Perovskite solar cell for weak light and preparation method and application thereof

Abstract

The invention relates to the technical field of perovskite solar cells, in particular to a perovskite solar cell for weak light and a preparation method and application thereof, and a precursor solution in a perovskite light absorption layer of the solar cell comprises 0.5-2mg / ml guanidine sulfamate. According to the invention, guanidine sulfamate (GAS) is introduced into the perovskite light absorption layer, so that the quality of the thin film is optimized, the open-circuit voltage and the photoelectric property of the solar cell are improved, and the solar cell with a band gap greater than 1.9 eV can have good power generation performance under the condition of weak light.

Description

Technical Field

[0001] The present invention relates to the technical field of perovskite solar cells, and in particular to a weak-light perovskite solar cell and a preparation method and application thereof. Background Art

[0002] As a renewable and environmentally friendly energy source, solar energy has attracted the attention of many researchers due to its flexibility, high efficiency and relatively low cost. However, the energy from indoor light sources and natural light entering through windows is lost every day, resulting in a waste of resources. It is considered that indoor photovoltaic power generation can be used to solve the problem of wasted light energy.

[0003] However, the serious non-radiative carrier recombination phenomenon under low light conditions restricts the application of perovskite-based indoor photovoltaics. At present, the band gap of the widely studied high-efficiency perovskite solar cells is mainly concentrated in 1.5-1.6eV, and its application in outdoor is not an ideal choice for indoor photovoltaic devices. There are very few studies on indoor photovoltaics with a band gap of 1.9eV and above, and the turn-on voltage loss of the wide band gap is also a problem that needs to be solved. In addition, the working mechanism and main challenges of photovoltaic devices under indoor light are also different from those under sunlight. Therefore, the development of efficient and multifunctional perovskite solar cells with a band gap greater than 1.9eV, exploring their unique characteristics under low light intensity and applying them to indoor photovoltaic devices is the key to filling this market gap. Summary of the invention

[0004] In order to solve the defects in the prior art, the present invention provides a weak-light perovskite solar cell and a preparation method and application thereof. The present invention introduces guanidine sulfamate (GAS) into the perovskite light-absorbing layer to optimize the film quality and the photoelectric performance of the solar cell, so that the solar cell with a band gap greater than 1.9 eV can have good power generation performance under weak light conditions.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a weak-light perovskite solar cell, wherein the components of the precursor solution in the perovskite light-absorbing layer of the solar cell include 0.5 to 2 mg / ml of guanidine sulfamate.

[0007] In some embodiments of the present invention, the dosage of guanidine sulfamate is any one of 0.5 mg / ml, 1 mg / ml, 1.5 mg / ml, 2 mg / ml or a value in between.

[0008] Preferably, the structure of the solar cell includes conductive glass, a hole transport layer, a perovskite light absorption layer, an electron transport layer, and a metal electrode.

[0009] Preferably, the illumination intensity of the weak light is 1000 lux.

[0010] Preferably, the band gap of the solar cell is greater than 1.9 eV.

[0011] In a second aspect, the present invention provides a method for preparing a perovskite solar cell for weak light, comprising the following steps: cleaning conductive glass, preparing a hole transport layer, preparing a perovskite light absorbing layer, preparing an electron transport layer, and preparing a metal electrode; wherein the step of preparing the perovskite light absorbing layer comprises adding 0.5 to 2 mg / ml of guanidine sulfamate to a precursor solution, spin coating it on a substrate, dripping an anti-solvent, and annealing to obtain the result.

[0012] Preferably, the components of the precursor solution include cesium iodide, formamidine hydroiodide, lead iodide and lead bromide.

[0013] Preferably, the spin coating adopts a two-step spin coating method, and the two-step speed parameters are respectively 1000 rpm for 10 seconds with an acceleration of 1000 rpm / s, and 6000 rpm for 30 seconds with an acceleration of 3000 rpm / s.

[0014] Preferably, the annealing temperature is 100° C. and the annealing time is 10 min.

[0015] Preferably, the raw material of the hole transport layer is selected from any one or more of Me-2PACz, 4PADBCz, and 4PACz.

[0016] Preferably, the raw material of the electron transport layer is selected from any one or more of PCBM, C60 and BCP.

[0017] Preferably, the metal electrode material is selected from any one or more of Ag, Au or Cu.

[0018] In a third aspect, the present invention provides an application of a perovskite solar cell in a weak light environment, wherein the perovskite solar cell is the above-mentioned solar cell, and the illumination intensity of the weak light is 1000 lux.

[0019] The beneficial effects of the present invention are:

[0020] The inventors of the present application have found that the halide phase separation phenomenon of wide bandgap perovskite occurs only under relatively high intensity light such as AM 1.5G, and does not occur when the light intensity is less than 1000 lux. Therefore, 1.9eV perovskite solar cells are more suitable for indoor photovoltaics. The doping of different concentrations of aminosulfonic acid guanidine (GAS) in the light absorption layer of the perovskite solar cell of the present invention has the following effects: (1) The S=O group of GAS can coordinate with Pb, and GA +It can form NHX (Cl / Br) with halogen ions, thereby reducing the defects inside the film and greatly improving the humidity stability of the film and the storage stability of the battery device. (2) It makes the grains on the surface of the film more uniform and dense, without any holes. SEM results show that the average grain size of the film is significantly increased from 245.4nm to 367.78nm. (3) The prepared battery device achieved a PCE of up to 37.7% under LED lighting of 1000lux, and had a Voc of 1.19V. The present invention directly optimizes the bulk structure of perovskite and optimizes the photoelectric performance of perovskite solar cells with a band gap greater than 1.9eV. The steps are simple and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 UV-vis spectra (a) and X-ray diffraction spectra (b) of the perovskite light-absorbing layers prepared in the examples and comparative examples;

[0022] Figure 2 The SEM images of the perovskite light-absorbing layers prepared in Example 1 and Comparative Example 1;

[0023] Figure 3 This is a performance test diagram of the perovskite solar cell prepared in Example 1 under weak light. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the technical solution of the invention, the present invention is further described in detail below in conjunction with specific implementation methods.

[0025] Example 1

[0026] This embodiment provides a perovskite solar cell, whose structure includes, from bottom to top, conductive glass, a hole transport layer, a perovskite light absorption layer, an electron transport layer, and a metal electrode.

[0027] The method for preparing the perovskite solar cell comprises the following steps:

[0028] (1) Cleaning of conductive glass: The indium tin oxide (ITO) conductive glass substrate was first gently wiped clean with anhydrous ethanol, then ultrasonicated with ultrapure water and anhydrous ethanol for 30 minutes respectively, and then dried with nitrogen. The ITO conductive glass was then placed in a UV light and ozone cleaning machine for 20 minutes to remove impurities on the substrate surface and improve wettability, so as to facilitate the subsequent spin coating of other layers.

[0029] (2) Preparation of hole transport layer: 70 μL of 0.6 mg / ml dimethoxycarbazole (Me-2PACz) solution (solvent: ethanol) was spin-coated on a conductive glass substrate at a speed of 3000 rpm for 30 s and an acceleration of 3000 rpm / s. To ensure uniformity of the film, the solution was allowed to stand for 10 s before spin coating. The film was then placed on a hot plate at 100°C for annealing for 10 min to obtain a hole transport layer.

[0030] (3) Preparation of perovskite light-absorbing layer: The precursor solution was prepared by dissolving 39.5 mg of cesium iodide (CsI), 153.2 mg of formamidine hydroiodide (FAI), 52.1 mg of lead iodide (PbI2) and 330.3 mg of lead bromide (PbBr2) in 1 mL of DFM:DMSO (volume ratio of 4:1) solvent and stirring for 1 hour to fully dissolve the solution. Then, GAS (weight average molecular weight of 156.164 g / mol) was added at a ratio of 1 mg / ml and mixed well. The second step is to spin-coat the hole transport layer, the spin coating amount is 50 μL, the two-step speed parameters are 1000 rpm for 10 s, the acceleration is 1000 rpm / s, and the second step is to spin-coat the hole transport layer for 30 s, the acceleration is 3000 rpm / s, and 200 μL of anisole is added as an anti-solvent in the last 15 s of the spin coating time to promote the crystallization of the perovskite film. Finally, the spin-coated film is placed on a hot plate at 100°C for thermal annealing for 10 min to obtain a perovskite light absorbing layer.

[0031] (4) Preparation of electron transport layer: 20 nm of fullerene material C60 and 8 nm of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) were evaporated on the perovskite light absorption layer by thermal evaporation method to serve as the electron transport layer;

[0032] (5) Preparation of metal electrode: Ag electrode was deposited onto the BCP layer by thermal evaporation method to form an electrode with a thickness of 120 nm.

[0033] The band gap of this perovskite solar cell is 1.96eV.

[0034] Example 2

[0035] Same as Example 1, except that the amount of GAS added in step (3) is 0.5 mg / ml.

[0036] The band gap of this perovskite solar cell is 1.96eV.

[0037] Example 3

[0038] Same as Example 1, except that the amount of GAS added in step (3) is 1.5 mg / ml.

[0039] The band gap of this perovskite solar cell is 1.96eV.

[0040] Example 4

[0041] Same as Example 1, except that the amount of GAS added in step (3) is 2.0 mg / ml.

[0042] The band gap of this perovskite solar cell is 1.96eV.

[0043] Comparative Example 1

[0044] The same as Example 1, except that GAS is not added in step (3).

[0045] The band gap of this perovskite solar cell is 1.96eV.

[0046] Effect Example 1: Optical properties and morphology analysis of perovskite films

[0047] The light absorption characteristics of the perovskite light-absorbing layers prepared in the examples and comparative examples were observed using UV-vis-NIR spectroscopy, which is mainly used to characterize the photon collection capability of the film. Figure 1 As shown in (a), the samples prepared in the examples all show approximately the same absorption edge, which is located at approximately 632 nm. This indicates that the introduction of GAS has no effect on the light absorption cutoff edge of the perovskite film and will not affect its band gap. At the same time, the light absorption intensity of the film after the introduction of GAS in the example is slightly higher than that of the film in the comparative example.

[0048] Figure 1 (b) is the crystal quality and phase purity of the film characterized by X-ray diffraction (XRD). The comparative sample has two typical characteristic peaks at 14.4° and 29.1°, corresponding to the (100) and (200) crystal planes of the perovskite, respectively. It is worth noting that after the GAS additive is introduced into the embodiment, the (100) crystal plane shifts to a low angle direction, confirming that GAS can partially enter the lattice structure. In addition, when the concentration of the GAS additive is 1 mg / ml, the diffraction peak intensity corresponding to the (100) crystal plane is the highest and the half-peak width is the narrowest, confirming that under this concentration condition, the crystal orientation of the perovskite film is optimal and the film quality is the best.

[0049] Next, a thermal field emission scanning electron microscope (SEM) was used to explore the planar images of the perovskite films obtained in Example 1 and Comparative Example 1. Figure 2As shown, a is the perovskite film obtained in comparative example 1, and b is the perovskite film obtained in example 1. It can be seen that the surface of the perovskite film before and after GAS treatment is uniform and dense, but the average grain size is quite different. The grain size of the film in example 1 is significantly increased, which is significantly increased to 367.78nm compared with 245.4nm in comparative example 1. Therefore, the appropriate introduction of GAS can improve the quality of the perovskite film and promote carrier transport.

[0050] Effect Example 2: Application Effect Test of Perovskite Solar Cells in Weak Light Environment

[0051] Test conditions: The JV performance of the perovskite solar cell prepared in Example 1 was tested under weak light conditions in air at a temperature of 27°C. The test was conducted with an upper light source LED lamp with a light intensity of 1000 lux. The results are shown in Figure 3 .

[0052] It can be seen that the open circuit voltage (Voc) is as high as 1.19 V, the fill factor (FF) is as high as 83.87%, and the indoor photovoltaic efficiency reaches 37.7%, which is mainly due to the significant reduction of the non-radiative recombination of the perovskite film by GAS, and the V oc It is related to the effective improvement of FF.

[0053] The above are only preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be regarded as limiting the present invention, and the protection scope of the present invention should be based on the scope defined by the claims. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A weak light perovskite solar cell, characterized in that: The components of the precursor solution in the perovskite light-absorbing layer of the solar cell include 0.5-2 mg / ml of guanidine sulfamate.

2. The weak light perovskite solar cell according to claim 1, characterized in that: The structure of the solar cell includes conductive glass, a hole transport layer, a perovskite light absorption layer, an electron transport layer, and a metal electrode.

3. The weak light perovskite solar cell according to claim 1, characterized in that: The band gap of the solar cell is greater than 1.9 eV.

4. The weak light perovskite solar cell according to any one of claims 1 to 3, characterized in that: The illumination intensity of the weak light is 1000 lux.

5. A method for preparing a weak light perovskite solar cell, characterized in that: The following steps are involved: Clean the conductive glass, prepare a hole transport layer, prepare a perovskite light-absorbing layer, prepare an electron transport layer, and prepare a metal electrode; wherein the step of preparing the perovskite light-absorbing layer comprises adding 0.5 to 2 mg / ml of aminosulfonic acid guanidine to a precursor solution, spin coating it on a substrate, dripping an anti-solvent, and annealing to obtain the result.

6. The preparation method according to claim 5, characterized in that: The components of the precursor solution include cesium iodide, formamidine hydroiodide, lead iodide and lead bromide.

7. The preparation method according to claim 5, characterized in that: The spin coating adopts a two-step spin coating method, and the two-step rotation speed parameters are respectively 1000 rpm for continuous rotation for 10s, an acceleration of 1000 rpm / s, and 6000 rpm for continuous rotation for 30s, and an acceleration of 3000 rpm / s.

8. The preparation method according to claim 5, characterized in that: The annealing temperature is 100° C. and the annealing time is 10 min.

9. The preparation method according to claim 5, characterized in that: The raw material of the hole transport layer is selected from any one or more of Me-2PACz, 4PADBCz and 4PACz.

10. An application of a perovskite solar cell in a weak light environment, characterized in that: The perovskite solar cell is a solar cell according to any one of claims 1 to 4 or a solar cell prepared by the preparation method according to any one of claims 5 to 9, and the illumination intensity of the weak light is 1000 lux.

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