CN106531888A - Porphyrin derivative used for interface modification of hole transport layer/perovskite layer in inverted perovskite solar cell - Google Patents

Abstract

The invention relates to the application of porphyrin derivatives in the interface modification of hole transport layer/perovskite layer in inverted perovskite solar cells. The device structure is: ITO/hole transport layer/perovskite layer/electron transport layer/cathode . Using porphyrin on the interface of the hole transport layer/perovskite layer in perovskite solar cells, firstly, it can adjust the morphology of the perovskite layer, reduce the defect density in the film, and improve the quality of the perovskite layer; secondly , the introduction of a porphyrin interface modification layer can effectively block the transport of electrons from the perovskite to the hole transport layer, and at the same time facilitate the injection and transport of holes from the perovskite to the hole transport layer, which is conducive to the improvement of device efficiency. improve. In addition, due to the good solubility of porphyrin, it can be introduced into perovskite solar cells by solution spin-coating method, which is very simple and reproducible.

Description

Porphyrin derivatives for hole transport layer/perovskite in inverted perovskite solar cells Interface Modification of Mineral Seams

technical field

The invention relates to the application of porphyrin derivatives in the interface modification of hole transport layer/perovskite layer in inverted perovskite solar cells.

Background technique

Since the 21st century, energy problems have become increasingly prominent. At present, non-renewable fossil energy such as coal and oil is the main energy source in today's society, but they will cause serious environmental pollution during the process of mining, transportation, processing and use, such as the greenhouse effect, Haze, soil agglomeration, etc., so the development of renewable clean energy is imminent. Among them, solar energy resources are inexhaustible, inexhaustible, clean and pollution-free, and can be used safely. Therefore, rational use of solar energy is one of the effective ways to solve energy problems, and solar cells can directly convert solar energy into electrical energy. received the attention of researchers.

Since the solar cell was reported, its development process can be divided into four generations: the first generation is silicon-based solar cells represented by monocrystalline silicon and polycrystalline silicon; the second generation is based on cadmium telluride (CdTe) and copper indium gallium selenide Thin-film solar cells represented by CIGS; the third generation is solar cells represented by dye-sensitized (DSSC), organic (OPV) and quantum dots; the fourth generation is a new type of solar cell represented by perovskite. Among them, the first- and second-generation solar cells have been commercialized, but the large-scale production of these solar cell technologies has problems such as large production energy consumption, high cost, and environmental pollution. In contrast, the third and fourth generation solar cells are low in cost, easy to prepare, and have broad development prospects, especially since the emerging perovskite solar cells were reported in 2009, their photoelectric conversion efficiency (PCE) has changed from the original 3.8 % increased to more than 22%, the development speed is very alarming, has become a research hotspot in the field of photovoltaics.

Perovskite solar cells use perovskite as the light-absorbing layer. The basic structure of perovskite materials is octahedral, and the chemical composition is ABX ₃ (A represents organic ammonium cations, such as CH ₃ NH ₃ ⁺ , HC(NH ₂ ) ₂ ⁺ ; B represents divalent metal cations, such as Pb ²⁺ , Sn ²⁺ ; X represents halide ions, such as I ^- , Cl ^- , Br ^- ). Perovskite itself has the advantages of wide optical absorption spectrum, adjustable energy gap, long carrier diffusion length and lifetime, low cost, and simple preparation process. The film-forming process of perovskite is diversified, mainly divided into one-step spin coating method, two-step spin coating or immersion method, and vacuum evaporation method; the device structure of perovskite solar cells is also diversified, mainly divided into two types: Two types, one is the traditional structure: FTO conductive glass/electron transport layer/perovskite layer/hole transport layer/metal electrode (gold or silver), and the other is an inverted structure: ITO conductive glass/hole transport layer/ Perovskite layer/electron transport layer/metal electrode. The working principle of perovskite solar cells involves the absorption of photons by the perovskite layer and the generation of excitons, the injection and transmission of electrons and holes to the electron and hole transport layers, and the collection process of electrodes. Among them, the extraction and injection of carriers occur between the interfaces of perovskite/electron transport layer, perovskite/hole transport layer and electron, hole transport layer/electrode, and the properties of the interface layer have a great influence on the performance of the device. Therefore, modifying the interface layer is one of the effective ways to obtain high-performance solar cells. The interface modification can not only increase the open circuit voltage, reduce or eliminate the hysteresis phenomenon of photocurrent, but also the interface modification between the carrier transport layer and the perovskite layer can effectively protect the perovskite layer from being corroded, thus improving to a certain extent device stability. Ogomi et al. first introduced HOCO-R-NH ₃ ⁺ I ^- self-assembled monolayer between the electron transport layer titanium dioxide (TiO ₂ )/perovskite layer, which can inhibit the recombination of electrons in TiO ₂ and holes in perovskite, Thereby improving the performance of the device; fullerene (C ₆₀ ) and its derivative self-assembled monolayers are used to modify the interface between TiO ₂ /perovskite, and at the same time increase the open circuit voltage and fill factor, thereby further improving the efficiency of the battery; Other materials used to modify the interface between the electron transport layer (TiO ₂ , zinc oxide) and perovskite, such as alanine, 4-aminobenzoic acid, organosilane, etc., can improve the quality of the perovskite film, thereby effectively It is conducive to the improvement of the photoelectric performance of the device. In addition, hydrophobic molecules such as C ₁₂ -silane are introduced into the interface of the perovskite/hole transport layer (spiro-OMeTAD), which can reduce the corrosion of the perovskite film by water and oxygen to a certain extent, thereby improving the performance of the device. stability.

At present, most of the reported work on the interface modification of perovskite devices is aimed at the traditional device structure, and there are not many works on the interface modification of the inverted device structure. The invention mainly modifies the interface of the hole transport layer/perovskite layer in the inverted perovskite device, and the modified material is a derivative of porphyrin. Porphyrin molecules have a large planar π-conjugated structure, strong light absorption, unique optoelectronic and magnetic properties, and excellent thermal stability. Using porphyrin on the interface of the hole transport layer/perovskite layer in perovskite solar cells, firstly, it can adjust the morphology of the perovskite layer, reduce the defect density in the film, and improve the quality of the perovskite layer; secondly , the introduction of a porphyrin interface modification layer can effectively block the transport of electrons from the perovskite to the hole transport layer, and at the same time facilitate the injection and transport of holes from the perovskite to the hole transport layer, which is conducive to the improvement of device efficiency. improve. In addition, due to the good solubility of porphyrin, it can be introduced into perovskite solar cells by solution spin-coating method, which is very simple and reproducible.

purpose of invention

The purpose of the present invention is to apply porphyrin derivatives to the interface modification of the hole transport layer/perovskite layer in an inverted perovskite solar cell.

Contents of the invention

1. Interface modification of hole transport layer/perovskite layer in an inverted perovskite solar cell based on porphyrin derivatives, the molecular structural formula is as follows:

n=1-16, M=Zn ²⁺ , Fe ²⁺ , Co ²⁺ , Ni ²⁺ , Cu ²⁺ , X=-SAc

2. The preparation method of porphyrin at the hole transport layer interface modification, including spin coating method, evaporation method, self-assembly and so on.

3. Preparation of solar cells based on porphyrin modified hole transport layer/perovskite layer.

Description of drawings

Figure 1: Schematic diagram of the device structure based on porphyrin-modified perovskite solar cells (PEDOT: PSS stands for poly-3,4-ethylenedioxythiophene/polystyrene sulfonate, Porphyrin stands for porphyrin, Perovskite stands for perovskite , PCBM represents a fullerene derivative, C ₆₀ represents fullerene, BCP represents dimethyl-4,7-diphenyl-1,10-phenanthroline, Al represents aluminum)

Figure 2: Photocurrent density-voltage curves of porphyrin-modified and unmodified solar cells (V _oc represents open circuit voltage, J _sc represents short-circuit current density, FF represents fill factor, and PCE represents photoelectric conversion efficiency)

detailed description

Implementation Case 1

Zinc(II) 5,10,15,20-tetrakis[5-(acetylmercaptopentyloxy)phenyl]porphyrin as poly(3,4-ethylenedioxythiophene/ The interface modification layer of polystyrene sulfonate (PEDOT:PSS)/perovskite has the following molecular structure formula:

Step 1: ITO substrate cleaning

Use a mixture of zinc powder and dilute hydrochloric acid to etch a 1.5cmx1.5cm ITO substrate, then ultrasonically clean the etched ITO in deionized water, acetone, and isopropanol for 15 minutes, and finally blow dry with nitrogen And irradiated in UV-ozone for 15 minutes.

Step 2: Device Preparation

(1) Preparation of modified layer device ITO/PEDOT:PSS/porphyrin/perovskite/PCBM/C ₆₀ /BCP/Al:

PEDOT:PSS was first spin-coated onto an ozone-treated ITO substrate (6000 revolutions per minute (rpm), 60 seconds (S)) and annealed at 120°C for 30 minutes, then transferred to a nitrogen atmosphere glove box In; Zinc (II) 5,10,15,20-tetra[5-(acetylmercaptopentyloxy)phenyl]porphyrin dichlorobenzene solution (0.5mM) is then spin-coated to ITO/PEDOT: On PSS (6000rpm, 30S), and dry overnight at room temperature; then spin-coat 1M lead iodide (PbI ₂ ) solution onto ITO/PEDOT:PSS/porphyrin (3000rpm, 40S), and immediately spin-coat A layer of methyl ammonium iodide (3000rpm, 40S), followed by annealing at 100°C for about 5 minutes; next, spin-coat a 20mg/ml solution of PCBM in dichlorobenzene onto the perovskite (6000rpm, 30S ), and placed at room temperature for more than 10 minutes; finally, C ₆₀ (20nm), BCP (8nm) buffer layer and Al (100nm) electrode were vapor-deposited.

(2) Preparation of ITO/PEDOT: PSS/perovskite/PCBM/C ₆₀ /BCP/Al without modification layer:

Using the same preparation process, the difference is that there is no porphyrin modification layer.

Step 3: Battery Performance Test

Use Keithley2400 to test the performance of the device: under the simulated AM 1.5G sunlight irradiation condition (light intensity is 100mW/cm ² ), the photocurrent-voltage curve can be obtained, and the scanning voltage range is reverse scanning 1.2V→-1.2V , Forward scan -1.2V→1.2V, scan rate 50mV/S.

Zinc(II) 5,10,15,20-tetrakis[5-(acetylmercaptopentoxane)phenyl]porphyrin was introduced at the interface of PEDOT:PSS/perovskite, and the porphyrin could pass through the -SCOCH The ₃ groups are chemically adsorbed on the surface of PEDOT:PSS, and this intermolecular electrostatic interaction can increase the surface coverage of the perovskite film on PEDOT:PSS, and the modified PEDOT:PSS surface has enhanced hydrophobicity, and the perovskite When the mineral film is formed on its surface, the density of heterogeneous nucleation sites can be reduced, which is conducive to the formation of larger grains in the film and improves the quality of the perovskite layer. In addition, the energy levels of the highest occupied orbital (HOMO) and the lowest unoccupied orbital (LUMO) of porphyrin are matched with perovskite, which can effectively block the transport of electrons from perovskite to PEDOT:PSS, while facilitating the transfer of holes from the perovskite to PEDOT:PSS. The implantation and transport of perovskite to PEDOT:PSS, the efficiency of the modified device was increased from 11.35% to 13.55%.

The above results show that the device performance of porphyrin-modified perovskite solar cells has been significantly improved, and the method of preparing the interface layer is simple and reproducible.

The interface modification of the hole transport layer of the porphyrin derivatives provided in the embodiments of the present invention in perovskite solar cells has been introduced in detail above, and the principles and implementation methods of the present invention have been described by using specific examples. The above examples It is only used to help understand the method and core idea of the present invention, and the content should not be construed as limiting the present invention.

Claims (3)

1. A kind of interface modification material of hole transport layer/perovskite layer in the perovskite solar cell based on porphyrin derivative, molecular structural formula is as follows: Wherein, n=1-16, M=Zn ²⁺ , Fe ²⁺ , Co ²⁺ , Ni ²⁺ , Cu ²⁺ , X=-SAc. 2. The preparation method of porphyrin as claimed in claim 1 in hole transport layer interface modification. 3. Application of porphyrin-modified hole transport layer/perovskite layer in solar cells.