CN114447228A - Perovskite solar cell with microcavity structure and preparation method thereof - Google Patents

Abstract

The invention discloses a preparation method of a perovskite solar cell microcavity. The layers together constitute a microcavity; the method for preparing a perovskite solar cell microcavity proposed in the present invention has wide applicability, and a high-quality perovskite dielectric film can be grown on the metal layer to obtain a resonant cavity that operates on the absorption edge. The method of the present invention prepares a microcavity perovskite solar cell, which is modulated and enhanced in a long-wavelength light field, the current is significantly increased, and its toxicity can be greatly reduced.

Description

Perovskite solar cell with microcavity structure and preparation method thereof

technical field

The invention relates to the technical field of perovskite solar cells, in particular to a perovskite solar cell with a microcavity structure and a preparation method thereof.

Background technique

Perovskite solar cell (PSC) is a new type of solar cell technology developed in recent years, which uses organic-inorganic mixed lead-halide perovskite material as the light absorption layer. The characteristics of tunable band gap, high light absorption, long carrier diffusion distance, and high carrier transfer rate have attracted extensive attention of researchers in the field of optoelectronics. Among them, its band gap can be continuously adjusted from 1.2 to 2.9 eV according to different components, which makes it have great potential in the field of solar cells.

However, current high-efficiency perovskite solar cells are difficult to avoid the use of lead-containing raw materials. The thickness of the traditional perovskite light absorbing layer is 700-1000 nm. Theoretical calculations have proved that the perovskite light absorbing layer thickness of at least 200 nm can reach the efficiency of more than 80% of the standard device and reduce the toxicity by at least 50%. However, since the absorption coefficient of perovskite is extremely high at short wavelengths and low at long wavelengths, reducing the thickness of the perovskite light absorption layer directly through concentration regulation and anti-solvent time regulation will make the long-wavelength part (>700nm) thin. The energy is not utilized, making it difficult to further improve the device efficiency. In relatively mature thin-film solar cells (GaAs cells, Copper Indium Gallium Selenide cells, etc.), an effective way to solve such problems is to make a microcavity in the solar cell, and improve the long-wave absorption through light field regulation. . However, for perovskite solar cells, due to the characteristics of solution-based preparation, the quality of the perovskite light absorption layer coated on the metal layer is limited by the interface properties, and it is also a challenge to prepare a dielectric layer with a specific thickness. .

SUMMARY OF THE INVENTION

The problems to be solved by the present invention are: how to stably obtain a workable perovskite solar cell with a microcavity structure, and how to improve the growth quality of the medium in the microcavity, so as to realize the regulation of the light field and further realize the enhancement of light absorption.

For solving the above problems, the technical scheme of the present invention is:

In one aspect, the present invention provides a perovskite solar cell with a microcavity structure, comprising a substrate, a transparent conductive layer, a first charge transport layer, a perovskite light absorption layer, a second charge transport layer and The second metal layer; it is characterized in that a first metal layer is further arranged between the transparent conductive layer and the first charge transport layer, the first metal layer serves as the light-inlet end of the microcavity, and the second metal layer is layer as the light-emitting end of the microcavity.

Preferably, the transparent conductive layer is one of indium tin oxide (ITO) or fluorine-doped tin oxide (FTO) material, and its thickness is 100-600 nm.

Preferably, the first metal layer is a metal material with strong reflectivity and electrical conductivity, one of gold Au, silver Ag, and copper Cu, and the thickness thereof is 5-15 nm.

Preferably, the heat treatment temperature of the step (1) is 80-120°C, and the time is 1-5 minutes; the heat treatment temperature of the heat treatment of the first charge transport layer precursor described in the step (2) is 30-50°C.

Preferably, the time interval between the completion of the heat treatment in step (2) and the preparation of the first charge transport layer is 0-3 s.

Preferably, the first charge transport layer and the second charge transport layer should have different charge transport properties, wherein the electron transport materials include: titanium dioxide TiO ₂ , tin dioxide SnO ₂ , zinc oxide ZnO, C ₆₀ solution, [6, 6]-Any one of the methyl phenyl C ₆₁ butyrate solution, the thickness of which is 20-120 nm; the hole transport material adopts triphenylamine derivatives, 2,2,7,7-tetrakis[N,N- Bis(4-methoxyphenyl)amino]-9,9-spirobifluorene Spiro-OMeTAD, poly3,4-ethylenedioxythiophene:polystyrenesulfonate PEDOT:PSS, poly(3-hexyl thiophene) P3HT, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanodimethane-doped polytricarboxyamine PTAA: F4-TCNQ, poly[bis(4-phenyl) (2,4,6-trimethylphenyl)amine] PTAA, any one of cuprous thiocyanate CuSCN, and nickel oxide NiO _x , and the thickness thereof is 10 to 200 nm.

Preferably, the perovskite light absorption layer adopts ABX ₃ -type three-dimensional perovskite, and the different ions in its molecular formula ABX ₃ are selected as follows: positive monovalent cation A, methylamine MA ⁺ , formamidine FA ⁺ , potassium K ⁺ , rubidium Rb ⁺ , cesium Cs ⁺ any one ion and any combination of several ions; positive divalent metal cation B, selects any one ion in lead Pb ²⁺ , germanium Ge ²⁺ , tin Sn ²⁺ and any combination of several ions; negative monovalent anion X, selects any one ion in chlorine Cl ^- , bromine Br ^- , iodine I ^- and any combination of several ions.

Preferably, the perovskite light absorbing layer is a two-dimensional perovskite material whose molecular formula is L ₂ A _n-1 B _n X _3n+1 or L ² A _n-1 B _n X _3n+1 The selection of different ions is as follows: the selection of positive monovalent cation A, positive divalent metal cation B, and negative monovalent anion X is the same as the selection of three-dimensional perovskite; positive monovalent organic cation A ¹ is selected from phenethylamine PEA ⁺ , butylamine BA ⁺ , ethylamine EA ⁺ , dimethylamine DMA ⁺ , methyltriethylammonium MTEA ⁺ , guanidine GA ⁺ , 2-thienylmethylammonium ThMA ⁺ , any ion and any kind of ions The combination; positive divalent organic cation A ² , selects 3-aminomethylpiperidine 3AMP ²⁺ , 4-aminomethylpiperidine 4AMP ²⁺ , 3-aminomethyl pyridine 3AMPY ²⁺ , 4-aminomethyl pyridine 4AMPY ²⁺ , ethylenediamine EDA ²⁺ , N,N-dimethylaniline DPA ²⁺ , propane 1,3-diammonium PDA ²⁺ , 1,4-butanediamine BDA ²⁺ , 2,5-diamine Any one of the ions of methylthiophene ThDMA ²⁺ , p-xylylenediamine PDMA ²⁺ , N,N-dimethylethylenediamine DMEDA ²⁺ and any combination of several ions.

Preferably, the second metal layer is one of gold Au, silver Ag, and copper Cu, and the thickness thereof is 90-300 nm.

On the other hand, the present invention also provides a method for preparing a perovskite solar cell with a microcavity structure, comprising the steps of:

(1) Prepare a first metal layer on the transparent conductive layer, as the light-inlet end of the microcavity, and perform heat treatment to make the first metal layer and the transparent conductive layer in a microthermal state;

(2) heat treating the first charge transport layer precursor, and preparing the first charge transport layer with slight heat on the first metal layer, and then performing annealing treatment;

(3) preparing a perovskite light absorption layer on the first charge transport layer, and performing annealing treatment;

(4) after preparing the second charge transport layer on the perovskite light absorption layer, annealing treatment is performed;

(5) A second metal layer is prepared on the second charge transport layer to serve as the light-emitting end and electrode of the microcavity.

Compared with the prior art, the advantages of the present invention are:

1. Because the first metal layer is used as the light incident end and the reflection end, and the second metal layer is used as the light reflection end, the light resonates in the cavity, resulting in a field enhancement effect, thereby reducing the loss of light energy.

2. Due to the heat treatment of the first metal layer and the first charge transport layer, the stress between the films is reduced, and the grown perovskite light absorption layer has the characteristics of high film formation quality, low film defect density and low surface roughness. , which greatly improves the efficiency of perovskite solar cells with microcavity structure.

3. The preparation process of the thin film resonant cavity involved in the present invention has a wide range of applicability, is suitable for various types of solar cell preparation processes, can be well adapted to the industrial wet film preparation process, and has great commercialization. value;

Fourth, the PSC prepared by the present invention has extremely high light absorption rate and efficiency at all wavelengths, and at the same time, the toxicity is more than 40% lower than that of the conventional PSC. The invention can greatly promote the commercial application of PSC, so that the toxicity can meet various environmental protection standards.

Description of drawings

FIG. 1 is a schematic flow chart of the preparation process of the perovskite solar cell microcavity involved in the present invention.

FIG. 2 is a schematic diagram of the structure of the device prepared by the present invention.

In the figure: substrate (1), transparent conductive layer (2), first metal layer (3), first charge transport layer (4), perovskite light absorption layer (5), second charge transport layer (6) ), the second metal layer (7).

Detailed ways:

The present invention will be further described below with reference to the accompanying drawings and embodiments.

Example 1: The substrate composed of the substrate and the transparent conductive layer was cleaned with a conventional solvent, followed by ultraviolet ozone treatment for 15 minutes, and the first metal layer of Cu (evaporation, 10 nm) was prepared on the substrate, and the PTAA holes were slightly heated on the hot stage. Transport layer solution (hot stage temperature 40°C, heating for 5min), the substrate containing the metal layer was heated on the hot stage (hot stage temperature 40°C, heating 3min), on which a PTAA hole transport layer was prepared (spin coating 2000rpm) , 30 s) and annealed for 10 min to obtain PTAA with a thickness of 10 nm. The perovskite precursor solution was deposited on top of the PTAA layer (spin coating at 4000 rpm, 60 s, dropwise addition of chlorobenzene at 45 s). The film was transferred to a hot stage (the temperature of the hot stage was 100 °C), and the perovskite film was thermally annealed for 20 min, and finally a perovskite film with a thickness of 400 nm was obtained. The film was cooled to room temperature, and a C ₆₀ electron transport layer of 40 nm was evaporated, and a Cu second metal layer of 90 nm was evaporated. The prepared PSC has V _OC =1.03V, J _SC =22.13mA/cm ² , FF=0.75, PCE=17.2%, the 750nm light amplitude is enhanced by 3.3 times, the light absorption rate above 650nm is above 85%, and the same power is achieved Toxicity reduced by 33%.

Example 2: The substrate composed of the substrate and the transparent conductive layer was cleaned with a conventional solvent, followed by ultraviolet ozone treatment for 15 minutes, and the Au first metal layer (evaporation, 10 nm) was prepared on the substrate, and the PTAA holes were slightly heated on the hot stage. Transport layer solution (hot stage temperature 40°C, heating for 5min), the substrate containing the metal layer was heated on the hot stage (hot stage temperature 40°C, heating 3min), on which a PTAA hole transport layer was prepared (spin coating 2000rpm) , 30 s) and annealed for 10 min to obtain PTAA with a thickness of 10 nm. The perovskite precursor solution was deposited on top of the PTAA layer (spin coating at 4000 rpm, 60 s, dropwise addition of chlorobenzene at 45 s). The film was transferred to a hot stage (the temperature of the hot stage was 100 °C), and the perovskite film was thermally annealed for 20 min, and finally a perovskite film with a thickness of 410 nm was obtained. The film was cooled to room temperature, and a C ₆₀ electron transport layer of 40 nm was evaporated, and a Cu second metal layer of 90 nm was evaporated. The prepared PSC has V _OC =1.01V, J _SC =21.53mA/cm2, FF=0.76, PCE=16.67%, the 750nm light amplitude is enhanced by 3.1 times, and the light absorption rate above 650nm is above 84%, achieving the same power toxicity 31% lower.

Example 3: The substrate composed of the substrate and the transparent conductive layer was cleaned with a conventional solvent, followed by ultraviolet ozone treatment for 15 minutes, and the first metal layer of Cu (evaporation, 10 nm) was prepared on the substrate, and the PTAA holes were slightly heated on the hot stage. Transport layer solution (hot stage temperature 40°C, heating for 5min), the substrate containing the metal layer was heated on the hot stage (hot stage temperature 40°C, heating 3min), on which a PTAA hole transport layer was prepared (spin coating 2000rpm) , 30 s) and annealed for 10 min to obtain PTAA with a thickness of 10 nm. The perovskite precursor solution was deposited on top of the PTAA layer (spin coating at 4000rpm, 60s, dropwise addition of chlorobenzene at 45s). The film was transferred to a hot stage (the temperature of the hot stage was 100 °C), and the perovskite film was thermally annealed for 20 min, and finally a perovskite film with a thickness of 410 nm was obtained. The film was cooled to room temperature, and a C ₆₀ electron transport layer of 40 nm was evaporated, and a Cu second metal layer of 90 nm was evaporated. The prepared PSC has V _OC =1.04V, J _SC =22.03mA/cm2, FF=0.74, PCE=17.09%, the 750nm light amplitude is enhanced by 3.2 times, and the light absorption rate above 650nm is above 84%, achieving the same power toxicity 33% lower.

Example 4: The substrate composed of the substrate and the transparent conductive layer was cleaned with a conventional solvent, followed by ultraviolet ozone treatment for 15 minutes, and the first metal layer of Cu (evaporation, 10 nm) was prepared on the substrate, and the PTAA holes were slightly heated on the hot stage. Transport layer solution (hot stage temperature 40°C, heating for 5min), the substrate containing the metal layer was heated on the hot stage (hot stage temperature 40°C, heating 3min), on which a PTAA hole transport layer was prepared (spin coating 2000rpm) , 30 s) and annealed for 10 min to obtain PTAA with a thickness of 10 nm. The perovskite precursor solution was deposited on top of the PTAA layer (spin coating at 4000 rpm, 60 s, dropwise addition of chlorobenzene at 45 s). The film was transferred to a hot stage (the temperature of the hot stage was 100 °C), and the perovskite film was thermally annealed for 20 min, and finally a perovskite film with a thickness of 410 nm was obtained. The film was cooled to room temperature, and a C ₆₀ electron transport layer of 40 nm was evaporated, and a Cu second metal layer of 90 nm was evaporated. The prepared PSC has V _OC =1.03V, J _SC =22.03mA/cm2, FF = 0.76, PCE = 17.57%, the 750nm light amplitude is enhanced by 3.3 times, the light absorption above 650nm is above 85%, and the same power toxicity is achieved. 34% lower.

Example 5: The substrate composed of the substrate and the transparent conductive layer was cleaned with a conventional solvent, followed by ultraviolet ozone treatment for 15 minutes, and the first metal layer of Cu (evaporation, 10 nm) was prepared on the substrate, and the PTAA holes were slightly heated on the hot stage. Transport layer solution (hot stage temperature 40°C, heating for 5min), the substrate containing the metal layer was heated on the hot stage (hot stage temperature 40°C, heating 3min), on which a PTAA hole transport layer was prepared (spin coating 2000rpm) , 30 s) and annealed for 10 min to obtain PTAA with a thickness of 10 nm. The perovskite precursor solution was deposited on top of the PTAA layer (spin coating at 4000 rpm, 60 s, dropwise addition of chlorobenzene at 45 s). The film was transferred to a hot stage (the temperature of the hot stage was 100 °C), and the perovskite film was thermally annealed for 20 min, and finally a perovskite film with a thickness of 410 nm was obtained. The film was cooled to room temperature, and a C ₆₀ electron transport layer of 40 nm was evaporated, and a Cu second metal layer of 90 nm was evaporated. The prepared PSC has V _OC =1.02V, J _SC =21.73mA/cm2, FF=0.76, PCE=16.94%, the 750nm light amplitude is enhanced by 3.2 times, and the light absorption rate above 650nm is above 84%, achieving the same power toxicity 32% lower.

The present invention has been described by the above-mentioned embodiments, but it should be understood that the above-mentioned embodiments are only for the purpose of illustration and description, and are not intended to limit the present invention to the scope of the described embodiments. In addition, those skilled in the art can understand that the present invention is not limited to the above-mentioned embodiments, and more variations and modifications can also be made according to the teachings of the present invention, and these variations and modifications all fall within the protection claimed in the present invention. within the range. The protection scope of the present invention is defined by the appended claims and their equivalents.

Claims (9)

1. A perovskite solar cell with a microcavity structure, comprising a substrate (1), a transparent conductive layer (2), a first charge transport layer (4), a perovskite light absorption layer (5) that are stacked in sequence ), a second charge transport layer (6) and a second metal layer (7); it is characterized in that a first metal layer is also provided between the transparent conductive layer (2) and the first charge transport layer (4) layer (3), the first metal layer (3) is used as the light input end of the microcavity, and the second metal layer (7) is used as the light output end of the microcavity. 2 . The perovskite solar cell with a microcavity structure according to claim 1 , wherein the thickness of the perovskite light absorbing layer is 100-500 nm, and the lead content is less than that of a conventional perovskite solar cell. 3 . 50%. 3. The perovskite solar cell with a microcavity structure according to claim 1, wherein the first metal layer (3) is a metal material with strong reflectivity and electrical conductivity, and the second metal layer (3) is a metal material with strong reflectivity and electrical conductivity. Layer (7) is a metallic material with a high work function. 4. The perovskite solar cell with a microcavity structure according to claim 3, wherein the first metal layer (3) adopts one of gold Au, silver Ag, and copper Cu, and has a thickness of 5 ~15nm. 5. The perovskite solar cell with a microcavity structure according to claim 1, wherein the perovskite light absorbing layer (5) is used for absorbing incident light, and has an ABX ₃ three-dimensional perovskite structure. Photovoltaic material; or a photovoltaic material of L ₂ A _n-1 B _n X _3n+1 or L ² A _n-1 B _n X _3n+1 two-dimensional perovskite structure. 6. The perovskite solar cell with a microcavity structure according to claim 1, wherein the first charge transport layer (4) and the second charge transport layer (5) are respectively an electron transport layer and a A hole transport layer, or a transport layer and an electron transport layer, respectively. 7. A preparation method of a perovskite solar cell with a microcavity structure, wherein the preparation method comprises the steps: (1) Prepare a first metal layer on the transparent conductive layer, as the light-inlet end of the microcavity, and perform heat treatment to make the first metal layer and the transparent conductive layer in a microthermal state; (2) heat treating the first charge transport layer precursor, and preparing the first charge transport layer with slight heat on the first metal layer, and then performing annealing treatment; (3) preparing a perovskite light absorption layer on the first charge transport layer, and performing annealing treatment; (4) after preparing the second charge transport layer on the perovskite light absorption layer, annealing treatment is performed; (5) A second metal layer is prepared on the second charge transport layer to serve as the light-emitting end and electrode of the microcavity. 8 . The method for preparing a microcavity in a perovskite solar cell according to claim 7 , wherein the heat treatment temperature in step (1) is 80 to 120° C., and the time is 1 to 5 min; step (1) 2) The heat treatment temperature of the first charge transport layer precursor in the heat treatment is 30-50°C. 9 . The method for preparing a microcavity in a perovskite solar cell according to claim 7 , wherein the time interval between the completion of the heat treatment in step (2) and the preparation of the first charge transport layer is 0 to 10 . 3s.

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