A method for preparing a selenium thin film solar cell by microwave-assisted spin coating

Abstract

The application discloses a method for preparing a selenium thin film solar cell by a microwave-assisted spin coating method, and comprises the following steps: preparing a transparent electrode layer, a titanium dioxide dense layer and a titanium dioxide mesoporous layer on a transparent substrate in sequence; placing the prepared layers on a suction disc of a glue uniformizing machine; dropping a selenium solution on the titanium dioxide mesoporous layer for spin coating; obtaining a uniform amorphous selenium thin film on the surface of the titanium dioxide mesoporous layer after solvent evaporation; generating a polycrystalline selenium thin film on the titanium dioxide mesoporous layer after microwave irradiation to obtain a selenium photovoltaic light-absorbing layer; depositing a hole transport layer on the selenium photovoltaic light-absorbing layer; evaporating a metal electrode on the hole transport layer to obtain the selenium thin film solar cell. The method is used to obtain a high-quality trigonal selenium thin film with a single phase, large crystal grains and dense arrangement by controlling microwave irradiation power and time, so that the device performance of the selenium-based solar cell is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of selenium-based solar cell, in particular to a method for preparing selenium thin film solar cell by microwave-assisted spin coating. BACKGROUND

[0002] In the field of semiconductor, the triclinic selenium has important application value in the field of optoelectronics due to its excellent photoelectric properties. As an important application of selenium, the selenium-based solar cell with triclinic selenium thin film as an absorption layer has the advantages of high absorption coefficient, low cost, good stability, green and non-toxic, and suitable band gap (~1.9eV), which makes it have broad application prospects in single-junction indoor photovoltaic and stacked photovoltaic device top cell.

[0003] When the amorphous semiconductor thin film is annealed at the general annealing temperature point of semiconductor (generally 85% of the melting point temperature of the semiconductor), a crystalline uniform polycrystalline semiconductor thin film can be obtained. However, due to the large lattice flexibility of the one-dimensional chain structure of selenium, it is difficult to make the bond angle of the one-dimensional chain selenium reach the ideal bond angle value of the crystal selenium even if the annealing is performed for a long time at 85% of the melting point temperature as the annealing temperature point, resulting in the occurrence of dihedral angle defects, thereby reducing the band gap and causing impurity states in the band gap. At the same time, long-time hot plate annealing is easy to cause the selenium chain to break in the annealing process and form dangling bonds in the lattice, increasing the defects in the lattice. In addition, the existence of temperature gradient in the lattice during the hot plate annealing is also easy to cause the difference in crystallinity in the selenium thin film, affecting the quality of the selenium thin film and ultimately affecting the device performance of the solar cell prepared by using the selenium thin film. SUMMARY

[0004] The purpose of the present application is to provide a method for preparing a selenium thin film solar cell by microwave-assisted spin coating, which can obtain a high-quality triclinic selenium thin film with single phase, large crystalline grains and dense arrangement by controlling the microwave irradiation power and time, thereby improving the device performance of the selenium-based solar cell.

[0005] To achieve the above-mentioned purpose, the present application provides a method for preparing a selenium thin film solar cell by microwave-assisted spin coating, comprising the following steps,

[0006] S1. Preparing a transparent electrode layer, a dense titanium dioxide layer and a mesoporous titanium dioxide layer on a transparent substrate in sequence, and placing the prepared substrate on the suction disc of a glue uniformizer. Then, drop the selenium solution on the mesoporous titanium dioxide layer, and spin at a speed of 1000-3000 rpm for 30-60 s. After the solvent is volatilized, a uniform amorphous selenium thin film is obtained on the surface of the mesoporous titanium dioxide layer.

[0007] S2, the amorphous selenium thin film obtained in S1 is subjected to microwave irradiation, the microwave frequency of the microwave irradiation is 2450 MHz, the irradiation power is 150-750 W, and the irradiation time is 30-500 s, and the amorphous selenium thin film generates a polycrystalline selenium thin film on the titanium dioxide mesoporous layer to obtain a selenium photovoltaic light absorption layer;

[0008] S3, depositing MoO 3-x or polybis(4-phenyl)(2,4,6-trimethylphenyl)amine to obtain a hole transport layer;

[0009] S4, evaporating a metal electrode on the hole transport layer in S3 to obtain a selenium thin film solar cell.

[0010] Preferably, in S1, the preparation step of the titanium dioxide dense layer is prepared by using a titanium bis(acetylacetonate) diisopropylate ethanol solution by spin coating, and after spin coating, preheating at a hot table of 50-200℃ for 5-15 min, then increasing the hot table temperature to 400-500℃, and keeping for 30-60 min to obtain the titanium dioxide dense layer.

[0011] Preferably, in S1, the preparation step of the titanium dioxide mesoporous layer is prepared by using a titanium dioxide slurry ethanol solution by spin coating, and after spin coating, transferring to a hot table of 150-200℃ for preheating for 5-15 min, then increasing the hot table temperature to 400-500℃, and keeping for 30-60 min to obtain the titanium dioxide mesoporous layer.

[0012] Preferably, in S1, the thickness of the titanium dioxide dense layer is 50-100 nm, the thickness of the titanium dioxide mesoporous layer is 100-300 nm, and both the titanium dioxide dense layer and the titanium dioxide mesoporous layer are in an anatase phase.

[0013] Preferably, in S4, the metal electrode is one or more of Mo, Cu, Au, Ag, and Al, and the thickness of the metal electrode is 80-200 nm.

[0014] The selenium thin film solar cell prepared by the above-mentioned microwave-assisted spin coating method.

[0015] The structure of the above-mentioned selenium thin film solar cell is: transparent substrate / transparent electrode layer / electron transport layer / seelenium photovoltaic light absorption layer / hole transport layer / metal electrode.

[0016] Preferably, the electron transport layer is a titanium dioxide dense layer and a titanium dioxide mesoporous layer.

[0017] Preferably, the transparent electrode layer is one or more of indium tin oxide (ITO) and fluorine tin oxide (FTO).

[0018] Preferably, the volume ratio of bis(acetylacetonato) titanium diisopropoxide to ethanol is 1:5-20.

[0019] Preferably, the average particle size of the titanium dioxide particles in the titanium dioxide slurry ranges from 15-40 nm, and the mass ratio of the titanium dioxide slurry to ethanol is 1:2-10.

[0020] Preferably, the concentration of the selenium solution is 50-500 mg / mL, the solvent in the selenium solution is hydrazine and ethylenediamine in a volume ratio of 1:1-10, and the solute is particulate or powdered elemental selenium with a purity of 99% or higher.

[0021] Therefore, the beneficial effects of the present application are:

[0022] 1. Microwaves have strong penetrating power. Compared with traditional hot table annealing, the temperature gradient is different. Using microwave irradiation of selenium film can make all selenium chains in the selenium film vibrate and rearrange simultaneously under the action of microwaves, and a selenium film with better uniformity can be obtained. By adjusting the microwave irradiation power and irradiation time, large-grained selenium film can be prepared, and the density of the selenium film can be better controlled.

[0023] 2. The present application uses a spin coating process combined with microwave annealing to prepare polycrystalline selenium film. Microwave annealing can be performed without removing the film from the film applicator, which can achieve high-quality, uniform, and large-area preparation of selenium film, effectively simplifying the complexity of selenium-based solar cell preparation and improving the device performance of selenium-based solar cells.

[0024] 3. The spin coating method can be performed in a closed inert gas or closed air environment, which has the advantage of a simple preparation environment compared to the vacuum environment of thermal evaporation.

[0025] The technical solutions of the present application will be further described in detail below with the aid of the accompanying drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is the XRD pattern of the selenium film in Example 1 of the present application.

[0027] Figure 2 is the SEM pattern of the selenium film in Example 1 of the present application. DETAILED DESCRIPTION

[0028] The technical solutions of the present application will be further described in detail below with the aid of the accompanying drawings and examples.

[0029] The present application can be explained in more detail by the following examples, and the purpose of disclosing the present application is to protect all variations and improvements within the scope of the present application, and the present application is not limited to the following examples.

[0030] Example 1

[0031] S1, on the cleaned blank transparent substrate, a transparent electrode layer, a titanium dioxide dense layer and a titanium dioxide mesoporous layer are prepared in sequence, after preparation, it is placed on the suction disc of the glue machine to be fixed by air suction, a selenium solution with a concentration of 280 mg / mL is added on the titanium dioxide mesoporous layer, the rotation speed is 1000 rpm, the time is 50 s, and after the solvent is volatilized, a uniform amorphous selenium film is obtained on the surface of the titanium dioxide mesoporous layer.

[0032] In S1, the preparation step of the titanium dioxide dense layer is as follows: an ethanol solution of bis(acetylacetonato) titanium diisopropylate is used to prepare the titanium dioxide dense layer on the transparent electrode layer by spin coating, the spin coating speed is 4000 rpm, the time is 50 s, after spin coating, the hot table is preheated at 150℃ for 12 min, the hot table temperature is increased to 450℃, and the temperature is kept for 45 min to obtain a titanium dioxide dense layer with a thickness of 60 nm.

[0033] In S1, the preparation step of the titanium dioxide mesoporous layer is as follows: an ethanol solution of titanium dioxide slurry is used to prepare the titanium dioxide mesoporous layer on the titanium dioxide dense layer by spin coating, the particle size of titanium dioxide particles in the titanium dioxide slurry is 30 nm, the spin coating speed is 5000 rpm, and the spin coating time is 55 s. After spin coating, it is transferred to a hot table preheated at 150℃ for 12 min, the hot table temperature is increased to 450℃, and the temperature is kept for 45 min to obtain a titanium dioxide mesoporous layer with a thickness of 100 nm.

[0034] The volume ratio of bis(acetylacetonato) titanium diisopropylate to ethanol is 1:10, and the mass ratio of titanium dioxide slurry to ethanol is 1:8.

[0035] The solvent in the selenium solution is hydrazine and ethylenediamine with a volume ratio of 1:5, and the solute is granular selenium with a purity of more than 99%.

[0036] S2, the surface of the amorphous selenium film obtained in S1 is irradiated by microwave, the microwave frequency of microwave irradiation is 2450 MHz, the irradiation power is 450 W, and the irradiation time is 120 s. After the amorphous selenium is irradiated by microwave, a polycrystalline selenium film is generated on the titanium dioxide mesoporous layer to obtain a selenium photovoltaic light absorption layer.

[0037] The XRD and scanning electron microscope images of the polycrystalline selenium film obtained by the above steps are shown in Figure 1 and Figure 2 .

[0038] S3, a poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine) is deposited on the selenium photovoltaic light absorption layer in S2 to obtain a hole transport layer.

[0039] S4, evaporating Au electrode on the hole transport layer in S3, the thickness of Au electrode is 80 nm, obtaining selenium thin film solar cell. The efficiency of the obtained selenium thin film solar cell under AM1.5G standard light is 5.1%, wherein, the open circuit voltage is 0.85V, the short circuit current is 10.9mA cm -2 , the fill factor is 55%, and the effective electrode area is 0.09cm -2 .

[0040] Example 2

[0041] S1, sequentially preparing transparent electrode layer, titanium dioxide dense layer and titanium dioxide mesoporous layer on the cleaned blank transparent substrate, after preparation, placing it on the suction disc of the glue uniformizing machine, vacuumizing and fixing, dropping selenium solution with concentration of 350mg / mL on the titanium dioxide mesoporous layer, when spinning, the speed is 2000rpm, and the time is 35s, after solvent volatilization, obtaining uniform spread amorphous selenium film on the surface of the titanium dioxide mesoporous layer.

[0042] In S1, the preparation steps of the titanium dioxide dense layer are as follows: using bis(acetylacetonato) titanium diisopropylate ethanol solution to prepare on the transparent electrode layer by spin coating, the spin coating speed is 3000rpm, and the time is 30s, after spin coating, preheating at 170℃ for 8min, increasing the temperature of the hot table to 500℃, and keeping warm for 60min, obtaining titanium dioxide dense layer with thickness of 80nm.

[0043] In S1, the preparation steps of the titanium dioxide mesoporous layer are as follows: using titanium dioxide slurry ethanol solution to prepare on the titanium dioxide dense layer by spin coating, the particle size of titanium dioxide particles in the titanium dioxide slurry is 18nm, the spin coating speed is 4500rpm, and the time is 40s. After spin coating, transferring to the hot table at 170℃ for preheating for 8min, increasing the temperature of the hot table to 500℃, keeping warm for 60min, and cooling to obtain titanium dioxide mesoporous layer with thickness of 120nm.

[0044] The volume ratio of bis(acetylacetonato) titanium diisopropylate to ethanol is 1:7, and the mass ratio of titanium dioxide slurry to ethanol is 1:6.5.

[0045] The solvent in the selenium solution is hydrazine and ethylenediamine with volume ratio of 1:8, and the solute is selenium element in powder form, and the purity of the selenium element is more than 99%.

[0046] S2, microwave irradiating the surface of the amorphous selenium film obtained in S1, the microwave frequency of microwave irradiation is 2450MHz, the irradiation power is 550W, and the irradiation time is 90s. After microwave irradiation of amorphous selenium, polycrystalline selenium film is generated on the titanium dioxide mesoporous layer, obtaining selenium photovoltaic light absorption layer.

[0047] S3, depositing MoO3-x to obtain a hole transport layer.

[0048] S4, evaporating Cu electrode on the hole transport layer in S3, thickness of the Cu electrode is 100 nm, to obtain a selenium thin film solar cell. The efficiency of the obtained selenium thin film solar cell under AM1.5G standard light is 4.18%, wherein, the open circuit voltage is 0.82V, the short circuit current is 9.7mA cm -2 , the fill factor is 52.5%, and the effective electrode area is 0.09cm -2 .

[0049] Finally, it should be noted that: the above examples are only to illustrate the technical solutions of the present application rather than limit them, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that: it can still be modified or equivalent to replace the technical solutions of the present application, and these modifications or equivalent to replace the technical solutions of the modified spirit and scope of the present application cannot be made.

Claims

1. A method for fabricating a selenium thin film solar cell by microwave assisted spin coating, characterized in that: The method comprises the following steps of: S1, sequentially preparing a transparent electrode layer, a titanium dioxide dense layer and a titanium dioxide mesoporous layer on a transparent substrate, placing the prepared layers on a suction disc of a glue uniformizing machine, dropping a selenium solution on the titanium dioxide mesoporous layer, and rotating at a speed of 1000-3000 rpm for 30-60 s, so that a uniform amorphous selenium film is obtained on the surface of the titanium dioxide mesoporous layer after the solvent is volatilized; In S1, the titanium dioxide dense layer is prepared by using a titanium bis(acetylacetonate) diisopropylate ethanol solution and a spin coating method, preheating at 50-200 DEG C on a hot table for 5-15 min, then increasing the temperature of the hot table to 400-500 DEG C, and keeping the temperature for 30-60 min to obtain the titanium dioxide dense layer; In S1, the titanium dioxide mesoporous layer is prepared by using a titanium dioxide slurry ethanol solution and a spin coating method, transferring to a hot table preheated at 150-200 DEG C for 5-15 min, then increasing the temperature of the hot table to 400-500 DEG C, and keeping the temperature for 30-60 min to obtain the titanium dioxide mesoporous layer; In S1, the thickness of the titanium dioxide dense layer is 50-100 nm, and the thickness of the titanium dioxide mesoporous layer is 100-300 nm; In S1, the concentration of the selenium solution is 50-500 mg / mL, the solvent in the selenium solution is hydrazine and ethylenediamine in a volume ratio of 1:1-10, the solute is granular or powdered selenium, and the purity of the selenium is more than 99%; S2, microwave irradiating the amorphous selenium film obtained in S1, the microwave frequency of the microwave irradiation is 2450 MHz, the irradiation power is 150-750 W, and the irradiation time is 30-500 s, so that a polycrystalline selenium film is generated on the titanium dioxide mesoporous layer to obtain a selenium photovoltaic light-absorbing layer; S3, depositing MoO on the selenium photovoltaic light absorbing layer in S2 3-x or polybis(4-phenyl)(2,4,6-trimethylphenyl)amine, to obtain a hole transport layer; S4, evaporating a metal electrode on the hole transport layer in S3 to obtain a selenium thin film solar cell; In S4, the metal electrode is one or more of Mo, Cu, Au, Ag and Al, and the thickness of the metal electrode is 80-200 nm; The structure of the selenium thin film solar cell is: transparent substrate / transparent electrode layer / electron transport layer / seelenium photovoltaic light-absorbing layer / hole transport layer / metal electrode.

2. The method for fabricating a selenium thin film solar cell by microwave assisted spin coating method according to claim 1, characterized in that: The electron transport layer is the titanium dioxide dense layer and the titanium dioxide mesoporous layer.

3. The selenium thin film solar cell prepared by the method of any one of claims 1-2.

Images