A trans-perovskite solar cell and a preparation method thereof

Abstract

The application relates to the technical field of solar cells, in particular to a transverse perovskite solar cell and a preparation method thereof. The structure of the transverse perovskite solar cell comprises, from bottom to top, a conductive substrate layer, a hole transport layer, a lower interface passivation layer, a perovskite light absorption layer, an upper interface passivation layer, an electron transport layer, a buffer layer and a top electrode; wherein the upper interface passivation layer material is a DSA and PEAI double interface material. The DSA and PEAI are introduced into the upper interface of the transverse perovskite solar cell to passivate various defects, so that the photoelectric conversion efficiency and stability of the perovskite solar cell are improved.

Description

Technical Field

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

[0002] Perovskite solar cells (PSCs) have the advantages of high energy conversion efficiency, low material cost, and simple preparation process. They are currently the most popular new generation of solar cells with high research value and commercial potential.

[0003] However, as ionic crystals, perovskite materials inevitably generate numerous defects during their preparation, particularly deep-level defects at the interface, which can cause severe non-radiative recombination and affect the performance of perovskite solar cells. Furthermore, interface defects can induce and accelerate the decomposition of perovskite under aging conditions, affecting device stability. Therefore, the interface of perovskite films is extremely important to the optoelectronic performance and stability of devices, and the search for effective interface materials is of great significance to the development of perovskite solar cell research.

[0004] Currently, a single material is typically used as the top interface material for inverse PSCs to passivate top interface defects, thereby improving device performance. However, this single material suffers from a single passivation site and low coordination strength with the perovskite. This makes it impossible to deeply passivate the numerous and complex defects on the perovskite top interface, nor can it guarantee the long-term effectiveness of the passivation effect. Summary of the Invention

[0005] To address the shortcomings of the prior art, the present invention provides an inverse perovskite solar cell and a method for preparing the same. By introducing a dual-interface material, DSA and PEAI, at the upper interface of the inverse perovskite solar cell, various defects can be passivated, thereby improving the photoelectric conversion efficiency and stability of the perovskite solar cell.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides an inverted perovskite solar cell, whose structure comprises, from bottom to top, a conductive substrate layer, a hole transport layer, a lower interface passivation layer, a perovskite light absorption layer, an upper interface passivation layer, an electron transport layer, a buffer layer and a top electrode; wherein the upper interface passivation layer material is a DSA and PEAI dual interface material.

[0008] The Chinese name of DSA is 2-[(diphenylmethyl)mercapto]acetic acid, and its structural formula is:

[0009]

[0010] The Chinese name of PEAI is phenylethylamine iodide, and its structural formula is:

[0011]

[0012] Preferably, the DSA interface material is at the bottom and the PEAI interface material is at the top.

[0013] Preferably, the mass ratio of DSA to PEAI is (2-4):(3-5). Exemplarily, the mass ratio of DSA to PEAI is any one of 3:5, 2:3, 4:5, or a value in between.

[0014] Preferably, the preparation process of the upper interface passivation layer material is: spin coating a DSA solution and a PEAI solution on the perovskite light absorption layer in sequence, and performing an annealing treatment after the spin coating is completed.

[0015] Preferably, the hole transport layer material is selected from one or more of [4-(7H-dibenzocarbazole-7-yl)butyl]phosphonic acid (4PADCB), (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid (Me-4PACz), and (2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl)phosphonic acid (MeO-2PACz).

[0016] Preferably, the material of the lower interface passivation layer is Al2O3.

[0017] Preferably, the perovskite light absorbing layer material is Rb 0.05 Cs 0.05 MA 0.05 FA 0.85 Pb(I 0.95 Br 0.05 )3 or Cs 0.05 MA 0.1 FA 0.85 PbI3.

[0018] Preferably, the electron transport layer material is [6,6]-phenyl C 61 Methyl butyrate (PCBM) or C 60 .

[0019] Preferably, the buffer layer material is BCP or SnO2.

[0020] In a second aspect, the present invention provides a method for preparing the inverse perovskite solar cell, comprising the following steps:

[0021] S1. Clean the conductive base layer;

[0022] S2, depositing a hole transport layer on a conductive substrate;

[0023] S3, depositing a lower interface passivation layer on the hole transport layer;

[0024] S4, depositing a perovskite light absorption layer on the lower interface passivation layer;

[0025] S5. Depositing an upper interface passivation layer on the perovskite light absorbing layer: spin-coating a DSA solution and a PEAI solution on the perovskite light absorbing layer in sequence, and performing an annealing treatment after the spin coating is completed;

[0026] S6, depositing an electron transport layer on the upper interface passivation layer;

[0027] S7, depositing a buffer layer on the electron transport layer;

[0028] S8. Depositing a top electrode on the electron transport layer.

[0029] Preferably, the concentration of the DSA solution in S5 is 0.4-2 mg / ml, and the concentration of the PEAI solution is 0.5-3 mg / ml. For example, the concentration of the DSA solution in S5 is any one of 0.4 mg / ml, 1.2 mg / ml, and 2 mg / ml, or a value between them; the concentration of the PEAI solution in S5 is any one of 0.5 mg / ml, 1.5 mg / ml, and 3 mg / ml, or a value between them.

[0030] More preferably, the concentration of the DSA solution in S5 is 1.2 mg / ml, and the concentration of the PEAI solution is 1.5 mg / ml.

[0031] Preferably, the solvent of the DSA solution and the PEAI solution is isopropyl alcohol (IPA).

[0032] Preferably, in S5 , the spin coating speed of DSA is 5000 rpm, the acceleration is 3000 rpm / s, and the spin coating time is 30 s; the spin coating speed of PEAI is 5000 rpm, the acceleration is 3000 rpm / s, and the spin coating time is 30 s.

[0033] Preferably, the annealing temperature of S5 is 100° C., and the annealing time is 10 minutes.

[0034] The beneficial effects of the present invention are:

[0035] The present invention introduces DSA and PEAI into the upper interface of the absorption layer of the inverse perovskite solar cell. Since DSA and PEAI contain structures such as sulfide, benzene ring and organic acid, they can passivate the uncoordinated Pb in the perovskite film. 2+ Defects, and I -Electrostatic interactions may occur between them and hydrogen bonds may be formed with FA / MA, which can passivate a variety of different defects. In addition, a lasting passivation effect can be obtained through the anchoring effect of organic acids, which can improve the energy band arrangement and inhibit the non-radiative recombination of carriers at the interface, thereby improving the photoelectric conversion efficiency and stability of perovskite solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is the X-ray photoelectron spectroscopy (XPS) spectrum in Effect Example 1;

[0037] Figure 2 This is a scanning electron microscope (SEM) image of Effect Example 1;

[0038] Figure 3 The steady-state photoluminescence spectrum and time-resolved spectrum in Effect Example 1;

[0039] Figure 4 JV curves of the solar cells prepared in Example 1 and Comparative Example 1;

[0040] Figure 5 This is a storage stability test chart of the solar cells prepared in Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0041] 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.

[0042] Example 1

[0043] This embodiment provides an inverted perovskite solar cell, which comprises, from bottom to top, a conductive substrate layer (made of ITO), a hole transport layer (made of 4PADCB), a lower interface passivation layer (made of Al2O3), a perovskite light absorption layer (made of Rb 0.05 Cs 0.05 MA 0.05 FA 0.85 Pb(I 0.95 Br 0.05 )3), upper interface passivation layer (materials are DSA and PEAI), electron transport layer (material is PCBM), buffer layer (material is BCP) and top electrode (material is Ag).

[0044] The method for preparing the inverse perovskite solar cell comprises the following steps:

[0045] (1) Cleaning of the transparent conductive substrate: Clean the ITO conductive substrate in a UV ozone cleaning machine for 15 minutes according to conventional methods in the art to remove impurities on the substrate surface and improve the substrate wettability;

[0046] (2) Depositing a hole transport layer on the conductive substrate: 90 μL of 4PADCB ethanol solution with a concentration of 0.5 mg / ml was spin-coated on the conductive substrate at a speed of 3000 rpm and an acceleration of 3000 rpm / s for 30 s, and the spin-coated film was placed on a hot stage at 100°C for thermal annealing treatment for 10 min to obtain a hole transport layer;

[0047] (3) Depositing a lower interface passivation layer on the hole transport layer: 90 μL of 0.4 wt% Al2O3 IPA solution was spin-coated on the hole transport layer at a speed of 5000 rpm and an acceleration of 3000 rpm / s for 30 s, and the spin-coated film was placed on a hot stage at 100°C for thermal annealing treatment for 10 min to obtain a lower interface passivation layer;

[0048] (4) Depositing a perovskite light absorption layer on the lower interface passivation layer: 8.4 mg of methylammonium bromide (MABr), 15.9 mg of rubidium iodide (RbI), 19.5 mg of cesium iodide (Csl), 27.5 mg of bromide iodide (PbBr2), 219.5 mg of formamidinium hydroiodide (FAI), and 656.9 mg of lead iodide (PbI2) were dissolved in 800 μL of DMF and 200 μL of DMSO mixed solvent to prepare a perovskite precursor solution; 50 μL of the perovskite precursor solution was spin-coated on the lower interface passivation layer by one-step spin coating, and the spin-coating parameters were as follows: a speed of 1000 rpm for 10 s, an acceleration of 1000 rpm / s, a speed of 3000 rpm for 40 s, and an acceleration of 3000 rpm / s; 100 μL of anisole was added as an anti-solvent at the 35th second of spin coating; and finally, the spin-coated film was placed on a hot stage at 100°C for thermal annealing treatment for 10 min to obtain a perovskite light absorption layer Rb 0.05 Cs 0.05 MA 0.05 FA 0.85 Pb(I 0.95 Br 0.05 )3;

[0049] (5) Depositing an upper interface passivation layer on the perovskite light absorption layer: 50 μL of a 1.2 mg / ml DSA IPA solution was spin-coated on the perovskite light absorption layer at a speed of 5000 rpm and an acceleration of 3000 rpm / s for 30 s; then 50 μL of a 1.5 mg / ml PEAI IPA solution was spin-coated on the perovskite light absorption layer coated with DSA at a speed of 5000 rpm and an acceleration of 3000 rpm / s for 30 s; and the spin-coated film was placed on a hot stage at 100°C for thermal annealing treatment for 10 min to obtain an upper interface passivation layer;

[0050] (6) Deposit the electron transport layer on the upper interface passivation layer: take 70 μL of [6,6]-phenyl C with a concentration of 20 mg / ml 61 A chlorobenzene solution of methyl butyrate (PCBM) was spin-coated on the upper interface passivation layer at a speed of 1500 rpm and an acceleration of 1500 rpm / s for 30 s to obtain an electron transport layer;

[0051] (7) Depositing a buffer layer on the electron transport layer: Take 90 μL of a 0.5 mg / ml BCP-isopropanol solution and spin-coat it on the upper interface passivation layer at a speed of 5000 rpm and an acceleration of 2500 rpm / s for 30 s to obtain a buffer layer;

[0052] (8) When the vacuum degree is lower than 7.5×10 -5 In the case of Pa, 120 nm of silver (Ag) was evaporated on the buffer layer as the top electrode.

[0053] Example 2

[0054] This embodiment provides an inverted perovskite solar cell, which comprises, from bottom to top, a conductive substrate layer (made of ITO), a hole transport layer (made of 4PADCB), a lower interface passivation layer (made of Al2O3), a perovskite light absorption layer (made of Rb 0.05 Cs 0.05 MA 0.05 FA 0.85 Pb(I 0.95 Br 0.05 )3), upper interface passivation layer (materials are DSA and PEAI), electron transport layer (material is PCBM), buffer layer (material is BCP) and top electrode (material is Ag).

[0055] The preparation method of the inverse perovskite solar cell is the same as that of Example 1, except that:

[0056] In step (5), during the process of depositing the upper interface passivation layer on the perovskite light absorption layer, the concentration of DSA is 0.4 mg / ml and the concentration of PEAI is 0.5 mg / ml.

[0057] Example 3

[0058] This embodiment provides an inverted perovskite solar cell, which comprises, from bottom to top, a conductive substrate layer (made of ITO), a hole transport layer (made of 4PADCB), a lower interface passivation layer (made of Al2O3), a perovskite light absorption layer (made of Rb 0.05 Cs 0.05 MA 0.05 FA 0.85 Pb(I 0.95 Br 0.05)3), upper interface passivation layer (materials are DSA and PEAI), electron transport layer (material is PCBM), buffer layer (material is BCP) and top electrode (material is Ag).

[0059] The preparation method of the inverse perovskite solar cell is the same as that of Example 1, except that:

[0060] In step (5), during the process of depositing the upper interface passivation layer on the perovskite light absorption layer, the concentration of DSA is 2 mg / ml and the concentration of PEAI is 3 mg / ml.

[0061] Comparative Example 1

[0062] This comparative example provides an inverted perovskite solar cell, which comprises, from bottom to top, a conductive substrate layer (made of ITO), a hole transport layer (made of 4PADCB), a lower interface passivation layer (made of Al2O3), a perovskite light absorption layer (made of Rb 0.05 Cs 0.05 MA 0.05 FA 0.85 Pb(I 0.95 Br 0.05 )3), upper interface passivation layer (material is PEAI), electron transport layer (material is PCBM), buffer layer (material is BCP) and top electrode (material is Ag).

[0063] The preparation method of the inverse perovskite solar cell is the same as that of Example 1, except that:

[0064] In step (5), during the process of depositing the upper interface passivation layer on the perovskite light absorption layer, the DSA solution is not spin-coated, but only the PEAI solution is spin-coated.

[0065] Comparative Example 2

[0066] This comparative example provides an inverted perovskite solar cell, which comprises, from bottom to top, a conductive substrate layer (made of ITO), a hole transport layer (made of 4PADCB), a lower interface passivation layer (made of Al2O3), a perovskite light absorption layer (made of Rb 0.05 Cs 0.05 MA 0.05 FA 0.85 Pb(I 0.95 Br 0.05 )3), upper interface passivation layer (materials are DSA and PEAI), electron transport layer (material is PCBM), buffer layer (material is BCP) and top electrode (material is Ag).

[0067] The preparation method of the inverse perovskite solar cell is the same as that of Example 1, except that:

[0068] In step (5), during the process of depositing the upper interface passivation layer on the perovskite light absorption layer, the concentration of DSA is 4 mg / ml and the concentration of PEAI is 4 mg / ml.

[0069] Comparative Example 3

[0070] This comparative example provides an inverted perovskite solar cell, which comprises, from bottom to top, a conductive substrate layer (made of ITO), a hole transport layer (made of 4PADCB), a lower interface passivation layer (made of Al2O3), a perovskite light absorption layer (made of Rb 0.05 Cs 0.05 MA 0.05 FA 0.85 Pb(I 0.95 Br 0.05 )3), upper interface passivation layer (materials are DSA and PEAI), electron transport layer (material is PCBM), buffer layer (material is BCP) and top electrode (material is Ag).

[0071] The preparation method of the inverse perovskite solar cell is the same as that of Example 1, except that:

[0072] In step (5), during the process of depositing the upper interface passivation layer on the perovskite light absorption layer, the concentration of DSA is 0.1 mg / ml and the concentration of PEAI is 0.1 mg / ml.

[0073] Effect Example 1 Characterization of Passivation Effect

[0074] A perovskite light absorbing layer film was prepared according to the method of Example 1 to obtain sample 1 (without spin coating of DSA). A DSA solution was spin coated on the perovskite light absorbing layer film to obtain sample 2. Samples 1 and 2 were characterized to study the passivation effect of DSA on perovskite.

[0075] First, XPS spectroscopy was used to characterize the chemical interaction between DSA and perovskite. Figure 1 (The gray line represents sample 1, and the red line represents sample 2). It can be seen that there are four peaks in the Pb 4f spectrum of sample 1: the two peaks at 138.09eV and 142.96eV belong to Pb 2+ 4f of (Pb-I bond) 7 / 2 and 4f 5 / 2 The two peaks at low binding energy are attributed to Pb 0 4f 7 / 2 and 4f 5 / 2 ; Differently, in the DSA-optimized perovskite film (sample 2), Pb 2+ 4f 7 / 2 and 4f 5 / 2The high binding energy shifts to 138.19eV and 143.06eV, indicating that DSA and Pb 2+ Lewis acid-base interaction or electrostatic interaction may have occurred. In addition, almost no Pb was observed in the spectrum. 0 The presence of the peak indicates that DSA can effectively passivate the uncoordinated Pb in the perovskite film. 2+ In the I 3d spectrum, a similar shift toward higher binding energy can also be observed, indicating that DSA and I - Electrostatic interactions may have occurred between them. The N 1s spectrum of the DSA-optimized perovskite film (sample 2) also shifts toward higher binding energies relative to sample 1. This shift is related to the delocalization of the electron cloud of the NH bond, which disrupts the chemical interaction between the N and H atoms, indicating hydrogen bonding between DSA and FA / MA.

[0076] Figure 2 The following are scanning electron microscope (SEM) images of the perovskite film after DSA passivation treatment (sample 2) and the perovskite film without DSA passivation treatment (sample 1). It can be seen that DSA treatment does not destroy the original morphology of the perovskite surface. In addition, the white granular substances in the image are non-conductive PbI2 and RbI. A small amount of RbI on the surface can play the role of passivating the interface, but excessive PbI2 and RbI will damage the performance of PSCs. It can be observed from the SEM image that after DSA treatment, the white granular substances on the surface are significantly reduced.

[0077] Steady-state photoluminescence (PL) spectra and time-resolved PL (TRPL) spectra were used to further study the effects of DSA and PEAI on the carrier dynamics behavior of perovskite films. The following samples were prepared for characterization: a perovskite light-absorbing layer was directly deposited on a transparent conductive substrate according to the method of Example 1 to obtain sample 3, DSA was spin-coated on sample 3 to obtain sample 4, an electron transport layer was deposited on sample 3 after spin-coating DSA, sample 5 was obtained, DSA and PEAI were spin-coated on sample 3 and then an electron transport layer was deposited to obtain sample 6, and an electron transport layer was deposited after the perovskite light-absorbing layer was deposited on a transparent conductive substrate to obtain sample 7.

[0078] The samples were prepared in the above manner and subjected to PL and TRPL spectrum characterization. The results are shown in Figure 3. The right figure shows the PL spectra of samples 3 and 4. It can be seen that the fluorescence emission peak of sample 4 has a blue shift relative to sample 3, and the luminescence intensity has increased. This shows that DSA can effectively passivate harmful defects in the perovskite film and inhibit non-radiative carrier recombination. The PL spectrum characterization of samples 5 to 7 is shown in the middle figure. It can be seen that after the electron transport layer is deposited, the luminescence intensity of samples 5 and 6 is greatly reduced. This shows that DSA and PEAI can promote the extraction and transmission of electrons at the perovskite / electron transport layer interface, among which sample 6 has a better effect. The left figure is the TRPL spectrum. From the TRPL decay curve and the fitted average carrier lifetime, it can be concluded that after DSA passivation, the average carrier lifetime of the perovskite film is extended from 345.47ns to 724.03ns. After the electron transport layer is deposited, we observed the opposite phenomenon. The fluorescence emission peak intensity and the average carrier lifetime of the DSA-optimized perovskite film are both reduced relative to the control perovskite film. The above PL and TRPL results reveal that the treatment of DSA and PEAI molecules can effectively passivate harmful defects in perovskite films, inhibit non-radiative carrier recombination, and promote the extraction and transmission of electrons at the perovskite / electron transport layer interface.

[0079] Effect Example 2 Photovoltaic Performance Test of Solar Cells

[0080] The photovoltaic performance of the solar cells prepared in the examples and comparative examples was tested. The results are shown in Table 1, where the JV curve test graph and storage stability test graph of Example 1 and Comparative Example 1 are shown in Table 1. Figure 4 and Figure 5 .

[0081] Table 1

[0082]

[0083]

[0084] As can be seen from Table 1, by adopting the method described in the embodiment of the present invention, devices with excellent photovoltaic performance can be prepared, among which the photovoltaic performance of Example 1 is the best. By comparing Example 1 and Comparative Example 1, the photovoltaic performance of the device based on the synergistic passivation of DSA and PEAI in Example 1 is better than the device modified with only PEAI interface in Comparative Example 1. By comparing Example 1 and Comparative Example 2, when the concentrations of DSA and PEAI are higher than the range defined by the present invention, the photovoltaic performance of the device will be reduced. By comparing Example 1 and Comparative Example 3, when the concentrations of DSA and PEAI are lower than the range defined by the present invention, the photovoltaic performance of the device will also be negatively affected.

[0085] Depend on Figure 5 It can be seen that the storage stability of the device based on the synergistic passivation of DSA and PEAI of the present invention is higher than that of the device modified with only PEAI interface in Comparative Example 1.

[0086] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be construed as limiting the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. Persons skilled in the art will appreciate that improvements and modifications may be made without departing from the spirit and scope of the present invention, and such improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An inverse perovskite solar cell, characterized in that: Its structure includes, from bottom to top, a conductive base layer, a hole transport layer, a lower interface passivation layer, a perovskite light absorption layer, an upper interface passivation layer, an electron transport layer, a buffer layer and a top electrode; wherein the upper interface passivation layer material is a DSA and PEAI dual interface material.

2. The inverted perovskite solar cell according to claim 1, characterized in that The mass ratio of DSA to PEAI is (2-4):(3-5).

3. The inverted perovskite solar cell according to claim 1, characterized in that The DSA interface material is at the bottom, and the PEAI interface material is at the top.

4. The inverted perovskite solar cell according to claim 1, characterized in that The preparation process of the upper interface passivation layer material is as follows: spin coating a DSA solution and a PEAI solution on the perovskite light absorption layer in sequence, and performing an annealing treatment after the spin coating is completed.

5. The inverted perovskite solar cell according to any one of claims 1 to 4, characterized in that: The hole transport layer material is selected from 4PADCB, Me-4PACz, and MeO-2PACz.

6. The inverted perovskite solar cell according to any one of claims 1 to 4, characterized in that: The material of the lower interface passivation layer is Al2O3.

7. The inverted perovskite solar cell according to any one of claims 1 to 4, characterized in that: The perovskite light absorption layer material is Rb 0.05 Cs 0.05 MA 0.05 FA 0.85 Pb(I 0.95 Br 0.05 )3 or Cs 0.05 MA 0.1 FA 0.85 PbI3.

8. The inverted perovskite solar cell according to any one of claims 1 to 4, characterized in that: The electron transport layer material is PCBM or C 60 .

9. A method for preparing an inverse perovskite solar cell according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Clean the conductive base layer; S2, depositing a hole transport layer on a conductive substrate; S3, depositing a lower interface passivation layer on the hole transport layer; S4, depositing a perovskite light absorbing layer on the lower interface passivation layer; S5. Depositing an upper interface passivation layer on the perovskite light absorbing layer: spin-coating a DSA solution and a PEAI solution on the perovskite light absorbing layer in sequence, and performing an annealing treatment after the spin coating is completed; S6, depositing an electron transport layer on the upper interface passivation layer; S7, depositing a buffer layer on the electron transport layer; S8. Depositing a top electrode on the electron transport layer.

10. The preparation method according to claim 9, characterized in that The concentration of the DSA solution in the S5 is 0.4-2 mg / ml, and the concentration of the PEAI solution is 0.5-3 mg / ml.

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