KR20190030188A - Non-fullerene electron transporting material and perovskite solar cells using the same - Google Patents

Abstract

The present invention relates to a perovskite planar solar cell having high efficiency and thermal stability, wherein a solar cell includes an electron transport layer manufactured using a naphthalene-diimide compound-based electron transport material instead of an existing fullerene-based electron transport material. Thus, the present invention can provide a perovskite solar cell having high efficiency and excellent time and thermal stability.

Description

[0001] The present invention relates to a non-fullerene electron transporting material and a perovskite solar cell using the same,

The present invention relates to a solar cell using a naphthalene-diimide compound, which is a non-fullerene electron transferring material, and relates to a perovskite solar cell having high efficiency, excellent temporal stability and thermal stability.

Due to limited energy sources and environmental issues, fuel is being gradually replaced by alternative renewable energy sources such as fuel cells, biomass energy, or solar energy. Extensive research into the development of environmentally friendly, renewable and abundant alternative energy sources is underway and has received considerable attention. However, the manufacturing cost of the power generation solar cell module is high, which has hindered solar energy as a main energy source. The use of low cost organic or polymer solar cells has reduced the cost associated with power conversion, but the low power conversion efficiency (PCE) has become a hurdle to commercialization.

On the other hand, since the perovskite material was first applied to the solar cell by the Tsutomu Miyasaka Group in Japan in 2009, its absorption coefficient is high, and since it can be easily synthesized through the solution process, It is in the limelight. The PCE of these perovskite solar cells has greatly increased from 3.8% in 2009 to more than 20% in the most recent research, thereby achieving high efficiency with performance equivalent to silicon solar cells in perovskite solar cells .

The device structure of a perovskite solar cell can be classified into a mesoscopic, bi-layer, planar and meso-super structure. Currently, dual-layer and planar device structures Most of them are used for obtaining high efficiency.

The device configuration is classified as perovskite solar cells of nip and reverse structures depending on what type (n-type or p-type) of material is deposited on the transparent conductive electrode. The bi-layer and planar type perovskite solar cells of the normal structure are made of n-type electron transport materials (ETM) such as TiO ₂ , ZnO, ZnSnO ₃ , and PCBM, And a p-type hole transport material (HTM) such as PEDOT: PSS and NiO _x is coated on the FTO or ITO transparent conductive electrode in the case of the reversed phase structure.

Perovskite solar cells with normal structure show a high power conversion efficiency (PCE) of 22% or more under 1 sun (100 mW / cm ² ) lighting (sunlight), but poly triarylamine (PTAA) or 2,2 ' (HTM) such as 7'-tetrakis- (N, N-di-4-methoxyphenylamino) -9,9'-spirobifluorene (spiro-OMeTAD) (trifluoromethanesulfonyl) imide (Li-TFSI) and the like, the stability of the solar cell is lowered.

On the other hand, reversed-phase perovskite solar cells are more stable, have smaller current density-voltage (JV) hysteresis characteristics for scan direction and speed, and are similar to power conversion efficiency (PCE) for normal structure. So far, PCBM, a fullerene-based material, has been used as an electron transport material (ETM) for reversed-phase perovskite solar cells.

However, since fullerene-based PCBM ETMs have lower solubility in toluene and dichlorobenzene than PTAA or spiro-OMeTAD HTM, it is relatively difficult to form a uniform and thick PCBM layer on the pinhole-free perovskite layer by conventional spin coating processes There is a difficult problem. In addition, since the morphology and crystallinity of the PCBM ETM vary with the use time, it is required to replace the existing PCBM ETM with a more stable and robust ETM.

1. Korean Registered Patent No. 10-1571528 (Nov.

1. A. Kojima, K. Teshima, Y. Shirai, T. Miyasaka, J. Am. Soc., 2009, 131, 6050.

SUMMARY OF THE INVENTION The present invention provides a perovskite solar cell using an n-type ETM based on naphthalene diimide (NDI) among organic n-type semiconductors.

However, the objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

The present invention provides a naphthalene-diimide compound represented by the following structural formula 1 as a compound for an electron transferring material of a perovskite solar cell.

[Structural formula 1]

(Wherein R ₁ and R ₂ are each independently hydrogen, hydroxyl, halogen, pseudohalogen, formyl, carboxyl, alkoxy, long chain alkoxy, alkyl, long chain alkyl, substituted or unsubstituted indenyl indenyl, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, tetrahydronaphthyl, 1,2,3,4-tetrahydronaphthyl, a condensed ring of an aliphatic ring having 9 to 30 carbon atoms and an aromatic ring, a cyclo Alkyl, haloalkyl, aryl, arylene, haloaryl, heteroaryl, heteroarylene, heterocycloalkylene, heterocycloalkyl, haloheteroaryl, alkenyl, haloalkenyl, alkynyl, haloalkynyl, Alkyl, alkenyl, aryl, haloalkenyl, alkynyl, alkynyl, aryl, haloketoaryl, ketoheteroaryl, ketoalkyl, halocetoalkyl, ketoalkenyl, halocetoalkenyl, phosphoalkyl, phosphonate, phosphate, phosphine, phosphine oxide, , Sulfonyl, sulfoalkyl, sulfoarenyl, sulfonate, sulfone Wherein the number of carbon atoms is in the range of 1 to 12 except for the specific case where carbon is included,

R ₃ is selected from the group consisting of hydrogen, hydroxyl, halogen, nitro, formyl, carboxyl, alkyl, alkoxy, cycloalkyl, haloalkyl, aryl, haloaryl, heteroaryl, heterocycloalkyl, haloheteroaryl, Alkynyl, haloalkynyl, keto, ketoaryl, halocetoaryl, ketoheteroaryl, ketoalkyl, halocetoalkyl, ketoalkenyl, halocetoalkenyl, phosphoalkyl, phosphonate, phosphate, phosphine At least one selected from the group consisting of phosphine oxide, phosphine oxide, phospholyl, phosphoaryl, sulfonyl, sulfoalkyl, sulfoarenyl, sulfonate, sulfate, sulfone, amine, polyether, silylalkyl or silylalkyloxy, The carbon number is within the range of 1 to 12,

n and m are each independently an integer of 0 to 5 and P is an integer of 0 to 4.)

The present invention also relates to a plasma display panel comprising a first electrode; A hole transport layer formed on the first electrode; A photoactive layer formed of perovskite on the hole transporting layer; An electron transport layer formed on the photoactive layer; And a second electrode formed on the electron transport layer, wherein the electron transport layer comprises a naphthalene-diimide compound represented by the structural formula 1 .

Further, the photoactive layer may include perovskite represented by the following Formula 1 (Methylammonium lead trihalide) or Formula 2 (Formamidinium lead halide).

[Chemical Formula 1]

CH ₃ NH ₃ PbX ₃

(Wherein X is any one halogen element selected from the group consisting of iodine, bromine and chlorine)

(2)

HC (NH ₂ ) ₂ PbX _3-x X ' _x

Wherein X and X 'are each independently a different halogen element selected from the group consisting of iodine, bromine and chlorine.

The present invention also provides a solar cell module including the perovskite solar cell.

The present invention relates to an organic n-type semiconductor which is easy to synthesize by a low cost one-step reaction, exhibits a high electron mobility of 0.1 cm ² V ^-1 s ^-1 or more, exhibits excellent solution processability due to high solubility in various organic solvents, By using an n-type ETM based on a naphthalene diimide (NDI) compound which exhibits high thermal and temporal stability and can control the physical properties and molecular arrangement in the crystalline state by N-substituted side chains, It is possible to provide a perovskite solar cell having superior temporal and thermal stability.

FIG. 1 shows the Hirshfeld surface analysis results of compounds according to Examples and Comparative Examples of the present invention.
2 shows the pore shape of the compound crystals according to Examples and Comparative Examples of the present invention.
Fig. 3 shows the DSC measurement results of the compounds according to Examples and Comparative Examples of the present invention.
4 shows the results of IV characteristics measurement of the compounds according to Examples and Comparative Examples of the present invention.
5 shows the measurement results of transient PL (photoluminescent) decay curves of compounds according to Examples and Comparative Examples of the present invention.
6 is a sectional SEM image of a perovskite solar cell according to an embodiment of the present invention.
FIG. 7 shows a JV (current density-voltage) curve of a perovskite solar cell according to an embodiment of the present invention and a comparative example.
FIG. 8 shows the results of measurement of external quantum efficiency (EQE) of a perovskite solar cell according to Examples and Comparative Examples of the present invention.
FIG. 9 shows the results of measurement of the efficiency of a perovskite solar cell according to Examples and Comparative Examples of the present invention.
10 is an atomic force microscope (AFM) topology image of a compound according to Examples and Comparative Examples of the present invention before heat treatment (0 min) and after heat treatment (100 min).

Before describing the present invention in detail, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention, which is defined solely by the appended claims. shall. All technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise stated.

Throughout this specification and claims, the word "comprise", "comprises", "comprising" means including a stated article, step or group of articles, and steps, , Step, or group of objects, or a group of steps.

On the contrary, the various embodiments of the present invention can be combined with any other embodiments as long as there is no clear counterpoint. Any feature that is specifically or advantageously indicated as being advantageous may be combined with any other feature or feature that is indicated as being preferred or advantageous. Hereinafter, embodiments of the present invention and effects thereof will be described with reference to the accompanying drawings.

A perovskite solar cell according to an embodiment of the present invention is a planar solar cell using a perovskite material as a photoactive layer, and includes an electron transporting material (ETM) of an electron transport layer (ETL) ), Instead of using a fullerene-based material such as phenyl-C61-butyric acid methyl ester (PCBM), a naphthalene-diimide compound-based electron transport material is used to produce a perovskite solar cell having high efficiency and thermal stability Thereby providing a battery.

The perovskite solar cell according to the present invention includes a first electrode, a hole transporting layer formed on the first electrode, a photoactive layer formed on the hole transporting layer, an electron transporting layer formed on the photoactive layer, and a second electrode formed on the electron transporting layer Wherein the photoactive layer is formed of a perovskite material, and the electron transport layer is formed of a naphthalene-diimide compound.

The first electrode may be a conductive electrode that is in ohmic contact with the hole transport layer, and may be a transparent conductive electrode to improve light transmission. For example, the first electrode may include at least one of aluminum-doped zinc oxide (AZO), indium-tin oxide (ITO), zinc oxide (ZnO) (AlO), AlO (AlO), AlO (SnO ₂ ) Al, and FTO (Fluorine-doped tin oxide). Preferably, indium tin oxide is used.

In addition, the first electrode 10 may further include a substrate positioned under the first electrode. The substrate can serve as a support for supporting the first electrode, and can be used without limitation as long as it is a transparent substrate through which light is transmitted. The substrate can be any substrate that can be placed on the front electrode in a conventional solar cell It can be used without. For example, the substrate may be a rigid substrate comprising a glass substrate or a rigid substrate comprising polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), polycarbonate (PC) (TAC), polyethersulfone (PES), and the like.

The hole transport layer is a layer formed on the first electrode, and may include a conductive polymer. The conductive polymer may be, for example, poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT: PSS).

The photoactive layer is a layer formed on the hole transport layer. The photoactive layer is a 250 to 400 nm thick perovskite layer including perovskite represented by Methylammonium lead trihalide or 2 (Formamidinium lead halide) to be. If the thickness of the perovskite layer is less than 250 nm, there is a problem that the absorption of light is insufficient and the current density is low and the efficiency is decreased. When the thickness is more than 400 nm, There is a problem that the exciton moves to the pn interface and can not be effectively separated, thereby decreasing the efficiency.

[Chemical Formula 1]

CH ₃ NH ₃ PbX ₃

(Wherein X is any one halogen element selected from the group consisting of iodine, bromine and chlorine)

(2)

HC (NH ₂ ) ₂ PbX _3-x X ' _x

Wherein X and X 'are each independently a different halogen element selected from the group consisting of iodine, bromine and chlorine.

The electron transport layer is a layer formed on the photoactive layer and uses an electron transport material based on a naphthalene-diimide compound. The structure of the naphthalene diimide compound is shown in the following structural formula 1.

[Structural formula 1]

(Wherein R ₁ and R ₂ are each independently hydrogen, hydroxyl, halogen, pseudohalogen, formyl, carboxyl, alkoxy, long chain alkoxy, alkyl, long chain alkyl, substituted or unsubstituted indenyl indenyl, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, tetrahydronaphthyl, 1,2,3,4-tetrahydronaphthyl, a condensed ring of an aliphatic ring having 9 to 30 carbon atoms and an aromatic ring, a cyclo Alkyl, haloalkyl, aryl, arylene, haloaryl, heteroaryl, heteroarylene, heterocycloalkylene, heterocycloalkyl, haloheteroaryl, alkenyl, haloalkenyl, alkynyl, haloalkynyl, Alkyl, alkenyl, aryl, haloalkenyl, alkynyl, alkynyl, aryl, haloketoaryl, ketoheteroaryl, ketoalkyl, halocetoalkyl, ketoalkenyl, halocetoalkenyl, phosphoalkyl, phosphonate, phosphate, phosphine, phosphine oxide, , Sulfonyl, sulfoalkyl, sulfoarenyl, sulfonate, sulfone Wherein the number of carbon atoms is in the range of 1 to 12 except for the specific case where carbon is included,

R ₃ is selected from the group consisting of hydrogen, hydroxyl, halogen, nitro, formyl, carboxyl, alkyl, alkoxy, cycloalkyl, haloalkyl, aryl, haloaryl, heteroaryl, heterocycloalkyl, haloheteroaryl, Alkynyl, haloalkynyl, keto, ketoaryl, halocetoaryl, ketoheteroaryl, ketoalkyl, halocetoalkyl, ketoalkenyl, halocetoalkenyl, phosphoalkyl, phosphonate, phosphate, phosphine At least one selected from the group consisting of phosphine oxide, phosphine oxide, phospholyl, phosphoaryl, sulfonyl, sulfoalkyl, sulfoarenyl, sulfonate, sulfate, sulfone, amine, polyether, silylalkyl or silylalkyloxy, The carbon number is within the range of 1 to 12,

n and m are each independently an integer of 0 to 5 and P is an integer of 0 to 4.)

Preferably, the naphthalene-diimide compound is such that R ₁ and R ₂ are each independently selected from the group consisting of alkyl (NDI-C6), long chain alkyl, substituted or unsubstituted indenyl (NDI-ID) (NDI-PM), substituted or unsubstituted naphthyl, tetrahydronaphthyl (NDI-TN), 1,2,3,4-tetrahydronaphthyl, an aliphatic ring having 9 to 30 carbon atoms and an aromatic ring And condensed rings.

More preferably, the naphthalene-diimide compound is a compound in which R ₁ and R ₂ each independently represents a substituted or unsubstituted indenyl, a substituted or unsubstituted phenyl, an aliphatic ring having 9 to 30 carbon atoms and a ring condensed with an aromatic ring And the like.

The thickness of the preferable electron transporting layer may be in the range of 1 nm to 3 m, but may not be limited thereto.

The perovskite plane solar cell using the naphthalene-diimide compound-based electron transport material according to the present invention exhibits a power conversion efficiency of 18.0 to 20.1% under 1 Sun (100 mW / cm ² ) illumination. This is similar to the power conversion efficiency provided by using a fullerene-based material (PCBM) as an ETM.

The improved thermal stability of perovskite solar cells using naphthalene-diimide compound-based electron transport materials is due to the stronger hydrogen bonds in the molecular crystals of naphthalene-diimide compounds than PCBM crystals.

The high temporal stability and thermal stability of a perovskite solar cell using an naphthalene-diimide compound-based electron transport material can be evaluated by comparing the intensity of molecular secondary bonds having molecular packing characteristics in a solid state .

More specifically, the temporal stability of the perovskite solar cell can be seen to be influenced by the migration tendency of the molecules constituting the crystal layer. The results of the analysis of electron transport material crystals by Hirshfeld surface analysis are shown in FIG. 1, the strongest hydrogen bonding distance is 2.31 A for NDI-PM, 2.6 A for NDI-ID, and 2.76 A for PCBM, so that the naphthalene-diimide compound It can be seen that the crystals exhibit much stronger intermolecular hydrogen bonds than crystals of fullerene-based materials.

1, the relative contribution of OH atomic contacts (i.e., hydrogen bonds between OH atoms) in the NDI compound crystals is 10 to 20% (10.4 and 10.5% in the case of NDI-PM crystals, (17.7%), which is significantly higher than PCBM (2.6%). Therefore, it can be explained that the migration of the NDI crystal molecules in the crystalline state having stronger secondary bonds can be suppressed more than the PCBM crystals, so that they have high temporal stability and thermal stability.

Also, the pore form of the naphthalene-diimide compound crystals is more suitable for inhibiting the migration of molecules than PCBM. The void properties in the crystals can be analyzed by the Cambridge Structural Database (CSD) MERCURY program, which shows similar contents of naphthalene-diimide compounds and PCBM crystals (27% and 25%, respectively) Is significantly different.

2, the naphthalene-diimide compound (NDI-PM) crystals form a two-dimensional pore structure, and the pores do not act on the planar NDI core along the pi-pi lamination direction (see the dotted circle in Fig. 2) . On the other hand, PCBM crystals form a three-dimensional pore structure, and pores act in all directions of the PCBM molecule. Pores present in all directions can carry higher migration tendencies than NDI-PM crystals.

Also, as shown in the DSC measurement results described later, the naphthalene-diimide compound crystal can inhibit phase transition prior to the melting temperature Tm and also prevent migration of the NDI-PM molecules in the crystalline state.

The second electrode is a layer formed on the electron transport layer. The second electrode is formed of a metal such as Al, Ca, Ag, Au, Pt, Cu, Zn, And chromium (Cr). Preferably, the second electrode may be an aluminum electrode, and the thickness of the electrode may be 50 to 200 nm.

The present invention also provides a method of manufacturing a light emitting device, comprising: forming a hole transport layer on a first electrode (step 1); Forming a photoactive layer, which is a perovskite layer containing perovskite represented by Formula 1 or Formula 2, on the hole transport layer formed in Step 1 (Step 2); Forming an electron transport layer of the naphthalene-diimide compound on the photoactive layer formed in step 2 (step 3); And forming a second electrode on the electron transport layer formed in step 3 (step 4).

Step 1 to Step 3 may be performed by a spin coating method, and Step 4 may be performed by thermal evaporation.

The present invention also provides a solar cell module including the perovskite solar cell. The present invention provides a solar cell module in which the above-described solar cell or a solar cell manufactured by the above-described manufacturing method is arranged as a unit cell and two or more cells are arranged and electrically connected to each other. The solar cell module may have an arrangement and structure of cells commonly used in the field of solar cells, and may further include a usual light collecting means for collecting solar light, and a usual optical block for guiding sunlight path.

Examples and Comparative Examples

To fabricate a perovskite solar cell, first, an In-doped SnO ₂ (ITO, 10 Ω, AMG) glass substrate was sequentially ultrasonically washed with 2-5% Hellmanex soap, ethanol and acetone, Plasma treatment was performed to obtain an ITO glass substrate from which organic substances were removed.

The filtered PEDOT: PSS (AI4083, Clevios) / methanol (1: 1 to 2 volume ratio) was spin coated on the cleaned ITO glass substrate at 2000 to 3000 rpm for 30 to 60 seconds and dried at 150 ° C. for 20 minutes to obtain PEDOT: PSS / ITO substrate was obtained.

For the MAPBI ₃ perovskite film, methylammonium iodide powder (MAI, DS LOGICS CO., LTD.) And lead (II) iodide (PbI ₂ , Aldrich) (1: 1 molar ratio) were dissolved in N, N-dimethylformamide , Aldrich) at 60 캜 for 30 min to prepare a 40 wt% MAPbI ₃ perovskite solution. 100 μl of hydriodic acid (HI, Aldrich) was added to 1 mL of MAPBI ₃ perovskite solution at room temperature. A 40 wt% MAPBI ₃ perovskite solution was spin-coated on a PEDOT: PSS / ITO substrate at 3000 rpm for 120 seconds and then dried on a hot plate at 100 ° C for 2 minutes to obtain a MAPbI ₃ perovskite film / PEDOT: PSS / ITO substrate ≪ / RTI >

For the FAPbI _3-x Br _x perovskite film, PbI ₂ (DMSO) complex was prepared by dissolving 50 g of PbI ₂ in 150 mL of dimethyl sulfoxide (DMSO, Aldrich) at 60 ° C. for 30 min. And slowly added dropwise to the PbI ₂ solution. The white precipitate was filtered and annealed in a vacuum oven at 60 [deg.] C for 5 hours. 1 M PbI ₂ (DMSO) complex was dissolved in DMF at 60 ° C for 5 minutes. The PbI ₂ (DMSO) complex solution was coated on the PEDOT: PSS / ITO substrate by spin coating at 3000 rpm for 30 seconds, and then 0.5 M FAI and MABr (0.85: 0.15 molar ratio) were sprayed on the iso-propanol (IPA, Aldrich) , And spin-coated with a solution mixed for 30 seconds. The film adjusted from transparent to dark brown during spin coating was dried on a hot plate at 150 캜 for 20 minutes to obtain a FAPbI _3-x Br _x perovskite film / PEDOT: PSS / ITO substrate.

A solution of a phenyl-C61-butyric acid methyl ester (PCBM, nano-C) / 1,2-dichlorobenzene (1,2-DCB) on the perovskite film / PEDOT: PSS / ID / 1,2-DCB solution (15 mg / 1 mL), NDI-C6 / 1,2-DCB solution (15 mg / DCB solution (15 mg / 1 mL) and NDI-TN / 1,2-DCB solution (15 mg / 1 mL) were coated by spin coating at 3000 rpm for 60 seconds to form an ETL / perovskite film / PEDOT: PSS / ITO substrate.

A 60 nm thick Al reflective electrode was finally deposited on the obtained ETL / perovskite film / PEDOT: PSS / ITO substrate by thermal deposition to obtain a solar cell composed of Al / ETL / perovskite film / PEDOT: PSS / ITO substrate. The active area was fabricated at 0.16 cm < ^{2 &} gt ;.

The structure of the solar cell manufactured in Table 1 is shown below.

TCO, substrate Hole transport layer Photoactive layer Electron transport layer Metal electrode Example 1 ITO Glass PEDOT: PSS MAPBI ₃ NDI-PM Al Example 2 ITO Glass PEDOT: PSS FAPbI _3-x Br _x NDI-ID Al Example 3 ITO Glass PEDOT: PSS MAPBI ₃ NDI-C6 Al Example 4 ITO Glass PEDOT: PSS MAPBI ₃ NDI-TN Al Comparative Example 1 ITO Glass PEDOT: PSS MAPBI ₃ PCBM Al Comparative Example 2 ITO Glass PEDOT: PSS FAPbI _3-x Br _x PCBM Al

Experimental Example

(1) Differential Scanning Calorimetry (DSC) measurement

FIG. 3 shows DSC measurement results of NDI-PM and PCBM. As shown in Fig. 3, the phase transition of NDI-PM did not appear before the melting temperature (269 ° C), whereas PCBM started to phase transition (recrystallization by migration in general) at 240 ° C below the melting temperature (279 ° C).

(2) Measurement of IV characteristic and direct current conductivity (σ ₀ )

IV characteristics were measured to compare the direct current conductivity (σ ₀ ) of PCBM, NDI-PM, MAPbI ₃ , and FAPbI _3-x Br _x . The results are shown in FIG.

Conductivity (σ ₀₎ also obtained from the formula 1 were respectively ^{0.0164mScm -1, 0.0150mScm -1, 0.0148mScm -1} , and 0.0161mScm ^-1. The sample area was 0.16 cm ² , and the thicknesses were 200 nm, 200 nm, 300 nm, and 300 nm, respectively.

I = σ ₀ Ad ^-1 V (A and d are the sample area and thickness)

From the above results, it can be seen that NDI-PM has conductivity similar to PCBM.

(3) Electron transportation characteristics

The SiO ₂ (300 nm thick) / Si substrate was rinsed with acetone and isopropyl alcohol for 15 minutes under ultrasonication. Subsequently, nitrogen (N ₂ ) was dried, and the substrate was exposed to 365 nm ultraviolet rays for 10 minutes. NDI-PM and NDI-ID single crystals were fabricated by Solvent Vapor Annealing (SVA) process. The NDI compound and poly (methyl methacrylate) (PMMA, average molecular weight ~ 15,000) were dissolved in dichloromethane (2.0 wt% PMMA / 0.08 wt% NDI compound). The mixed solution was stirred for 2 hours and then spin-coated on a cleaned substrate at 2500 rpm for 1 minute. After spin coating, 10.0 mL of dichloromethane was injected into a 20 mL vial, and the vial was covered with the prepared NDI compound / PMMA film for 5 hours to allow the NDI compound single crystal to grow on the PMMA matrix. After the SVA process, the film was annealed at 65 DEG C for 15 minutes to completely remove the residual solvent. In order to complete the fabrication of the BG / TC FET, a 50 nm thick gold S / D electrode was heated in a vacuum of 2.0 × 10 ^-6 Torr through a shadow mask in a vacuum chamber at a deposition rate of 0.1-0.2 Ås ^-1 Respectively. The two channel lengths and widths defined by the shadow mask are 30, 50, and 1 mm, respectively. The field effect mobility (μ) was evaluated in the saturation region using Equation 2 below.

[Formula 2]

In Equation 1, W and L are the channel width and length, respectively, C _i is the gate dielectric capacitance (10 nF cm ² ) per unit area, and VG, VT and ID are the gate voltage, threshold voltage and drain.

Electronic devices for SCLC mobility estimation were fabricated with ITO / ZnO / NDI-PM (ID) / LiF / Al. The mobility is determined using the SCLC model shown in Equation 3 below.

[Formula 3]

Where ε ₀ is the dielectric constant of free space (8.85 × 10 ^-12 Fm ^-1 ), ε _r is the dielectric constant of the NDI compound (assuming 3), μ is the electron mobility, V is the voltage and L is the film thickness )to be. All current-voltage (IV) characteristics of field effect transistors (FETs) were measured with a Keithley 4200 semiconductor characterization system connected to the probe station of an N ₂ fill chamber.

The electron mobility (μ) of OFETs based on single crystals of the measured NDI compound is 0.1 cm ² V ^-1 S ^-1 (maximum value) for NDI-PM and 0.2 cm ² V ^{-1 for NDI-} S ^-1 (maximum value), and it was confirmed that it has high electron mobility.

(4) Photoluminescent (PL) measurement

PL life was measured by ChronosBH-ISS technical measurement equipment.

PL of MAPBI ₃ , MAPBI ₃ / PCBM, and MAPBI ₃ / NDI-PM and FAPbI _3-x Br _x , FAPbI _3-x Br _x / PCBM and FAPbI _3-x Br _x / NDI- 5 shows the measurement results of transient photoluminescent (PL) decay curves.

The mean values of the PL lifetimes (τ _avg ) obtained by fitting the temporary PL decay curve results to the 2-charge function are 9.03 ns, 2.42 ns and 4.18 ns, respectively, and 9.65 ns, 2.96 ns and 3.64 ns, respectively.

 The PL lifetime of all samples is shown in Table 2 below.

A ₁ (%) τ ₁ (ns) A ₁ (%) τ ₁ (ns) τ _avg (ns) MAPBI ₃ 65.79 4.45 34.21 13.60 9.03 MAPBI ₃ / NDI-PM 60.49 2.51 39.51 5.84 4.18 FAPbI ₃ 50.72 4.41 49.28 14.88 9.65 MAPBI ₃ / PCBM 58.92 1.08 41.08 3.76 2.42 FAPbI ₃ / NDI-PM 60.87 2.06 39.13 5.22 3.64 FAPbI ₃ / PCBM 55.87 1.60 44.13 4.33 2.96

(5) Scanning Electron Microscopy (SEM) measurement

FIG. 6 shows a cross-sectional SEM image of a perovskite solar cell composed of glass / ITO / PEDOT: PSS / perovskite (MAPbI ₃ ) / NDI-PM / Al. The thickness of each layer except Glass was ~ 150 nm, ~ 50 nm, ~ 300 nm, ~ 40 nm, and ~ 40 nm, respectively.

(6) Measurement of J-V (current density-voltage) curves and photovoltaic characteristics (power conversion efficiency)

The current density voltage curve was measured with a solar simulato (Peccell, PEC-L01) with potentiostat (IVIUM, IviumStat) under illumination of 1 Sun (100 mW / cm ² AM 1.5G). The JV curve of all solar cells was measured by masking the active area with a 0.096 cm ² metal mask. In order to measure the hysteresis of the JV curve, a scan rate of 50 mV / s was set as a standard condition at 10 mV intervals in a forward (initial) direction and a reverse (final) direction.

Respectively in Fig. _{7 NDI-PM / MAPbI 3 (} a), PCBM / MAPbI 3 (b), NDI-PM / FAPbI 3-x Br x (c), PCBM / FAPbI 3-x Br x (d), NDI- _{C6 / MAPbI 3 (e),} NDI-TN / MAPbI 3 (f) and reverse-phase structure of the _{NDI-ID / FAPbI 3-x} Br x (g), NDI-ID / FAPbI 3-x Br x (h) MAPbI 3 Or FAPbI _3-x Br _x planar perovskite solar cell. The photovoltaic characteristics of the perovskite solar cell are shown in Table 3 below.

ETM Perovskite Scan
direction V _oc (V) J _sc (mA / cm ² ) FF (%) 侶 (%) Avg. η (%) for
40 samples NDI-PM MAPBI ₃ Forward 1.10 21.2 77.2 18.0 16.23 + - 1.24 Reverse 1.10 21.2 79.1 18.4 NDI-ID FAPbI _3-x Br _x Forward 1.10 22.9 79.7 20.1 17.92 + 1.15 Reverse 1.06 22.2 76.6 18.0 PCBM MAPBI ₃ Forward 1.11 21.4 78.8 18.7 16.81 + - 1.14 Reverse 1.11 21.4 79.6 18.9 PCBM FAPbI _{3 - x} Br _x Forward 1.08 23.0 78.6 19.5 17.67 ± 1.10 Reverse 1.09 23.0 79.8 20.0

The NDI-PM / MAPbI ₃ based device has a 1.10V open circuit voltage (Voc), 21.2mA cm ^-2 shortcurrent density (Jsc), 77.2% fill factor (FF) and 18.0% power conversion efficiency And showed 1.10 V Voc, 21.2 mA cm ^-2 Jsc, 79.1% FF, and 18.4%? In the reverse scan condition.

_{NDI-ID / FAPbI 3-x} Br x based device is 1.10V Voc, Jsc 22.9mA cm ^-2, and having a 79.7% FF% η 20.10, 1.06 Voc V, 22.2 mA cm in reverse scanning conditions in the scanning conditions Forward ^{- 2} Jsc, 76.6% FF, and 18.03%?.

PCBM / MAPbI ₃ based devices showed 1.11 V Voc, 21.4 mA cm ^-2 Jsc, 78.8% FF, and 18.7% η at the forward scan condition and 1.11 V Voc, 21.4 mA cm ^-2 Jsc, and 79.6% FF, and 18.9%, respectively.

PCBM / FAPbI _3-x Br _x based devices exhibited 1.09 V Voc, 23.0 mA cm ^-2 Jsc, 79.8% FF, and 20.01% η in the forward scan conditions and 1.04 V Voc and 21.7 mA cm ^-2 Jsc, 75.5% FF, and 17.03% η.

The average power conversion efficiency of the 40 samples is 16.23 ㅁ 1.24% for NDI-PM-based samples and 16.81 賊 1.14% for PCBM-based samples. When applied to the inverted FAPbI _{3 - x} Br _x planar perovskite solar cell, the NDI-PM based devices showed 19.1% and 19.6% η (average η = 17.15 ± 1.22%, respectively) ) While PCBM-based devices showed 19.5% and 20.0% η (average η = 17.67 ± 1.10%) in the forward and reverse scan conditions, respectively.

(7) External Quantum Efficiency (EQE) measurement

External quantum efficiency (EQE) was measured with a power supply (ABET, 150 W xenon lamp, 13014) equipped with a monochromator (OPTRON Co., Ltd., MonoRa-500i) and potentiostat (IVIUM, IviumStat). The measurement range was measured in the range of 300 to 900 nm at intervals of 5 nm.

Respectively in Figure _{8 NDI-PM / MAPbI 3 (} a), PCBM / MAPbI 3 (b), NDI-PM / FAPbI 3-x Br x (c), PCBM / FAPbI 3-x Br x (d), NDI- EQE measurement results of MAPBI ₃ or FAPbI _3-x Br _x planar perovskite solar cells with reversed phase structure of C6 / MAPbI ₃ (e) and NDI-TN / MAPbI ₃ (f)

NDI-PM ETM, which exhibits excellent solution processability and high power conversion efficiency (comparable to PCBM widely used) as shown, is a material that can be used for electron transport materials of perovskite solar cells without fullerene .

(8) Measurement of efficiency

In order to confirm the temporal stability of the MAPbI ₃ perovskite solar cell using NDI-PM and PCBM ETM, the solar cell was stored in a hot plate at 90 ° C for 100 minutes in an atmospheric state, and the efficiency was compared as shown in FIG.

The NDI-PM-based solar cell showed ~ 2.5% efficiency reduction compared to the initial efficiency after 100 minutes heat treatment, but the PCBM-based solar cell showed ~ 7.2% efficiency reduction.

(9) Measurement of thermal stability

FIG. 10 shows AFM (atomic force microscope) topology images of NDI-PM and PCBM ETM before heat treatment (0 min) and after heat treatment (100 min). It can be seen that the shape of PCBM ETM is changed by recrystallization by heat treatment, but the shape of NDI-PM ETM is not affected by heat treatment because it has better thermal stability than PCBM.

The features, structures, effects, and the like illustrated in the above-described embodiments can be combined and modified in other embodiments by those skilled in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

Claims (6)

A naphthalene-diimide compound represented by the following structural formula (1) as a compound for an electron transferring material of a perovskite solar cell.
[Structural formula 1]

(Wherein R ₁ and R ₂ are each independently hydrogen, hydroxyl, halogen, pseudohalogen, formyl, carboxyl, alkoxy, long chain alkoxy, alkyl, long chain alkyl, substituted or unsubstituted indenyl indenyl, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, tetrahydronaphthyl, 1,2,3,4-tetrahydronaphthyl, a condensed ring of an aliphatic ring having 9 to 30 carbon atoms and an aromatic ring, a cyclo Alkyl, haloalkyl, aryl, arylene, haloaryl, heteroaryl, heteroarylene, heterocycloalkylene, heterocycloalkyl, haloheteroaryl, alkenyl, haloalkenyl, alkynyl, haloalkynyl, Alkyl, alkenyl, aryl, haloalkenyl, alkynyl, alkynyl, aryl, haloketoaryl, ketoheteroaryl, ketoalkyl, halocetoalkyl, ketoalkenyl, halocetoalkenyl, phosphoalkyl, phosphonate, phosphate, phosphine, phosphine oxide, , Sulfonyl, sulfoalkyl, sulfoarenyl, sulfonate, sulfone Wherein the number of carbon atoms is in the range of 1 to 12 except for the specific case where carbon is included,
R ₃ is selected from the group consisting of hydrogen, hydroxyl, halogen, nitro, formyl, carboxyl, alkyl, alkoxy, cycloalkyl, haloalkyl, aryl, haloaryl, heteroaryl, heterocycloalkyl, haloheteroaryl, Alkynyl, haloalkynyl, keto, ketoaryl, halocetoaryl, ketoheteroaryl, ketoalkyl, halocetoalkyl, ketoalkenyl, halocetoalkenyl, phosphoalkyl, phosphonate, phosphate, phosphine At least one selected from the group consisting of phosphine oxide, phosphine oxide, phospholyl, phosphoaryl, sulfonyl, sulfoalkyl, sulfoarenyl, sulfonate, sulfate, sulfone, amine, polyether, silylalkyl or silylalkyloxy, The carbon number is within the range of 1 to 12,
n and m are each independently an integer of 0 to 5 and P is an integer of 0 to 4.)
The method according to claim 1,
The compound is characterized in that R ₁ and R ₂ are each independently selected from the group consisting of alkyl, long chain alkyl, substituted or unsubstituted indenyl, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, tetrahydronaphthyl , 1,2,3,4-tetrahydronaphthyl, a ring condensed with an aliphatic ring having 9 to 30 carbon atoms and an aromatic ring, and a naphthalene-diimide compound.
A first electrode;
A hole transport layer formed on the first electrode;
A photoactive layer formed of perovskite on the hole transporting layer;
An electron transport layer formed on the photoactive layer; And
And a second electrode formed on the electron transporting layer,
Wherein the electron transport layer comprises a naphthalene-diimide compound represented by the following structural formula (1).
[Structural formula 1]

(Wherein R ₁ and R ₂ are each independently hydrogen, hydroxyl, halogen, pseudohalogen, formyl, carboxyl, alkoxy, long chain alkoxy, alkyl, long chain alkyl, substituted or unsubstituted indenyl indenyl, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, tetrahydronaphthyl, 1,2,3,4-tetrahydronaphthyl, a condensed ring of an aliphatic ring having 9 to 30 carbon atoms and an aromatic ring, a cyclo Alkyl, haloalkyl, aryl, arylene, haloaryl, heteroaryl, heteroarylene, heterocycloalkylene, heterocycloalkyl, haloheteroaryl, alkenyl, haloalkenyl, alkynyl, haloalkynyl, Alkyl, alkenyl, aryl, haloalkenyl, alkynyl, alkynyl, aryl, haloketoaryl, ketoheteroaryl, ketoalkyl, halocetoalkyl, ketoalkenyl, halocetoalkenyl, phosphoalkyl, phosphonate, phosphate, phosphine, phosphine oxide, , Sulfonyl, sulfoalkyl, sulfoarenyl, sulfonate, sulfone Wherein the number of carbon atoms is in the range of 1 to 12 except for the specific case where carbon is included,
R ₃ is selected from the group consisting of hydrogen, hydroxyl, halogen, nitro, formyl, carboxyl, alkyl, alkoxy, cycloalkyl, haloalkyl, aryl, haloaryl, heteroaryl, heterocycloalkyl, haloheteroaryl, Alkynyl, haloalkynyl, keto, ketoaryl, halocetoaryl, ketoheteroaryl, ketoalkyl, halocetoalkyl, ketoalkenyl, halocetoalkenyl, phosphoalkyl, phosphonate, phosphate, phosphine At least one selected from the group consisting of phosphine oxide, phosphine oxide, phospholyl, phosphoaryl, sulfonyl, sulfoalkyl, sulfoarenyl, sulfonate, sulfate, sulfone, amine, polyether, silylalkyl or silylalkyloxy, The carbon number is within the range of 1 to 12,
n and m are each independently an integer of 0 to 5 and P is an integer of 0 to 4.)
The method of claim 3,
Wherein the photoactive layer comprises perovskite represented by Formula (Methylammonium lead trihalide) or Formula (Formamidinium lead halide).
[Chemical Formula 1]
CH ₃ NH ₃ PbX ₃
(Wherein X is any one halogen element selected from the group consisting of iodine, bromine and chlorine)
(2)
HC (NH ₂ ) ₂ PbX _3-x X ' _x
Wherein X and X 'are each independently a different halogen element selected from the group consisting of iodine, bromine and chlorine.
The method of claim 3,
Wherein the electron transporting layer is formed to a thickness of 1 nm to 3 m.
A solar cell module comprising the perovskite solar cell according to any one of claims 3 to 5.

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