Formal perovskite / quantum dot two-end stack solar cell and preparation method

Abstract

The application belongs to the field of solar photovoltaic preparation, and particularly relates to a formal perovskite / quantum dot two-end stacked solar cell and a preparation method. The cell structure is conductive glass, a first electron extraction layer, a perovskite light absorption layer, a first hole extraction layer, a dense tunneling layer, a quantum dot light absorption layer, a second hole extraction layer and a counter electrode in sequence. The tunneling layer can protect the perovskite and efficient recombination while having the function of transporting electrons, simplifying the process while improving the efficiency. The application introduces inorganic PbS quantum dots as a hole transport layer of the stack by orthogonal transformation of the solvent, and solves the problem of incompatibility of the hole layer solvent and the perovskite sub-cell. The application replaces the original tunneling layer plus electron transport layer structure by the design of the tunneling layer structure, and solves the problem of lack of a second hole transport layer in the perovskite / quantum dot two-end stacked system by solvent transformation. The efficiency and stability of the stacked cell are greatly improved, and the potential of 1+1>1 is realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of solar photovoltaic preparation, and more particularly relates to a formal perovskite / quantum dot two-end stacked solar cell and a preparation method. BACKGROUND

[0002] Efficient use of clean solar energy is the only way to achieve the strategic goal of "carbon peak and carbon neutral". Among them, solar energy has always been the focus of attention and research because of its inexhaustible, inexhaustible, safe and pollution-free characteristics. Solar cells are the most direct and effective way to use solar energy. At present, crystalline silicon cells are widely used because of their mature technology and high efficiency, but the high cost of components has become a considerable limitation. The current single crystal silicon cell efficiency has reached 26.7%, approaching its theoretical upper limit of 29.4%. Therefore, if the preparation cost of solar cells can be reduced while improving their conversion efficiency, it will bring great development prospects to the entire photovoltaic market. In summary, the preparation of two-end stacked cells is the best choice.

[0003] At present, the all-perovskite stacked solar cell of Nanjing University Tan Hai-ren team has achieved an certified efficiency of 28%, and the large-area component efficiency has reached 21.7%. Although the efficiency of all-perovskite stacked cells is high, there are also corresponding problems with wide-bandgap and narrow-bandgap perovskite sub-cells: the wide-bandgap perovskite thin film has high requirements for process and environment; and the B-site cation of the narrow-bandgap perovskite is lead-tin mixed. The above problems have brought great challenges to the commercialization of all-perovskite stacked solar cells. Because at present, the efficiency of perovskite cells is not a problem, but their stability has become increasingly important.

[0004] Inorganic quantum dot materials have the advantages of multi-exciton effect, high absorption coefficient, highly adjustable band gap, good stability, etc. As a narrow-bandgap sub-cell of stacked cells, its main advantages are as follows: first, the band gap of quantum dots is highly adjustable (~ 0.5-2.0eV), which can maximize the current matching with conventional perovskite stacks, and fully exert the advantages of conventional perovskite (the band gap of lead-tin perovskite cannot be made narrower and has poor stability); second, quantum dots have high full-spectrum absorption coefficient and excellent stability, and also provide encapsulation protection for the underlying perovskite; and the low cost, strong process compatibility, and large-area manufacturing of quantum dots provide convenience for subsequent industrial production. The two-end stacked cell of perovskite and quantum dots has a theoretical limit efficiency of up to 43%.

[0005] A perovskite-lead sulfide quantum dot tandem solar cell and a preparation method thereof are disclosed in Chinese Patent Application 201410697608.4, but the perovskite / quantum dot two-end lamination process is difficult to be compatible, and it is impossible to obtain the effect of 1+1>1; it is also mentioned in Patent Application 201710200871.1 that the above-mentioned patent has a certain competitive relationship in light absorption due to the existence of two light-absorbing materials on the same light-incident surface (photoanode), and at the same time, the photoanode has a prominent problem of electron recombination, and the improvement of the photoelectric efficiency of the device is not very ideal. In 2021, Tavakoli et al. reported a formal structure perovskite / quantum dot two-end tandem cell in the literature and achieved an efficiency of 17.4%, but its tunneling layer adopts Au / MoO3 / ITO, which introduces MoO3 to increase the interface and increase the loss of the cell, and does not have the potential to achieve the effect of 1+1>1.

[0006] In general, from 2018 to 2021, the perovskite / quantum dot two-end tandem solar cell has achieved a rapid growth from 1.1% to 17.1%. Therefore, by selecting inorganic quantum dots with adjustable and stable band gap as narrow-band-gap sub-cells instead of lead tin perovskite for tandem photovoltaic, and by using high-efficiency and low-loss tunneling layer, the stability challenge faced by the tandem cell can be basically solved while meeting the efficiency requirement. Combined with the development advantages of conventional perovskite, a more efficient and stable perovskite / quantum dot two-end tandem solar cell is constructed to further accelerate the commercialization development of tandem photovoltaic. SUMMARY

[0007] In view of the defects of the prior art and the need for improvement, the present application provides a formal perovskite / quantum dot two-end tandem solar cell and a preparation method, which aims to improve the efficiency and stability of the perovskite / quantum dot tandem solar cell, so as to achieve the effect of 1+1>1 in combination of perovskite cells and quantum dot cells.

[0008] To achieve the above-mentioned purpose, according to one aspect of the present application, a formal structure perovskite / quantum dot two-end tandem solar cell is provided, and the device structure comprises: conductive glass, first electron extraction layer, perovskite light-absorbing layer, first hole extraction layer, dense tunneling layer, quantum dot light-absorbing layer and counter electrode, which are sequentially stacked from top to bottom.

[0009] The dense tunneling layer is obtained by vapor deposition, and the low work function N-type semiconductor material in the dense tunneling layer has an electron transport function; the functional material of the first hole extraction layer is inorganic PbS quantum dots or P-type organic polymer.

[0010] Further, the dense tunneling layer is a composite layer composed of a single low work function N-type semiconductor material layer and a single high work function P-type semiconductor material layer.

[0011] Further, the N-type semiconductor material layer is deposited by atomic force deposition or plasma deposition.

[0012] Further, the dense tunneling layer is composed of a gold layer and an aluminum-doped zinc oxide Al-ZnO layer or a gold layer and an indium oxide In2O3 layer, wherein the Al-ZnO layer and the In2O3 layer are deposited by atomic force deposition or plasma deposition.

[0013] Further, the second hole extraction layer is further arranged between the quantum dot light-absorbing layer and the counter electrode.

[0014] Further, the second hole extraction layer adopts inorganic PbS quantum dots or P-type organic polymers.

[0015] Further, the P-type organic polymer is a Spiro-OMeTAD, PTAA molecule or a P3HT organic molecule.

[0016] Further, the material of the quantum dot light-absorbing layer is lead sulfide or lead selenide.

[0017] The application further provides a preparation method of the perovskite / quantum dot two-end stacked solar cell.

[0018] Further, when the P-type organic polymer is used to prepare any hole extraction layer of the perovskite / quantum dot two-end stacked solar cell, the P-type organic polymer is doped to improve the mobility.

[0019] Overall, the above technical solutions conceived by the application can achieve the following beneficial effects:

[0020] (1) The application considers that the tunneling layer cannot block the solvent of the upper and lower sub-cells in the battery preparation and thus exists the interference problem, and the application specifically proposes a new blocking idea different from the prior art, that is, starting from the process, a dense tunneling layer is directly prepared by a gas phase deposition method, the tunneling layer obtained by the method is a high-transparency and high-density protective layer capable of blocking the solvent and resisting acid and alkali corrosion, which can meet the requirements of non-interference between the sub-cells, efficient recombination of electrons and holes and electron transmission.

[0021] (2) The formal structure perovskite / quantum dot two-end stacked solar cell proposed in the embodiment adopts inorganic PbS quantum dots or P-type organic polymer as the hole transport material of the quantum dot perovskite stack, and the valence band is compatible with perovskite, which can improve the efficiency of the cell.

[0022] (3) The present application solves the problem that the hole transport material solvent is not compatible with perovskite by solvent conversion, which is caused by the introduction of inorganic PbS quantum dots as the hole transport material of the quantum dot perovskite stack in the perovskite / quantum dot two-end stacked solar cell. Since the inorganic PbS quantum dots are relatively stable, they can protect the perovskite layer to a certain extent. In addition, the inorganic PbS can withstand annealing, water and oxygen corrosion and other problems in the subsequent multi-step manufacturing process, ensuring the stability of the stacked cell. At the same time, the efficiency of the quantum dot sub-cell is increased, which ensures that the perovskite / quantum dot two-end stacked solar cell of embodiment one has the positive superposition effect of perovskite and quantum dot cells.

[0023] In summary, the formal structure perovskite / quantum dot two-end stacked solar cell in the present application not only has an ultra-wide spectral response range, but also has the advantages of high efficiency and stability, low cost, simple preparation process, easy large-scale preparation, etc., and has excellent commercial development prospects. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 A formal structure perovskite / quantum dot two-end stacked solar cell structure schematic diagram is provided for the present application;

[0025] Figure 2 A perovskite and quantum dot absorption spectrum combination diagram with a first exciton absorption peak position of 800 nm is provided for the embodiment of the present application;

[0026] Figure 3 A planar SEM diagram of the dense PbS quantum dot hole transport layer formed by solvent modification and spin coating on the surface of the perovskite thin film is provided for the embodiment of the present application;

[0027] Figure 4 A planar structure schematic diagram of the formal structure perovskite / quantum dot two-end stacked cell device structure is provided for the embodiment of the present application;

[0028] Figure 5 A corresponding Figure 4 Device structure schematic diagram of the stacked cell I-V curve and cell performance parameters. DETAILED DESCRIPTION

[0029] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0030] Embodiment one

[0031] A formal structure of perovskite / quantum dot two-end stacked solar cell, as shown in the figure, comprises: conductive glass, first electron extraction layer, perovskite light absorption layer, first hole extraction layer, dense tunneling layer, quantum dot light absorption layer and counter electrode, which are sequentially stacked from top to bottom. The dense tunneling layer is obtained by vapor deposition, and the low work function N-type semiconductor material in the dense tunneling layer has an electron transport function; the functional material of the first hole extraction layer is inorganic PbS quantum dot or P-type organic polymer. Figure 1

[0032] In the stacked cell, the tunneling layer is an intermediate layer with high transmittance and high conductivity. In view of the problem that the tunneling layer cannot block the solvents of the upper and lower sub-cells in the preparation of the cell and is interfered, the present embodiment proposes a new blocking idea different from the prior art, that is, from the process point of view, a dense tunneling layer is directly prepared by vapor deposition. The tunneling layer obtained by this method is a high-transmittance and high-conductivity dense protective layer that can block solvents and resist acid and alkali corrosion. It can meet the requirements of not interfering with each other between sub-cells, and also meet the requirements of efficient recombination of electrons and holes and have the function of transporting electrons, replacing the original structure of tunneling layer and electron transport layer.

[0033] In addition, the formal structure of perovskite / quantum dot two-end stacked solar cell proposed in the present embodiment uses inorganic PbS quantum dot or P-type organic polymer as the hole transport material of quantum dot perovskite stack, which can be compatible with perovskite in terms of valence band, etc., and can improve the efficiency of the cell.

[0034] In summary, the present embodiment can improve the working efficiency and stability of the perovskite / quantum dot two-end stacked solar cell, and can achieve the effect of 1+1>1 under the combination of perovskite cell and quantum dot cell, and can accelerate the commercialization development of stacked photovoltaics.

[0035] Preferably, the above dense tunneling layer is a composite layer composed of a single low work function N-type material layer and a single high work function P-type material layer. The single high work function P-type material can be a noble metal.

[0036] ​In the preferred embodiment, there is only a single low work function conductive N-type material and a single high work function P-type material in the tunneling layer, without introducing additional materials, which will not increase too many interfaces in the cell, avoiding the sacrifice of cell efficiency while improving the barrier ability (such as the formal structure of perovskite / quantum dot tandem cell reported by Tavakoli et al. in the literature, the tunneling layer is Au / MoO3 / ITO, which introduces MoO3 to increase the interface and increase the loss of the cell). In the preferred embodiment, the dense tunneling layer is prepared by vapor deposition, so even without additional materials, it can well block the solvents of the upper and lower sub-cells. Therefore, the tunneling layer of the preferred embodiment is low-loss and high-efficiency, and the perovskite / quantum dot tandem solar cell obtained has high efficiency.

[0037] Preferably, the single low work function conductive N-type material layer is deposited by atomic force deposition or plasma deposition. For example, the dense tunneling layer is composed of an ultra-thin gold layer and an AZO layer; the AZO layer is deposited by atomic force deposition or plasma deposition; for another example, In2O3 obtained by atomic force deposition is combined with gold; or SnO2 obtained by atomic force deposition is combined with ITO prepared by magnetron sputtering. The prepared tunneling layer has high transparency and density, can realize solvent blocking between the two sub-cells and has high transparency and conductivity, can realize efficient recombination of electrons and holes, and replaces the original electron transport layer.

[0038] Preferably, it further comprises a second hole extraction layer arranged between the quantum dot light absorption layer and the counter electrode. The efficiency of the tandem cell can be further improved. This embodiment is different from the perovskite / quantum dot tandem cell reported in the literature, which does not have a second hole transport layer, and this embodiment solves the problem of the absence of a second hole transport layer. The second hole transport layer ensures the efficiency and stability of the tandem cell.

[0039] Preferably, the second hole extraction layer can be the same as the first hole extraction layer, that is, inorganic PbS quantum dots or P-type organic polymers can also be used.

[0040] Preferably, the P-type organic polymer is PTAA molecule or P3HT, Spiro-OMeTAD, etc.

[0041] In addition, the high-transparency conductive glass can be indium-doped tin oxide, hydrogen-doped indium tin oxide, high-conductivity flexible polymer substrate, or fluorine-doped tin oxide coated glass, including but not limited to the above types. The thickness of the first electron extraction layer is 20-300 nm. The wide-bandgap semiconductor oxide thin film as the electron extraction layer, wherein the oxide is titanium oxide, zinc oxide, or tin oxide; the electron extraction layer can also be an organic polymer, including but not limited to the above types. The perovskite light absorption layer is Cs x FA y MAz Pb α Sn 1-α I 3-β D β wherein 0≦x,y,z,α≦1,0≦β≦3,D is Cl or Br. The first and second hole extraction layers have a thickness of 10-200 nm, and can be organic polymers, metal oxides, or inorganic semiconductors, etc. The quantum dots in the quantum dot light-absorbing layer include, but are not limited to, lead sulfide and lead selenide quantum dots, and have a particle size of 2-10 nm. The quantum dot light-absorbing layer has a thickness of 100-1000 nm. The counter electrode is a noble metal electrode, an alloy electrode, or a metal semiconductor oxide.

[0042] Example Two

[0043] A method for preparing a perovskite / quantum dot tandem solar cell as described in Example One, when inorganic PbS quantum dots are used to prepare any of the hole extraction layers in the perovskite / quantum dot tandem solar cell as described in Example One, a dispersant for the inorganic PbS quantum dots is selected to be a solvent having a polarity of less than 3 and a boiling point of less than 150°C; and after spin-coating a solution of inorganic PbS quantum dots on the perovskite light-absorbing layer, a short-chain ligand containing a mercapto group is used to remove oleic acid from the surface of the inorganic PbS quantum dot film, and a dispersant for the short-chain ligand containing a mercapto group is selected to be a solvent having a polarity of greater than 3.0 and less than 5.0 and a boiling point of less than 100°C.

[0044] Example One proposes that a perovskite / quantum dot tandem solar cell having the formal structure uses inorganic PbS quantum dots or P-type organic polymers as the hole transport layer functional material on the perovskite light-absorbing layer, and further, this example develops a new solvent system to solve the problem that the solvent for the hole transport layer is incompatible with the perovskite film, and uses a solvent having a weak polarity (<3.0) and a low boiling point (<150°C) (such as toluene 2.4, chlorobenzene 2.7, or non-polar n-hexane) as a dispersant, and after spin-coating on the perovskite film, a short-chain ligand containing a mercapto group, such as ethanedithiol or mercaptopropionic acid, is used to perform solid-phase exchange in another weakly polar, low-boiling-point solvent (polarity greater than 3.0 and less than 5.0; boiling point <100°C) (such as isopropanol 4.3, ethyl acetate 4.3) to obtain a dense P-type semiconductor film.

[0045] That is, the embodiment solves the problem of incompatibility between the hole transport material solvent and the perovskite by solvent conversion, which is caused by the introduction of inorganic PbS quantum dots as a hole transport material for quantum dot perovskite stacking. Since the inorganic PbS quantum dots are relatively stable, they can protect the perovskite layer to some extent. In addition, the inorganic PbS can withstand annealing, water and oxygen corrosion and other problems in subsequent multi-step manufacturing steps. The present scheme is different from the preparation method of perovskite / quantum dot stacked cells reported in the literature. The second hole transport layer is not present in the literature, but the present scheme adds the problem of the absence of the second hole transport layer. The second hole transport layer ensures the efficiency and stability of the stacked cell, and ensures that the perovskite / quantum dot stacked solar cell of embodiment one has the effect of 1+1>1 of perovskite cells and quantum dot cells.

[0046] Preferably, when any of the hole extraction layers in the perovskite / quantum dot stacked solar cell as described in embodiment one is prepared using a P-type organic polymer, the P-type organic polymer is doped to improve the mobility.

[0047] That is, the present embodiment can also use P-type organic polymers such as temperature-resistant and high-efficiency PTAA or P3HT with a weight average molecular weight Mw of about 20000 g / mol or Spiro-OMeTAD for doping or modification to improve the mobility, which is compatible with perovskite without sacrificing perovskite efficiency, and is also compatible with the subsequent preparation of PbS stacked sub-cells. It can be covered on the perovskite film by spin coating or thermal evaporation.

[0048] In summary, the preparation method of the present embodiment can obtain a hole transport layer compatible with perovskite and quantum dot / perovskite stacked photovoltaic devices.

[0049] In order to make the preparation method of the present embodiment more clear, the following flow chart is given:

[0050] A preparation method of a formal structure perovskite / quantum dot stacked solar cell, comprising the following steps:

[0051] (1) The first electron extraction layer is prepared on a high-transparency conductive glass, and is treated by heating at 60-400°C for 10 min-5h to obtain a first electron extraction layer with a thickness of 20-300 nm.

[0052] (2) The perovskite light-absorbing layer is prepared on the first electron extraction layer, and is heated at 60-180°C for 10 min-2h to obtain a perovskite light-absorbing layer with a thickness of 200-1500 nm.

[0053] (3) The first hole extraction layer is prepared on the perovskite light-absorbing layer by spin coating, blade coating, spray coating, slot coating or vacuum deposition process using organic polymers, metal oxides or inorganic semiconductors, etc. The first hole extraction layer with a thickness of 10-200 nm is obtained by heating at 60-400 ℃ for 10 min-5 h or directly taking out.

[0054] (4) The tunneling layer is prepared on the first hole extraction layer by, but not limited to, solution method or deposition method to obtain a 10-150 nm high-transparency and high-conductivity functional layer.

[0055] (5) The quantum dot light-absorbing layer is directly prepared on the tunneling layer with electron transport function, heated at 60-180 ℃ for 10 min-2 h to obtain a quantum dot light-absorbing layer with a thickness of 100-1000 nm.

[0056] (6) The second hole extraction layer is prepared on the quantum dot light-absorbing layer, heated at 60-400 ℃ for 10 min-5 h or directly taken out to obtain a second hole extraction layer with a thickness of 10-200 nm.

[0057] (7) The noble metal electrode, alloy electrode or metal semiconductor oxide is deposited on the second hole extraction layer under vacuum conditions to obtain a formal structure of perovskite / quantum dot two-end stacked solar cell.

[0058] The specific preparation method is shown in the following examples:

[0059] Example 1

[0060] (1) Preparation of the first electron extraction layer: tin dioxide, 15% hydrogel dispersion liquid and ultrapure water are mixed uniformly at a ratio of 1:5, filtered and used as a precursor solution. In an air environment with a humidity of less than 40%, spin coating is performed on high-transparency conductive glass at an acceleration of 2000 rpm·s-2 and a speed of 4000 rpm·min-1 for 30 seconds. Then, heating is performed at 180 ℃ for 30 min to form a first electron extraction layer with a thickness of 30 nm.

[0061] (2) Perovskite light-absorbing layer. In a glove box, Cs x FA y MA z Pb α Sn 1-α I 3-β D β solution (solvent is dimethylformamide: N-methylformamide = 7:3) is spin-coated on the first electron extraction layer at a speed of 2000 and 5000 rpm·min -1 , 100 ℃ annealing for 15 min to obtain a perovskite light-absorbing layer with a thickness of 450 nm.

[0062] (3) Preparation of the first hole extraction layer: using PbS quantum dots with a band gap of 1.4 eV, the above-mentioned solvent-modified solid-phase exchange layer spin coating method is used to spin coat a 40 nm thick layer on the perovskite light-absorbing layer. The thin film planar SEM is shown in FIG. 2, which shows that the PbS QD hole transport layer is evenly and orderly laid in a relatively dense manner. Figure 3

[0063] (4) Preparation of the tunneling layer: first, 1 nm of gold is evaporated on the first hole extraction layer, and then In2O3 vapor deposition is performed at 100°C, with a thickness of 60 nm.

[0064] (5) Preparation of the quantum dot light-absorbing layer: PbS / PbSe quantum dots with matching band gaps are spin-coated on the second electron extraction layer in a nitrogen atmosphere, annealed at 90°C for 10 min, to obtain a 400 nm thick, dense and flat quantum dot thin film.

[0065] (6) Preparation of the second hole extraction layer. MoO3 is used for thermal evaporation, with a vacuum degree of 10 -4 Pa, a deposition rate of 0.1 nm / s, and a thickness of 25 nm on the quantum dot light-absorbing layer.

[0066] (7) Preparation of the metal electrode. Thermal evaporation is used under a vacuum condition of 10 -4 Pa to form a 40-200 nm thick metal electrode, to obtain a formal structure of perovskite / quantum dot tandem solar cell.

[0067] (8) Testing. The battery is tested under the conditions of AM1.5, 100 mW / cm 2 light intensity, and an active layer effective area of 0.09 cm 2 .

[0068] Example Two

[0069] (1) Preparation of the first electron extraction layer: tin dioxide, 15% hydrogel dispersion, and ultrapure water are mixed in a ratio of 1:5, filtered, and used as a precursor solution. In an air environment with a humidity of less than 40%, the solution is spin-coated on high-transparency conductive glass at an acceleration of 2000 rpm·s -2 , a rotation speed of 4000 rpm·min -1 , and a spin-coating time of 30 seconds. Then, the sample is heated at 180°C for 30 min to form an electron extraction layer with a thickness of 30 nm.

[0070] (2) Perovskite light-absorbing layer. In a glove box, Cs x MA y FA z Pb α Sn​​1-α I 3-β D β Solution (solvent is dimethylformamide: N-methylformamide = 7:3) is spin-coated on the first electron extraction layer in steps at 2000 and 5000 rpm·min -1 -1, annealed at 100°C for 15 min, to obtain a perovskite light-absorbing layer with a thickness of 450 nm.

[0071] (3) Preparation of the first hole extraction layer: spin-coating using doped macromolecular PTAA or P3HT, PEDOT-F, in an air environment with humidity less than 40%, thickness of 40 nm.

[0072] (4) Preparation of the tunneling layer: first evaporating 1 nm thickness of gold on the first hole extraction layer, then performing atomic layer vapor deposition of AZO (aluminum-doped zinc oxide) at 100°C, thickness of 90 nm.

[0073] (5) Preparation of the quantum dot light-absorbing layer: spin-coating the band-gap matched lead sulfide / lead selenide quantum dots on the second electron extraction layer in a nitrogen atmosphere, annealed at 90°C for 10 min, to obtain a 400 nm-thick, dense and smooth quantum dot film.

[0074] (6) Preparation of the second hole extraction layer. Using lead sulfide quantum dots with a band gap of 1.4 eV, spin-coating a 40 nm-thick layer on the quantum dot light-absorbing layer using the above-mentioned solvent-modified solid-phase exchange layer method (Note: The modified solvent PbS QD as a hole transport layer is generally applicable to the first and second hole transport layers).

[0075] (7) Preparation of the metal electrode. Using thermal evaporation, a 40-200 nm-thick metal electrode is prepared under a vacuum condition of 10 -4 Pa, to obtain a perovskite / quantum dot tandem solar cell with the formal structure.

[0076] (8) Testing. The battery is tested under the condition of an active layer effective area of 0.09 cm2 under an AM1.5 (100 mW / cm2) light intensity. The device structure is shown in Figure 4 , the structure being: ITO / SnO2 / Perovskite / PTAA / Au / ALD-AZO / ZnO / PbS QD / PbS-EDT / Au, and the I-V curve and performance parameters are shown in Figure 5 , the open voltage reaching 1.43 V, much greater than the open voltage of a single-junction quantum dot or perovskite battery, and achieving an efficiency close to 10%. It is proved that the sub-batteries are successfully stacked together, and have great potential to achieve a tandem efficiency of 1+1>1.

[0077] In general, the present application provides a formal structure of perovskite / quantum dot two-end stacked solar cell and a preparation method thereof. The functional layers of the cell structure are stacked from bottom to top as follows: conductive glass, first electron extraction layer, perovskite light absorption layer, first hole extraction layer, dense tunneling layer, quantum dot light absorption layer, second hole extraction layer and counter electrode. The dense tunneling layer can protect the perovskite absorption layer and efficient recombination while having the function of transporting electrons, reducing interface defects and process complexity while improving efficiency. The functional material of the first hole extraction layer is inorganic PbS quantum dots or P-type organic polymer. The present application introduces inorganic PbS quantum dots as the hole transport material of the perovskite / quantum dot two-end stacked solar cell through solvent transformation, solving the problem of incompatibility between the solvent of the hole transport material and the perovskite sub-cell in the stacked solar cell. The present application replaces the original tunneling layer plus electron transport layer structure through the design of the tunneling layer, and overcomes the problem of lack of second hole transport layer in the perovskite / quantum dot two-end stacked system through solvent modification. The present application can improve the efficiency and stability of the perovskite / quantum dot stacked solar cell, and has the potential to achieve 1+1>1 in combination of perovskite solar cells and quantum dot solar cells.

[0078] Those skilled in the art will readily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A perovskite / quantum dot tandem solar cell of formal structure, characterized by, The device structure comprises, from top to bottom, a conductive glass, a first electron extraction layer, a perovskite light-absorbing layer, a first hole extraction layer, a dense tunneling layer, a quantum dot light-absorbing layer, and a counter electrode. The dense tunneling layer is obtained by a vapor deposition method, and is matched by a single low work function N-type semiconductor material layer and a single high work function P-type semiconductor material layer, and has the function of transmitting electrons; specifically, the dense tunneling layer is composed of an ultrathin gold layer and an AZO layer, and the AZO layer is obtained by an atomic force deposition method or a plasma deposition method; or the dense tunneling layer is a combination of In2O3 obtained by an atomic force deposition method and gold; or the dense tunneling layer is a combination of SnO2 obtained by an atomic force deposition method and ITO obtained by a magnetron sputtering method. The functional material of the first hole extraction layer is inorganic PbS quantum dots, and the battery is prepared by the following method: a solvent with a polarity less than 3 and a boiling point less than 150 DEG C is selected as a dispersant of the inorganic PbS quantum dots; after spin coating an inorganic PbS quantum dot solution on the perovskite light-absorbing layer, a short-chain ligand containing a mercapto group is used to remove oleic acid on the surface of the inorganic PbS quantum dot film, and a solvent with a polarity greater than 3 and less than 5 and a boiling point less than 100 DEG C is selected as a dispersant of the short-chain ligand containing a mercapto group. 2.The perovskite / quantum dot tandem solar cell of claim 1, wherein, Further comprising: A second hole extraction layer arranged between the quantum dot light-absorbing layer and the counter electrode. 3.The perovskite / quantum dot tandem solar cell of claim 2, wherein, The second hole extraction layer adopts inorganic PbS quantum dots or a P-type organic polymer. 4.The perovskite / quantum dot tandem solar cell of claim 3, wherein, The P-type organic polymer is a Spiro-OMeTAD, PTAA molecule or a P3HT organic molecule. 5.The perovskite / quantum dot tandem solar cell of claim 1, wherein, The material of the quantum dot light-absorbing layer is lead sulfide or lead selenide quantum dots.

6. A method of manufacturing a perovskite / quantum dot tandem solar cell as claimed in any one of claims 1 to 5, characterized in that, When inorganic PbS quantum dots are used to prepare any of the hole extraction layers in the perovskite / quantum dot two-end stacked solar cell according to any one of claims 1 to 5, a solvent with a polarity less than 3 and a boiling point less than 150 DEG C is selected as a dispersant of the inorganic PbS quantum dots; after spin coating an inorganic PbS quantum dot solution on the perovskite light-absorbing layer, a short-chain ligand containing a mercapto group is used to remove oleic acid on the surface of the inorganic PbS quantum dot film, and a solvent with a polarity greater than 3 and less than 5 and a boiling point less than 100 DEG C is selected as a dispersant of the short-chain ligand containing a mercapto group.

7. The method for fabricating a perovskite / quantum dot tandem solar cell according to claim 6, characterized in that, When a P-type organic polymer is used to prepare the second hole extraction layer in the perovskite / quantum dot two-end stacked solar cell according to any one of claims 2 to 4, the P-type organic polymer is doped to improve the mobility.

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