CN107565027B - Based on nano-onions carbon: PC61The perovskite solar battery of BM composite electron transport layer - Google Patents

Abstract

The invention relates to a perovskite solar cell based on a nano-onion carbon: PC ₆₁ BM composite electron transport layer. The solar cell adopts a positive structure and comprises a substrate layer, an ITO transparent conductive anode layer, an empty conductive layer and a hollow layer arranged in sequence from bottom to top. Hole transport layer, perovskite photoactive layer, composite electron transport layer and metal cathode layer; the composite electron transport layer is a solid composite layer structure composed of PC61BM material and nano onion carbon material in proportion; nano onion carbon material in the composite layer structure The mass percentages of the material and PC61BM are respectively: nano-onion carbon 1%-10%; _PC61BM 99%-90%. The invention effectively reduces the series resistance of the device, reduces the recombination probability of electrons at the interface of the electron transport layer/photoactive layer, and improves the filling factor of the device; at the same time, the quantity of electrons transferred to the cathode is increased, and the carrier transport is improved rate.

Description

Perovskite solar cells based on nanoonion carbon: PC61BM composite electron transport layer

technical field

The invention relates to a solar cell, belonging to the field of new energy solar cells, and in particular to a perovskite solar cell based on a nano-onion carbon: PC ₆₁ BM composite electron transport layer.

Background technique

With the global energy demand increasing year by year, the effective use of renewable energy has become an urgent problem to be solved. Most of the energy currently used in the world comes from the extraction of fossil fuels, including oil, natural gas and coal. However, these resources are limited. Solar energy, which accounts for more than 99% of the earth's total energy, is inexhaustible, inexhaustible, and pollution-free, so it has become one of the new energy sources developed and utilized by scientists from all over the world. Perovskite is a perovskite rock sample discovered by German mineralogist Gustav Rose in the Ural Mountains in central Russia in 1839, and decided to use the great geologist Lev in his heart. Perovski to name this ore. The ore is a common metal organic compound crystal, the main component is calcium titanate (CaTiO3). The perovskite cells that people later referred to were not made of the ore material he discovered, but compounds with a crystal structure similar to that of perovskite. In 2009, Miyasaka Li of Toin Yokohama University was the first to create perovskite solar cells by applying a thin layer of perovskite as a light-absorbing layer to dye-sensitized solar cells. The photoelectric conversion rate at that time was 3.8%. Later, researchers improved the battery, and the conversion efficiency doubled. Although the conversion efficiency has been improved, it still faces a fatal problem - the metal halide in the perovskite is easily destroyed by the liquid electrolyte of the battery, resulting in low battery stability and short lifespan.

In August 2012, the laboratory of Sungkyunkwan University and EPFL, led by Gr tzel, introduced a solid-state hole transport material (HTM) into solar cells to make the cell more efficient. This has been increased to 10%, and the problem of cell instability has also been solved, and the new perovskite solar cells are easier to encapsulate than before with liquid electrolytes. Since then, perovskite solar cells have become a new research hotspot.

In the endless research related to perovskite solar cells, scientists also found that perovskite not only has good light absorption, but also is a good charge transport material. They continue to improve perovskite materials and structures to improve the photoelectric conversion rate of perovskite cells. So in the same year, Henry Sinais of Oxford University replaced the TiO2 in the battery with aluminum, so that the perovskite in the battery is not only a light absorbing layer, but also a semiconductor material that transmits charges. . As a result, the conversion efficiency of perovskite cells climbed to 15%. In August 2015, a research team led by Yang Yang, a Chinese scientist at the University of California, Los Angeles, published the latest research paper in the journal Science, saying that they selected materials more suitable for transporting charges by improving the perovskite structure layer. Allow the electrodes at both ends of the battery to collect more electricity. In this study, the conversion efficiency of perovskite solar cells reached a maximum of 19.3%, the highest in the field.

However, although perovskite solar cells have high photoelectric conversion efficiency, their perovskite structure is extremely unstable and easily decomposed in a water-oxygen environment, and perovskite cells are prone to performance hysteresis due to their special charge transport mechanism. , that is, when the forward voltage and reverse voltage are applied, the performance difference is large. The above shortcomings lead to the fact that perovskite batteries still need time to be practical. At present, research groups around the world have improved the photoelectric conversion efficiency of perovskite solar cells by preparing suitable electron and hole transport layers, increasing their stability and reducing performance hysteresis. Conventional planar-structure perovskite solar cell devices generally use PC ₆₁ BM as their electron transport layer, which significantly improves the efficiency of perovskite solar cells. However, due to the low conductivity and poor air stability of PC ₆₁ BM, the stability of the device in the air is poor, and the device life is short. In addition, most of the planar structure perovskite solar cells using the PC ₆₁ BM electron transport layer have obvious performance hysteresis, which is also an urgent scientific research problem to be solved.

Carbon Onions (CNOs) is the abbreviation of nano-onion-like fullerenes. It is a large carbon atom cluster composed of several layers of concentric spherical graphite shells, and the innermost layer is composed of 60 carbon atoms. C ₆₀ , the number of carbon atoms in each shell can be calculated as 60n ² (n is the number of layers). Nano onion carbon is a set of spherical full carbon molecules, which is equivalent to carbon nanotubes with an aspect ratio of approximately 1:1, and is a special form of carbon nanotubes. As a new type of carbon material, nano-onion carbon has the characteristics of ultra-high conductivity, transparency, and strong stability. Since then, research on special fullerene substances such as carbon nano onions has begun to emerge quietly and has become a research hotspot.

By combining a variety of organic and inorganic materials, studying how to optimize the electron transport layer is the key to improving the photoelectric conversion efficiency of perovskite solar cells, reducing performance hysteresis, and improving stability, and is also the focus and difficulty of current research in this field.

SUMMARY OF THE INVENTION

Based on the above technical problems, the present invention provides a perovskite solar cell based on nano-onion carbon: PC ₆₁ BM composite electron transport layer, thereby solving the problems of slow carrier transport speed, hysteresis and stability of performance in previous perovskite solar cells Poor technical issues.

For solving the above technical problems, the technical scheme adopted in the present invention is as follows:

A perovskite solar cell based on nano-onion carbon: PC ₆₁ BM composite electron transport layer, the solar cell adopts a positive structure and includes a substrate layer, an ITO transparent conductive anode layer and a hole transport layer arranged in sequence from bottom to top , perovskite photoactive layer, composite electron transport layer and metal cathode layer;

in,

The composite electron transport layer is a solid-state composite layer structure composed of PC ₆₁ BM material and nano-onion carbon material mixed in proportion;

The mass percentages of nano-onion carbon material and PC ₆₁ BM material in the composite layer structure are:

Nano onion carbon 1% to 10%;

PC ₆₁ BM 99% to 90%.

Based on the above technical solutions, the hole transport layer is a solid film prepared from an aqueous dispersion of PEDOT:PSS, and the concentration of the aqueous dispersion is 0.5-2 mg/ml.

Based on the above technical solutions, the perovskite photoactive layer is a CH ₃ NH ₃ PbI ₃ perovskite structure film, and the thickness is 240-300 nm.

Based on the above technical solutions, the thickness of the composite electron transport layer is 5-20 nm.

Based on the above technical solutions, the nano onion carbon material is prepared from nano onion carbon dispersion liquid, the particle size is 20-40 nm, and the concentration is 1-5 mg/ml.

Based on the above technical solutions, the metal material of the metal cathode layer is one or a mixture of two or more of Ag, Al, and Cu, and the thickness of the metal cathode layer ranges from 100 to 200 nm.

Based on the above technical solutions, the substrate layer material is glass or transparent polymer, and the transparent polymer material is polyethylene, polymethyl methacrylate, polycarbonate, polyurethane, polyimide, chlorine One or more mixtures of vinegar resin and polyacrylic acid.

To sum up, due to the adoption of the above-mentioned technical solutions, the beneficial effects of the present invention are:

1. The present invention fills the gap between the PC ₆₁ BM and the perovskite thin film by mixing nano-onion carbon to optimize the interface contact, which is beneficial to the transport of carriers, and the charge hysteresis effect of the nano-onion carbon itself can offset the hysteresis of the perovskite battery. effect, thereby reducing the overall performance hysteresis of the battery.

2. The present invention effectively reduces the series resistance of the device by introducing high-conductivity nano-onion carbon, reduces the recombination probability of electrons at the interface of the electron transport layer/photoactive layer, and improves the filling factor of the device; The amount transferred to the cathode increases the carrier transfer rate, thereby increasing the short-circuit current of the device.

3. By mixing the stable nano-onion carbon particles, the voids and voids in the PC ₆₁ BM film are filled, which effectively improves the ability of the electron transport layer to isolate water and oxygen, and avoids the entry of water and oxygen into the photoactivity of the perovskite. The layer leads to the decomposition of the perovskite structure, which improves the water-oxygen stability of the device.

Description of drawings

Fig. 1 is the structural representation of the present invention;

Labels in the figure: 1, substrate layer; 2, ITO transparent conductive anode layer; 3, hole transport layer; 4, perovskite photoactive layer; 5, composite electron transport layer; 6, metal cathode layer.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings. Embodiments of the present invention include, but are not limited to, the following examples.

Example

As shown in Figure 1, a perovskite solar cell based on nano-onion carbon: PC ₆₁ BM composite electron transport layer, the solar cell adopts a positive structure, including a substrate layer 1, ITO transparent conductive layer arranged from bottom to top in order Anode layer 2 (ITO, English name Indium Tin Oxides, namely indium tin oxide), hole transport layer 3, perovskite photoactive layer 4, composite electron transport layer 5 and metal cathode layer 6;

in,

The composite electron transport layer 5 is a solid composite layer structure composed of PC ₆₁ BM material and nano onion carbon material mixed in proportion;

The mass percentages of nano-onion carbon material and PC ₆₁ BM material in the composite layer structure are:

Nano onion carbon 1% to 10%;

PC ₆₁ BM 99% to 90%.

In the above embodiments, the thickness of the ITO transparent conductive anode layer 2 ranges from 20 to 40 nm.

Preferably, the hole transport layer 3 is a solid film prepared from an aqueous dispersion of PEDOT:PSS, and the concentration of the aqueous dispersion is 0.5-2 mg/ml.

Preferably, the perovskite photoactive layer 4 is a CH ₃ NH ₃ PbI ₃ perovskite structure film with a thickness of 240-300 nm.

Preferably, the composite electron transport layer 5 has a thickness of 5-20 nm.

Preferably, the nano onion carbon material is prepared from nano onion carbon dispersion liquid, the particle size is 20-40 nm, and the concentration is 1-5 mg/ml.

Preferably, the metal material of the metal cathode layer 6 is one or a mixture of two or more of Ag, Al, and Cu, and the thickness of the metal cathode layer ranges from 100 to 200 nm.

Preferably, the material of the substrate layer 1 is glass or transparent polymer, and the transparent polymer material is polyethylene, polymethyl methacrylate, polycarbonate, polyurethane, polyimide, chloroacetate One or more mixtures of resin and polyacrylic acid.

In this example, the gap between the PC ₆₁ BM and the perovskite film is filled by mixing nano-onion carbon to optimize the interface contact and facilitate the transport of carriers, and the charge hysteresis effect of the nano-onion carbon itself can offset the hysteresis effect of the perovskite battery. , thereby reducing the overall performance hysteresis of the battery; by introducing high-conductivity nano-onion carbon, the series resistance of the device is effectively reduced, the recombination probability of electrons at the electron transport layer/photoactive layer interface is reduced, and the fill factor of the device is improved. ; At the same time, the number of electrons transferred to the cathode is increased, and the carrier transfer rate is increased, thereby increasing the short-circuit current of the device; by mixing stable nano-onion carbon particles, the voids and voids in the PC ₆₁ BM film are filled, effectively It improves the ability of the electron transport layer to isolate water and oxygen, avoids the decomposition of the perovskite structure due to the entry of water and oxygen into the perovskite photoactive layer, and improves the water and oxygen stability of the device.

Hereinafter, the present invention will be further explained and illustrated by listing specific examples in conjunction with specific data.

specific embodiment

control group 1

Clean the substrate composed of the substrate layer 1 and the ITO transparent conductive anode layer 2 with a surface roughness of less than 1 nm, and dry it with nitrogen after cleaning; spin-coat the PEDOT:PSS solution on the surface of the ITO transparent conductive anode layer 2 (working parameters). : rotating speed 3000rpm, time 40s) to prepare hole transport layer 3; bake the formed film (working parameters: temperature 135°C, time 30min); spin coating on ITO transparent conductive anode layer 2 to prepare perovskite light Active layer 4 (thickness 250nm); spin coating on the surface of perovskite photoactive layer 4 to prepare nano-onion carbon to prepare composite electron transport layer 5 (thickness 20nm; metal cathode Ag (thickness 100nm) is evaporated on metal cathode layer 6, forming calcium Titanite solar cell devices.

Under standard test conditions: air quality AM 1.5, light intensity 100mW/cm ² , the performance parameters of the battery are shown in Table 1:

Table 1 Performance parameters of batteries composed of control group 1

It can be seen from Table 1 that the composite electron transport layer 4 mixed with nano-onion carbon and PC ₆₁ BM can effectively improve the fill factor and short-circuit current of the perovskite solar cell, thereby improving its photoelectric conversion efficiency.

Secondly, the forward and reverse scan fill factor of the battery and its photoelectric conversion efficiency data are shown in Table 2:

Table 2 Positive and negative scan fill factors and photoelectric conversion efficiencies of cells composed of control group 1

It can be seen from Table 2 that the composite electron transport layer 4 mixed with nano-onion carbon and PC ₆₁ BM can effectively reduce the performance hysteresis of perovskite solar cells.

Finally, the performance attenuation data of the battery when stored in air are shown in Table 3:

Table 3 Performance attenuation of the battery composed of control group 1 when stored in air

It can be seen from Table 3 that the composite electron transport layer 4 mixed with nano-onion carbon and PC ₆₁ BM can effectively improve the stability of perovskite solar cells in air.

The above are the embodiments of the present invention. The foregoing are various preferred embodiments of the present invention. If the preferred embodiments in each preferred embodiment are not obviously self-contradictory or are premised on a certain preferred embodiment, each preferred embodiment can be used in any combination. The examples and the specific parameters in the examples are only for the purpose of clearly describing the inventor's invention verification process, not for limiting the scope of patent protection of the present invention. The scope of patent protection of the present invention is still based on the claims. Equivalent structural changes made in the contents of the description and drawings of the invention shall be included within the protection scope of the present invention.

Claims (7)

1. based on nano onion carbon: the perovskite solar cell of PC ₆₁ BM composite electron transport layer, it is characterized in that, this solar cell adopts positive type structure, comprises the substrate layer that is arranged sequentially from bottom to top, ITO transparent conductive anode layer, hole transport layer, perovskite photoactive layer, composite electron transport layer and metal cathode layer; in, The composite electron transport layer is a solid-state composite layer structure composed of PC ₆₁ BM material and nano-onion carbon material mixed in proportion; The mass percentages of nano-onion carbon material and PC ₆₁ BM material in the composite layer structure are: Nano onion carbon 1% to 10%; PC ₆₁ BM 99% to 90%. 2. The perovskite solar cell according to claim 1, wherein the hole transport layer is a solid film prepared from an aqueous dispersion of PEDOT:PSS, and the aqueous dispersion has a concentration of 0.5 to 2 mg/ml . 3 . The perovskite solar cell according to claim 1 , wherein the perovskite photoactive layer is a CH ₃ NH ₃ PbI ₃ perovskite structure film with a thickness of 240-300 nm. 4 . 4 . The perovskite solar cell according to claim 1 , wherein the composite electron transport layer has a thickness of 5-20 nm. 5 . 5 . The perovskite solar cell according to claim 1 , wherein the nano-onion carbon material is prepared from nano-onion carbon dispersion, the particle size is 20-40 nm, and the concentration is 1-5 mg/ml. 6 . 6. The perovskite solar cell according to claim 1, wherein the metal material of the metal cathode layer is one or more mixtures of Ag, Al, and Cu, and the thickness of the metal cathode layer is in the range of 100～200nm. 7. The perovskite solar cell according to claim 1, wherein the substrate layer material is glass or transparent polymer, and the transparent polymer material is polyethylene, polymethyl methacrylate, polycarbonate One or a mixture of two or more of ester, polyurethane, polyimide, vinyl acetate resin and polyacrylic acid.