KR102571492B1 - 2-D Perovskite Light-Emitting Material for Red Emission - Google Patents

Abstract

A lead-free two-dimensional perovskite is disclosed. [SnI ₆ ] ^-4 has an octahedral structure and forms an inorganic planar structure sharing a corner with an adjacent octahedron. Organic spacers are disposed between the inorganic planar structures. The spacers have cations derived from 2-thiophenmethylammonium or cations derived from tetrahydrofurfurylammonium.

Description

2-D Perovskite Light-Emitting Material for Red Emission}

The present invention relates to a perovskite light emitting body acting as a red light source, and more particularly, to a lead-free, organic-inorganic hybrid type perovskite light emitting body having a two-dimensional structure.

Perovskite has a mixed crystal structure of body-centered cubic structure and face-centered cubic structure, and is divided into inorganic perovskite and organic-inorganic perovskite. In addition, it may have a two-dimensional structure and a three-dimensional structure.

The three-dimensional structure has the form of nanoparticles, and typically has a crystal structure of ABX ₃ . Recently, nanoparticles of CH ₃ NH ₃ PbBr ₃ or CH ₃ NH ₃ PbI ₃ were synthesized by introducing methyl ammonium ion, an organic material, into the A site, and green and red light emission was confirmed through this.

The two-dimensional structure has a crystal structure of A ₂ BX ₄ . First, the octahedron structure of BX ₄ forms planes with each other, and A is placed between the planes. A placed between the planes acts as a kind of spacer within the crystal structure. In addition, an organic material is used as A acting as a spacer. “Efficient Two-Dimensional Tin Halide Perovskite Light-Emitting Diodes via Spacer Cation Substitution Strategy” regarding the two-dimensional perovskite structure [J. Phys. Chem. Lett. 2020, 11, 1120-1127], a non-lead structure is disclosed. Phenylethylammonium ion (PEA) is available as an organic material, and iodine (I) is located at the B site and is used as a central metal. In addition, 2-thiopheneethylammonium ion (TEA) may be used, and PEA ₂ SnI ₄ and TEA ₂ SnI ₄ are formed, respectively.

In addition, in recent years, the demand for lead-free perovskite has increased. Since lead (Pb), which is a central metal, can cause environmental problems, research to replace it with other metals is actively conducted. In particular, tin (Sn) is mainly reviewed. Perovskite is characterized in that the emission wavelength is determined by the halogen element introduced into the structural formula, and I needs to be included as the halogen element in order to emit red light. A perovskite material containing a halogen element is referred to as a halide perovskite in the art. Unlike oxide-based perovskite, halide perovskite is characterized in that a crystal structure is formed through ionic bonding. Therefore, the binding force between the central metal B and the halogen element X is relatively weak compared to that of the oxide system, which becomes one of the factors deteriorating the reliability of the halide perovskite.

That is, due to the influence of moisture and oxygen in the air, a problem occurs in which Pb or Sn, which is a central metal, is oxidized. In addition, TEA or PEA acting as a spacer in the two-dimensional structure is required to cap the octahedron structure composed of BX4. However, when the capping of the octahedron structure is not smooth, thermal stability and operational stability are deteriorated.

A technical problem to be achieved by the present invention is to provide a halide perovskite capable of securing stability even in a moisture and oxygen environment and forming red light.

The present invention for achieving the above technical problem is a two-dimensional inorganic plane formed through corner sharing of octahedral structures by [SnI ₆ ] ^4- ; and a spacer disposed between the two-dimensional planar structures, wherein the spacer is a cation derived from 2-thiophenemethylammonium (TPM).

In addition, the above object of the present invention is a two-dimensional inorganic plane formed through corner sharing of octahedral structures by [SnI ₆ ] ^4- ; And a spacer disposed between the two-dimensional planar structures, wherein the spacer is a cation derived from tetrahydrofurfurylammonium (TFF), and has a separation space defined by a sliding plane between the spacers. It is also achieved through the provision of a two-dimensional perovskite light emitting body that does.

According to the present invention described above, two-dimensional inorganic planes form a frame, and a spacer is disposed between the inorganic planes. The organic spacer is cationized, forms an ionic bond with an anion on an inorganic plane, and forms a hydrogen bond with a halide element on an inorganic plane. Through this, the inorganic plane is capped by the organic spacer and the influence of moisture and oxygen is blocked. In addition, the two-dimensional perovskite provided by the present invention emits red light, and through this, high color purity can be secured.

1 is a schematic diagram showing the crystal structure of (TPM) ₂ SnI ₄ perovskite prepared by Preparation Example 1 of the first embodiment of the present invention.
2 is another schematic diagram showing the crystal structure of (TPM) ₂ SnI ₄ perovskite prepared by Preparation Example 1 of the first embodiment of the present invention.
3 is a schematic diagram showing the crystal structure of (TFF) ₂ SnI ₄ perovskite prepared by Preparation Example 2 of the second embodiment of the present invention.
4 is a graph showing absorption spectra of perovskites according to the first and second embodiments of the present invention.
5 are graphs showing PXRD patterns of powders pulverized from (TPM) ₂ SnI ₄ and (TFF) ₂ SnI ₄ perovskite single crystals.
6 are graphs and images showing damping characteristics of (TPM) ₂ SnI ₄ and (TFF) ₂ SnI ₄ perovskite.
7 are graphs showing the photoluminescence characteristics of perovskite according to temperature.
8 shows emission characteristics of (TPM) ₂ SnI ₄ of the first embodiment and (TFF) ₂ SnI ₄ of the second embodiment of the present invention.

Since the present invention may have various changes and various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, it should be understood that this is not intended to limit the present invention to the specific disclosed form, and includes all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. Like reference numerals have been used for like elements throughout the description of each figure.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in the present application, they should not be interpreted in an ideal or excessively formal meaning. don't

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in more detail.

Example 1

In this embodiment, a perovskite (TPM) ₂ SnI ₄ having a two-dimensional structure using 2-thiophenemethylammonium (C ₄ SH ₃ CH ₂ NH ₃ , hereinafter referred to as TPM) is disclosed. . In the (TPM) ₂ SnI ₄ perovskite, [SnI ₆ ] ^-4 constitutes the frame of the inorganic plane, and TMP acts as a spacer between the inorganic planes. A spacer disposed between the inorganic planes forms a hydrogen bond with the halide element iodine of the inorganic planes. That is, the terminal cationized amine group of TMP caps the inner surface of the inorganic plane.

Preparation Example 1: (TPM) ₂ SnI ₄ synthesis of

1 mmol SnCl ₂ .2H ₂ O powder is dissolved in 5 ml HI solution (HI is 57 wt% in H ₂ O). The solution in which the powder is dissolved is heated to 180° C. to 220° C. while stirring for 5 minutes in the flask. Through stirring and heating, a yellow first solution is formed in the flask. This allows Sn cations and halide anions to float in the solution.

Also, in a separate container, 2 mmol of 2-thiophenemethylamine is dissolved in 1 ml of H ₃ PO ₂ solution (H ₃ PO ₂ is 50 wt% in H ₂ O), and a second solution is formed.

Subsequently, the second solution is gradually added to the heated first solution. Upon addition, the two solutions are stirred until completely mixed. After that, stirring is stopped, and the stirring solution is gradually cooled. Through cooling, purple plate-like crystals precipitate at the bottom of the flask of the mixed solution.

The collected crystals are dried at 60° C. for 24 hours in a vacuum oven.

1 is a schematic diagram showing the crystal structure of (TPM) ₂ SnI ₄ perovskite prepared by Preparation Example 1 of the first embodiment of the present invention.

For the analysis of the crystal structure, X-ray diffraction is used, and the disclosed crystal structure is a crystal structure in the 100 K state.

At 100 K, the a-axis lattice constant is 28.881 Å, the b-axis lattice constant is 8.707 Å, and the c-axis lattice constant is 8.638 Å. In addition, the volume of the lattice is 2172.7 Å ³ , crystallized within the noncentrosymmetric space group Cmc2 ₁ . Crystallization in the orthorhombic space group Cmc2 ₁ consists of [SnI ₆ ] ^-4 , and forms a layered structure while sharing a corner with each other. In addition, the monovalent organic cation TPM ⁺ is disposed between the layered structures, and the cationized amine group at the terminal is linked to iodine, a halide, through a hydrogen bond.

In particular, two TMPs are arranged between [SnI ₆ ] ^-4 forming one octahedral structure and [SnI ₆ ] ^-4 in another inorganic plane in an inorganic plane forming a layered structure, and are arranged in opposite directions. do.

In addition, the TPMs forming the spacer are stabilized through the π-σ interaction. The length of a pi (π) bond is 3.45 Å, and the length of a sigma (σ) bond is 3.29 Å. This stabilizes the spacers between the layered structures.

That is, [SnI ₆ ] ^-4 , which is an inorganic substance in the crystal structure, forms an inorganic frame and forms a planar structure. The organic TPM between the planar structures forms a spacer. The hydrogen bonding between the spacer and the inorganic frame affects the angle of Sn-I-Sn which affects the band gap. In addition, the structure in which the distortion of the crystal structure is reduced by the angle of Sn-I-Sn increases the overlap of the s orbital of Sn and the p orbital of I (iodine), resulting in a decrease in band gap and a tendency to widen the emission bandwidth there is The bonding angle of Sn-I-Sn is divided into an angle based on the inorganic plane and an angle based on the vertical axis of the layered structure.

The bonding angle based on the inorganic plane is less affected by the interaction of the spacer with the cation, and the angle based on the vertical axis considers the inorganic layer exposed to the organic cation.

In the structure of (TPM) ₂ SnI ₄ of the present invention, the angle of Sn-I-Sn in the inorganic frame is 153.91°, and the angle based on the vertical axis is 154.27°. Also, the angle at 100 K appears to be more distorted than the angle measured at 298 K.

2 is another schematic diagram showing the crystal structure of (TPM) ₂ SnI ₄ perovskite prepared by Preparation Example 1 of the first embodiment of the present invention.

For the analysis of the crystal structure, X-ray diffraction is used, and the disclosed crystal structure is a crystal structure at room temperature of 298 K.

Referring to FIG. 2, (TPM) ₂ SnI ₄ at 298 K has values of lattice constants a=8.797 Å, b=8.688 Å and c=29.17 Å, and the centrosymmetric orthorhombic space group Pbca form The volume of the lattice is 2229.4 Å ³ . [SnI ₆ ] ^4- forms a two-dimensional inorganic layer and shares corners in the octahedron. Also, the weapon frames, which are composed of octahedrons and form a planar structure, are separated into two layers of TPMs. In addition, the nitrogen and hydrogen atoms of the TPM are stabilized by forming hydrogen bonds with iodine at the octahedral apex, respectively.

In addition, since the electronegativity of iodine is weak, the strength of the bond between the iodine atom and the hydrogen atom is weak, whereas the electrostatic mutual attraction between the ammonium cation constituting the spacer and the anionic two-dimensional inorganic layer is stronger. In addition, an aromatic ring is included in the structure of the TPM. Therefore, a weak interlayer stabilizing force acts, which is a weak interlayer stabilizing force generated by the π-σ interaction in which the distances between the vector of the C–H bond and the center of the aromatic ring are 3.60 Å and 3.58 Å, as shown in FIG. 2c. am.

Structural distortions in the planar inorganic frame affect the optical and electrical properties of the perovskite. The angle of Sn-I-Sn in the inorganic frame is 156.1°, the degree of distortion is very weak compared to the structure at 100 K, and the distance between the inorganic layers increases from 7.99 Å to 9.32 Å.

Second embodiment

In this embodiment, unlike the first embodiment, tetrahydrofurfurylammonium (tetrahydrofurfurylammonium, C ₄ OH ₇ CH ₂ NH ₃ , hereinafter referred to as TFF) is used as a spacer.

Preparation Example 2: (TFF) ₂ SnI ₄ synthesis of

The first solution prepared in Preparation Example 1 is prepared. Also, in a separate vessel, 2 mmol of tetrahydrofurfurylamine is dissolved in 1 ml of H ₃ PO ₂ solution (H ₃ PO ₂ is 50 wt % in H ₂ O), and a second solution is formed.

The second solution is slowly added to the heated first solution. Through the addition, the two types of solutions are stirred until completely mixed. After that, stirring is stopped, and the stirring solution is gradually cooled. Through cooling, purple plate-like crystals precipitate at the bottom of the flask of the mixed solution.

The collected crystals are dried at 60° C. for 24 hours in a vacuum oven.

3 is a schematic diagram showing the crystal structure of (TFF) ₂ SnI ₄ perovskite prepared by Preparation Example 2 of the second embodiment of the present invention.

Referring to FIG. 3, (a) shows the crystal structure of (TFF) ₂ SnI ₄ perovskite along the b axis at 100 K, and (b) shows the crystal structure of (TFF) ₂ SnI ₄ perovskite at 100 K. A structure for explaining the bonding angle of Sn-I-Sn constituting the inorganic plane in the crystal structure of the crystal is disclosed. In addition, (c) shows the crystal structure of (TFF) ₂ SnI ₄ perovskite along the (b) side at 298 K, which is room temperature, and (TFF) ₂ SnI ₄ perovskite at 298 K in (d). A structure for explaining the bonding angle of Sn-I-Sn constituting an inorganic plane in the crystal structure of skyt is disclosed.

(TFF) ₂ SnI ₄ crystallizes in monoclinic space group P2 ₁ /c at 100 K and 298 K. In addition, (TFF) ₂ SnI ₄ perovskite forms a separation space between spacers composed of TFF. The surface of the two spaces defining the separation space is defined as a gliding plane. The two cations associated with the glide plane have tetrahydrofuran-CH ₂ NH ₂ ⁺ groups oriented in opposite directions, forming a centrosymmetric space group illustrated in FIG. 3 . The cationized amine group of the spacer forms a hydrogen bond with iodine (I) of [SnI ₆ ] ^4- constituting the inorganic plane and stabilizes the inorganic plane. In addition, since the oxygen atom included in tetrahydrofuran has an unshared electron pair, it is possible to block the oxidation of Sn (tin) atoms on the inorganic plane.

The inorganic frames are separated by bilayer TFF chains that are separated from each other and share corners with each other based on an octahedron by [SnI ₆ ] ^4- . Through this, a two-dimensional inorganic planar structure is formed.

The separation space between the TFF chains has a width of 2.1235 Å. The TFF chain forms a structure that maximizes quantum confinement by capping the weapon frame. At 100 K, the Sn-I-Sn angles in the planar direction of the weapon frame are 159.78°, and at 298 K, they are 161.42° and 161.44°.

At 298 K the distance between interlayer iodines increases to 10.15 Å compared to 10.02 Å at 100 K. This means that as the temperature increases, the structural distortion decreases and the interlayer spacing between the inorganic planes increases, resulting in an increase in the volume of the structural unit.

Third embodiment

In this embodiment, characterization is performed on the (TPM) ₂ SnI ₄ perovskite according to the first embodiment and the (TFF) ₂ SnI ₄ perovskite according to the second embodiment.

Table 1 below shows the crystallographic data at 100 K and 298 K of the (TPM) ₂ SnI ₄ perovskite of the first example and the 100 K of the (TFF) ₂ SnI ₄ perovskite of the second example. and crystallographic data at 298 K.

[Table 1]

Absorption spectrum analysis

4 is a graph showing absorption spectra of perovskites according to the first and second embodiments of the present invention.

Referring to FIG. 4 , a fluorescent xenon lamp is used to measure an absorption spectrum. The fluorescent xenon lamp used emits continuous light to excite the sample. Due to the high amount of light, excitation due to bandgap energy is predominantly generated rather than excitation due to structural distortion.

Absorption spectral data is calculated through the Kubelka-Munk equation.

In (a), the band gap is determined. The band gap is determined by the intersection point between the energy axis and a straight line inserted in the linear portion of the absorption spectrum graph. Both compounds (TPM) ₂ SnI ₄ and (TFF) ₂ SnI ₄ exhibit exciton peaks near steep regions of their absorption spectra, indicating that they are direct bandgap materials. Therefore, it can be used as a light emitting material. The band gap of (TPM) ₂ SnI ₄ is 1.8 eV, and the band gap of (TFF) ₂ SnI ₄ is 1.73 eV. (TPM) ₂ SnI ₄ has a smaller Sn-I-Sn bond angle than (TFF) ₂ SnI ₄ , which means that (TPM) ₂ SnI ₄ is more distorted in the inorganic frame. Therefore, (TPM) ₂ SnI ₄ has a larger bandgap than (TFF) ₂ SnI ₄ due to distortion in the inorganic frame.

In (b) the excitation and emission spectra are shown. Excitation spectra of both compounds have the largest peak at 535 nm. In addition, a large Stokes shift is shown between the excitation spectrum and the emission spectrum. That is, the wavelength of the maximum energy has a large shift in the spectrum between when energy is absorbed and when it is emitted. The red emission of (TPM) ₂ SnI ₄ is centered at 621 nm and exhibits a narrow peak. The material has a full width at half maximum (FWHM) of 20 nm. In addition, the red emission of (TFF) ₂ SnI ₄ appears over a relatively broad band, with a Schallter peak at 675 nm, and a broadband emission from 600 nm to 750 nm. The broadband emission of (TFF) ₂ SnI ₄ is due to the dissociation of inorganic frames by TFF cations within the bulk crystal and the local formation of excitons within the separated inorganic frames.

4c and 4d show Raman spectrographs of (TPM) ₂ SnI ₄ and (TFF) ₂ SnI ₄ according to temperature, respectively. The temperature of the sample is 80 K, 200 K and 300 K, and the lattice vibration of the octahedral structure of [SnI ₆ ] ^4- is investigated.

Referring to FIG. 4c, the Raman spectrum of (TPM) ₂ SnI ₄ at 80 K shows three active Raman modes at 22 cm ⁻¹ , 33 cm ⁻¹ , and 44 cm ⁻¹ , which constitute the inorganic frame [SnI ₆ ] is assigned to the bending mode of I-Sn-I at ^-4 . In addition, the wide bandwidths at 101 cm ^-1 and 124 cm ^-1 are due to the librational mode of organic cations bound to Sn-I.

As the temperature increases to 200 K, the modes at 26 cm ^-1 and 34 cm ^-1 are formed by merging with each other while blue-shifting the 22 cm ^-1 , 33 cm ^-1 and 44 cm ^-1 modes at low temperatures, which are relatively high temperatures. indicates an increase in dynamic disorder scattering at . These peaks appear at 25 cm ^-1 and 30 cm ^-1 at 300 K and are shifted to lower wavenumbers (redshift).

In FIG. 4d, a Raman spectrum of (TFF) ₂ SnI ₄ is disclosed, and the band observed at 62 cm ⁻¹ under 80 K conditions is presumed to be due to the bending of I-Sn-I. In addition, the three peaks at 113 cm ^-1 , 127 cm ^-1 and 150 cm ^-1 at 80 K correspond to the vibrational modes of bound [SnI ₆ ] ^4- and TFF cations. However, the vibrational mode of this coupling disappears due to the activation of the rotational mode at 200 K and 300 K. Symmetrical modes of I-Sn-I at 200 K and 300 K are observed at 21 cm ^-1 and 20 cm ^-1 , respectively, which correspond to the vibration band.

Identification of perovskite single crystals

5 are graphs showing PXRD patterns of powders pulverized from (TPM) ₂ SnI ₄ and (TFF) ₂ SnI ₄ perovskite single crystals.

Referring to Figure 5, the purity of the single crystal powder is shown. In FIG. 5, bulk crystal shows the measurement result of actually pulverized powder, and calculated shows the result calculated from the single crystal structure of (TPM) ₂ SnI ₄ and (TFF) ₂ SnI ₄ perovskite. It can be seen that the calculated values and the measured values agree well with each other.

Confirmation of damping characteristics

6 are graphs and images showing damping characteristics of (TPM) ₂ SnI ₄ and (TFF) ₂ SnI ₄ perovskite.

FIG. 6A shows the photoluminescence attenuation characteristics of (TPM) ₂ SnI ₄ perovskite over time, and FIG. 6B shows a mapping image of the luminescence attenuation of (TPM) ₂ SnI ₄ perovskite. FIG. 6c shows the photoluminescence attenuation characteristics of (TFF) ₂ SnI ₄ perovskite over time, and FIG. 6d shows a mapping image of the luminescence attenuation of (TFF) ₂ SnI ₄ perovskite. The photoluminescence attenuation of (TPM) ₂ SnI ₄ perovskite can be graphed using a biexponential function, and the photoluminescence attenuation of (TFF) ₂ SnI ₄ perovskite is It is analyzed using exponential decay dynamics.

Table 2 below shows the photoluminescence lifetimes of the (TPM) ₂ SnI ₄ perovskite of the first embodiment and the (TFF) ₂ SnI ₄ perovskite of the second embodiment through a transient photoluminescence decay analysis.

[Table 2]

In Table 2, the luminescence attenuation can be calculated by Equation 1 below.

[Equation 1]

Luminescence decay I(t) = A ₁ exp(-t/τ ₁ ) + A ₂ exp(-t/τ ₂ ) + A ₃ exp(-t/τ ₁ ) + ...

In Equation 1 above, Σ _i A _i /(A ₁ +A ₂ +A ₃ +...)=1.

In addition, in Table 2, the average lifetime τ _avg is derived by Equation 2 below.

[Equation 2]

τ _avg = Σ _i A _i τ _i ² /Σ _i A _i τ _i , and τ _amp denotes the amplitude of the mean lifetime.

The relatively fast decay components (time) τ ₁ are due to the radiative recombination of excitons, while the slow decay components (time) τ ₂ and τ ₃ are due to the formation of trap states within the layered structure.

As shown in Table 2, in (TPM) ₂ SnI ₄ , the attenuation component τ ₁ having a value of 0.51 ns is 90.43%, and the attenuation component τ ₂ having a value of 1.49 ns is only 9.14%. That is, in (TPM) ₂ SnI ₄ , photoluminescence is predominantly caused by recombination of excitons.

On the other hand, in (TFF) ₂ SnI ₄ , the attenuation component τ ₁ having a value of 88 ns is only 8.18%, the attenuation component τ ₂ having a value of 20 ns is 38.11%, and the attenuation component τ having a value of 3.9 ns ₃ has 51.64%. That is, it can be seen that the light emitting operation by the trap state of the layered structure is dominant, indicating that the light emitting operation is by self-trapped exciton (STE) due to structural distortion. In conclusion, the average attenuation component τ _avg of (TPM) ₂ SnI ₄ is 0.73 ns, and the average attenuation component τ _avg of (TFF) ₂ SnI ₄ is 47 nm.

As the mapping images in FIGS. 6B and 6D are disclosed, it can be seen that (TMP) ₂ SnI ₄ performs a uniform light emission operation for a very short time through the entire powder crystal, and (TFF) ₂ SnI ₄ is relatively It can be seen that a uniform light emission operation is performed for a long emission time.

Investigation of photoluminescent properties according to temperature of perovskite

7 are graphs showing the photoluminescence characteristics of perovskite according to temperature.

To measure photoluminescence characteristics, a 514 nm laser is applied to the sample, and the laser has a period of 30 ps. Also, the amount of light of the pulse laser is weaker than that of the fluorescent lamp applied in FIG. 4 .

Referring to FIG. 7a, (TPM) ₂ SnI ₄ shows peak wavelengths of 615 nm and 665 nm at 10 K temperature, which are the longitudinal optical phonon mode and I-Sn coupling according to the bending of I-Sn-I, respectively. This is due to the longitudinal optical phonon mode according to . The widening of the distribution of PL emission with temperature is related to distortion in the octahedral structure of perovskite.

As the temperature increases, the peak wavelength of the PL spectrum shows a blue shift to a shorter wavelength, the spectrum broadens, and the intensity of luminescence decreases. The phenomenon that appears in the PL peak of perovskite according to temperature is due to a structural change from a distorted orthorhombic phase ( Cmc2 ₁ ) at 100 K to a less distorted orthorhombic phase ( Pbca ) at room temperature.

Similarly, FIG. 7B shows (TFF) ₂ SnI ₄ photoluminescence data, and the strong photoluminescence emission at 10 K is due to a decrease in thermal oscillation at low temperatures. In addition, as the temperature increases, the photoluminescence spectrum broadens, and a blue shift appears. This is due to lattice expansion and exciton-photon coupling with increasing temperature. When the temperature increases, the thermal fluctuations of the octahedral structure are motivated to induce a strong polarization around [SnI ₆ ] ^4- frames forming inorganic planes.

8 shows emission characteristics of (TPM) ₂ SnI ₄ of the first embodiment and (TFF) ₂ SnI ₄ of the second embodiment of the present invention.

Referring to FIG. 8, (a) shows the color coordinates of perovskite, and (b) shows the stabilized photoluminescence characteristics of the perovskite when an excitation wavelength of 470 nm is incident. Also, (c) is an image showing red emission of perovskites excited by infrared light of 365 nm.

The CIE color coordinates of the prepared compounds appear at the same point in the red region in FIG. 8a. CIE color coordinates and correlated color temperature (CCT) were calculated using Osram's ColorCalculator.

Table 3 below shows the color coordinates, correlated color temperature, color purity, color rendering index (CRI, and PLQY) of perovskites.

[Table 3]

As shown in Table 3, the color coordinates of (TPM) ₂ SnI ₄ are (0.6216, 0.3740), and the color coordinates of (TFF) ₂ SnI ₄ are (0.6211, 0.3733). In addition, the CCT of (TPM) ₂ SnI ₄ is 1217.9K, and the CCT of (TFF) ₂ SnI ₄ is 1196.6 K, indicating that the materials emit warm light. In addition, in Table 3, the color rendering indexes (CRI) of (TPM) ₂ SnI ₄ and (TFF) ₂ SnI ₄ are 57.1 and 52.26, respectively.

The PLQY _{of (} TPM) ₂ SnI _{4 is 0.3} %, and the PLQY of (TFF) ₂ SnI ₄ is 1.17%. This is due to the highly separated inorganic chains from each other by TFF cations. In particular, (TFF) ₂ SnI ₄ perovskite is charge-balanced by the double-layered TFFs separating the inorganic frame inside, an empty space is formed in the middle, and quantum confinement is achieved by capping the inner surface of the inorganic frame. Maximize.

In the present invention described above, two-dimensional inorganic planes form a frame, and a spacer is disposed between the inorganic planes. The organic spacer is cationized, forms an ionic bond with an anion on an inorganic plane, and forms a hydrogen bond with a halide element on an inorganic plane. Through this, the inorganic plane is capped by the organic spacer and the influence of moisture and oxygen is blocked. In addition, the two-dimensional perovskite provided by the present invention emits red light, and through this, high color purity can be secured.

Claims (10)

a two-dimensional inorganic plane formed through corner sharing of octahedral structures by [SnI ₆ ] ^4- ; and
Including a spacer disposed between the two-dimensional planar structures,
The spacer is a cation derived from 2-thiophenemethylammonium (TPM),
The two-dimensional perovskite light emitting body, characterized in that the cationized amine group at the end of the TPM is connected to iodine, which is a halide, through a hydrogen bond. delete The two-dimensional perovskite light emitting body of claim 1, wherein the nitrogen and hydrogen atoms of the TPM form a hydrogen bond with iodine at the apex of the octahedral structure. The method according to claim 1, wherein between [SnI ₆ ] ^4- forming the one octahedral structure in the two-dimensional inorganic plane and [SnI ₆ ] ^4- of another two-dimensional inorganic plane facing the one octahedron, Two-dimensional perovskite light emitting body, characterized in that two of the TPMs are disposed, and the two TPMs are opposite to each other. The two-dimensional perovskite emitter according to claim 1, characterized in that it forms a non-centrosymmetric space group Cmc2 ₁ in the crystal structure at 100 K and an internally symmetric orthorhombic space group Pbca at 298 K. Dimensional perovskite luminaries. a two-dimensional inorganic plane formed through corner sharing of octahedral structures by [SnI ₆ ] ^4- ; and
Including a spacer disposed between the two-dimensional planar structures,
The spacer is a cation derived from tetrahydrofurfurylammonium (TFF), and the two-dimensional perovskite light emitting body, characterized in that it has a spaced space defined by a gliding plane between the spacers. The two-dimensional perovskite light-emitting body according to claim 6, characterized in that the cationized amine group at the TFF terminal is connected to iodine, which is a halide, through a hydrogen bond. The two-dimensional perovskite light-emitting body according to claim 6, characterized in that the two-dimensional perovskite light-emitting body is crystallized in monoclinic space group P2 ₁ /c at 100 K and 298 K. The two-dimensional perovskite light emitting body according to claim 6, characterized in that the light emission operation by self-trapped exciton (STE) due to the structural distortion of the crystal is predominantly generated on the photoluminescence data. Lobsite luminary. The method according to claim 6, wherein between [SnI ₆ ] ^4- forming the one octahedral structure in the two-dimensional inorganic plane and [SnI ₆ ] ^4- of another two-dimensional inorganic plane facing the one octahedron, Two-dimensional perovskite light emitting body, characterized in that two of the TFFs are disposed, and the two TFFs face each other.