KR102472294B1 - Inorganic-organic Perovskite Compound Having Improved Stability - Google Patents

Abstract

Organic/inorganic perovskite compounds according to the present invention include organic/inorganic cations including amidinium-based monovalent cations, alkylenediammonium-based divalent cations, and cesium ions; Inorganic cations containing divalent metal ions; and anions including halogen ions.

Description

Inorganic-organic Perovskite Compound Having Improved Stability

The present invention relates to an inorganic perovskite compound having improved stability and, in detail, to an inorganic perovskite compound having improved structural stability and thermal stability through stress control and excellent photoelectric conversion characteristics, including the same It is about a perovskite solar cell that does.

Inorganic-organic halide perovskite crystals of the perovskite structure, called inorganic perovskite compounds, are usually organic cations (A), metal cations (M) and halide anions. It is composed of (X) and is a substance represented by the chemical formula of AMX ₃ .

Non-organic hybrids of perovskite structures have excellent light absorption properties, long charge carrier diffusion length, high absorption coefficient, low trap density, and small exciton binding energy, so they can be used in various fields such as light emitting devices, photovoltaic devices, and semiconductor devices. Interest in non-organic hybrids of perovskite structures is increasing.

Currently, perovskite solar cells using non-organic hybrid materials as light absorbers are closest to commercialization among next-generation solar cells, including dye-sensitized and organic solar cells, and have reported an efficiency of up to 20% comparable to silicon solar cells ( Korean Patent Publication No. 2014-0035284).

In addition, the non-organic hybrid of the perovskite structure has a very low material price and excellent commerciality because it can be processed at a low temperature or a low-cost solution process.

However, despite having such commercial/physical advantages, the non-organic hybrid of the perovskite structure has very poor stability against light, heat and moisture, so for commercialization, development of technology that can improve stability above all this is being requested

On the other hand, non-organic hybrids known to exhibit the highest photoelectric conversion efficiency are based on amidinium-based cations. However, amidinium-based cation-based non-organic hybrid materials exhibiting the highest efficiency have instability to light, heat and moisture as well as phase instability (formation of δ-phase inactive to light and phase transition from α-phase to δ-phase) There are also problems with it.

In order to solve the phase instability, a technique of simultaneously mixing a small amount of methylammonium and bromide ions with amidinium-based cations as a stabilizer to stabilize the α-phase has been proposed, but methylammonium is very easily decomposed by heat or moisture and There is a problem in that the moisture and thermal stability of the medium-based cation-free non-organic hybrid is greatly reduced, and the addition of bromine ions increases the band gap of the non-organic hybrid material to narrow the light absorption region.

Republic of Korea Patent Publication No. 2014-0035284

The present invention provides an inorganic perovskite compound having more improved stability and photoelectric conversion efficiency by controlling the lattice residual stress.

Organic/inorganic perovskite compounds according to the present invention include organic/inorganic cations including amidinium-based monovalent cations, alkylenediammonium-based divalent cations, and cesium ions; Inorganic cations containing divalent metal ions; and anions including halogen ions.

In the organic-inorganic perovskite compound according to an embodiment of the present invention, the alkylenediammonium-based divalent cation may include a C1-C3 alkylenediammonium cation.

In the organic-inorganic perovskite compound according to an embodiment of the present invention, in the organic-inorganic cation, the molar ratio between the divalent alkylenediammonium cation and the cesium ion may be 1:0.9 to 1.1.

In the organic-inorganic perovskite compound according to an embodiment of the present invention, 0.010 to 0.050 moles of alkylenediammonium-based divalent cations may be contained based on 1 mole of the inorganic cations.

In the organic-inorganic perovskite compound according to an embodiment of the present invention, 0.025 to 0.035 moles of alkylenediammonium-based divalent cations may be contained based on 1 mole of the inorganic cations.

The organic-inorganic perovskite compound according to an embodiment of the present invention may satisfy Formula 1 below.

AMX ₃

A is the organic-inorganic cation, M is the inorganic cation, and X is the anion.

The organic-inorganic perovskite compound according to an embodiment of the present invention is an amidinium-based perovskite containing 90% or more of amidinium-based monovalent cations, with the total number of moles of the organic-inorganic cations as 100%. can be a compound.

The present invention includes a perovskite solar cell including the above-described organic-inorganic perovskite compound layer as a light absorption layer.

In the perovskite solar cell according to an embodiment of the present invention, Urbach energy (Eu) of the light absorption layer is amidinium-based monovalent cation, alkylenediammonium-based divalent cation, and divalent metal It may be 90% or less of the Ubach energy of the reference light absorption layer composed of ions and halogen anions.

In the perovskite solar cell according to an embodiment of the present invention, the residual strain (ε) of the light absorption layer calculated using the Williamson-hall method may be 0.0010 or less.

In the perovskite solar cell according to an embodiment of the present invention, the trap density of the light absorption layer calculated from the result of measuring the thermally stimulated current is amidinium-based monovalent cation, alkyl The trap density may be 60% or less of the trap density of the reference light absorbing layer composed of rendiammonium-based divalent cations, divalent metal ions, and halide anions.

The perovskite solar cell according to an embodiment of the present invention was tested for thermal stability exposed to a temperature of 85° C. and a relative humidity of 15% or less for 1300 hours under light-shielding conditions, and the photoelectric conversion efficiency before the test was 80%. The above photoelectric conversion efficiency can be maintained.

A perovskite solar cell according to an embodiment of the present invention may have a photoelectric conversion efficiency of 22.0% or more at a standard air mass (AM) of 1.5G.

A perovskite solar cell according to an embodiment of the present invention includes a first charge carrier positioned under the light absorption layer; a second charge carrier located above the light absorption layer and transporting charges complementary to the first charge carrier; a first electrode positioned below the first charge carrier; and a second electrode positioned on the second charge carrier.

The inorganic perovskite compound according to the present invention minimizes the residual stress of the lattice without significantly increasing the energy band gap by substituting alkylenediammonium divalent cations and cesium ions in the perovskite structure. And, by suppressing the residual stress, the formation of deep traps and non-radiative recombination in the perovskite compound are prevented, so that excellent photoelectric conversion efficiency can be obtained.

In addition, in the inorganic perovskite compound according to an advantageous example, alkylenediammonium-based divalent cations and cesium ions are mixed in the perovskite structure, and substantially the same amount of cesium as alkylenediammonium-based divalent cations is used. By introducing ions, there is an advantage of having excellent thermal and light stability as well as phase stability.

1 is a view showing a Cu Kα X-ray diffraction pattern of a perovskite compound film prepared according to an embodiment of the present invention.
Figure 2 is a view showing in detail the 2θ 13.5 ~ 14.4 ° region in the Cu Kα X-ray diffraction pattern of the perovskite compound film prepared according to an embodiment of the present invention.
3 is a grazing angle incidence wide-angle X-ray scattering spectrum (FIG. 3(a)) of a perovskite compound film prepared according to an embodiment of the present invention and the scattering intensity of the (001) plane according to the azimuthal It is a diagram showing the spectrum (FIG. 3(b)).
4 is a diagram showing a UV-Vis absorption spectrum and a leveled photoluminescence spectrum of a perovskite compound film prepared according to an embodiment of the present invention.
5 is a diagram showing measurement of the performance of a perovskite solar cell manufactured according to an embodiment of the present invention.
6 is a scanning electron micrograph of the surface of a perovskite compound film prepared according to an embodiment of the present invention.
7 is a view showing residual strain (ε) of a perovskite compound film manufactured according to an embodiment of the present invention.
8 is a diagram showing a steady-state light emission spectrum of a perovskite compound film prepared according to an embodiment of the present invention.
9 is a diagram showing time-resolved photoluminescence characteristics of a perovskite compound film prepared according to an embodiment of the present invention.
10 is a diagram showing Ubach energy (Eu) of a perovskite compound film prepared according to an embodiment of the present invention.
11 is a view showing the thermal stimulation current measurement result (FIG. 11(a)) and trap density (FIG. 11(b)) of a perovskite solar cell manufactured according to an embodiment of the present invention.
12 is a diagram showing current density-voltage characteristics of a perovskite solar cell manufactured according to an embodiment of the present invention.
13 is a diagram showing the results of a thermal stability test of a perovskite solar cell manufactured according to an embodiment of the present invention.
14 is a diagram illustrating long-term thermal stability test results of a perovskite solar cell manufactured according to an embodiment of the present invention.
15 is a diagram showing a maximum power point tracking result of a perovskite solar cell manufactured according to an embodiment of the present invention.

Hereinafter, the inorganic perovskite compound of the present invention will be described in detail with reference to the accompanying drawings. The drawings introduced below are provided as examples to sufficiently convey the spirit of the present invention to those skilled in the art. Therefore, the present invention may be embodied in other forms without being limited to the drawings presented below, and the drawings presented below may be exaggerated to clarify the spirit of the present invention. At this time, unless there is another definition in the technical terms and scientific terms used, they have meanings commonly understood by those of ordinary skill in the art to which this invention belongs, and the gist of the present invention in the following description and accompanying drawings Descriptions of well-known functions and configurations that may be unnecessarily obscure are omitted.

Also, the singular forms used in the specification and appended claims may be intended to include the plural forms as well, unless the context dictates otherwise.

In this specification and the appended claims, terms such as first and second are used for the purpose of distinguishing one element from another, not in a limiting sense.

In this specification and the appended claims, terms such as include or have mean that features or elements described in the specification exist, and unless specifically limited, one or more other features or elements may be added. It does not preclude the possibility that it will happen.

In this specification and the appended claims, when a part of a film (layer), region, component, etc. is on or on another part, not only when it is in contact with and directly on top of another part, but also when another film ( layer), other areas, other components, etc. are interposed.

As a result of research to improve the phase stability of the amidinium-based perovskite compound, which exhibits the best photoelectric conversion efficiency among inorganic perovskite compounds, the present applicant has found that alkylenediammonium-based divalent cations are When introduced into the medium-based perovskite compound, it was confirmed that the α-phase was stabilized by the entropic stabilization effect and the high δ-phase generation energy. It was confirmed that the ionic bonding force between the cations was increased, and thus, it had better thermal and moisture stability than conventional amidinium-based perovskite compounds.

However, the introduction of alkylenediammonium-based divalent cations into the amidinium-based perovskite compound causes a large residual strain in the perovskite lattice structure to deteriorate the physical properties of the perovskite compound. It was found that Shiki acts as a major factor.

Therefore, as a result of conducting research to further improve the physical properties and stability of amidinium-based perovskite compounds, when alkylenediammonium-based divalent cations and Cs ⁺ are simultaneously introduced into the perovskite structure, The present invention confirmed that the photoelectric conversion efficiency and stability of the material are greatly improved, and unwanted physical property changes such as an increase in energy band gap do not appear while the phase stability improvement effect by the introduction of alkylenediammonium-based divalent cations is maintained. has been completed.

The inorganic perovskite compound according to the present invention based on the above findings includes organic and inorganic cations including amidinium-based monovalent cations, alkylenediammonium-based divalent cations, and cesium ions; Inorganic cations containing divalent metal ions; and anions including halogen ions.

In the present invention, the inorganic perovskite compound, the organic-inorganic perovskite compound, or the perovskite compound may mean a non-organic hybrid material having a perovskite structure. The perovskite structure includes an organic cation (A), a metal cation (M), and an anion (X), and A (organic cation) is AX ₁₂ and is combined with 12 X (anions) to form a cubic octahedral structure, M (metal cation) is MX ₆ and may mean a three-dimensional structure combined with X (anion) in an octahedral structure. That is, the perovskite structure generally has a three-dimensional network in which MX ₆ octahedrons share edges, and A may generally be a cation located in the 12-fold coordination holes between MX ₆ octahedrons. At this time, although the A site ion combining with the anion to form a cubic octahedral structure is collectively referred to as an organic cation, the alkylenediammonium divalent cation and the cesium ion introduced in the present invention form the A site in the perovskite lattice structure. As substituting in , A should not be construed to refer strictly to organic cations only, but to both monovalent organic cations and introduced alkylenediammonium divalent cations and cesium ions. . Accordingly, when considering the cesium ion introduced at the A site, A in the perovskite structure may be referred to as an organic/inorganic cation.

The inorganic perovskite compound according to one embodiment may be an amidinium-based perovskite compound, and the amidinium-based perovskite compound may be the total number of moles of organic/inorganic cations contained in the perovskite compound. 100%, the monovalent amidinium-based cation (amidinium-based monovalent cation) content (number of moles) is at least 80% or more, 85% or more, 90% or more, 92% or more, 93% or more, or 94% It may mean the above perovskite compound. In this case, the content of monovalent amidinium-based cations may be 99% or less, 98% or less, 97% or less, 96% or less, or 95% or less, but is not necessarily limited thereto.

By introducing alkylenediammonium-based divalent cations and Cs ⁺ into the lattice structure of amidinium-based perovskite compounds, the α phase is firmly stabilized without the help of ammonium-based monovalent cations such as thermally unstable methylammonium. The lattice stress caused by the alkylenediammonium divalent cation is remarkably relieved without increasing the band gap energy, and the deep trap formation, which acts as a major loss of photocurrent, is suppressed, resulting in amidinium-based perovskites. The photoelectric properties and stability of these compounds can be greatly improved.

In the inorganic perovskite compound according to one embodiment, the alkylenediammonium-based divalent cation may be a C1-C3 alkylenediammonium cation. Specifically, the C1-C3 alkylenediammonium cation may advantageously be a C1-C2 alkylenediammonium cation, more advantageously a methylenediammonium cation. C1-C3 alkylenediammonium cations, advantageously C1-C2 alkylenediammonium cations, more advantageously alkylenediammonium-based divalent cations when a methylenediammonium cation and a cesium ion are introduced together into the perovskite structure and cesium ions can be homogeneously substituted at the site of organic cation (A) in the lattice structure of the perovskite compound. It is advantageous because little lattice stress is caused.

As a practical example, when a C1-C3 alkylenediammonium cation, advantageously a C1-C2 alkylenediammonium cation, more advantageously a methylenediammonium cation is introduced into the perovskite structure together with a cesium ion, the Williamson-Hall method ( The residual strain (ε) of the perovskite compound calculated using the Williamson-hall method) may be 0.0010 or less, specifically 0.0008 or less, more specifically 0.0006 or less, and even more specifically 0.0005 or less. At this time, the lower limit of the residual stress may be 0.0001 or more, but is not limited thereto. Experimentally, the residual stress of the perovskite compound fills the empty pores (voids) of the porous metal oxide layer and is based on the Williamson-Hall diffraction results measured for the perovskite compound film covering the porous oxide layer. It may be calculated according to the law.

The lattice strain remaining in the perovskite compound increases the defect concentration and increases the non-radiative recombination to increase the open voltage-loss (V _oc -loss). Accordingly, according to an advantageous example, when a C1-C3 alkylenediammonium cation, advantageously a C1-C2 alkylenediammonium cation, and more advantageously a methylenediammonium cation and a cesium ion are introduced into the perovskite structure, By suppressing the open-circuit voltage-loss, the photoelectric conversion efficiency of the perovskite compound can be improved.

In the inorganic perovskite compound according to one embodiment, the molar ratio between the divalent alkylenediammonium cation and the cesium ion is 1:0.9 to 1.1, specifically 1:0.95 to 1.05, more specifically 1:0.98 to 1.02, substantially 1:1. This may mean that alkylenediammonium-based divalent cations and cesium ions are incorporated into the perovskite structure in substantially equal amounts. By incorporation of such a substantially equal amount, the amidinium-based perovskite compound can have lattice stress relieved to a level substantially reaching the undoped level, and also the phase in which the alkylenediammonium-based divalent cation is introduced alone It can have significantly improved thermal stability and light stability than rovskite compounds.

When the alkylenediammonium-based divalent cation and the cesium ion are incorporated into the perovskite structure in substantially equal amounts, the perovskite compound, specifically the amidinium-based perovskite compound, is based on 1 mole of the inorganic cation. , and may contain 0.010 to 0.050 moles of alkylenediammonium-based divalent cations. In this case, the amount of cesium ions may be 0.009 to 0.055, specifically 0.0095 to 0.0525, more specifically 0.0098 to 0.051, and substantially 0.010 to 0.050 based on 1 mole of inorganic cations.

The content of the above-mentioned alkylenediammonium-based divalent cation and cesium ion can ensure phase stabilization while excluding monovalent ammonium cations such as methylammonium, which are thermally unstable, and also, the alkylenediammonium-based divalent cation is The lattice stress caused by the alkylenediammonium-based divalent cation can be alleviated without increasing the band gap energy compared to the perovskite compound contained alone, and furthermore, the alkylenediammonium-based divalent cation is alone It is a range in which thermal stability and light stability can be improved more than the perovskite compound contained in .

Advantageously, when the alkylenediammonium-based divalent cation and the cesium ion are incorporated into the perovskite structure in substantially equal amounts, the perovskite compound, specifically the amidinium-based perovskite compound, is an inorganic cation 1 On a mole basis, it may contain from 0.025 to 0.035 moles of alkylenediammonium-based divalent cations. In this case, the cesium ion may be 0.0225 to 0.0385, specifically 0.02375 to 0.03675, more specifically 0.0245 to 0.0357, and substantially 0.025 to 0.035 based on 1 mole of the inorganic cation.

Residual stress of a perovskite compound calculated using the Williamson-Hall method when alkylenediammonium divalent cations and cesium ions are incorporated into the perovskite structure in substantially equal amounts and in an advantageous content range (ε) may be only 0.0007 or less, substantially 0.0006 or less, and more substantially 0.0005 or less.

Due to such a low residual stress, the formation of deep traps and non-radiative recombination of the perovskite compound are greatly suppressed, and the photoelectric conversion efficiency may be substantially greater than 25%.

Through previous experiments, it has been confirmed that phase stability, photoelectric conversion efficiency, thermal stability, etc. are improved by incorporating an alkylenediammonium-based divalent cation alone into the perovskite structure. Therefore, by comparing the physical properties of the perovskite compound according to an embodiment of the present invention with the physical properties of the reference compound using the perovskite compound in which only these alkylenediammonium-based divalent cations are mixed as a reference compound, alkyl The technical effect of co-introduction of rendiammonium-based divalent cations and Cs ⁺ can be more clearly shown.

The reference compound may be a perovskite compound composed of an amidinium-based monovalent cation, an alkylenediammonium-based divalent cation, a divalent metal ion, and a halogen anion, and substantially, the reference compound is Cs ⁺ It is composed of the same organic and inorganic cations, inorganic cations and anions as the perovskite compound according to one embodiment of the present invention, except that it is not incorporated into the rovsite structure, and the best photoelectric conversion properties and stability through previous experiments It may be a perovskite compound in which 0.038 mol of alkylenediammonium-based divalent cations relative to 1 mol of inorganic cations are incorporated into the perovskite lattice structure.

As described above, when the alkylenediammonium divalent cation and the cesium ion are incorporated into the perovskite structure in substantially the same amount, and incorporated in an advantageous content range, the residual stress (ε) of the perovskite compound It may be 0.0007 or less, substantially 0.0006 or less, and more substantially 0.0005 or less, and the residual stress of the reference compound may be 0.0015 level. That is, alkylenediammonium-based divalent cations and cesium ions are incorporated into the perovskite structure in an advantageous content range, and the residual stress can be reduced by about 60% or more compared to the reference compound.

In addition, when the alkylenediammonium-based divalent cation and the cesium ion are incorporated into the perovskite structure in substantially the same amount and incorporated in an advantageous content range, the Urbach energy (Eu) of the perovskite compound It may be 90% or less compared to the Ubach energy of the reference compound. As a practical example, when the alkylenediammonium-based divalent cation and the cesium ion are incorporated into the perovskite structure in substantially equal amounts, and incorporated in an advantageous content range, the Ubach energy of the perovskite compound is 28 meV or less, specifically It may be 27 meV or less. At this time, the lower limit of the Ubach energy is not particularly limited, but may be 10 meV, 15 meV, or 20 meV or more.

In addition, when the alkylenediammonium-based divalent cation and the cesium ion are incorporated into the perovskite structure in substantially the same amount, and incorporated in an advantageous content range, the perovskite calculated from the measurement result of the thermally stimulated current The trap density of the skyte compound may be 60% or less, specifically 55% or less, and more specifically 50% or less, compared to the trap density of the reference compound. As a practical example, when the alkylenediammonium-based divalent cation and the cesium ion are incorporated into the perovskite structure in substantially equal amounts and in an advantageous content range, the trap density of the perovskite compound is 8x10 ¹⁶ cm ^-3 Or less, specifically 6x10 ¹⁶ cm ^-3 or less, more specifically 5x10 ¹⁶ cm ^-3 or less. At this time, the lower limit of the trap density is not particularly limited, but may be 1x10 ¹⁵ cm ^-3 or more, or 5x10 ¹⁵ cm ^-3 or more.

In addition, when the alkylenediammonium-based divalent cation and the cesium ion are incorporated into the perovskite structure in substantially the same amount and in an advantageous content range, a temperature of 85 ° C. and a relative humidity of 15% or less under light-shielding conditions In the thermal stability test, the perovskite compound exhibited a photoelectric conversion efficiency of 80% or more, specifically 81% or more, more specifically 82% or more, based on the photoelectric conversion efficiency before the test, at the time of exposure for 1300 hours (test time point). Conversion efficiency can be maintained. For comparison, looking at the stability of the reference compound during the same thermal stability test, the photoelectric conversion efficiency of the reference compound is already reduced to less than 80% at the time of 700 hours of the test.

In addition, when the alkylenediammonium divalent cation and the cesium ion are incorporated into the perovskite structure in substantially the same amount and in an advantageous content range, conditions of 150 ° C. temperature, atmospheric atmosphere, and 15 to 25% relative humidity During the long-term thermal stability test performed in , the perovskite compound can maintain a photoelectric conversion efficiency of 80% or more based on the photoelectric conversion efficiency before the test at the time of the 30-hour test. For comparison, looking at the stability of the reference compound in the same long-term thermal stability test, the photoelectric conversion efficiency of the reference compound is already reduced to less than 80% at the time of the 15-hour test.

In addition, when the alkylenediammonium-based divalent cation and the cesium ion are incorporated into the perovskite structure in substantially the same amount and in an advantageous content range, under AM 1.5G, UV-non-filtering (including UV) conditions, the maximum When light stability is tested through power point tracking, the perovskite compound can maintain a photoelectric conversion efficiency of 85% or more, specifically, 90% or more based on the photoelectric conversion efficiency before the test at the time of 400 hours of testing.

As described above, the alkylenediammonium-based divalent cations and cesium ions may be incorporated into the lattice structure of the perovskite compound and may occupy lattice sites. In detail, alkylenediammonium-based divalent cations and cesium ions may be substituted for organic cations (A) in the lattice structure of the perovskite compound, and a homogeneous solid phase may be formed.

In terms of doping, the perovskite compound according to an embodiment of the present invention may be co-doped with an alkylenediammonium divalent cation and a cesium ion dopant. In detail, the perovskite compound is a base material of a perovskite structure containing an amidinium-based monovalent cation, an inorganic cation including a divalent metal ion, and an anion including a halogen ion; and a dopant of divalent cations and cesium ions doped into the base material.

In terms of chemical formula, the perovskite compound according to an embodiment of the present invention may satisfy Chemical Formula 1.

(Formula 1)

AMX ₃

A is an organic/inorganic cation containing an amidinium-based monovalent cation, an alkylenediammonium-based divalent cation, and a cesium ion, M is a cation containing a divalent metal ion, and X is an anion containing a halogen ion .

A perovskite compound according to an advantageous example may satisfy Formula 2.

(Formula 2)

A _1-2x DA _x C _x MX ₃

A is an amidinium-based monovalent cation, DA is an alkylenediammonium-based divalent cation, C is a cesium ion, M is a cation containing a divalent metal ion, and X is an anion containing a halogen ion , x is a real number between 0.010 and 0.050, advantageously between 0.025 and 0.035.

Although the perovskite compound according to one embodiment has been described above based on Formulas 1 and 2, according to the laws of thermodynamics, the perovskite compound is located at an interstitial site in the perovskite crystal structure Of course, it may include non-metallic anions, organic cation (A) vacancies (vacancy, V _A ^- ) or anions located at interstitial sites and vacancies at organic cation sites, and formulas 1 and 2 are stable ( Thermodynamic equilibrium state, charge neutral state) should be analyzed in consideration of defects that occur.

In one embodiment of the present invention, the amidinium-based cation may satisfy Formula 3 below.

(Formula 3)

In Formula 3, R ₇ to R ₁₁ are each independently hydrogen, C1-C24 alkyl, C3-C20 cycloalkyl or C6-C20 aryl.

In Formula 3, R ₇ to R ₁₁ may be appropriately selected depending on the use of the perovskite compound. In detail, the size of the unit cell of the perovskite compound is related to the band gap, and may have a band gap energy (eg, 1.1 to 1.5V level) suitable for use as a solar cell in a small unit cell size. Accordingly, when considering bandgap energy suitable for use as a solar cell, R ₇ to R ₁₁ are each independently hydrogen, amino or C1-C24 alkyl, specifically, hydrogen, amino or C1-C7 alkyl, More specifically, it may be hydrogen, amino, or methyl, and more specifically, R ₇ may be hydrogen, amino, or methyl, and R ₃ to R ₆ may be hydrogen. As a practical example, the amidinium-based ion is a formamidinium (NH ₂ CH=NH ₂ ⁺ ) ion, acetamidinium (NH ₂ C(CH ₃ )=NH ₂ ⁺ ) ion, or guamidine Niium (Guamidinium, NH ₂ C (NH ₂ )=NH ₂ ⁺ ) ion, etc. may be mentioned, but is not limited thereto. This specific example is an example considering the use of the perovskite compound, that is, the use as a light absorber of sunlight, design of the wavelength band of light to be absorbed, design of the emission wavelength band when used as a light emitting layer of a light emitting device, When used as a semiconductor element of a transistor, R ₇ to R ₁₁ may be appropriately selected in consideration of an energy band gap and a threshold voltage.

In one embodiment, the inorganic cation may be a divalent metal ion, and the divalent metal ion is Cu ²⁺ , Ni ²⁺ , Co ²⁺ , Fe ²⁺ , Mn ²⁺ , Cr ²⁺ , Pd ²⁺ , Cd ²⁺ , Ge ²⁺ , Sn ²⁺ , Pb ²⁺ , Eu ²⁺ , Yb ²⁺ or any combination thereof.

In one embodiment, the anion may be a halogen ion, and the halogen of the halogen ion may be F, Cl, Br, I or any combination thereof.

When considering the use of a light absorber, which is the main use of the perovskite compound, the anion preferably contains I ^- as a halide anion. In one embodiment of the present invention, as the α-phase stabilization is very firmly achieved by the alkylenediammonium divalent cation and the cesium ion, the halide anion may be free from Br, which has a smaller band gap energy. This means that the implementation of perovskite compounds is possible. However, this can be obtained by the effect according to one embodiment of the present invention, if necessary, the perovskite compound may contain Br as an anion, and the present invention provides a perovskite compound containing Br does not exclude

In one embodiment, the perovskite compound may be in the form of a film or particle, but is not limited thereto.

The present invention includes a film of the perovskite compound described above.

The present invention includes a method for producing the above-described perovskite compound. The above-described perovskite compound is co-doped with two types of dopants, and substantially the same solution and method used for preparing a conventional perovskite compound are used, but adding dopants to the solution (only ), co-doped perovskite compounds can be prepared.

Accordingly, the solution used in preparing the perovskite compound (hereinafter, the precursor solution) is a halide of a monovalent amidinium group cation, a halide of an alkylenediammonium-based divalent cation, a cesium halide, May contain metal (of divalent metal) halides and solvents. Independently, the precursor solution may contain a monovalent amidinium cation, a cesium ion, an alkylenediammonium divalent cation, a divalent metal ion, an anion, and a solvent. Independently of this, the precursor solution may contain a base material, a cesium halide, a halide of an alkylenediammonium-based divalent cation, and a solvent. In this case, the base material may be a perovskite compound (base material) composed of amidinium-based monovalent cations, divalent metal ions, and halogen ions.

As the ions contained in the solution are crystallized into a perovskite compound (spontaneous crystallization) by spontaneous crystallization following application of the precursor solution and removal of the solvent, the precursor solution is a monovalent phosphor to satisfy the desired composition of the perovskite compound. It may contain medium-based cations, alkylenediammonium-based divalent cations, cesium ions, inorganic cations including metal ions, and anions including halogen ions.

Considering the specific use of the perovskite compound, if necessary, the precursor solution may further contain conventionally known additives. As a specific example, the precursor solution may further contain a surface treatment agent known as an additive for improving interfacial properties with an electron carrier in a perovskite solar cell. As is known, the surface treatment agent may be a C1 to C3 alkylammonium chloride capable of thermally decomposing at a temperature of 200° C. or lower and generating chlorine. One example of a practical surface treatment agent is methylammonium chloride. The precursor solution may contain 0.20 to 1.00 moles of C1 to C3 alkylammonium chloride based on 1.00 moles of the ionic metal contained in the solution, but of course the present invention cannot be limited by the specific type and content of the additive. to be.

The solvent in the precursor solution may be a polar organic solvent in which the perovskite compound is dissolved and can be easily volatilized and removed when dried. For example, the polar organic solvent is gamma-butyrolactone, formamide, N,N-dimethylformamide, diformamide, acetonitrile, tetrahydrofuran, dimethyl sulfoxide, diethylene glycol, 1-methyl- 2-pyrrolidone, N,N-dimethylacetamide, acetone, α-terpineol, β-terpineol, dihydro terpineol, 2-methoxy ethanol, acetylacetone, methanol, ethanol, propanol, It may be one or two or more selected from butanol, pentanol, hexanol, ketone, methyl isobutyl ketone, etc., but the present invention is not limited by the specific material of the solvent. In this case, the molar concentration of the metal ion in the precursor solution may be 0.5M to 1.4M, specifically 1.0 M to 1.4 M, but the present invention is not limited thereto.

A film of the above-described perovskite compound may be prepared by coating and drying the above-described precursor solution on a substrate. The sphere coating and drying method for producing a perovskite compound film can be prepared using a conventional solution coating method, and further, a solvent-non-solvent coating method in which a perovskite solution and a non-solvent are sequentially applied can be manufactured using Such a solution coating method and a solvent-non-solvent coating method may be performed with reference to Korean Registered Patent No. 10-1547877 or No. 10-1547870 of the present applicant. However, when the precursor solution further contains a surface treatment agent such as methylammonium chloride, annealing of the film prepared using the precursor solution at a temperature equal to or higher than the pyrolysis temperature of the surface treatment agent may be performed, of course. For example, when the precursor solution further includes methylammonium chloride as a surface treatment agent, annealing may be performed at 100 to 180 °C, specifically 140 to 180 °C, and more specifically 150 to 160 °C.

The present invention includes a device equipped with (including a perovskite compound) the above-described perovskite compound.

As a specific example, the perovskite-based device includes a photovoltaic device (hereinafter referred to as a perovskite solar cell) including the above-described perovskite compound as a light absorber. At this time, the perovskite solar cell is a solar cell in which the above-described perovskite compound is attached to a porous support in the form of particles (quantum dots or nanoparticles), and a layer of the above-described perovskite compound is included as a light absorbing layer. It may contain solar cells.

In one embodiment, the perovskite solar cell may include the above-described perovskite compound layer as a light absorption layer, and together with the first charge carrier positioned under the light absorption layer; a second charge carrier located above the light absorption layer and transporting charges complementary to the first charge carrier; a first electrode positioned below the first charge carrier; and a second electrode positioned on the second charge carrier. That is, a perovskite solar cell according to a practical example includes a first electrode; a first charge carrier; a light absorption layer comprising the above-described perovskite compound; a second charge carrier that transfers charges complementary to those transferred in the first charge carrier; and a second electrode. In this case, at least one of the first electrode and the second electrode may be a transparent electrode.

The electrode (first electrode or second electrode) may be a conductive electrode that is in ohmic contact with the charge carrier, and any material commonly used as an electrode material for a front electrode or a rear electrode in a solar cell may be used. As a non-limiting example, when the electrode (first electrode or second electrode) is the electrode material of the rear electrode, the second electrode is gold, silver, platinum, palladium, copper, aluminum, carbon, cobalt sulfide, copper sulfide, oxide It may be one or more materials selected from nickel and composites thereof. As a non-limiting example, if the electrode (first electrode or second electrode) is a transparent electrode, the electrode may be fluorine-doped tin oxide (FTO), indium-doped tin oxide (ITO), or ZnO. , CNT (carbon nanotube), may be an inorganic conductive electrode such as graphene (Graphene), may be an organic conductive electrode such as PEDOT: PSS.

The electrode may be formed on a transparent substrate (support) that is a rigid substrate (support) or a flexible substrate (support) through a deposition process such as physical vapor deposition or chemical vapor deposition. can As an example of the transparent substrate (support), the hard substrate may be a glass substrate, and the flexible substrate may be polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), polycarbonate (PC), polypropylene ( PP), triacetyl cellulose (TAC), or polyethersulfone (PES), but it goes without saying that the present invention cannot be limited to specific materials of the substrate.

As the first charge carrier and the second charge carrier move complementary charges, the second charge carrier may be a hole carrier when the first charge carrier is an electron carrier, and the second charge carrier may be a hole carrier when the first charge carrier is a hole carrier. The charge carrier may be an electron carrier. In addition, the charge carrier (first charge carrier or second charge carrier) may be a porous film, a non-porous film (dense film), or a laminated film of a non-porous film and a porous film.

The hole transporter may be an organic hole transporter, an inorganic hole transporter, or a laminate thereof. The inorganic hole transporter may include an oxide semiconductor, a sulfide semiconductor, a halide semiconductor, or a mixture thereof having hole conductivity, that is, a p-type semiconductor. As specific examples, examples of oxide semiconductors include NiO, CuO, CuAlO ₂ , CuGaO ₂ and the like, examples of sulfide semiconductors include PbS and examples of halide semiconductors include PbI ₂ , but the present invention provides inorganic holes It is not limited by the delivery material. The thickness of the inorganic hole transporter may be 50 nm to 10 μm, specifically 10 nm to 1000 nm, and more specifically 50 nm to 1000 nm. When the hole transporter is porous, the specific surface area may be 10 to 100 m ² /g, and the average diameter of the p-type semiconductor particles constituting the hole transporter may be 5 to 500 nm. The porosity (apparent porosity) of the porous hole transporter may be 30% to 65%, specifically 40% to 60%.

When the hole transporter includes an organic hole transporter, the organic hole transporter may include an organic hole transporter, specifically, a monomolecular or polymeric organic hole transporter (hole conducting organic material). Any organic hole transport material used in a conventional inorganic semiconductor-based solar cell using inorganic semiconductor quantum dots as a dye may be used as the organic hole transport material. Non-limiting examples of single- or low-molecular organic hole transport materials include pentacene, coumarin 6, 3-(2-benzothiazolyl)-7-(diethylamino)coumarin, zinc phthalocyanine (ZnPC), and CuPC (copper phthalocyanine), TiOPC (titanium oxide phthalocyanine), Spiro-MeOTAD (2,2',7,7'-tetrakis(N,N-p-dimethoxyphenylamino)-9,9'-spirobifluorene), F16CuPC (copper (II) 1 ,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25-hexadecafluoro-29H,31H-phthalocyanine), SubPc (boron subphthalocyanine chloride) and N3 (cis -di(thiocyanato)-bis(2,2'-bipyridyl-4,4'-dicarboxylic acid)-ruthenium (II)), but may include one or more materials selected from, but is not limited thereto.

If the organic hole transport material is a polymer, it may include one or more materials selected from a thiophene-based, para-phenylene-vinylene-based, carbazole-based, and triphenylamine-based material as a hole-conducting polymer, but is not limited thereto. As a non-limiting example of the polymer organic hole transport material, P3HT (poly[3-hexylthiophene]), MDMO-PPV (poly[2-methoxy-5-(3',7'-dimethyloctyloxyl)]-1,4-phenylene vinylene), MEH-PPV (poly[2-methoxy-5-(2''-ethylhexyloxy)-p-phenylene vinylene]), P3OT (poly(3-octyl thiophene)), POT (poly(octyl thiophene)), P3DT (poly(3-decyl thiophene)), P3DDT (poly(3-dodecyl thiophene), PPV (poly(p-phenylene vinylene)), TFB (poly(9,9'-dioctylfluorene-co-N-(4- butylphenyl)diphenyl amine), Polyaniline, Spiro-MeOTAD ([2,22′,7,77′-tetrkis (N,N-di-p-methoxyphenyl amine)-9,9,9′-spirobi fluorine]), PCPDTBT (Poly[2,1,3-benzothiadiazole- 4,7-diyl[4,4-bis(2-ethylhexyl-4H- cyclopenta [2,1-b:3,4-b']dithiophene-2,6- diyl]], Si-PCPDTBT(poly[(4,4′-bis(2-ethylhexyl)dithieno[3,2-b:2′,3′-d]silole)-2,6-diyl-alt-( 2,1,3-benzothiadiazole)-4,7-diyl]), PBDTTPD (poly((4,8-diethylhexyloxyl) benzo([1,2-b:4,5-b']dithiophene)-2,6 -diyl)-alt-((5-octylthieno[3,4-c]pyrrole-4,6-dione)-1,3-diyl)), PFDTBT(poly[2,7-(9-(2-ethylhexyl )-9-hexyl-fluorene)-alt-5,5-(4', 7, -di-2-thienyl-2',1' , 3'-benzothiadiazole)]), PFO-DBT (poly[2,7-.9,9-(dioctyl-fluorene)-alt-5,5-(4',7'-di-2-.thienyl- 2', 1', 3'-benzothiadiazole)]), PSiFDTBT (poly[(2,7-dioctylsilafluorene)-2,7-diyl-alt-(4,7-bis(2-thienyl)-2,1, 3-benzothiadiazole)-5,5′-diyl]), PSBTBT(poly[(4,4′-bis(2-ethylhexyl)dithieno[3,2-b:2′,3′-d]silole)-2 ,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl]), PCDTBT (Poly [[9-(1-octylnonyl)-9H-carbazole-2,7-diyl] -2 ,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediazole]), PFB (poly(9,9′-dioctylfluorene-co-bis(N,N′-(4, butylphenyl))bis(N,N′-phenyl-1,4-phenylene)diamine), F8BT (poly(9,9′-dioctylfluorene-co-benzothiadiazole), PEDOT (poly(3,4-ethylenedioxythiophene)), PEDOT :PSS (poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate)), PTAA (poly(triarylamine)), Poly(4-butylphenyl-diphenyl-amine), and copolymers thereof. However, it is not limited thereto. The hole transport layer is tertiary butyl pyridine (TBP), lithium bis(trifluoro methanesulfonyl)imide (LiTFSI), bis(trifluoromethane) sulfonimide (HTFSI), 2,6-lutidine and Tris(2-(1H-pyrazol-1-yl) Of course, known additives such as pyridine) cobalt (III) may be further contained. The hole transporter may be a thin film of an organic hole transport material, and the thickness of the thin film may be 10 to 500 nm, but is not limited thereto.

The electron transporter may be an organic electron transporter, an inorganic electron transporter, or a laminate thereof. The electron transporting material may be an electron conductive organic material layer, an inorganic material layer, or a laminate thereof.

The electron conductive organic material may be an organic material used as an n-type semiconductor in a typical organic solar cell. As specific examples, electron conductive organic materials include fullerenes (C60, C70, C74, C76, C78, C82, C95), PCBM ([6,6]-phenyl-C61butyric acid methyl ester) and C71-PCBM, C84-PCBM, PC ₇₀ Fulleren-derivatives including BM ([6,6]-phenyl C ₇₀ -butyric acid methyl ester), PBI (polybenzimidazole), PTCBI (3,4,9,10-perylenetetracarboxylic bisbenzimidazole), F4 -TCNQ (tetra urorotetracyanoquinodimethane) or mixtures thereof may be included, but is not limited thereto.

The electron-conductive inorganic material may be an electron-conductive metal oxide used for electron transfer in a conventional quantum dot-based solar cell or dye-sensitized solar cell. As a specific example, the electron conductive metal oxide may be an n-type metal oxide semiconductor. An example of an n-type metal oxide semiconductor is Ti oxide, Zn oxide, In oxide, Sn oxide, W oxide, Nb oxide, Mo oxide, Mg oxide, Ba oxide, Zr oxide, Sr oxide, Yr oxide, La oxide, V oxides, Al oxides, Y oxides, Sc oxides, Sm oxides, Ga oxides, In oxides, and SrTi oxides, and the like may be selected from one or more materials, and mixtures thereof or composite oxides thereof may be mentioned, but are limited thereto. it is not going to be

The electron transporting material may have a thickness of 50 nm to 10 μm, specifically 50 nm to 1000 nm. When the electron transporting material is porous, its specific surface area may be 10 to 100 m ² /g, and the average diameter of metal oxide particles constituting the electron transporting material may be 5 to 500 nm. The porosity (apparent porosity) of the porous electron transporting material may be 30% to 65%, specifically 40% to 60%.

When the electron transporting body has a porous structure, an electron-conductive inorganic or organic film is further provided between the first electrode and the electron transporting body to prevent direct contact between the light absorber and the electrode and simultaneously transfer electrons. can

The thickness of the light absorption layer may be 1 to 2,000 nm, specifically 10 to 1000 nm, and more specifically 50 to 800 nm. Such a thickness is advantageous in that it is possible to sufficiently secure a photoactive region generating photoelectrons and photoholes by absorbing light while preventing current extinction due to recombination during photocurrent movement, and to sufficiently absorb irradiated light.

The present invention includes a solar cell module in which two or more cells are arranged and electrically connected to each other, using the above-described solar cell as a unit cell. The solar cell module may have an array and structure of cells commonly used in the field of solar cells, and may further include a conventional concentrating means for concentrating sunlight and a conventional optical block for guiding a path of sunlight.

The present invention includes a device to which power is supplied by the solar cell or solar cell module described above.

In another embodiment, the device includes an electronic device including the above-described perovskite compound as a semiconductor material. Electronic devices may include diodes (p-n diodes, p-i-n diodes, etc.), junction transistors (BJTs), field effect transistors (FETs), and the like.

In another embodiment, a device includes a sensor comprising the perovskite compound described above.

Hereinafter, based on the perovskite solar cell, which is the most representative use of the perovskite compound, the excellence of the perovskite compound according to the present invention is experimentally shown, but the present invention can be limited by the examples presented. Of course none.

(Manufacture example)

Formamidinium iodide (FAI) was synthesized by adding 20 mg of formamidine acetate salt and 30 mL of HI to a round bottom flask and rotating the flask at 60° C. and 1 mba for 1 hour. The synthesized FAI was dissolved in ethanol, recrystallized using ethyl ether, and dried at room temperature for 24 hours in a vacuum chamber.

Formamidinium lead triiodide (FAPbI ₃ , Formamidinium lead triiodide) powder was retrograde in an oil bath at 120 ° C after adding FAI and PbI ₂ to 11 mL of 2methoxyethanol at a molar ratio of 1: 1 and stirring. (retrograde method) was prepared by precipitation. The FAPbI ₃ powder recovered by filtration was baked at 150° C. for 30 minutes.

(Example 1-4)

A TiO ₂ thin film having a thickness of 50 nm was prepared on a fluorine doped tin oxide (FTO)-glass substrate (Asahi glass) by a spray pyrolysis method. Spray pyrolysis was performed using a titanium diisopropoxide bis(acetylacetonate) solution (75 wt.% in isopropanol, Sigma-Aldrich), which was placed on a hot plate maintained at 450 °C. The thickness was adjusted by repeating the method of spraying on the FTO substrate for 3 seconds and stopping for 10 seconds.

TiO ₂ paste (Sharechem) was diluted with a mixed solvent of 2-methoxyethanol:terpineol in a weight ratio of 3.5:1, and the diluted TiO ₂ paste was spun on a substrate on which a TiO ₂ thin film was formed at 1500 rpm for 40 seconds. After coating, a porous TiO ₂ layer having a thickness of about 150 to 200 nm was prepared by heat treatment at 500° C. for 1 hour.

The precursor solution for preparing the perovskite compound film (light absorption layer) is synthesized in Preparation Example in a mixed solvent in which NN-dimethylformamide (DMF):dimethylsulfoxide (DMSO) is mixed in a volume ratio of 8:1 It was prepared by adding FAPbI ₃ , CsI, MDACl ₂ (methylenediamine dihydrochloride) and MACl (methylammonium chloride) and stirring. At this time, the FA _1-2x Cs _x MDA _x PbI ₃ (FA=Formamidinium, MDA=methylenediammonium) perovskite compound of the light absorption layer has a molar ratio of FAPbI ₃ : CsI : MDACl ₂ : MACl of 1 : x : x : 0.35 It was prepared using the precursor solution introduced so that x = 0.01 (Example 1), 0.02 (Example 2), 0.03 (Example 3) or 0.04 (Example 4). The prepared precursor solution had a molar concentration of about 1.26 M based on FAPbI ₃ and MDACl ₂ .

After dropping a certain amount of the prepared perovskite solution on the porous TiO ₂ layer, spin coating (1 mL of ethyl ether was quickly dropped on top at 1000 rpm for 10 seconds and 5000 rpm for 15 seconds) to prepare a thin film at 150 ° C. After heat treatment for 15 minutes, annealing was performed at 100 °C for 15 minutes to prepare a light absorption layer of FA _1-2x Cs _x MDA _x PbI ₃ . As is known, in the heat treatment process, all of the additive MACl along with the solvent remaining in the film evaporated and disappeared.

Then, after spin-coating (5000 rpm, 30 seconds) a solution in which phenylethylammonium iodide (hereinafter referred to as PEAI) was dissolved in 2-propanol on the surface of the light absorption layer, spiro-OMeTAD Dissolved in chlorobenzene (90 mg (spiro-OMeTAD) / chlorobenzene 1 mL), t-BP (tert-Butylpyridine) 39.5 μL, Li-TFSI (bis (trifluoromethane) sulfonimide lithium salt) 23 μL and Co-TFSI (FK209 Co( Ⅲ) After forming an organic hole transport layer by spin-coating (3000 rpm, 30 seconds) a hole transfer solution to which 10 μL of TFSI salt, Lumtec.) was added, on the light absorption layer, Au (70 nm) was thermally deposited as a second electrode to A battery was made. Hereinafter, the solar cell or the perovskite compound film prepared in Example 1, 2, 3 or 4 is FA _1-x MC _x PbI ₃ (x = 1, 2, 3 or 4) in the drawing or description for ease of recognition. ) or x = 1, 2, 3 or 4, but this designation does not mean the actual formula or content. The perovskite compound film, substantially referred to as 'FA _1-x MC _x PbI ₃ (x=1, 2, 3 or 4)' or 'x=1, 2, 3 or 4', has the formula FA _1-2x Cs _x MDA _x PbI ₃ (x=0.01, 0.02, 0.03 or 0.04).

(Comparative example)

To prepare a perovskite compound film of FA _(1-0.038) DMA _(0.038) PbI ₃ , as a precursor solution, NN-dimethylformamide (DMF) : dimethylsulfoxide (DMSO) was mixed at a volume ratio of 8:1. A perovskite solar cell was prepared in the same manner as in Examples 1 to 4, except that a precursor solution prepared by adding FAI: PbI ₂ : MDACl ₂ : MACl to the mixed solvent at a molar ratio of 1: 1: 0.038: 0.5 was used. manufactured. Hereinafter, the solar cell manufactured in Comparative Example may be referred to as 'control' in drawings or descriptions.

(Examples 5 and 6)

The perovskite solar cell for the thermal stability test and the long-term thermal stability test is manufactured in the same manner as in the previous embodiment in order to prevent the test result from being influenced by the thermal degradation of the hole transport material, but the material of the hole transport layer prepared differently.

The solar cell (Example 5) used in the thermal stability test was prepared in the same manner as in Example 3, but PTAA (poly (triaryl amine), Mn = 17,500 g mol ^-1 , EM index) was added to chlorobenzene on the surface of the light absorption layer. was dissolved in (10 mg PTAA/chlorobenzene 1 mL) and spin-coated (3000 rpm, 30 seconds) the hole transfer solution to which 4 μL of t-BP and 7.5 μL of Li-TFSI were added on the light absorption layer to form an organic hole transport layer. .

The solar cell (Example 6) used in the long-term thermal stability test was prepared in the same manner as in Example 3, but CuPc (copper phthalocyanine) was dissolved in chlorobenzene (10 mg CuPc / chlorobenzene 1 mL) hole transfer on the surface of the light absorption layer The solution was prepared by spin-coating (3000 rpm, 30 seconds) on the light absorption layer to form an organic hole transport layer.

<Analysis method>

Optical properties were analyzed using ultraviolet-visible light (UV-Vis) spectroscopy (Shimadzu UV-2600).

The crystal structure was analyzed using X-ray diffraction (D/MAX2500V/PC). X-ray diffraction analysis was performed with Cu kα rays, 5-50°, scan rate 0.02°.

Photoluminescence spectra were obtained using a commercial time-correlated single photon counting (TCSPC) set-up (FluoTime 300, PicoQuant GmbH) equipped with a PMA-C-192-M detector and a high-resolution excitation monochromator. was measured.

Current density-voltage (JV) characteristics were measured using a solar simulator (Newport, Oriel Sol3A class AAA) and a Keithley 2420 source meter with an AM1.5 filter and an irradiation intensity of 100 mWcm ^-2 . To avoid overestimation of the photocurrent density, the active area was determined by a metal mask placed in front of the solar cell. Excluding the case of measuring a large area of 1 cm x 1 cm, the active area was 4 mm x 4 mm when measuring the current density-voltage of the solar cell. A spectral mismatch factor of 1.05 was used for all JV measurements.

External quantum efficiency (EQE) was measured using an internal quantum efficiency system (Oriel, IQE 200B) under irradiation with a 100 W xenon lamp.

The microstructure and thickness of the film were measured through a scanning electron microscope (Cold FE-SEM, SU-8220).

Thermally stimulated current (TSC) measurements were performed in an actual solar cell structure, and TSC signals were measured in a closed cycle He cryostat. The solar cell sample was cooled to 30 K in the dark and then exposed to light for 10 minutes to generate a photo carrier. A Xe lamp (254 W) was used as a light source, and the distance between the light source and the solar cell was fixed at 33 cm. After a dwell time of 10 min in the dark, the sample was heated to 300 K at a rate of 17 Kmin ⁻¹ . The sample's TSC signal was measured using a Keithley 2636B source meter with zero bias.

<Stability test conditions>

Thermal stability test: A thermal stability test was performed by leaving the perovskite solar cell in an unencapsulated state under conditions of a relative humidity of less than 15%, a temperature of 85 ° C., ambient air and dark conditions.

Long-term thermal stability test: A long-term thermal stability test was performed by leaving the non-encapsulated perovskite solar cell under conditions of 15-25% relative humidity, 150 °C temperature, and ambient air.

Maximum power point tracking stability test: Under 1 Sun, AM 1.5G lighting, the voltage was fixed at the maximum power point voltage (V _MPP ), and then the current output was tracked to conduct a stability test during continuous maximum power point operation.

In the following description, the measurement results of the perovskite compound film prepared in Examples or Comparative Examples are measured for the perovskite compound film formed on the porous TiO2 layer and before the hole transport layer is formed in Examples or Comparative Examples This is the result.

1 shows Example 1 (x=1 in FIG. 1), Example 2 (x=2 in FIG. 1), Example 3 (x=3 in FIG. 1), and Example 4 (x=4 in FIG. 1). And in Comparative Example (Control in FIG. 1), it is a view showing the measured Cu Kα X-ray diffraction pattern of the perovskite compound film (light absorption layer) formed on the porous TiO ₂ layer. As can be seen in FIG. 1, diffraction peaks appeared at 2θ of about 14 ° and 28 °, and it can be seen that no diffraction peak was detected at 11.6 °, which is the main peak of the δ phase. The diffraction peaks at 14 ° and 28 ° are the (001) and (002) crystal plane diffraction peaks of the α-phase amidinium-based perovskite compound. production can be seen.

In addition, in FIG. 1, compared to Control in which only alkylenediammonium-based divalent cations are added, when alkylenediammonium-based divalent cations and Cs ⁺ are added at the same time, diffraction peaks of 14 ° and 28 °, which are the main peaks of the α phase, It can be seen that the strength increases significantly. The increase in peak intensity is due to the crystallinity of the amidinium-based perovskite compound or the preferential orientation of the perovskite compound grains forming the film as the alkylenediammonium-based divalent cation and Cs ⁺ are added at the same time ( means an increase in preferred orientation.

FIG. 2 is a diagram showing only the 2θ 13.5 to 14.4° region in FIG. 1 . Control's perovskite compound is a sample containing 3.8 mol% of alkylenediammonium-based divalent cations. Therefore, looking at the peak positions of x = 3 (3 mol%) and x = 4 (4 mol%) and the peak position of the control in FIG. 2, the direction in which 2θ increases relative to the peak center of the perovskite compound of Control You can check that the . The shift of this peak means that the alkylenediammonium divalent cation and Cs ⁺ are homogeneously substituting in the perovskite lattice structure and solid-phase alloyed, and the peak shifts in the direction of increasing 2θ compared to Control An alkylenediammonium-based divalent cation is added to the silver amidinium-based perovskite compound, and the increased interplanar distance can mitigate the size difference between the alkylenediammonium-based divalent cation and the amidinium-based monovalent cation. This means that the interplanar distance is reduced again as Cs ⁺ that can be added together.

In addition, looking at the crystal size in the perovskite compound film calculated through Scherrer's equation based on the X-ray diffraction results of FIGS. 1 and 2, in the case of the comparative example (Control), 51.9 nm, 52.6 nm for Example 1, 50.0 nm for Example 2, 50.8 nm for Example 3, and 54.6 nm for Example 4, the perovskite compound in Control and the perovskite prepared in Example There was no significant difference between the compounds.

3 shows porous TiO in Example 1 (FIG. 3 (a), x = 1), Example 2 (FIG. 3 (b), x = 3), and Example 3 (FIG. 3 (c), x = 3). Grazing- _angle incident wide-angle X-ray scattering spectrum (FIG. 3(a)) and (001) plane scattering intensity spectrum (Fig. 3 (b)) is shown.

3, it can be seen that relatively strong spots appear in the ring pattern, and it can be seen that the intensity of the spots increases as the amount of alkylenediammonium-based divalent cations and Cs ⁺ added increases. From this, it can be seen that the preferential orientation in the [100]c and [200]c directions becomes stronger as the addition amount of alkylenediammonium divalent cations and Cs ⁺ increases.

4 shows Example 1 (x=1 in FIG. 4), Example 2 (x=2 in FIG. 4), Example 3 (x=3 in FIG. 4), and Example 4 (x=4 in FIG. 4). and a UV-Vis absorption spectrum and a leveled photoluminescence (PL) spectrum of the perovskite compound film prepared in Comparative Example (Control in FIG. 4). 4, unlike the case of adding Cs+ alone, when the alkylenediammonium-based divalent cation and Cs ⁺ are simultaneously added, a significant change in the light absorption spectrum or a significant change in the photoluminescence peak position is substantially independent of the addition amount. It can be seen that it does not appear. This means that the alkylenediammonium-based divalent cation and Cs ⁺ are introduced into the perovskite structure and the band gap energy of the amidinium-based perovskite compound is not changed (increased).

5 is a measurement of the performance of perovskite solar cells prepared in Example 3 (x = 3 in FIG. 5), Example 4 (x = 4 in FIG. 5) and Comparative Example (Control in FIG. 5). That is, 24 solar cells were manufactured by the methods of Examples 3 to 4 and Comparative Example, respectively, and the performance of each solar cell was measured and shown.

As can be seen in FIG. 5 , it can be seen that the performance deviation of the solar cells manufactured in Examples compared to Control of Comparative Examples is narrow, resulting in better reliability. In addition, looking at the short-circuit current density (J _sc ), open-circuit voltage (V _oc ), and fill factor (FF) that affect power conversion efficiency (PCE), the solar cell manufactured in the example is open versus control It can be seen that the electric potential increases and the photoelectric conversion efficiency (22.72 ㅁ 0.45%) is improved.

6 shows Example 1 (x=1 in FIG. 6), Example 2 (x=2 in FIG. 6), Example 3 (x=3 in FIG. 6), and Example 4 (x=4 in FIG. 6). This is a scanning electron microscope image of the surface of the perovskite compound film prepared in As can be seen from FIG. 6, it can be seen that the grain size, microstructure, and surface roughness of the perovskite compound film are substantially the same regardless of the amount of alkylenediammonium-based divalent cations and Cs ⁺ introduced. In addition, as a result of observing the cross-section of the perovskite compound film with a scanning electron microscope, it was confirmed that the thickness of the film was also substantially the same. Through this, it can be seen that the simultaneous introduction of alkylenediammonium-based divalent cations and Cs ⁺ into the amidinium-based perovskite compound does not affect the morphology of the perovskite compound film, and these microstructure results are It also coincides with the results of X-ray diffraction and crystal size calculation using the Scherrer equation.

6 (substantially the same grain size, microstructure, surface roughness, light absorption layer thickness), as shown in FIG. As shown in FIG. 5, the fact that the control and the solar cells manufactured in the examples have substantially the same short-circuit current density (J _sc ) and the solar cells manufactured in the examples have a larger open junction compared to the control and have improved photoelectric conversion efficiency, It can be seen that the solar cells of Comparative Example and Example have substantially the same charge collection characteristics, and the perovskite compound film prepared according to one embodiment of the present invention has a higher performance than the perovskite compound film of Comparative Example. It can be seen that it has a lower defect concentration and exhibits lower non-radiative losses.

As is known, the lattice strain of perovskite compounds increases defect concentration and non-radiative recombination. Accordingly, in the perovskite compound prepared according to an embodiment of the present invention, the lattice stress caused by the alkylenediammonium-based divalent cation capable of improving the phase stability of the α phase is reduced by the alkylenediammonium-based divalent cation. It can be seen that open junction loss is greatly relaxed by the co-doping of Cs+ and low defect concentration and low non-radiative loss, resulting in reduced open junction loss.

FIG. 7 is a diagram showing residual strain (ε) calculated using the Williamson-Hall method based on the X-ray diffraction measurement results using Cu Kα rays of FIG. 1, where x=1 in FIG. is the perovskite compound film of Example 1, x = 2 is the perovskite compound film of Example 2, x = 3 is the perovskite compound film of Example 3, x = 4 is the perovskite compound film of Example 4 The perovskite compound film, FA-MDA3.8 marked with an asterisk, means the perovskite compound film of Control.

As can be seen in FIG. 7, a residual stress of about 0.0015 is formed in the perovskite lattice when doped alone with alkylenediammonium-based divalent cations, but co-doping of alkylenediammonium-based divalent cations and Cs ⁺ ( It can be seen that the residual stress of the crystal lattice is greatly alleviated by co-doping, and in particular, the solar cell of Example 3 equipped with the perovskite compound having the lowest residual stress exhibits the highest photoelectric conversion efficiency. Able to know. At this time, the residual stress of the perovskite compound film prepared in Example 3 was only about 30% of the residual stress of the perovskite compound film prepared in Comparative Example.

Through this, alkylenediammonium-based divalent cations and Cs+ are incorporated into the perovskite lattice, and the residual stress caused by contraction or expansion of the perovskite compound lattice is greatly reduced. It can be seen that the generation of defects or traps that can dissipate photocharges is prevented, and the photoelectric conversion efficiency of the solar cell is improved.

FIG. 8 shows Example 1 (x=1 in FIG. 8), Example 2 (x=2 in FIG. 8), Example 3 (x=3 in FIG. 8), and Example 4 (x in FIG. 8) on a glass substrate. = 4) and Comparative Example (Control in FIG. 8). As can be seen in FIG. 8, it can be seen that the photoluminescence intensity is increased by co-doping of alkylenediammonium-based divalent cations and Cs+, and the perovskite compound in Example 3 having the lowest residual stress It can be seen that this has the highest luminous intensity. An increase in photoluminescence intensity indicates a decrease in non-radiative recombination.

FIG. 9 shows Example 1 (x=1 in FIG. 9), Example 2 (x=2 in FIG. 9), Example 3 (x=3 in FIG. 9), and Example 4 (x in FIG. 9) on a glass substrate. = 4) and Comparative Example (Control in FIG. 9), a perovskite compound film was formed, and time-resolved light measured using time-correlated single photon counting (TCSPC) It is a diagram showing time-resolved photoluminescence characteristics.

As is known, time-resolved photoluminescence properties are mainly determined by non-radiative trap-assisted recombination, and τ1 (fast decay time) related to the radiative recombination process and A slow decay time (τ2) related to the non-radiative trap-assisted recombination process, and an average carrier life time (τ _avg ) can be calculated. As a result of the calculation, τ _avg of the perovskite compound according to Example 3 was 1472nsec, and τ _avg of the perovskite compound according to Control was 1263nsec. The life time increased by co-doping of alkylenediammonium divalent cation and Cs + reduces the trap state by stress relaxation by co-doping of alkylenediammonium divalent cation and Cs + This is consistent with the result that non-radiative recombination is inhibited.

10 shows Example 1 (x=1 in FIG. 10), Example 2 (x=2 in FIG. 10), Example 3 (x=3 in FIG. 10), and Example 4 (x=4 in FIG. 10). and Ubach energy (E _u ) calculated from the UV-Vis absorption spectrum of the perovskite compound film prepared in Comparative Example (Control in FIG. 10). Ubach energy can be calculated using the equation α(E) = α ₀ exp(hν/E _u ). In the equation, α(E) is an absorption coefficient according to photon energy, α ₀ is a material property, and hν is a photon energy.

As shown in FIG. 10, it can be seen that the Ubach energy value decreases as alkylenediammonium divalent cations and Cs ⁺ are incorporated into the perovskite structure. In addition, when looking at the Ubach energy value according to the amount of alkylenediammonium divalent cation and Cs ⁺ introduced, it can be seen that the change in the Ubach energy value has a substantially similar form to the change in the residual stress value, and the lowest residual stress It can be seen that the perovskite compound in Example 3 having a has the smallest Ubach energy. At this time, the Ubach energy of the perovskite compound of Comparative Example doped with an alkylenediammonium divalent cation alone was 30.18 meV, and the Ubach energy of the perovskite compound of Example 3 was 26.88 meV.

(I_TSC는 열자극 전류, e는 기본 전하(elemental charge), Vol은 페로브스카이트 화합물 막의 부피)에 의해 산출되었다. 11 shows Example 1 (1 in FIG. 11 ), Example 2 (2 in FIG. 11 ), Example 3 (3 in FIG. 11 ), Example 4 (4 in FIG. 11 ) and Comparative Example (Control in FIG. 11 ). It is a diagram showing the thermal stimulation current measurement result (FIG. 11 (a)) and the trap density (FIG. 11 (b)) calculated from the thermal stimulation current measurement result of the solar cell manufactured in ). At this time, in the trap density diagram, 1, 2, 3, 4 and Control on the x axis mean the results of Examples 1, 2, 3, 4 and Comparative Example, and the trap density (N _T,TSC ) is known as the formula

(I _TSC is the thermal stimulation current, e is the elemental charge, and Vol is the volume of the perovskite compound film).

As can be seen in FIG. 11, as the alkylenediammonium divalent cation and Cs ⁺ are incorporated into the perovskite structure, it can be seen that the trap density decreases, and Example 3 with minimum residual stress It can be seen that the perovskite compound of has the lowest trap density. In addition, when the alkylenediammonium divalent cation alone is doped, as predicted from the high residual stress, it has a trap density of up to 8.86x10 ¹⁶ cm ^-3 , but the alkylene diammonium divalent cation and Cs ⁺ co -It can be confirmed that the trap density is greatly reduced to the level of 4.76x10 ¹⁶ cm ^-3 by doping.

In addition, as a result of calculating the activation energy of the trap state using the initial increase slope of the thermal stimulation current in the thermal stimulation current measurement result of FIG. It was confirmed that Example 3 had an activation energy of 130 meV and Example 4 had an activation energy of 272 meV. A high activation energy means that the trap is located in a deep region toward the center of the bandgap. That is, a high activation energy trap is a deep trap. These deep traps promote non-radiative recombination.

12 is a solar cell showing the maximum efficiency among the solar cells manufactured in Comparative Example, among the solar cells used for calculating the statistical characteristics of FIG. 5, and co-doping of alkylenediammonium-based divalent cations and Cs ⁺ Among the solar cells manufactured in Example 3 in which the lattice stress was minimized by lattice stress, solar cells exhibiting the maximum efficiency were selected, and an anti-radiation coating was formed on the surface of each selected solar cell, and then the measured current density-voltage characteristics are shown. it is a drawing

As shown in FIG. 12, in the case of the solar cell of Example 3 in which the lattice stress was minimized by co-doping under AM 1.5 conditions, the short-circuit current density, open-circuit voltage, and fill factor (%) were 26.23 mAcm ^-2 , 1.168V and 82.15%, and the photoelectric conversion efficiency (PCE) was 25.17%. On the other hand, in the case of the solar cell of Comparative Example having a large lattice stress by doping with an alkylenediammonium divalent cation, the short-circuit current density, open-circuit voltage and fill factor (%) were 26.25 mAcm ^-2 , 1.138V and 81.95%, respectively. , and the photoelectric conversion efficiency (PCE) was 24.48%. In addition, the photoelectric conversion efficiency of the large-area perovskite solar cell having the minimum lattice stress and having an active area of 1x1 cm ² according to Example 3 was 21.63%, and this efficiency was comparable to that of a large-area perovskite solar cell having an active area of 1 cm ² or more. This is the highest efficiency that has never been reported in a single solar cell.

13 is a solar cell prepared in Example 5 (hole transport material = PTAA, target in FIG. 13) and a solar cell in which a PTAA hole transport layer is formed in the same manner as in Example 5 in place of the spiro-OMeTAD hole transport layer in a comparative example ( It is a diagram showing the thermal stability test results of Control) in FIG. 13. As shown in FIG. 13, in the case of Control, the efficiency decreased to 80% or less of the initial efficiency at 600 h, but the lattice residual stress was suppressed by co-doping of alkylenediammonium divalent cations and Cs ⁺ It can be seen that the example solar cell maintains its efficiency at 80% or more of the initial efficiency even at 1300h.

14 is a solar cell prepared in Example 6 (hole transport material=CuPc, Target in FIG. 14) and a solar cell in which a CuPc hole transport layer was formed in the same manner as in Example 6 instead of the spiro-OMeTAD hole transport layer in Comparative Example ( It is a diagram showing the long-term thermal stability test results of Control) in FIG. 14. At the time of exposure to a high temperature of 150 ° C for 30 hours, the photoelectric conversion efficiency rapidly decreased to 40% of the initial efficiency in the case of Control, but the ^lattice residual stress was It can be seen that the efficiency of the solar cell (Target) of this suppressed embodiment is maintained at 80% or more of the initial efficiency even at the time of exposure for 30 hours.

15 is a diagram showing the maximum power point tracking result of the solar cell manufactured in Example 3; As shown in FIG. 15, it can be seen that the efficiency is maintained at 90% or more of the initial efficiency even when tracking the maximum power point for 400 hours at AM 1.5G, 100 mW/cm ² , and without UV removal.

From the stability test results of FIGS. 13, 14, and 15, the co-doped amidinium-based perovskite compound of alkylenediammonium-based divalent cation and Cs ⁺ improves the phase stability of α, and the residual stress It can be seen that, through defect passivation by relaxation, it has improved photoelectric properties and significantly improved optical and thermal stability.

As described above, the present invention has been described by specific details and limited embodiments and drawings, but this is only provided to help a more general understanding of the present invention, the present invention is not limited to the above embodiments, and the present invention Those skilled in the art can make various modifications and variations from these descriptions.

Therefore, the spirit of the present invention should not be limited to the described embodiments, and it will be said that not only the claims to be described later, but also all modifications equivalent or equivalent to these claims belong to the scope of the present invention. .

Claims (14)

organic/inorganic cations including amidinium-based monovalent cations, alkylenediammonium-based divalent cations, and cesium ions;
Inorganic cations containing divalent metal ions; and
anions including halogen ions;
contains,
In the organic-inorganic cation, the molar ratio of alkylenediammonium-based divalent cation to cesium ion is 1:0.9 to 1.1,
An organic-inorganic perovskite compound containing 0.010 to 0.050 moles of alkylenediammonium-based divalent cations based on 1 mole of the inorganic cations. According to claim 1,
The alkylenediammonium-based divalent cation is an organic-inorganic perovskite compound containing a C1-C3 alkylenediammonium cation. delete delete According to claim 1,
An organic-inorganic perovskite compound containing 0.025 to 0.035 moles of alkylenediammonium-based divalent cations based on 1 mole of the inorganic cations. According to claim 1,
An organic-inorganic perovskite compound that satisfies Formula 1 below.
AMX ₃
(A is the organic-inorganic cation, M is the inorganic cation, and X is the anion) According to claim 1,
The organic-inorganic perovskite compound is an organic-inorganic perovskite compound containing 90% or more of amidinium-based monovalent cations, with the total number of moles of the organic-inorganic cations as 100%. t compound. A perovskite solar cell comprising a layer of the organic-inorganic perovskite compound according to any one of claims 1 to 2 and 5 to 7 as a light absorption layer. According to claim 8,
The Urbach energy (Eu) of the light absorption layer is 90% or less compared to the Urbach energy of the reference light absorption layer composed of amidinium-based monovalent cations, alkylenediammonium-based divalent cations, divalent metal ions, and halogen anions. Perovskite solar cells. According to claim 8,
The perovskite solar cell wherein the residual strain (ε) of the light absorption layer calculated using the Williamson-hall method is 0.0010 or less. According to claim 8,
The trap density of the light absorption layer calculated from the result of measuring the thermally stimulated current is amidinium-based monovalent cation, alkylenediammonium-based divalent cation, divalent metal ion, and halogen anion. A perovskite solar cell that is less than 60% of the trap density of the reference light absorption layer formed. According to claim 8,
A perovskite solar cell that maintains a photoelectric conversion efficiency of 80% or more based on the photoelectric conversion efficiency before the test during a thermal stability test exposed to a temperature of 85 ° C and a relative humidity of 15% or less under shaded conditions for 1300 hours. According to claim 8,
A perovskite solar cell having a photoelectric conversion efficiency of 22.0% or more at 1.5G of standard air mass (AM). According to claim 8,
a first charge carrier positioned under the light absorption layer;
a second charge carrier located above the light absorption layer and transporting charges complementary to the first charge carrier;
a first electrode positioned below the first charge carrier; and
A perovskite solar cell comprising a; second electrode positioned on the second charge carrier.

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