CN110635043B - Organic hole transport layer, perovskite solar cell and preparation method thereof - Google Patents

Abstract

The invention provides an organic hole transport layer, a perovskite solar cell and a preparation method thereof. The prepared solar cell device structure includes from bottom to top: a substrate, an anode, a hole transport layer, a photoactive layer, and an electron transport layer , cathode modification layer and cathode; wherein the hole transport layer is prepared into an organic small molecule monomer BTCV by organic chemical synthesis, by dissolving it in an organic solvent, and then spin-coating on a glass substrate substrate, using high temperature annealing or Ultraviolet lamp irradiation causes polymerization and crosslinking reaction to occur to form a network hole transport layer, which is used to transport holes and improve the photoelectric conversion efficiency of the battery. The photoelectric conversion efficiency can reach 17.58%; the organic small molecule monomer BTCV synthesis steps are simple, The low cost, high yield and stable properties allow for commercial production, which greatly reduces the cost of perovskite solar cells. The organic hole transport material, small molecule monomer BTCV, can also be applied to fabricate other photovoltaic devices.

Description

Organic hole transport layer, perovskite solar cell and preparation method thereof

technical field

The invention belongs to the technical field of semiconductor devices, and particularly relates to an organic hole transport layer, a perovskite solar cell and a preparation method thereof.

Background technique

Organometallic halide perovskite-based solar cells (pero-SCs) are one of the most promising candidates for future energy power generation. The photoelectric conversion efficiency (PCE) of ore solar cells has exceeded 20%. Planar perovskite solar cells combine low cost and layer-by-layer processing technology due to their low-temperature solution processing.

The earliest structure of this type of battery device is: glass/indium tin oxide (ITO)/PEDOT:PSS/CH ₃ NH ₃ PbI ₃ /C ₆₀ /BCP/Al, PEDOT:PSS is a hole transport layer, although PEDOT:PSS As an interface layer, it is widely used in organic electronic devices, but its acidity and easy water absorption affect the performance of the device, and the high price of PEDOT:PSS also limits its industrialization prospects in planar perovskite solar cells. Malinkiewicz et al. used poly-TPD as the hole transport layer. The high LUMO energy level (-2.4eV) can block electron transport to the anode. However, some polymer hole transport materials are used in planar perovskite solar cells. The cost of poly-TPD is also relatively expensive. In the preparation of planar perovskite solar cells, it is required that the polymer hole transport in the lower layer must be able to resist the dissolution of the polar precursor solution. Therefore, a stable hole transport is sought. Layer materials are crucial for the fabrication of planar perovskite solar cells.

Therefore, it is necessary to provide an improved technical solution for the deficiencies of the above-mentioned prior art.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an organic hole transport layer, a perovskite solar cell and a preparation method thereof, so as to reduce the cost of the planar perovskite solar cell and improve the energy conversion efficiency of the cell.

In order to achieve the above object, the present invention provides the following technical solutions:

A preparation method of a perovskite solar cell, the preparation method comprises the following steps:

Step S1, cleaning and drying the glass substrate coated with the anode material, and then performing ultraviolet light cleaning treatment to obtain a pretreated substrate substrate;

Step S2, depositing a polymer of BTCV on the pretreated substrate to form an organic hole transport layer;

Step S3, spin-coating a perovskite precursor solution on the organic hole transport layer, then adding a chlorobenzene solvent to continue spin-coating, and annealing at 90-110° C. to obtain a perovskite crystal thin film, that is, a photoactive layer;

Step S4, spin-coating the chlorobenzene solution of PCBM on the photoactive layer to form an electron transport layer;

Step S5, spin-coating a methanol solution of PDINO on the electron transport layer to form a cathode modification layer;

In step S6, the cathode material is evaporated onto the cathode modification layer by thermal evaporation under vacuum to obtain a perovskite solar cell.

In the above-mentioned preparation method of a perovskite solar cell, preferably, the specific steps of forming the organic hole transport layer in the step S2 include:

Step s21, placing the organic small molecule monomer BTCV in N,N-dimethylformamide, fully stirring and dissolving to prepare a BTCV solution;

Step s22, after filtering the BTCV solution, spin-coating on a glue spinner for 30-60 seconds, and then performing curing treatment to form a cross-linked organic hole transport layer;

Preferably, the concentration of the BTCV solution is 0.5-1.5 mg mL ⁻¹ ;

Preferably, the thickness of the organic hole transport layer is 10-20 nm.

In the above-mentioned preparation method of a perovskite solar cell, preferably, in step s22, the curing treatment is annealing at 130-170° C. for 8-12 minutes on a hot stage or irradiating with an ultraviolet lamp for 25-35 minutes.

In the above-mentioned preparation method of perovskite solar cell, preferably, the specific preparation method of the organic small molecule monomer BTCV includes:

After heating 2-bromocarbazole, 4-vinylbenzyl chloride and acetone to 60-90°C, add sodium hydroxide and tetrabutylammonium hydrogen sulfate, stir, filter, spin dry the solvent, and obtain a white solid by column chromatography 9-(4-vinylbenzyl)-2-bromocarbazole;

Add 9-(4-vinylbenzyl)-2-bromocarbazole, 5,5'-bis(trimethyltin)-2,2'-bisthiophene, tetrakistriphenylphosphine palladium, and freshly distilled toluene into the container 2-4 times, heat to 110-130°C under argon atmosphere for reaction, cool to room temperature after the reaction, spin dry the solvent and add saturated potassium fluoride solution, extract with dichloromethane, spin dry the solvent After column chromatography, yellow solid 5,5'-bis[9-(4-vinylbenzyl)-2-carbazolyl]-2,2'-bisthiophene, ie, the organic small molecule BTCV, was obtained.

In the above-mentioned preparation method of a perovskite solar cell, preferably, the molar ratio of the 2-bromocarbazole to the 4-vinylbenzyl chloride is 1:1.

In the above-mentioned preparation method of perovskite solar cell, preferably, the 9-(4-vinylbenzyl)-2-bromocarbazole and the 5,5'-bis(trimethyltin)-2 , The molar ratio of 2'-bisthiophene is 2:1.

In the above-mentioned preparation method of perovskite solar cell, preferably, in step S3, the preparation method of the perovskite precursor solution includes:

Dissolving donor A in an organic solvent, then adding donor B, and stirring to obtain a perovskite precursor solution;

Wherein, described donor A is lead chloride, lead bromide, lead acetate, lead thiocyanate or lead iodide;

Described donor B is methylammonium chloride, formamidine hydrochloride, methylammonium bromide, formamidine hydrobromide, methylammonium iodide or formamidine hydroiodide;

Preferably, the organic solvent is dimethylformamide, dimethylsulfoxide or γ-butyrolactone.

In the above-mentioned preparation method of a perovskite solar cell, preferably, the molar ratio of the donor A to the donor B is 1:(1-5);

Preferably, the total mass percentage of the donor A and the donor B in the organic solvent is 35-50 wt %.

A perovskite solar cell prepared by the preparation method of the perovskite solar cell.

An application of an organic hole transport layer in preparing a photovoltaic device; the organic hole transport layer is prepared by the preparation method of the perovskite solar cell.

Compared with the closest prior art, the technical solution provided by the present invention has the following excellent effects:

The invention adopts the cross-linking reaction of organic small molecular monomer substances to form a network hole transport layer to replace the existing hole transport layer, and prepares a high-efficiency planar perovskite solar cell, which mainly has the following excellent effects:

1. The performance of the perovskite solar cell is improved; the present invention uses the polymer material obtained after the cross-linking reaction of the organic small molecule monomer as the hole transport layer of the perovskite solar cell, which has good film-forming properties and light transmittance. It has the characteristics of high HOMO energy level and high LUMO energy level matching the energy level of perovskite. The hole transport layer can not only transport holes but also block electrons well, reducing the interface The probability of occurrence of electronic coupling or charge recombination, thereby improving the open-circuit voltage, short-circuit current density and filling factor of the perovskite solar cell, and finally realizing the improvement of the photoelectric conversion efficiency of the perovskite solar cell. The photoelectric conversion efficiency of the mass junction perovskite cell reaches 17.58%.

2. The cost of the perovskite solar cell is reduced; the present invention prepares a solution of an organic small molecule monomer BTCV and spin-coats it directly on the anode substrate glass, and then prepares a hole transport layer after cross-linking, and the operation is simple, Large-area thin film fabrication can be achieved.

At the same time, the synthetic steps of the organic small-molecule monomer BTCV are simple, low-cost, high-yield and stable in properties, which can be commercialized and greatly reduce the cost of perovskite solar cells.

Compared with the existing hole transport material, the perovskite solar cell prepared by using the organic small-molecule monomer polymer material as the hole transport layer of the present invention has better performance and lower cost.

Description of drawings

The accompanying drawings forming a part of the present application are used to provide further understanding of the present invention, and the exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. in:

1 is a schematic structural diagram of a perovskite solar cell according to Example 1 of the present invention;

2 is a flow chart of preparing a perovskite solar cell according to an embodiment of the present invention;

Fig. 3 is the molecular structural formula of the hole transport layer material BTCV according to the embodiment of the present invention;

Fig. 4 is the mass spectrum of the hole transport layer material BTCV according to the embodiment of the present invention;

5 is a current density-voltage characteristic curve (forward and reverse scan) of the perovskite solar cells prepared in Example 1 and Comparative Example 1 of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art fall within the protection scope of the present invention.

The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments. It should be noted that the embodiments of the present invention and the features of the embodiments may be combined with each other under the condition of no conflict.

The perovskite solar cell provided by the present invention is aimed at the hole transport material PEDOT:PSS (3,4-ethylenedioxythiophene monomer-polystyrene sulfonate polymerization) commonly used in current planar perovskite solar cells In order to reduce the cost of the planar perovskite solar cell and improve the energy conversion efficiency of the cell, a planar perovskite solar cell based on an organic cross-linked hole transport layer and a preparation method thereof are provided.

The solar cell device structure of the present invention includes from bottom to top: a substrate, an anode, a hole transport layer, a photoactive layer, an electron transport layer, a cathode modification layer and a cathode; wherein the hole transport layer is made of organic materials with a thickness of about 10-20 nm. The hole transport layer material is prepared into an organic small molecule monomer BTCV by an organic chemical synthesis method. It is dissolved in an organic solvent, and then spin-coated on a glass substrate. High temperature annealing or ultraviolet light irradiation is used to make it happen. Polymerization and cross-linking reaction to form a network hole transport layer, which is used to block electrons, transport holes, inhibit the close contact between the anode and the photoactive layer, reduce the probability of carrier recombination at the interface, and improve the photoelectric conversion efficiency of the battery . The organic small molecule monomer BTCV has simple synthesis steps, low cost, high yield and stable properties, which can be commercialized and greatly reduce the cost of perovskite solar cells.

The organic hole transport material small-molecule monomer BTCV prepared in the present invention can also be applied to prepare other photovoltaic devices.

A preparation method of a perovskite solar cell provided by the present invention comprises the following steps:

A preparation method of a perovskite solar cell, comprising the following steps:

In step S1, the glass substrate plated with the anode material is cleaned and blown dry, and then subjected to ultraviolet light cleaning treatment to obtain a pretreated substrate.

Preferably, the anode material is indium tin oxide (ITO) or fluorine-doped tin oxide (FTO) for collecting holes.

Step S2, depositing a BTCV polymer on the pretreated substrate to form an organic hole transport layer. Preferably, the thickness of the organic hole transport layer is 10-20 nm (eg 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm).

Preferably, the specific steps of forming the organic hole transport layer in step S2 include:

Step s21, placing the organic small molecular monomer BTCV in N,N-dimethylformamide, fully stirring and dissolving to prepare a BTCV solution; preferably, the concentration of the BTCV solution is 0.5-1.5 mg mL ^-1 (such as 0.6 mg mL ^-1 , 0.7 mg mL ^-1 , 0.8 mg mL ^-1 , 0.9 mg mL ^-1 , 1.0 mg mL ^-1 , 1.1 mg mL ^-1 , 1.2 mg mL ^-1 , 1.3 mg mL ^-1 , 1.4 mg mL-1 ^-1 );

In step s22, after filtering the BTCV solution, spin-coat on a glue spinner for 30-60 seconds, and then perform curing treatment to form a cross-linked organic hole transport layer; in step s22, curing treatment is performed on a hot stage at 130-170° C. (eg 135°C, 138°C, 140°C, 145°C, 148°C, 150°C, 155°C, 158°C, 160°C, 165°C, 168°C) Annealing for 8-12min (eg 9min, 10min, 11min, 12min) or Use ultraviolet light for 25-35min (such as 26min, 27min, 28min, 29min, 30min, 31min, 32min, 33min, 34min);

Preferably, the specific preparation method of the organic small molecule monomer BTCV comprises:

Heat 2-bromocarbazole, 4-vinylbenzyl chloride and acetone to 60-90°C (e.g. 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C , 80°C, 82°C, 84°C, 86°C, 88°C, 90°C), then add sodium hydroxide and tetrabutylammonium hydrogen sulfate, filter after stirring, and then spin off the solvent to obtain a white solid 9-( 4-vinylbenzyl)-2-bromocarbazole;

Add 9-(4-vinylbenzyl)-2-bromocarbazole, 5,5'-bis(trimethyltin)-2,2'-bisthiophene, tetrakistriphenylphosphine palladium, and freshly distilled toluene into the container In the middle, after 2-4 times of pumping and ventilation, heat to 110-130°C under argon atmosphere (such as 112°C, 114°C, 116°C, 118°C, 120°C, 122°C, 124°C, 126°C, 128°C, 130 ℃) reaction, cooled to room temperature after the reaction, spin-dried the solvent and added saturated potassium fluoride solution, use dichloromethane extraction, spin-dried the solvent after column chromatography to obtain a yellow solid 5,5'-bis[9-( 4-Vinylbenzyl)-2-carbazolyl]-2,2'-bisthiophene, namely BTCV, an organic small molecule monomer.

Freshly distilled toluene means that ordinary toluene is distilled before use to ensure no water and no impurities.

Preferably, the molar ratio of 2-bromocarbazole to 4-vinylbenzyl chloride is 1:1.

Preferably, the molar ratio of 9-(4-vinylbenzyl)-2-bromocarbazole to 5,5'-bis(trimethyltin)-2,2'-bisthiophene is 2:1.

Step S3, spin-coating the perovskite precursor solution (CH ₃ NH ₃ PbI ₃ ) on the organic hole transport layer, and then adding chlorobenzene solvent to continue the spin-coating, after 90-110 ° C (such as 92 ° C, 94 ° C, 96 ° C) °C, 98 °C, 100 °C, 102 °C, 104 °C, 106 °C, 108 °C, 110 °C) annealing treatment to obtain a perovskite crystal thin film, that is, a photoactive layer;

Preferably, in step S3, the preparation method of the perovskite precursor solution includes:

Dissolving donor A in an organic solvent, then adding donor B, and stirring to obtain a perovskite precursor solution;

Wherein, donor A is lead chloride, lead bromide, lead acetate, lead thiocyanate or lead iodide;

Donor B is methylammonium chloride, formamidine hydrochloride, methylammonium bromide, formamidine hydrobromide, methylammonium iodide or formamidine hydroiodide;

Preferably, the organic solvent is dimethylformamide, dimethylsulfoxide or γ-butyrolactone.

Preferably, the molar ratio of Donor A to Donor B is 1:(1-5) (such as 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4 , 1:4.5, 1:5);

Preferably, the total mass percentage of Donor A and Donor B in the organic solvent is 35-50wt% (such as 36wt%, 37wt%, 38wt%, 39wt%, 40wt%, 41wt%, 42wt%, 43wt% %, 44wt%, 45wt%, 46wt%, 47wt%, 48wt%, 49wt%).

Step S4, spin coating the chlorobenzene solution of PCBM ([6,6]-phenyl-C61-butyric acid methyl ester) on the photoactive layer to form an electron transport layer;

Step S5, spin-coating a methanol solution of PDINO (perylene diimide derivative) on the electron transport layer to form a cathode modification layer;

In step S6, the cathode material is evaporated to the cathode modification layer by thermal evaporation under vacuum to obtain a perovskite solar cell.

Preferably, the cathode material is metal aluminum (Al) or silver (Ag).

The materials, reagents, etc. used in this example and the comparative example are all commercially available products.

Example 1

As shown in FIG. 1 and FIG. 2 , the preparation method of a perovskite solar cell provided in this embodiment includes the following steps:

Step S1, the anode glass substrate substrate sputtered with indium tin oxide (ITO) is ultrasonically washed twice with detergent, deionized water, acetone, and isopropanol in turn, for 10 to 15 minutes each time, and blowing with nitrogen after the cleaning is completed. Dry. The blown-dried ITO glass substrate was placed in an ultraviolet light cleaning surface treatment equipment for 20 minutes to obtain a pretreated substrate.

Step S2, depositing a BTCV polymer with a thickness of 20 nm on the pretreated substrate to form an organic hole transport layer. The specific steps mainly include two steps.

Preparation of Organic Small Molecular Monomer BTCV

Step s21, add 0.588g (2.4mmol) of 2-bromocarbazole, 0.364g (2.4mmol) of 4-vinylbenzyl chloride and 20ml of acetone into a 100ml two-necked flask, heat to 75°C, and then add 0.110g (2.8g) of sodium hydroxide. mmol) and tetrabutylammonium hydrogen sulfate 0.02g (0.0589mmol), stirred for 4h and filtered, and then spin-dried the solvent to obtain a white solid 9-(4-vinylbenzyl)-2-bromocarbazole 0.5g ( 1.38 mmol);

0.5 g (1.38 mmol) of 9-(4-vinylbenzyl)-2-bromocarbazole, 0.0339 g (0.690 mmol) of 5,5'-bis(trimethyltin)-2,2'-bisthiophene, 0.05 g (0.04 mmol) of palladium tetrakistriphenylphosphine and 50 ml of freshly distilled toluene were added to the two-necked flask. After 3 times of pumping and ventilation, they were heated to 130° C. under an argon atmosphere and reacted for 12 h. After the reaction was completed, the reaction was cooled to room temperature and the solvent was spin-dried. Saturated potassium fluoride solution was added and extracted with dichloromethane (30ml×3), that is, 30ml of dichloromethane was used for each extraction, a total of 3 times of extraction, and the solvent was spin-dried and column chromatography was performed to obtain a yellow solid 5,5'- Bis[9-(4-vinylbenzyl)-2-carbazolyl]-2,2'-bisthiophene 0.11g (0.151mmol), namely the organic small molecule BTCV, the molecular structure of the organic small molecule BTCV As shown in Figure 3, the mass spectrum of BTCV is shown in Figure 4.

The synthetic route of small molecular monomer BTCV is as follows:

Cross-linking reaction of BTCV polymers

Step s22, placing the organic small molecular monomer BTCV in N,N-dimethylformamide (DMF), fully stirring and dissolving, and preparing a BTCV solution of 1 mg mL ^-1 ;

Step s23, after filtering the BTCV solution through a 0.45-micron filter head, spin-coating at a speed of 4000 r/min on a glue spinner for 60 seconds, and then annealing at 150° C. for 10 minutes on a hot stage to cause a cross-linking reaction to form a cross-linked network. Organic hole transport layer with a thickness of 20 nm.

Step S3, PbI ₂ and CH ₃ NH ₃ I were dissolved in N,N-dimethylformamide (DMF) solution in a molar ratio of 1:2, and the total mass fraction of PbI ₂ and CH ₃ NH ₃ I in the solution was 40wt %, stirring at room temperature to obtain a perovskite precursor solution (CH ₃ NH ₃ PbI ₃ ). The perovskite precursor solution was spin-coated on the organic hole transport layer at a speed of 5000 r/min, and then the anti-solvent chlorobenzene solvent was added dropwise during rotation for 4.5 s to promote the rapid crystallization of the perovskite layer, and then transferred to the air for 100 s. ℃ thermal annealing treatment for 10min to obtain a black perovskite layer with a thickness of 300nm, that is, a photoactive layer.

Step S4, spin-coating a chlorobenzene solution of PCBM ([6,6]-phenyl-C61-butyric acid methyl ester) with a concentration of 20 mg mL ^-1 on the photoactive layer at a rotational speed of 1500 r/min for 30- 60 s on the above perovskite layer to obtain an electron transport layer with a thickness of 20 nm.

Step S5, spin-coating a methanol solution of 1 mg mL ^-1 of PDINO (perylene diimide derivative) at a rotational speed of 3000 r/min for 30-60 s on the perovskite layer covered with PCBM to obtain a 15 nm-thick Cathode modification layer.

Step S6, finally, vacuum evaporation of Al with a thickness of 100 nm is performed under 5×10 ^-5 Pa as a metal electrode to obtain a perovskite solar cell.

As shown in FIG. 1 , the structure of the device obtained in the embodiment of the present invention is ITO/BTCV/CH ₃ NH ₃ PbI ₃ /PCBM/PDINO/Al, and the performance of the device is shown in FIG. 5 . Under optimal conditions, at 100mW The open-circuit voltage was 1.00V, the short-circuit current was 21.70mA cm- ² , the fill factor was 81%, and the photoelectric conversion efficiency was 17.58% under the simulated sunlight of cm ^-2 .

Example 2

The preparation method of a perovskite solar cell provided in this embodiment includes the following steps:

Step S1, the anode glass substrate substrate sputtered with indium tin oxide (ITO) is ultrasonically washed twice with detergent, deionized water, acetone, and isopropanol in turn, for 10 to 15 minutes each time, and blowing with nitrogen after the cleaning is completed. Dry. The blown-dried ITO glass substrate was placed in an ultraviolet light cleaning surface treatment equipment for 20 minutes to obtain a pretreated substrate.

Step S2, depositing a BTCV polymer with a thickness of 10 nm on the pretreated substrate to form an organic hole transport layer. The specific steps mainly include two steps.

Preparation of Organic Small Molecular Monomer BTCV

Step s21, add 0.588g (2.4mmol) of 2-bromocarbazole, 0.364g (2.4mmol) of 4-vinylbenzyl chloride and 20ml of acetone into a 100ml two-necked flask, heat to 75°C, and then add 0.110g (2.8g) of sodium hydroxide. mmol) and tetrabutylammonium hydrogen sulfate 0.02g (0.0589mmol), stirred for 4h and filtered, and then spin-dried the solvent to obtain a white solid 9-(4-vinylbenzyl)-2-bromocarbazole 0.5g ( 1.38 mmol);

0.5 g (1.38 mmol) of 9-(4-vinylbenzyl)-2-bromocarbazole, 0.0339 g (0.690 mmol) of 5,5'-bis(trimethyltin)-2,2'-bisthiophene, 0.05 g (0.04 mmol) of palladium tetrakistriphenylphosphine and 50 ml of freshly distilled toluene were added to the two-necked flask. After 3 times of pumping and ventilation, they were heated to 130° C. under an argon atmosphere and reacted for 12 h. After the reaction was completed, the reaction was cooled to room temperature and the solvent was spin-dried. Saturated potassium fluoride solution was added, extracted with dichloromethane (30ml×3), that is, extracted three times with 30ml of dichloromethane each time, the solvent was spin-dried and column chromatography was performed to obtain a yellow solid 5,5'-bis[9 0.11 g (0.151 mmol) of -(4-vinylbenzyl)-2-carbazolyl]-2,2'-bisthiophene, which is an organic small molecule BTCV, as shown in FIG. 3 .

Cross-linking reaction of BTCV polymers

Step s22, placing the organic small molecular monomer BTCV in N,N-dimethylformamide (DMF), fully stirring and dissolving, and preparing a BTCV solution of 1 mg mL ^-1 ;

Step s23, after filtering the BTCV solution through a 0.45-micron filter head, spin-coating at 4000 r/min for 30 seconds on a glue spinner, and then irradiating it under an ultraviolet lamp for 30 minutes to cause a cross-linking reaction to form a cross-linked organic hole transport layer , with a thickness of 10 nm.

Step S3, PbI ₂ and CH ₃ NH ₃ I were dissolved in N,N-dimethylformamide (DMF) solution in a molar ratio of 1:1, and the total mass fraction of PbI ₂ and CH ₃ NH ₃ I in the solution was 40wt %, stirring at room temperature to obtain a perovskite precursor solution (CH ₃ NH ₃ PbI ₃ ). The perovskite precursor solution was spin-coated on the organic hole transport layer at a speed of 5000 r/min, and then the anti-solvent chlorobenzene solvent was added dropwise during rotation for 4.5 s to promote the rapid crystallization of the perovskite layer, and then transferred to the air for 100 s. ℃ thermal annealing treatment for 10min to obtain a black perovskite layer with a thickness of 300nm, that is, a photoactive layer.

Step S4, spin-coating the chlorobenzene solution of PCBM ([6,6]-phenyl-C61-butyric acid methyl ester) with a concentration of 20 mg mL ^-1 on the perovskite layer at a rotational speed of 1500 r/min for 30-60 s , an electron transport layer with a thickness of 20 nm was obtained.

Step S5, spin-coating a methanol solution of 1 mg mL ^-1 of PDINO (perylene diimide derivative) at a rotational speed of 3000 r/min for 30-60 s on the perovskite layer covered with PCBM to obtain a 15 nm-thick Cathode modification layer.

Step S6, finally, vacuum evaporation of Al with a thickness of 100 nm below 5×10 ^-5 Pa is used as a metal electrode to obtain a perovskite solar cell.

The structure of the device obtained in the embodiment of the present invention is ITO/BTCV/CH ₃ NH ₃ PbI ₃ /PCBM/PDINO/Al, and the performance of the device is tested. Under optimal conditions, the open circuit voltage is irradiated by 100mW cm ^-2 of simulated sunlight. is 1.00V, the short-circuit current is 21.39mA cm ^-2 , the fill factor is 79.95%, and the photoelectric conversion efficiency is 17.10%.

Example 3

The preparation method of a perovskite solar cell provided in this embodiment includes the following steps:

Step S1, the anode glass substrate substrate sputtered with indium tin oxide (ITO) is ultrasonically washed twice with detergent, deionized water, acetone, and isopropanol in turn, for 10 to 15 minutes each time, and blowing with nitrogen after the cleaning is completed. Dry. The blown-dried ITO glass substrate was placed in an ultraviolet light cleaning surface treatment equipment for 20 minutes to obtain a pretreated substrate.

Step S2, depositing a BTCV polymer with a thickness of 15 nm on the pretreated substrate to form an organic hole transport layer. The specific steps mainly include two steps.

Preparation of Organic Small Molecular Monomer BTCV

Step s21, add 0.588g (2.4mmol) of 2-bromocarbazole, 0.364g (2.4mmol) of 4-vinylbenzyl chloride and 20ml of acetone into a 100ml two-necked flask, heat to 60°C, and then add 0.110g (2.8g of sodium hydroxide) mmol) and tetrabutylammonium hydrogen sulfate 0.02g (0.0589mmol), stirred for 4h and filtered, and then spin-dried the solvent to obtain a white solid 9-(4-vinylbenzyl)-2-bromocarbazole 0.5g ( 1.38 mmol);

0.5 g (1.38 mmol) of 9-(4-vinylbenzyl)-2-bromocarbazole, 0.0308 g (0.627 mmol) of 5,5'-bis(trimethyltin)-2,2'-bisthiophene, 0.05 g (0.04 mmol) of palladium tetrakistriphenylphosphine and 30 ml of freshly distilled toluene were added to the two-necked flask. After 3 times of pumping and ventilation, they were heated to 120° C. for 12 h under argon atmosphere. The solvent was added with saturated potassium fluoride solution, extracted with dichloromethane (30ml × 3), that is, extracted 3 times with 30ml of dichloromethane each time, the solvent was spin-dried and the column chromatography was performed to obtain a yellow solid 5,5'-bis[ 0.11 g (0.151 mmol) of 9-(4-vinylbenzyl)-2-carbazolyl]-2,2'-bisthiophene, namely BTCV, a small organic monomer, as shown in FIG. 3 .

Cross-linking reaction of BTCV polymers

Step s22, placing the organic small-molecule monomer BTCV in N,N-dimethylformamide (DMF), fully stirring and dissolving, and preparing a BTCV solution of 0.8 mg mL ^-1 ;

Step s23, after filtering the BTCV solution through a 0.45-micron filter head, spin-coating at 4000 r/min on a glue spinner for 45 seconds, and then annealing at 160° C. for 12 min on a hot stage to cause a cross-linking reaction to form cross-linked organic holes Transport layer, with a thickness of 15 nm.

In step S3, lead acetate and methyl ammonium iodide are dissolved in a γ-butyrolactone solution in a molar ratio of 1:3, the total mass fraction of PbI ₂ and CH ₃ NH ₃ I in the solution is 50 wt %, and the mixture is stirred at room temperature to prepare Perovskite precursor solution (CH ₃ NH ₃ PbI ₃ ). The perovskite precursor solution was spin-coated on the organic hole transport layer at a speed of 5000 r/min, and then the anti-solvent chlorobenzene solvent was added dropwise during rotation for 4.5 s to promote the rapid crystallization of the perovskite layer, and then transferred to the air for 90 s. ℃ thermal annealing treatment for 10min to obtain a black perovskite layer with a thickness of 300nm, that is, a photoactive layer.

Step S4, spin-coating a chlorobenzene solution of PCBM ([6,6]-phenyl-C61-butyric acid methyl ester) with a concentration of 20 mg mL ^-1 on the photoactive layer at a rotational speed of 1500 r/min for 30- 60 s on the above perovskite layer to obtain an electron transport layer with a thickness of 20 nm.

Step S5, spin-coating a methanol solution of 1 mg mL ^-1 of PDINO (perylene diimide derivative) at a rotational speed of 3000 r/min for 30-60 s on the perovskite layer covered with PCBM to obtain a 15 nm-thick Cathode modification layer.

In step S6, finally, Ag with a thickness of 100 nm is vacuum-evaporated below 5×10 ^-5 Pa as a metal electrode to obtain a perovskite solar cell.

The structure of the device obtained in the embodiment of the present invention is ITO/BTCV/CH ₃ NH ₃ PbI ₃ /PCBM/PDINO/Ag. The performance of the device is tested. Under optimal conditions, the open circuit voltage is irradiated by 100mW cm ^-2 of simulated sunlight. is 1.01V, the short-circuit current is 20.84mA cm ^-2 , the fill factor is 78.13%, and the photoelectric conversion efficiency is 16.44%.

Example 4

The preparation method of a perovskite solar cell provided in this embodiment includes the following steps:

Step S1, the anode glass substrate substrate sputtered with fluorine-doped tin oxide FTO is ultrasonically washed twice with detergent, deionized water, acetone, and isopropanol in turn, for 10 to 15 minutes each time. Blow dry with nitrogen. The blown-dried FTO glass substrate was placed in an ultraviolet light cleaning surface treatment device for 20 minutes to obtain a pretreated substrate.

Step S2, depositing a BTCV polymer with a thickness of 18 nm on the pretreated substrate to form an organic hole transport layer. The specific steps mainly include two steps.

Preparation of Organic Small Molecular Monomer BTCV

Step s21, add 0.588g (2.4mmol) of 2-bromocarbazole, 0.364g (2.4mmol) of 4-vinylbenzyl chloride and 20ml of acetone into a 100ml two-necked flask, heat to 75°C, and then add 0.110g (2.8g) of sodium hydroxide. mmol) and tetrabutylammonium hydrogen sulfate 0.02g (0.0589mmol), stirred for 4h and filtered, and then spin-dried the solvent to obtain a white solid 9-(4-vinylbenzyl)-2-bromocarbazole 0.5g ( 1.38 mmol);

0.5 g (1.38 mmol) of 9-(4-vinylbenzyl)-2-bromocarbazole, 0.0308 g (0.627 mmol) of 5,5'-bis(trimethyltin)-2,2'-bisthiophene, 0.05 g (0.04 mmol) of palladium tetrakistriphenylphosphine and 30 ml of freshly distilled toluene were added to the two-necked flask. After 3 times of pumping and ventilation, they were heated to 120° C. for 12 h under argon atmosphere. The solvent was added with saturated potassium fluoride solution, extracted with dichloromethane (30ml × 3), that is, extracted 3 times with 30ml of dichloromethane each time, the solvent was spin-dried and the column chromatography was performed to obtain a yellow solid 5,5'-bis[ 0.11 g (0.151 mmol) of 9-(4-vinylbenzyl)-2-carbazolyl]-2,2'-bisthiophene, namely BTCV, a small organic monomer, as shown in FIG. 3 .

Cross-linking reaction of BTCV polymers

Step s22, placing the organic small-molecule monomer BTCV in N,N-dimethylformamide (DMF), fully stirring and dissolving, and preparing a BTCV solution of 1.5 mg mL ^-1 ;

Step s23, after filtering the BTCV solution through a 0.45-micron filter head, spin-coating at 4000 r/min for 55 seconds on a glue spinner, and then irradiating it under an ultraviolet lamp for 25 minutes to cause a cross-linking reaction to form a cross-linked organic hole transport layer. , with a thickness of 18 nm.

In step S3, lead chloride and formamidine hydroiodide are dissolved in a dimethyl sulfoxide solution in a molar ratio of 1:1, the total mass fraction of PbI ₂ and CH ₃ NH ₃ I in the solution is 50 wt %, and stirring at room temperature, A perovskite precursor solution (CH ₃ NH ₃ PbI ₃ ) was prepared. The perovskite precursor solution was spin-coated on the organic hole transport layer at a speed of 5000 r/min, and then the anti-solvent chlorobenzene solvent was added dropwise during rotation for 4.5 s to promote the rapid crystallization of the perovskite layer, and then transferred to the air for 100 s. ℃ thermal annealing treatment for 10min to obtain a black perovskite layer with a thickness of 300nm, that is, a photoactive layer.

Step S4, spin-coating a chlorobenzene solution of PCBM ([6,6]-phenyl-C61-butyric acid methyl ester) with a concentration of 20 mg mL ^-1 on the photoactive layer at a rotational speed of 1500 r/min for 30- 60 s on the above perovskite layer to obtain an electron transport layer with a thickness of 20 nm.

Step S5, spin-coating a methanol solution of 1 mg mL ^-1 of PDINO (perylene diimide derivative) at a rotational speed of 3000 r/min for 30-60 s on the perovskite layer covered with PCBM to obtain a 15 nm-thick Cathode modification layer.

In step S6, finally, Ag with a thickness of 100 nm is vacuum-evaporated below 5×10 ^-5 Pa as a metal electrode to obtain a perovskite solar cell.

The structure of the device obtained in the embodiment of the present invention is FTO/BTCV/CH ₃ NH ₃ PbI ₃ /PCBM/PDINO/Ag, and the performance of the device is tested. Under optimal conditions, the open circuit voltage is irradiated by simulated sunlight of 100mW cm ^-2 is 1.00V, the short-circuit current is 20.51mA cm ^-2 , the fill factor is 80.05%, and the photoelectric conversion efficiency is 16.42%.

Example 5

The difference between this example and Example 1 is that in step s23, after the BTCV solution is filtered through a filter head, spin-coated on a glue spinner, and then annealed on a hot stage at 130°C for 12 minutes to cause a cross-linking reaction to occur, forming a The other steps and methods are the same as those in Embodiment 1 for the cross-linked organic hole transport layer, which will not be repeated here.

The structure of the perovskite solar cell prepared in this example is FTO/BTCV/CH ₃ NH ₃ PbI ₃ /PCBM/PDINO/Al, and the performance test of the perovskite cell in this example is carried out at 100 mW cm ^-2 Under the simulated sunlight, the open circuit voltage is 1.00V, the short circuit current is 21.03mA cm ^-2 , the fill factor is 79.21%, and the photoelectric conversion efficiency is 16.66%.

Comparative Example 1

The difference between this comparative example and Example 1 is that in step S2, the organic hole transport layer adopts PEDOT:PSS solution, and other steps and methods are the same as those in Example 1, and will not be repeated here.

The structure of the perovskite solar cell prepared in this comparative example is ITO/PEDOT: PSS/CH ₃ NH ₃ PbI ₃ /PCBM/PDINO/Al. The performance test of the perovskite cell in this comparative example is carried out, and the test results are shown in the figure 5, the JV curve was measured under simulated sunlight irradiation of 100 mW cm ^-2 , and the open-circuit voltage was 0.91 V, the short-circuit current was 19.77 mA cm ^-2 , the fill factor was 77.03%, and the photoelectric conversion efficiency was 13.86%.

Comparative Example 2

The difference between this comparative example and Example 1 is that in step s22, the small organic monomer BTCV is prepared into a BTCV solution of 0.5 mg mL ⁻¹ , and other steps and methods are the same as those in Example 1, and will not be repeated here.

The structure of the perovskite solar cell prepared in this comparative example is ITO/BTCV/CH ₃ NH ₃ PbI ₃ /PCBM/PDINO/Al. The performance of the perovskite cell in this comparative example was tested at 100 mW cm ^-2 The JV curve was measured under simulated sunlight, and the open-circuit voltage was 1.00V, the short-circuit current was 18.28mA cm ^-2 , the fill factor was 70.64%, and the photoelectric conversion efficiency was 12.91%.

Comparative Example 3

The difference between this comparative example and Example 1 is that in step s23, the BTCV solution is spin-coated and then annealed on a hot stage at 100°C for 10 min. Other steps and methods are the same as those in Example 1, and will not be repeated here.

The structure of the perovskite solar cell prepared in this comparative example is ITO/BTCV/CH ₃ NH ₃ PbI ₃ /PCBM/PDINO/Al. The performance of the perovskite cell in this comparative example was tested at 100 mW cm ^-2 The JV curve was measured under simulated sunlight, and the open-circuit voltage was 1.00V, the short-circuit current was 20.33mA cm ^-2 , the fill factor was 75.87%, and the photoelectric conversion efficiency was 15.42%.

Comparative Example 4

The difference between this control example and Example 1 is that when preparing the organic small molecule BTCV, 1.176 g (4.8 mmol) of 2-bromocarbazole and 0.364 g (2.4 mmol) of 4-vinylbenzyl chloride were added in step s21. , 0.110g (2.8mmol) of sodium hydroxide and 0.02g (0.0589mmol) of tetrabutylammonium hydrogen sulfate, other steps and methods are the same as in Example 1, and will not be repeated here.

The structure of the perovskite solar cell prepared in this comparative example is ITO/BTCV/CH ₃ NH ₃ PbI ₃ /PCBM/PDINO/Al. The performance of the perovskite cell in this comparative example was tested at 100 mW cm ^-2 The JV curve was measured under simulated sunlight, and the open-circuit voltage was 0.824V, the short-circuit current was 16.33mA cm ^-2 , the fill factor was 60.85%, and the photoelectric conversion efficiency was 8.188%.

Comparative Example 5

The difference between this control example and Example 1 is that in step S3, PbI ₂ and CH ₃ NH ₃ I were dissolved in N,N-dimethylformamide (DMF) solution in a molar ratio of 2:1, and PbI in the solution The total mass fraction of ₂ and CH ₃ NH ₃ I is 40wt%, stirring at room temperature to prepare a perovskite precursor solution (CH ₃ NH ₃ PbI ₃ ), other steps and methods are the same as those in Example 1, and will not be repeated here. .

The structure of the perovskite solar cell prepared in this comparative example is ITO/BTCV/CH ₃ NH ₃ PbI ₃ /PCBM/PDINO/Al. The performance of the perovskite cell in this comparative example was tested at 100 mW cm ^-2 The JV curve was measured under simulated sunlight, and the open-circuit voltage was 0.800V, the short-circuit current was 17.28mA cm ^-2 , the fill factor was 65.21%, and the photoelectric conversion efficiency was 9.014%.

The low photoelectric conversion efficiency of the solar cell is due to the fact that PbI ₂ has a large amount of surplus, does not generate CH ₃ NH ₃ PbI ₃ , and cannot absorb light energy; PbI ₂ is an insulator, which hinders the transfer of charges, increases resistance, and ultimately reduces the photoelectricity of the solar cell. Conversion efficiency.

In summary: a perovskite solar cell based on an organic cross-linked hole transport layer of the present invention, the cell structure includes from bottom to top: an anode, a hole transport layer, a photoactive layer, an electron transport layer, and a cathode modification layer and cathode, wherein the hole transport layer adopts organic small molecule BTCV with a thickness of 10-20nm, and the hole transport layer is prepared by spin-coating the BTCV solution and crosslinking it. The hole transport layer of the present invention can reduce the The probability of electron coupling or charge recombination at the interface, the photoelectric conversion efficiency of the planar heterojunction perovskite cell prepared by this method reaches 17.58%, which improves the performance of the perovskite solar cell and can be used for photoelectric conversion.

At the same time, the organic small-molecule monomer BTCV has simple synthesis steps, low cost, high yield and stable properties, which can be commercialized and greatly reduce the cost of perovskite solar cells.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (14)

1. A method of fabricating a perovskite solar cell, the method comprising the steps of:

step S1, cleaning and drying the glass substrate plated with the anode material, and then carrying out ultraviolet cleaning treatment to obtain a pretreated substrate;

step S2, depositing BTCV polymer on the pretreated substrate to form an organic hole transport layer;

s3, spin-coating a perovskite precursor solution on the organic hole transport layer, adding a chlorobenzene solvent, continuing spin-coating, and annealing at 90-110 ℃ to obtain a perovskite crystal film, namely a photoactive layer;

step S4, spin-coating a chlorobenzene solution of PCBM on the photoactive layer to form an electron transport layer;

step S5, spin-coating a methanol solution of PDINO on the electron transport layer to form a cathode modification layer;

s6, evaporating a cathode material to the cathode modification layer through thermal evaporation in vacuum to obtain the perovskite solar cell;

the molecular structural formula of BTCV is as follows:

。

2. the method for manufacturing a perovskite solar cell as claimed in claim 1, wherein the step of forming the organic hole transport layer in step S2 comprises:

step s21, placing the organic small molecular monomer BTCV in N, N-dimethylformamide, fully stirring and dissolving to prepare a BTCV solution;

and step s22, filtering the BTCV solution, spin-coating the BTCV solution on a spin coater for 30 to 60 seconds, and then carrying out curing treatment to form the crosslinked reticular organic hole transport layer.

3. The method of making the perovskite solar cell of claim 2, wherein the concentration of the BTCV solution is 0.5-1.5mg mL _^-1。

4. The method of fabricating the perovskite solar cell as claimed in claim 2, wherein the organic hole transport layer has a thickness of 10 to 20 nm.

5. The method for preparing a perovskite solar cell as claimed in claim 2, wherein in step s22, the curing treatment is annealing at 130-170 ℃ for 8-12min on a hot bench or irradiation with an ultraviolet lamp for 25-35 min.

6. The method for preparing the perovskite solar cell as claimed in claim 2, wherein the specific method for preparing the organic small molecule monomer BTCV comprises the following steps:

heating 2-bromocarbazole, 4-vinylbenzyl chloride and acetone to 60-90 ℃, adding sodium hydroxide and tetrabutylammonium hydrogen sulfate, stirring, filtering, spin-drying a solvent, and performing column chromatography to obtain white solid 9- (4-vinylbenzyl) -2-bromocarbazole;

adding 9- (4-vinylbenzyl) -2-bromocarbazole, 5 '-bis (trimethyltin) -2,2' -bithiophene, palladium tetratriphenylphosphine and newly evaporated toluene into a container, pumping gas for 2-4 times, heating to 110 ℃ and 130 ℃ in an argon atmosphere for reaction, cooling to room temperature after the reaction is finished, spin-drying the solvent, adding a saturated potassium fluoride solution, extracting by using dichloromethane, and performing column chromatography after spin-drying the solvent to obtain a yellow solid 5,5 '-bis [9- (4-vinylbenzyl) -2-carbazolyl ] -2,2' -bithiophene, namely the organic small molecular monomer BTCV.

7. The method of making the perovskite solar cell of claim 6, wherein the molar ratio of the 2-bromocarbazole to the 4-vinylbenzyl chloride is 1:1.

8. The method of making the perovskite solar cell of claim 6, wherein the molar ratio of the 9- (4-vinylbenzyl) -2-bromocarbazole to the 5,5 '-bis (trimethyltin) -2,2' -bithiophene is 2: 1.

9. The method for producing a perovskite solar cell as claimed in claim 1, wherein the method for producing the perovskite precursor solution in step S3 comprises:

dissolving the donor A in an organic solvent, then adding the donor B, and stirring to obtain a perovskite precursor solution;

wherein the donor A is lead chloride, lead bromide, lead acetate, lead thiocyanate or lead iodide;

the donor B is methyl ammonium chloride, formamidine hydrochloride, methyl ammonium bromide, formamidine hydrobromide, methyl ammonium iodide or formamidine hydroiodide.

10. The method of making the perovskite solar cell of claim 9, wherein the organic solvent is dimethylformamide, dimethylsulfoxide, or γ -butyrolactone.

11. The method of fabricating the perovskite solar cell of claim 9, wherein the molar ratio of the donor a to the donor B is 1: (1-5).

12. The method for producing a perovskite solar cell as claimed in claim 11, wherein the total mass percentage of the donor a and the donor B in the organic solvent is 35 to 50 wt%.

13. A perovskite solar cell manufactured by the method for manufacturing a perovskite solar cell as defined in any one of claims 1 to 12.

14. Use of an organic hole transport layer for the preparation of a photovoltaic device; the organic hole transport layer is prepared by the preparation method of the perovskite solar cell as set forth in any one of claims 1 to 8.

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