5.

[0100] Table 1 compares the parameters of the perovskite solar cell devices prepared in Examples 1-4 and Comparative Example 1.

[0101] Table 1 Comparison of parameters between Examples 1-4 and Comparative Example 1

[0102]

[0103] As can be seen from Table 1, the short-circuit current density J in Examples 1, 2, and 3 is... s They are 19.12 mA / cm 2 18.12 mA / cm 2 18.11 mA / cm 2 All were higher than the 16.52 mA / cm² of comparison example 1. 2 The final photoelectric conversion efficiency of Example 1 was improved by 29.11% compared to Comparative Example 1, which means that at 0.03 mg·mL⁻¹, the efficiency was significantly higher. -1The graphitic carbon nitride (g-C3N5) doped active layer exhibits strong photocharge transport capabilities, significantly improving the photoelectric conversion efficiency of perovskite solar cells. Since the perovskite active layer inevitably contains numerous defects during its fabrication process, doping it with graphitic carbon nitride (g-C3N5) can passivate bulk and interface defects, enhancing its charge transport efficiency. Furthermore, Table 1 shows the open-circuit voltage V0 for Examples 1, 2, and 3. oc Compared to Comparative Example 1, the fill factor FF is also significantly improved, indicating that the incorporation of graphitic carbon nitride g-C3N5 can improve the crystallinity of the active layer, increase the carrier concentration, improve light absorption, and enhance photoelectric conversion performance. Furthermore, the incorporation of graphitic carbon nitride g-C3N5 can also improve the hydrophobicity of the perovskite film, thereby enhancing the stability of the device. It should be noted that the open-circuit voltage Voc and short-circuit current density J of the perovskite solar cell prepared in Example 4 are different. sc The efficiency decreased compared to Comparative Example 1 because excessive doping increased roughness, leading to higher charge recombination. Therefore, doping the active layer with an appropriate amount of graphitic carbon nitride (g-C3N5) can effectively improve the photoelectric conversion efficiency of perovskite solar cells and help improve device lifespan. A suitable doping amount is 0.03–0.08 mg·mL⁻¹. -1 This is mainly attributed to the passivation of bulk and surface defects by graphitic carbon nitride (g-C3N5) and the promotion of crystallization of the active layer. This invention involves blending a graphitic carbon nitride (g-C3N5) solution with a perovskite precursor solution, followed by spin-coating to form a film. The process is simple, low-cost, and can be directly mass-produced, showing great application potential.

[0104] The embodiments described above represent only a few implementations of the present invention, and while the descriptions are detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various changes and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A perovskite solar cell doped with a graphite carbon nitride g-C3N5 active layer, characterized in that, It includes an anode layer, a hole transport layer, an active layer, an electron transport layer and a cathode substrate stacked in sequence, wherein the active layer is a perovskite layer doped with graphitic carbon nitride g-C3N5; The preparation steps of the active layer include: (1) Preparation of perovskite precursor solution: The compound raw material of the active layer material is dissolved in a mixed organic solution composed of N,N-dimethylformamide and dimethyl sulfoxide; (2) Preparation of C3N5 solution: 3-amino-1,2,4-triazole powder was placed in an Al2O3 crucible and covered with an Al2O3 lid to maintain a semi-covered state. The crucible was then heated to 500~550℃ in a muffle furnace and kept at that temperature for 3~5 h. After cooling to room temperature, the obtained brown sample was ground into powder. The prepared C3N5 powder was dispersed in a mixed organic solution composed of N,N-dimethylformamide and dimethyl sulfoxide and stirred. (3) C3N5 solutions of different concentrations were mixed with perovskite precursor solutions and magnetically stirred for 8-10 h. The mixed solution was then spin-coated onto the surface of the electron transport layer. First, the spin coating was carried out at 1000-1500 rpm for 5-10 s, and then at 4000-5000 rpm for 30-40 s. At 8-15 s, chlorobenzene was dropped onto the rotating perovskite film. The spin-coated film substrate was then annealed at 100-150℃ for 15-30 min.

2. The perovskite solar cell with a graphitic carbon nitride g-C3N5 doped active layer according to claim 1, characterized in that, The electron transport layer is a TiO2 or SnO2 thin film with a thickness of 30~50 nm. 3.The perovskite solar cell doped with graphitic carbon nitride (g-C 3N 5) active layer according to claim 1, characterized in that, The active layer has ABX m Y 3-m The material has a crystal structure, wherein A is CH3NH3 or C4H9NH3; B is Pb or Sn; X and Y are Cl, Br or I; m is 1, 2 or 3; and the thickness of the active layer is 150~300 nm.

4. The perovskite solar cell doped with graphitic carbon nitride (g-C3N5) active layer according to claim 1, characterized in that, The hole transport layer is NiO, CuO, CuSCN, CuI, tungsten trioxide, molybdenum trioxide, vanadium pentoxide, Spiro one of OMeTAD, P3HT, PTAA, NPB, TPD or a mixture of two or more thereof in any ratio; the thickness of the hole transport layer is 100-200 nm.

5. The perovskite solar cell with a graphitic carbon nitride g-C3N5 doped active layer according to claim 1, characterized in that, The cathode substrate is selected from conductive glass with indium tin oxide (ITO), fluorine-doped SnO2 (FTO), or Al-doped zinc oxide (AZO) as the conductive layer; the anode layer is Ag with a thickness of 800~850 Å.

6. A method for preparing a perovskite solar cell with a graphitic carbon nitride g-C3N5 doped active layer as described in any one of claims 1-5, characterized in that, Includes the following steps: (1) Clean the cathode substrate and perform surface oxygen Plasma treatment on the cathode substrate surface; (2) Spin-coating an electron transport layer onto the surface of the cathode substrate that has undergone surface treatment in step (1); (3) An active layer of doped graphitic carbon nitride g-C3N5 is prepared by spin coating on the surface of the electron transport layer in step (2); (4) Prepare a hole transport layer by spin coating on the surface of the active layer in step (3); (5) Vacuum evaporation of an anode layer on the surface of the hole transport layer in step (4); After the above process steps are completed, the perovskite solar cell with graphite carbon nitride g-C3N5 doped active layer is obtained.

7. The method for preparing perovskite solar cells doped with graphitic carbon nitride g-C3N5 active layer according to claim 6, characterized in that, In step (1), the cathode substrate treatment includes: firstly, ultrasonically cleaning the cathode substrate with detergent, deionized water, acetone, anhydrous ethanol and isopropanol for 15-20 min each; then drying it in a vacuum drying oven at 80-90℃; and finally performing plasma surface treatment on the cleaned and dried cathode substrate surface for 13-15 min.

8. The method for preparing perovskite solar cells doped with graphitic carbon nitride g-C3N5 active layer according to claim 6, characterized in that, In step (2), the electron transport layer preparation steps include: coating an electron transport layer material solution onto the surface of the treated cathode substrate, spin-coating at 3000~4000 rpm for 30~40 s; then annealing at 160~180℃ for 30~50 min to form an electron transport layer on the surface of the cathode substrate.

9. The method for preparing a perovskite solar cell with a graphitic carbon nitride g-C3N5 doped active layer according to claim 6, characterized in that, In step (4), the preparation steps of the hole transport layer include: (1) Solution preparation: Dissolve hole transport layer material powder in chlorobenzene, add 4-tert-butylpyridine and lithium bis(trifluoromethanesulfonyl)imide, and stir; (2) Preparation of hole transport layer: The prepared solution is spin-coated onto a thin film substrate with the active layer spin-coated, and spin-coated at 4000~5000 rpm for 30~40 s, and oxidized in an atmospheric environment.

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