CN115084391A - Perovskite solar cell with hole interface gradient structure, perovskite precursor solution, perovskite composite thin film layer and preparation method - Google Patents

Abstract

The invention discloses a perovskite solar cell with a hole interface gradient structure, which sequentially comprises a transparent conductive film FTO, a hole transport layer with an interface gradient structure, and Al ₂ O ₃ A thin film layer and a perovskite composite thin film layer; the hole transport layer sequentially comprises a lithium-doped nickel oxide thin film layer, a nickel oxide thin film layer and poly [ bis (4-phenyl) (2,4, 6-trimethylphenyl) amine]A thin film layer; the perovskite film is F4-TCNQ- (OAm) ₂ PbI ₄ ‑FA _0.93 MA _0.07 Pb(I _0.79 Br _0.07 Cl _0.14 ) ₃ . The invention also discloses a perovskite precursor solution, a perovskite composite thin film layer and a preparation method thereof. The invention effectively solves the problem of trans-plane structure of calcium and titaniumThe problem that holes generated by light induction in the mine solar cell are transmitted to the transparent conductive film FTO, the barrier is high, and the energy level between interfaces is not matched is solved.

Description

Perovskite solar cells with hole interface gradient structure, perovskite precursor solutions, Perovskite composite thin film layer and preparation method

technical field

The invention relates to the field of solar cells, in particular to a perovskite solar cell with a hole interface gradient structure, a perovskite precursor solution, a perovskite composite thin film layer and a preparation method thereof.

Background technique

Trans-perovskite solar cells based on inorganic nickel oxide (NiO _x ) have shown great potential in the fabrication of highly stable and low-cost large-area photovoltaic modules and tandem cells. However, the large open-circuit voltage and fill factor loss have become the main factors restricting the further improvement of the performance of _NiOx -based trans-perovskite solar cells.

In _NiOx -based trans-perovskite solar cells, optimizing the _NiOx surface or constructing an efficient hole-transport gradient structure through interfacial engineering strategies is helpful to reduce device non-radiative recombination losses and improve device efficiency.

In the patent (CN106531888B), Gao used porphyrin derivatives for the interface modification of hole transport layer/perovskite layer in inverted perovskite solar cells. Although the morphology of the perovskite layer was adjusted and the defect density was reduced, the hole interface The energy level mismatch and stability issues remain unresolved.

SUMMARY OF THE INVENTION

In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the purpose of the present invention is to provide a perovskite solar cell with a hole interface gradient structure, which effectively solves the problem of light-induced holes in the trans-planar structure perovskite solar cell. The problem of higher potential barrier of FTO transmission to transparent conductive film and energy level mismatch between interfaces.

Another object of the present invention is to provide a perovskite precursor solution, and the prepared perovskite thin film has a low defect density.

Another object of the present invention is to provide a perovskite composite thin film layer and a preparation method thereof.

The object of the present invention is achieved through the following technical solutions:

The perovskite solar cell with a hole interface gradient structure sequentially includes a transparent conductive film FTO, a hole transport layer with an interface gradient structure, an Al ₂ O ₃ thin film layer and a perovskite composite thin film layer;

The hole transport layer sequentially comprises a lithium-doped nickel oxide thin film layer, a nickel oxide thin film layer and a poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] thin film layer;

The perovskite composite thin film layer is prepared from a perovskite precursor solution; in parts by weight, the perovskite precursor solution includes the following components dissolved in a solvent:

Preferably, a PEA ₂ PbI ₄ two-dimensional perovskite thin film layer is further provided on the perovskite composite thin film layer.

Preferably, the perovskite composite thin film layer contains two-dimensional perovskite (OAm) ₂ PbI ₄ and three-dimensional perovskite FA _0.93 MA _0.07 Pb(I _0.79 Br _0.07 Cl _0.14 ) ₃ .

Preferably, the solvent includes DMF and DMSO, wherein the volume ratio of DMF and DMSO is (0.8-0.86):(0.2-0.25).

Preferably, the hole transport layer with an interface gradient structure has a graded valence band structure, and the valence bands are -4.98 eV, -5.1 eV and -5.2 eV in sequence.

Preferably, the perovskite solar cell with the hole interface gradient structure has the following structure:

FTO/Li:NiO _x /NiO _x /PTAA/Al ₂ O ₃ /F4-TCNQ-(OAm) ₂ PbI ₄ -FA _0.93 MA _0.07 Pb(I _0.79 Br _0.07 Cl _0.14 ) ₃ /PEA ₂ PbI ₄ /PCBM/ BCP/Ag; wherein Li:NiO _x is a lithium-doped nickel oxide thin film layer; NiO _x is a nickel oxide thin film layer; PTAA is poly[bis(4-phenyl)(2,4,6-trimethylphenyl) ) amine] thin film layer; Al ₂ O ₃ is mesoporous alumina; F4-TCNQ-(OAm) ₂ PbI ₄ -FA _0.93 MA _0.07 Pb(I _0.79 Br _0.07 Cl _0.14 ) ₃ is the perovskite composite thin film layer, wherein F4-TCNQ is a p-type organic material 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone; (OAm) ₂ PbI ₄ is two three-dimensional perovskite; FA _0.93 MA _0.07 Pb(I _0.79 Br _0.07 Cl _0.14 ) ₃ is a three-dimensional trihalide perovskite; PEA ₂ PbI ₄ is a two-dimensional perovskite thin film layer; PCBM is an electron transport layer; BCP is a buffer layer; Ag is the top electrode.

The perovskite precursor solution, by weight, includes the following components dissolved in a solvent:

In the preparation method of the perovskite composite thin film layer, the perovskite precursor solution is spin-coated, and ethyl acetate is used for anti-solvent treatment during the spin coating process, and the gradient perovskite composite thin film layer is obtained after heat treatment.

Preferably, the heat treatment is specifically: heating at 95-105° C. for 18-22 minutes.

The perovskite composite thin film layer is prepared by the method for preparing the perovskite composite thin film layer.

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

(1) In the perovskite solar cell with the hole interface gradient structure of the present invention, a hole transport layer with an interface gradient structure is constructed: FTO/Li:NiO _x /NiO _x /PTAA; wherein the valence band of Li:NiO _x (-4.98eV) matches the work function (-4.7eV) of the transparent conductive film FTO, which effectively reduces the hole transport barrier; in addition, these three hole transport layers further build a graded valence band structure, which is - 4.98eV, -5.1eV and -5.2eV, this structure is beneficial to enhance hole transport; meanwhile, the present invention adopts gradient perovskite film F4-TCNQ-(OAm) ₂ PbI ₄ -FA _0.93 MA _0.07 Pb(I _0.79 Br _0.07 Cl _0.14 ) ₃ /PEA ₂ PbI ₄ as a light absorption layer; compared with the undoped perovskite film (bandgap=-1.58eV, valence band=5.80eV), F4-TCNQ and OAmI doping simultaneously Effectively adjust the band gap (-1.56eV, valence band=-5.3eV) of the perovskite film, so that the valence band (-5.71eV) and conduction band (-4.15eV) of the perovskite composite film are respectively related to the hole transport layer. It is matched with the electron transport layer to further construct effective hole and electron transport paths, and suppress non-radiative recombination and interface defects.

(2) The perovskite solar cell with the hole interface gradient structure of the present invention has high efficiency.

(3) The perovskite precursor solution of the present invention forms two-dimensional (2D) perovskite (OAm) ₂ PbI ₄ by adding oleylamine iodide (OAmI), and the appearance of 2D perovskite inhibits three-dimensional (3D) The defects in the perovskite FA _0.93 MA _0.07 Pb(I _0.79 Br _0.07 Cl _0.14 ) ₃ , the prepared perovskite composite thin film layer has a low defect density. 2D perovskite can effectively occupy the grain boundaries of 3D perovskite films, forming a 2D-3D-2D crystal structure, reducing the density of defect states at the grain boundaries, inhibiting non-radiative recombination, and ultimately improving charge transport.

(4) The perovskite precursor solution of the present invention can effectively adjust the band gap of the perovskite thin film by doping the p-type organic molecule F4-TCNQ.

Description of drawings

Fig. 1 is the FTO/Li:NiOx (a), FTO/Li: _NiOx / _NiOx (b), FTO/Li: _NiOx / _NiOx / _PTAA (c) thin film prepared by the embodiment of the present invention E _F Fermi level test results.

Fig. 2 is the FTO/Li:NiOx (a), FTO/Li: _NiOx / _NiOx (b), FTO/Li: _NiOx / _NiOx / _PTAA (c) thin film prepared by the embodiment of the present invention E _cut-off binding energy test results.

Figure 3 shows the band gap test results of films prepared from perovskite precursor solutions without additives (a), with F4-TCNQ (b), and with F4-TCNQ and OAmI (c).

Figure 4 shows the E _cut-off binding energy test results of thin films prepared from perovskite precursor solutions without additives (a), with F4-TCNQ (b), and with F4-TCNQ and OAmI (c).

Figure 5 shows the EF Fermi level test results of films prepared from perovskite precursor solutions without additives (a), with F4-TCNQ (b), and with _F4 -TCNQ and OAmI (c).

Fig. 6 is the FTO/Li:NiO _x /NiO _x /PTAA/Al ₂ O ₃ /F4-TCNQ-(OAm) ₂ PbI ₄ -FA _0.93 MA _0.07 Pb(I _0.79 Br _0.07 prepared by the embodiment of the present invention Energy level diagram of the cell with Cl _0.14 ) ₃ /PEA ₂ PbI ₄ /PCBM/BCP/Ag structure.

FIG. 7 is a graph showing the results of the GIWAXS bulk phase test of the additive-free perovskite composite thin film according to the embodiment of the present invention.

FIG. 8 is a graph showing the results of a GIWAXS bulk phase test of the perovskite composite thin film added with F4-TCNQ according to an embodiment of the present invention.

FIG. 9 is a graph showing the results of the bulk phase test of GIWAXS with the addition of F4-TCNQ and OAmI perovskite composite thin films according to an embodiment of the present invention.

FIG. 10 is a low-resolution TEM image, a high-resolution TEM image and a fast Fourier transform crystal phase diagram of the 3D/2D perovskite interface and the perovskite body of the embodiment of the present invention.

FIG. 11 is a performance comparison diagram of a perovskite solar cell with a hole interface gradient structure according to an embodiment of the present invention and a control group.

Detailed ways

The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto.

Example

In one embodiment of the present invention, the preparation method of the perovskite solar cell with the hole interface gradient structure includes the following steps:

(1) Preparation of lithium-doped nickel oxide solution: dissolve 0.04g of lithium carbonate in 3mL of distilled water and 1ml of ethanol to fully dissolve it, labeled as solution A; dissolve 0.25g of Ni(OCOCH ₃ ) ₂ ·4H ₂ O In 10mL of absolute ethanol and 60μL of ethanolamine mixed solvent, and heated at 60 ℃ for 30 minutes, the solution is light blue and clear, marked as B solution; 1ml A solution was mixed with 4ml B solution to prepare the required lithium Doped nickel oxide solution, labeled as C solution.

(2) Preparation of lithium-doped nickel oxide thin film (FTO/Li:NiO _x ): spin coating (rotation speed 4000 rpm, time 30 s) the above C solution on the cleaned FTO substrate, and heated at 200 °C for 5 minutes , FTO/Li:NiO _x thin films were obtained.

(3) Preparation of FTO/Li:NiO _x /NiO _x thin film: spin coating (rotation speed 4000rpm, time 30s) the above solution B on the cleaned FTO/Li:NiO _x thin film, and heat at 450 ℃ for 30 minutes , to obtain high-quality FTO/Li:NiO _x /NiO _x thin films.

(4) Preparation of FTO/Li:NiO _x /NiO _x /PTAA thin film: spin coating PTAA (concentration 0.2mg/mL～0.5mg/mL, rotating speed 6000rpm, time 30s) solution on the cleaned FTO/Li:NiO _x /NiO _x film and heated at 120 °C for 10 min.

(5) Preparation of FTO/Li:NiO _x /NiO _x /PTAA/Al ₂ O ₃ thin film: spin coating Al ₂ O ₃ (concentration 0.2wt%～0.6wt%, rotating speed 3500rpm, time 30s) solution on FTO/ On the Li:NiO _x /NiO _x /PTAA films, the annealing temperature was 120 °C, and the annealing time was 10 minutes.

(6) Preparation of perovskite composites (PCs): spin-coated perovskite composite precursors (70-73 mg FAI, 20-25 mg PbI _{2 , 10-15 mg PbBr 2 ,} 4-5 mg MABr, 8 ~9mg MACl, 0.7~0.8mg F4-TCNQ and 0.5~0.8mg oleyl amiodine (OAmI) dissolved in 0.8-0.86mL DMF and 0.2-0.25mL DMSO solvent) in cleaned FTO/Li: _NiOx /NiO _x /PTAA/Al ₂ O ₃ film, and anti-solvent treatment with ethyl acetate during spin coating, and finally heated at 100 °C for 20 min to form a 2D/3D perovskite-F4-TCNQ composite thin film layer , a film with a structure of FTO/Li:NiO _x /NiO _x /PTAA/Al ₂ O ₃ /F4-TCNQ-(OAm) ₂ PbI ₄ -FA _0.93 MA _0.07 Pb(I _0.79 Br _0.07 Cl _0.14 ) ₃ was constructed.

Wherein, the perovskite composite thin film layer contains two-dimensional perovskite (OAm) ₂ PbI ₄ and three-dimensional perovskite FA _0.93 MA _0.07 Pb(I _0.79 Br _0.07 Cl _0.14 ) ₃ .

(7) Construction of 2D/3D/2D perovskite structure:

Spin coating PEAI (0.5～2mg/mL, preferably 1mg/mL. The rotating speed of spin coating is 1500rpm～2500rpm, preferably 2000rpm; The time of spin coating is 30～50s, preferably 40s) solution in FTO/Li:NiO _x /NiO _x /PTAA/Al ₂ O ₃ /F4-TCNQ-(OAm) ₂ PbI ₄ -FA _0.93 MA _0.07 Pb(I _0.79 Br _0.07 Cl _0.14 ) ₃ films, the annealing temperature was 120℃, and the annealing time was 10 minute.

(8) Preparation of complete devices: spin coating and thermal steaming in sequence, and finally the device structure is constructed as

FTO/Li:NiO _x /NiO _x /PTAA/Al ₂ O ₃ /F4-TCNQ-(OAm) ₂ PbI ₄ -FA _0.93 MA _0.07 Pb(I _0.79 Br _0.07 Cl _0.14 ) ₃ /PEA ₂ PbI ₄ /PCBM/ BCP/Ag.

test:

Ultraviolet photoelectron spectroscopy (UPS) test was performed on the FTO/Li:NiO _x , FTO/Li:NiO _x /NiO _x , FTO/Li:NiO _x /NiO _x /PTAA thin films prepared in the embodiment of the present invention, and the results were as follows As shown in Figure 1, it can be seen from the figure that the three films have different _EF Fermi levels.

Ultraviolet photoelectron spectroscopy (UPS) test was performed on the FTO/Li:NiO _x , FTO/Li:NiO _x /NiO _x , FTO/Li:NiO _x /NiO _x /PTAA thin films prepared in the embodiment of the present invention, and the results were as follows As shown in Figure 2, the three films have different E _cut-off binding energies.

Perovskite thin films were prepared from additive-free, F4-TCNQ, F4-TCNQ, and OAmI perovskite precursor solutions, respectively, and constructed solar cells with consistent structure, which were subjected to bandgap and ultraviolet photoelectron spectroscopy UPS, respectively. The results are shown in Figures 3 to 5 respectively. It can be seen from the figures that the introduction of additives can effectively regulate the energy band of the perovskite film and effectively match the energy band of the hole transport layer.

Fig. 6 is the FTO/Li:NiO _x /NiO _x /PTAA/Al ₂ O ₃ /F4-TCNQ-(OAm) ₂ PbI ₄ -FA _0.93 MA _0.07 Pb(I _0.79 Br _0.07 prepared by the embodiment of the present invention The energy level diagram of the battery with Cl _0.14 ) ₃ /PEA ₂ PbI ₄ /PCBM/BCP/Ag structure, it can be seen from the figure that the introduction of additional interfacial layers and additives can effectively adjust the energy level structure of the battery and form a gradient hole transport structure.

The GIWAXS bulk phase test and characterization of the perovskite films with no additives, addition of F4-TCNQ, addition of F4-TCNQ and OAmI were carried out, and the results are shown in Figures 7 to 9 respectively. After the surface, a 2D perovskite layer can be built on the surface, but part of PbI ₂ can still be observed (Fig. 7); when OAmI is introduced, the excess PbI ₂ is completely reacted to form 2D perovskite (OAm) ₂ PbI ₄ (Fig. 8); when F4-TCNQ was introduced, the crystallization of the perovskite film was not affected (Fig. 9).

In Fig. 10, (a), (b) and (c) are low-resolution TEM images, high-resolution TEM images and fast Fourier transform crystal phase diagrams at the 3D/2D perovskite interface, respectively; (d), (e) and (f) are low-resolution, high-resolution TEM images of the perovskite bulk phase and fast Fourier transform crystal phase images, respectively. The upper and lower images in (f) are 2D and 3D perovskite, respectively. Fast Fourier Transform crystal phase diagram of ore. It can be seen from the figure that 2D(PEA) ₂ PbI ₄ is formed on the surface of the 3D perovskite, and at the same time, the bulk phase also forms a 2D/3D perovskite heterojunction structure, and finally a 2D/3D/2D perovskite heterojunction film can be constructed.

The perovskite solar cells with the hole interface gradient structure prepared in this example (experimental group) and the control group (the device structure is FTO/NiO _x /FA _0.93 MA _0.07 Pb(I _0.79 Br _0.07 Cl _0.14 ) ₃ /PEA ₂ PbI ₄ /PCBM/BCP/Ag, i.e. the control device without Li:NiO _x layer, without OAmI and F4-TCNQ additives) performance is shown in Figure 11 and Table 1.

Table 1 Performance test of the perovskite solar cell of the present invention and the control group.

The above-mentioned embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the described embodiments, and any other changes, modifications, substitutions, and combinations made without departing from the spirit and principle of the present invention , simplification, all should be equivalent replacement modes, and are all included in the protection scope of the present invention.

Claims (10)

1. the perovskite solar cell of hole interface gradient structure, is characterized in that, comprises transparent conductive film FTO, the hole transport layer with interface gradient structure, Al ₂ O ₃ thin film layer and perovskite composite thin film layer successively; The hole transport layer sequentially comprises a lithium-doped nickel oxide thin film layer, a nickel oxide thin film layer and a poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] thin film layer; The perovskite composite thin film layer is prepared from a perovskite precursor solution; in parts by weight, the perovskite precursor solution includes the following components dissolved in a solvent:

2 . The perovskite solar cell with a hole interface gradient structure according to claim 1 , wherein a PEA ₂ PbI ₄ two-dimensional perovskite thin film layer is further provided on the perovskite composite thin film layer. 3 . 3. The perovskite solar cell with a hole interface gradient structure according to claim 1, wherein the perovskite composite thin film layer contains two-dimensional perovskite (OAm) ₂ PbI ₄ and three-dimensional perovskite FA _0.93 MA _0.07 Pb(I _0.79 Br _0.07 Cl _0.14 ) ₃ . 4. The perovskite solar cell with hole interface gradient structure according to claim 1, wherein the solvent comprises DMF and DMSO, wherein the volume ratio of DMF and DMSO is (0.8-0.86): (0.2 -0.25). 5 . The perovskite solar cell with a hole interface gradient structure according to claim 1 , wherein the hole transport layer with the interface gradient structure has a graded valence band structure, and the valence bands are -4.98 eV in sequence. 6 . , -5.1eV and -5.2eV. 6. the perovskite solar cell of hole interface gradient structure according to claim 1, is characterized in that, its structure is: FTO/Li:NiO _x /NiO _x /PTAA/Al ₂ O ₃ /F4-TCNQ-(OAm) ₂ PbI ₄ -FA _0.93 MA _0.07 Pb(I _0.79 Br _0.07 Cl _0.14 ) ₃ /PEA ₂ PbI ₄ /PCBM/ BCP/Ag. 7. Perovskite precursor solution, characterized in that, by weight, comprising the following components dissolved in a solvent:

8. the preparation method of perovskite composite thin film layer, it is characterised in that the perovskite precursor solution described in claim 7 is carried out spin coating, and utilizes ethyl acetate to carry out anti-solvent treatment in the spin coating process, after heat treatment A gradient perovskite composite thin film layer is obtained. 9 . The method for preparing a perovskite composite thin film layer according to claim 8 , wherein the heat treatment is specifically: heating at 95 to 105° C. for 18 to 22 minutes. 10 . 10 . The perovskite composite thin film layer, characterized in that, it is prepared by the preparation method of the perovskite composite thin film layer according to any one of claims 8 to 9 .

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