Buried bottom interface modified trans-perovskite solar cell and preparation method thereof

Abstract

The invention relates to the field of solar cells, and discloses a buried interface modified trans-perovskite solar cell and a preparation method thereof. The trans-perovskite solar cell structurally comprises a substrate, a conductive layer, a hole transport layer, a perovskite light absorption layer, an electron transport layer and a metal counter electrode which are sequentially layered, the hole transport layer adopts a hole transport material [4-(3, 6-dimethyl-9H-carbazole-9-yl) butyl] phosphoric acid (Me-4PACz), and the hole transport layer adopts a hole transport material [4-(3, 6-dimethyl-9H-carbazole-9-yl) butyl] phosphoric acid (Me-4PACz). According to bottom-buried interface modification provided by the invention, a hole transport material Me-4PACz is modified by adopting a (2-phenethyl) phosphonic acid small molecule material, the modified Me-4PACz hole transport layer has high perovskite layer coverage rate, the preparation process is simple, the efficiency of the assembled solar cell is high, the stability is obviously improved, and the commercial application value is very good.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic cells, and in particular to a buried interface modified trans-perovskite solar cell and a preparation method thereof. Background Art

[0002] Inverse-structured perovskite solar cells have become a research hotspot due to their advantages of simple preparation process, low cost, high operational stability, easy large-scale preparation and easy stacking. Currently, the efficiency of single-junction small-area cells has exceeded 26%, but there is still much room for improvement compared to its theoretical efficiency limit.

[0003] In trans-structured perovskite solar cells, the hole transport layer not only needs to quickly extract holes and block electrons, but also needs to be able to regulate the morphology of the bottom of the perovskite to form a good contact between the hole transport layer and the perovskite light-absorbing layer. The small molecule self-assembled hole transport material Me-4PACz is highly polar and has high thermal stability and solubility, so it is considered to be one of the preferred materials for preparing high-efficiency trans-structured perovskite solar cells. However, the perovskite precursor solution has poor wettability on the Me-4PACz hole transport layer, resulting in defects such as low perovskite coverage, easy formation of pinholes, and imperfect crystal structure. In order to obtain high-quality perovskite films, a large amount of perovskite precursor liquid needs to be consumed during the preparation process, resulting in a huge waste of perovskite precursor liquid. Summary of the invention

[0004] Based on the technical problems existing in the background technology, one of the objects of the present invention is to provide a buried interface modified trans perovskite solar cell, which can effectively improve the wettability of the perovskite precursor solution on the Me-4PACz hole transport layer by adding a buried interface modification material (2-phenylethyl)phosphonic acid to the hole transport material, improve the interface contact between the hole transport layer and the perovskite layer, and reduce the use of the perovskite precursor solution.

[0005] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a buried interface modified trans-perovskite solar cell, which structurally includes a substrate, a conductive layer, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer and a metal counter electrode arranged in sequence, wherein the hole transport layer components include a hole transport material [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphoric acid, i.e., Me-4PACz, and a buried interface modification material (2-phenylethyl)phosphonic acid for modifying the hole transport material, wherein the mass ratio of (2-phenylethyl)phosphonic acid to Me-4PACz is (1-2):5.

[0006] Further improvement of inverse perovskite solar cells as buried interface modification:

[0007] Preferably, the thickness of the hole transport layer is 3 nm to 6 nm.

[0008] Preferably, the material of the perovskite light absorbing layer is Cs 0.05 (FA 0.98 MA 0.02 ) 0.95 Pb(I 0.98 Br 0.02 )3.

[0009] Preferably, the material of the metal counter electrode is gold, silver, copper or aluminum, and the thickness of the metal counter electrode is 80 nm to 120 nm.

[0010] The second object of the present invention is to provide a method for preparing a buried interface modified inverse perovskite solar cell as described in any one of the above, comprising the following steps:

[0011] S1, preparing a substrate having a conductive layer;

[0012] S2, adding [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphoric acid and (2-phenylethyl)phosphonic acid to the organic solution in sequence to prepare a hole transport layer precursor solution; using the hole transport layer precursor solution to prepare a hole transport layer on the conductive layer;

[0013] S3, preparing a perovskite light absorbing layer on the surface of the hole transport layer;

[0014] S4, preparing an electron transport layer on the perovskite light absorbing layer;

[0015] S5. Preparing a metal counter electrode layer on the surface of the electron transport layer, that is, preparing a buried interface modified inverse perovskite solar cell.

[0016] The preparation method of the inverse perovskite solar cell as a buried interface modification is further improved:

[0017] Preferably, in the hole transport layer precursor solution described in step S2, the concentration of Me-4PACz is 0.3 mg / ml to 0.5 mg / ml, wherein the mass ratio of (2-phenylethyl)phosphonic acid to Me-4PACz is (1 to 2):5, and the organic solvent is one or a combination of two or more of ethanol, methanol, and isopropanol.

[0018] Preferably, in step S3, dimethylformamide DMF and dimethyl sulfoxide DMSO are mixed in a volume ratio of 6:1 to obtain a mixed solvent, methylammonium chloride MACl and Cs 0.05 (FA 0.98 MA 0.02 ) 0.95 Pb(I 0.98 Br 0.02)3 is added into a mixed solvent, heated and stirred at 60°C for 2 hours to obtain a perovskite precursor solution; the perovskite precursor solution is used to prepare a perovskite light absorbing layer on the surface of the hole transport layer through a film forming process.

[0019] Preferably, the concentration of MACl added to the perovskite precursor solution is 0.195 M, Cs 0.05 (FA 0.98 MA 0.02 ) 0.95 Pb(I 0.98 Br 0.02 )3 is added at a concentration of 1.3M.

[0020] Preferably, in step S2, a hole transport layer is prepared on a clean conductive layer by solution spin coating or solution immersion; in step S3, a perovskite light absorption layer is prepared on the surface of the hole transport layer by a spin coating method, a coating method, or a film-making process of evaporation coating; in step S4, an electron transport layer is prepared on the perovskite light absorption layer by spin coating, atomic layer deposition, vacuum evaporation, or magnetron sputtering technology; in step S5, a metal counter electrode layer is prepared on the surface of the electron transport layer by vacuum evaporation coating technology.

[0021] Preferably, when the perovskite light-absorbing layer is prepared by spin coating in step S3, an anti-solvent is added dropwise to the surface of the spin-coated layer during the spin coating process, and the anti-solvent is one of chlorobenzene, toluene, methyl ether, ethyl ether, ethyl acetate, and ethanol.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1) The present invention provides a trans-perovskite solar cell with buried interface modification. By adding a buried interface modification material (2-phenylethyl)phosphonic acid to the hole transport material, the wettability of the perovskite precursor solution on the Me-4PACz hole transport layer can be effectively improved, and the interface contact between the hole transport layer and the perovskite layer can be improved. When the amphiphilic Me-4PACz is dissolved in an organic solvent, it will spontaneously form a micro-cluster structure, which will cause the material to agglomerate and incompletely cover the surface of the conductive glass. The incorporation of (2-phenylethyl)phosphonic acid can not only inhibit the formation of Me-4PACz micro-cluster, but also the hydrophilic phosphate group in (2-phenylethyl)phosphonic acid can be adsorbed on the surface of the conductive glass, thereby promoting the regular arrangement of Me-4PACz molecules on the surface of the conductive glass. The present invention effectively improves the surface wettability of the hole transport layer by introducing (2-phenylethyl)phosphonic acid, improves the perovskite crystal morphology, and greatly reduces the use of the perovskite precursor solution.

[0024] 2) The present invention can form Cs 0.05 (FA 0.98 MA 0.02 ) 0.95Pb(I 0.98 Br 0.02 )3 and methyl ammonium chloride MACl are added to a mixed solvent to dissolve to obtain a perovskite precursor solution; then a film-making process is used to obtain a material Cs 0.05 (FA 0.98 MA 0.02 ) 0.95 Pb(I 0.98 Br 0.02 )3 perovskite light-absorbing layer. The material has a bandgap of 1.54eV, and the spectral absorption range covers visible light to a wavelength of 805nm, which effectively guarantees the photocurrent density of the solar cell. At the same time, the solar cell prepared with this material can also obtain an open circuit voltage of up to 1.2V, thereby achieving a higher photoelectric conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic structural diagram of a buried interface modified inverse perovskite solar cell according to the present invention;

[0026] Figure 2 The pictures are of perovskite films prepared in Examples 1-4 and Comparative Example at different contents of (2-phenylethyl)phosphonic acid;

[0027] Figure 3 The IV curves of the buried interface modified inverse perovskite solar cells prepared in Examples 1-4 of the present invention and the comparative example correspond to curves ae in sequence.

[0028] Explanation of the reference numerals: 1-substrate, 2-conductive layer, 3-hole transport layer, 4-perovskite light absorbing layer, 5-electron transport layer, 6-metal counter electrode. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. Based on the embodiments of the present invention, all other embodiments prepared by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0030] Example 1

[0031] This embodiment provides a buried interface modified hole transport layer, such as Figure 1 As shown, the structure includes a substrate 1, a conductive layer 2, a hole transport layer 3, a perovskite light absorbing layer 4, an electron transport layer 5 and a metal counter electrode 6 which are sequentially arranged, wherein the components of the hole transport layer 3 include a hole transport material [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphoric acid, i.e., Me-4PACz, and a buried interface modification material (2-phenylethyl)phosphonic acid for modifying the hole transport material.

[0032] The specific steps include:

[0033] S1, select ITO conductive glass (with a conductive layer on the substrate), ultrasonically clean it with a cleaning agent, deionized water, acetone and isopropanol for 15 minutes in sequence, then use compressed air to blow dry the ITO conductive glass 1, and then use ultraviolet ozone to treat the substrate for 15 minutes to obtain a clean and hydrophilic surface;

[0034] S2, 2 mg of (2-phenylethyl)phosphonic acid and 5 mg of Me-4PACz were added to 10 ml of ethanol solution in sequence, the concentration of Me-4PACz was 0.5 mg / ml, the mass ratio of (2-phenylethyl)phosphonic acid to Me-4PACz was 2:5, and the mixture was stirred evenly at room temperature to obtain a (2-phenylethyl)phosphonic acid modified hole transport layer spin coating solution;

[0035] The hole transport layer spin coating liquid is spin coated on the surface of the conductive layer 2 by a spin coating process. The spin coating process is as follows: the hole transport layer spin coating liquid is spread on the ITO surface, the spin coating is performed at a speed of 3000 rpm for 30 seconds, and the film is annealed at 100° C. for 10 minutes to obtain a (2-phenylethyl)phosphonic acid-modified Me-4PACz film, that is, a hole transport layer 3 with a thickness of 5 nm is obtained;

[0036] S3, DMF and DMSO were mixed in a volume ratio of 6:1 to obtain a mixed solvent, methylammonium chloride MACl and Cs 0.05 (FA 0.98 MA 0.02 ) 0.95 Pb(I 0.98 Br 0.02 )3 materials are added to the mixed solvent and dissolved, Cs 0.05 (FA 0.98 MA 0.02 ) 0.95 Pb(I 0.98 Br 0.02 )3 concentration is 1.3M, MACl addition amount is 0.195M, heated and stirred at 60°C for 2 hours, and the perovskite precursor solution is obtained after it is completely dissolved;

[0037] 40 μL of the perovskite precursor solution was added dropwise to the surface of the hole transport layer 3, and the layer was spin-coated at 4000 rpm for 30 seconds. 10 seconds before the end of the spin coating, 110 μL of the anti-solvent chlorobenzene was added dropwise to the surface of the substrate to promote the rapid volatilization of the solvent, and then the layer was annealed at 120° C. for 30 minutes and cooled to room temperature to obtain a perovskite light absorbing layer 4 with a thickness of 500 nm.

[0038] S4, take 60ul of 3mg / ml isopropanol solution of phenylethylamine iodide (PEAI), add it dropwise to the surface of the perovskite light absorbing layer 4, and spin coat it at 5000 rpm for 30 seconds to obtain a perovskite surface defect modification layer; then add 40μL of 20mg / ml chlorobenzene solution of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) dropwise to the spin-coated layer, and spin coat it at 2000 rpm for 30 seconds to obtain an electron transport layer 5 with a thickness of 20nm;

[0039] S5, adding BCP to isopropanol to prepare a saturated BCP isopropanol solution, taking 60 μL of the saturated BCP isopropanol solution and dropping it onto the electron transport layer 5, spin coating it at a speed of 5000 rpm for 30 seconds, then covering the surface with a mask plate, and then placing it in a thermal evaporation chamber and evacuating it to 10 -4 Pa below A Ag film with a thickness of 100 nm was deposited as the metal counter electrode layer 6 .

[0040] Example 2

[0041] The present embodiment provides a method for preparing a buried interface modified hole transport layer. The specific preparation process refers to Example 1, except that step S2: 1.5 mg of (2-phenylethyl)phosphonic acid and 5 mg of Me-4PACz are sequentially added to 10 ml of ethanol solution, the concentration of Me-4PACz is 0.5 mg / ml, the mass ratio of (2-phenylethyl)phosphonic acid to Me-4PACz is 1.5:5, and the mixture is stirred evenly at room temperature to obtain a (2-phenylethyl)phosphonic acid modified hole transport layer spin coating solution.

[0042] Example 3

[0043] The present embodiment provides a method for preparing a buried interface modified hole transport layer. The specific preparation process refers to Example 1, except that step S2: 1 mg of (2-phenylethyl)phosphonic acid and 5 mg of Me-4PACz are sequentially added to 10 ml of ethanol solution, the concentration of Me-4PACz is 0.5 mg / ml, the mass ratio of (2-phenylethyl)phosphonic acid to Me-4PACz is 1:5, and the mixture is stirred evenly at room temperature to obtain a (2-phenylethyl)phosphonic acid modified hole transport layer spin coating solution.

[0044] Example 4

[0045] The present embodiment provides a method for preparing a buried interface modified hole transport layer. The specific preparation process refers to Example 1, and the only difference is step S2: 0.5 mg of (2-phenylethyl)phosphonic acid and 5 mg of Me-4PACz are sequentially added to 10 ml of ethanol solution, the concentration of Me-4PACz is 0.5 mg / ml, the mass ratio of (2-phenylethyl)phosphonic acid to Me-4PACz is 0.5:5, and the mixture is stirred evenly at room temperature to obtain a (2-phenylethyl)phosphonic acid modified hole transport layer spin coating liquid.

[0046] Comparative Example

[0047] This comparative example provides a method for preparing a hole transport layer without (2-phenylethyl)phosphonic acid modification. The specific preparation process refers to Example 1, and the only difference is step S2: adding 5 mg of Me-4PACz to 10 ml of ethanol solution, the concentration of Me-4PACz is 0.5 mg / ml, stirring evenly at room temperature, to obtain a hole transport layer spin coating liquid.

[0048] The perovskite light absorbing layer prepared in Example 1 is as follows Figure 2 As shown in a; the perovskite light absorbing layer prepared in Example 2 is as shown in Figure 2 As shown in b; the perovskite light absorbing layer prepared in Example 3 is as shown in Figure 2 As shown in c; the perovskite light absorbing layer prepared in Example 4 is as shown in Figure 2 As shown in d; the perovskite light absorbing layer prepared in the comparative example is as Figure 2 As shown in e. Figure 2 It can be seen that the wettability of the perovskite precursor on the Me-4PACz hole transport layer is poor. On the ITO conductive glass with an area of ​​2 cm × 1.5 cm, even if 100 μl of the perovskite precursor is dropped, only Figure 2 When the hole transport layer modified with (2-phenylethyl)phosphonic acid is used, the wettability of the perovskite precursor on the hole transport layer is greatly improved, and the following can be obtained using 40 μl of the perovskite precursor: Figure 2 The perovskite film shown in a and 2b is completely covered.

[0049] The IV curves of the buried interface modified inverse perovskite solar cells prepared in Examples 1-4 and Comparative Examples were measured under a standard simulated light source of one sun (AM1.5), as shown in FIG. Figure 3 As shown, curves ae correspond to Examples 1-4 and the comparative example in turn. Figure 3 It can be seen that after the hole transport materials in Examples 1-4 were modified with (2-phenylethyl)phosphonic acid, the performance of the solar cells was improved to varying degrees, among which the solar cell prepared by Example 2 had the best performance, with an open circuit voltage of 1.13 V and a short circuit current density of 25.28 mA / cm 2, the fill factor is 0.83, and the photoelectric conversion efficiency is 23.71%. Under the same test conditions, the solar cell prepared in Example 1 obtains an open circuit voltage of 1.12V and a short circuit current density of 25.21mA / cm 2 , the fill factor is 0.798, and the photoelectric conversion efficiency is 22.53%; the solar cell prepared in Example 3 has an open circuit voltage of 1.122V and a short circuit current density of 25.06mA / cm 2 , the fill factor is 0.826, and the photoelectric conversion efficiency is 23.22%; the solar cell prepared in Example 4 has an open circuit voltage of 1.089V and a short circuit current density of 24.57mA / cm 2 , the fill factor is 0.781, and the photoelectric conversion efficiency is 20.90%; the solar cell prepared in the comparative example has an open circuit voltage of 1.05V and a short circuit current density of 24.54mA / cm 2 , the filling factor is 0.76, and the photoelectric conversion efficiency is 19.58%.

[0050] Those skilled in the art should understand that the above are only some specific embodiments of the present invention, rather than all embodiments. It should be noted that for those of ordinary skill in the art, many modifications and improvements can be made, and all modifications or improvements that do not exceed the scope of protection of the present invention should be regarded as the scope of protection of the present invention.

Claims

1. A buried interface modified inverse perovskite solar cell, which structurally comprises a substrate, a conductive layer, a hole transport layer, a perovskite light absorption layer, an electron transport layer and a metal counter electrode arranged in sequence, characterized in that: The hole transport layer components include a hole transport material [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphoric acid, i.e., Me-4PACz, and a buried interface modification material (2-phenylethyl)phosphonic acid for modifying the hole transport material. The mass ratio of (2-phenylethyl)phosphonic acid to Me-4PACz is (1-2):

5.

2. The buried interface modified inverse perovskite solar cell according to claim 1, characterized in that: The thickness of the hole transport layer is 3nm to 6nm.

3. The buried interface modified inverse perovskite solar cell according to claim 1, characterized in that: The material of the perovskite light absorbing layer is Cs 0.05 (FA 0.98 MA 0.02 ) 0.95 Pb(I 0.98 Br 0.02 )3.

4. The buried interface modified inverse perovskite solar cell according to claim 1, characterized in that: The material of the metal counter electrode is gold, silver, copper or aluminum, and the thickness of the metal counter electrode is 80nm-120nm.

5. A method for preparing a buried interface modified trans-perovskite solar cell according to any one of claims 1 to 4, characterized in that: The steps include: S1, preparing a substrate having a conductive layer; S2, adding [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphoric acid and (2-phenylethyl)phosphonic acid to the organic solution in sequence to prepare a hole transport layer precursor solution; Using a hole transport layer precursor solution, preparing a hole transport layer on the conductive layer; S3, preparing a perovskite light absorbing layer on the surface of the hole transport layer; S4, preparing an electron transport layer on the perovskite light absorbing layer; S5. Preparing a metal counter electrode layer on the surface of the electron transport layer, that is, preparing a buried interface modified inverse perovskite solar cell.

6. The method for preparing a buried interface modified trans-perovskite solar cell according to claim 5, characterized in that: In the hole transport layer precursor solution described in step S2, the concentration of Me-4PACz is 0.3 mg / ml~0.5 mg / ml, wherein the mass ratio of (2-phenylethyl)phosphonic acid to Me-4PACz is (1~2):5, and the organic solvent is one or a combination of two or more of ethanol, methanol, and isopropanol.

7. The method for preparing a buried interface modified trans-perovskite solar cell according to claim 5, characterized in that: In step S3, dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) are mixed in a volume ratio of 6:1 to obtain a mixed solvent, and methylammonium chloride (MACl) and a Cs 0.05 (FA 0.98 MA 0.02 ) 0.95 Pb(I 0.98 Br 0.02 )3 is added into a mixed solvent, heated and stirred at 60°C for 2 hours to obtain a perovskite precursor solution; the perovskite precursor solution is used to prepare a perovskite light absorbing layer on the surface of the hole transport layer through a film forming process.

8. The method for preparing a buried interface modified trans-perovskite solar cell according to claim 5, characterized in that: The concentration of MACl added to the perovskite precursor solution is 0.195 M, Cs 0.05 (FA 0.98 MA 0.02 ) 0.95 Pb(I 0.98 Br 0.02 )3 is added at a concentration of 1.3M.

9. The method for preparing a buried interface modified trans-perovskite solar cell according to claim 5, characterized in that: In step S2, a hole transport layer is prepared on a clean conductive layer by solution spin coating or solution immersion; in step S3, a perovskite light absorption layer is prepared on the surface of the hole transport layer by spin coating, coating or evaporation coating; in step S4, an electron transport layer is prepared on the perovskite light absorption layer by spin coating, atomic layer deposition, vacuum evaporation or magnetron sputtering technology; in step S5, a metal counter electrode layer is prepared on the surface of the electron transport layer by vacuum evaporation coating technology.

10. The method for preparing a buried interface modified trans-perovskite solar cell according to claim 5, characterized in that: When the perovskite light-absorbing layer is prepared by spin coating in step S3, an anti-solvent is added dropwise to the surface of the spin-coated layer during the spin coating process, and the anti-solvent is one of chlorobenzene, toluene, methyl ether, ethyl ether, ethyl acetate, and ethanol.

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