JP7317161B2 - Evaluation method of physical structure - Google Patents

Description

The present invention relates to analytical methods. More specifically, the present invention evaluates the difference in the physical structure of the entire sample quickly and at low cost for each component with high sensitivity, regardless of the number and layer structure of the constituent components of the sample, and evaluates multiple factors. It relates to analytical methods that can be collectively evaluated.

In the field of organic electronics, organic films are mainly produced by a vapor deposition method. However, for the development of industry, it is essential to increase the area of the device and reduce the cost. It is known that the film quality of an organic film has a great influence on device characteristics. A major problem is that the film quality of the organic film produced by the coating method is inferior to that produced by the vapor deposition method. Therefore, it is necessary to optimize the organic material forming the organic film, the process method, the process conditions, and the like.

Therefore, a method for evaluating the difference in film quality between a film obtained by a vapor deposition method (vapor-deposited film) and a film obtained by a coating method (coated film), or a difference between coated films produced under different conditions is required. ing. In particular, organic films are composed of multiple components and often have a multi-layered structure, requiring evaluation of each component. Film quality includes various factors such as film density, orientation of substances constituting the film, crystallinity, cohesiveness and amorphousness, film hardness, film surface roughness, and film thickness. Therefore, various methods such as microscopic observation (optical microscope, SEM, TEM, AFM, SPM, etc.) and spectroscopic analysis (XRR, spectroscopic ellipsometry, Raman spectroscopy, FTIR, SAXS, WAXS, and XRD) are used for film quality evaluation. It is

For example, Non-Patent Document 1 describes evaluation of molecular orientation by spectroscopic ellipsometry. Non-Patent Documents 2 and 3 describe the analysis of the structure of a thin film using X-ray scattering or the like.

On the other hand, in the field of organic electronics, analysis using TOFMS, which can extract data for each chemical component, is also performed. Non-Patent Document 4 describes a technique for evaluating chemical degradation in organic light-emitting diodes by LDI-TOFMS. Non-Patent Document 5 describes a technique in which an organic film sample having a multilayer structure is separated into layers by LDI-TOFMS, and the distribution of constituent chemical components in the depth direction of the film is evaluated.

Daisuke Yokoyama, Vol.22, No.4 (November 2011) 203-208 G. Gupta et al., Appl. Mater. Interfaces 2015, 7, 12309-12318 Yuko Kojima, Green Energy Study Group, SPring-8 Utilization Promotion Council, "Nanostructural Analysis of Thin Films for Coated Organic Solar Cells", November 5, 2012, [online], [searched April 13, 2016], Internet <http://www.spring8.or.jp/ext/ja/iuss/htm/text/12file/green_energy/7th/2.kojima.pdf> I.R. de Moraes et. al., Organic Electronics 13 (2012) 1900-1907 Takaya Sato et al., ``Study of depth profile analysis of organic thin films by laser desorption ionization,'' Proceedings of the Symposium on Mass Spectrometry Vol. 62, Page.

However, the above-described conventional techniques have room for improvement in terms of providing analytical methods capable of evaluating differences in the physical structure of samples with high sensitivity at low cost or quickly and evaluating multiple factors. rice field. In addition, when a sample is composed of multiple components or has a multi-layered structure, analysis is often difficult.

For example, the techniques described in Non-Patent Documents 1 to 3 measure limited factors. Therefore, when measuring a plurality of factors, it is necessary to combine a plurality of measurement methods, resulting in problems of cost and time for evaluation. In the technique described in Non-Patent Document 1, in principle, the optical properties of the entire sample are evaluated by calculating the physical constants of the sample itself and the fitting parameters optimized using a theoretically constructed calculation formula. ing. Therefore, in the technique described in Non-Patent Document 1, when a sample is composed of a plurality of components or has a multilayer structure, it is difficult to separate and evaluate each component or each layer.

Moreover, in the prior art, it was sometimes difficult to evaluate the physical structure of the sample from the viewpoint of sensitivity. With the technique described in Non-Patent Document 1, it is difficult to make an appropriate evaluation for a thin film sample of 100 nm or less, which is used in organic electronics, because the accuracy of fitting is theoretically reduced.

Furthermore, although the techniques of Non-Patent Documents 2 and 3 using synchrotron radiation X-rays have high evaluation sensitivity, they themselves are expensive and are used in specific facilities, so the frequency of evaluation is limited. In addition, if the sample consists of multiple components or has a multi-layer structure, it is theoretically difficult to separate and evaluate each component or layer, and the penetration depth of X-rays into the sample is limited. Therefore, evaluation of the entire sample may not be possible. In particular, the GI-SAXS method or GI-WAXS method used to improve sensitivity is limited to evaluation of the sample surface only.

The technique described in Non-Patent Document 4 evaluates chemical changes, not physical structures of organic films.

One aspect of the present invention has been made in view of the above problems, and an object of the present invention is to quickly and inexpensively determine differences in the physical structure of the entire sample, regardless of the number and layer structure of the constituent components of the sample. An object of the present invention is to realize an analysis method capable of evaluating each component with high sensitivity and collectively evaluating a plurality of factors.

As a result of intensive studies to solve the above problems, the present inventors have found that by analyzing the ionization behavior of a sample using MALDI-TOFMS, the difference in the physical structure of the sample can be evaluated quickly at a low cost and with high sensitivity. , and found that an analysis method capable of evaluating a plurality of factors can be realized, leading to the completion of the present invention. That is, the present invention includes the following configurations.

[1] An analysis method characterized by including an evaluation step of evaluating the physical structure of a sample based on the ionization behavior of the sample obtained by MALDI-TOFMS.

[2] The analysis method according to [1], wherein the sample is composed of a plurality of components, and each component is evaluated.

[3] The analysis method according to [1] or [2], wherein the sample is composed of a plurality of layers, and each layer is evaluated.

[4] The analysis method according to any one of [1] to [3], wherein the sample contains an organic film.

[5] The analysis method according to [4], wherein the organic film has a thickness of 0.1 nm to 2 μm.

[6] The analysis method according to any one of [1] to [5], wherein the sample is used in the field of organic electronics.

[7] The analysis method according to any one of [1] to [6], wherein the index of the ionization behavior is ion intensity or ion production ratio obtained by MALDI-TOFMS.

[8] The ionization behavior is obtained by changing any one or more selected from the group consisting of laser intensity, laser frequency, laser wavelength, temperature and measurement atmosphere [1] to [7]. ] The analysis method as described in any one of ].

[9] The ionization behavior is characterized by being represented by a graph showing changes in ion intensity accompanying changes in any one selected from the group consisting of laser intensity, laser frequency, laser wavelength, temperature, and measurement atmosphere. The analysis method according to any one of [1] to [8].

[10] The analysis method according to any one of [1] to [9], which includes a comparison step of performing the evaluation step on a plurality of samples and comparing the results.

[11] The analysis method according to [10], wherein the plurality of samples are samples obtained by different manufacturing methods.

[12] that the above plurality of samples are samples obtained by any one selected from the group consisting of cooling, heat, light, electricity, under pressure, under reduced pressure, and left in an environment after production; The analytical method according to [10], characterized in that:

One aspect of the present invention is to evaluate the difference in the physical structure of the entire sample quickly and at low cost with high sensitivity for each component, regardless of the number and layer structure of the constituent components of the sample, and to collectively evaluate a plurality of factors. There is an effect that a possible analysis method can be realized.

FIG. 4 is a graph showing the ion intensity of molecular ions of TPBi and Ir(t-buppy) 3 when laser intensity is varied. FIG. 4 is a graph showing the ionic strength of molecular ions of TPBi and Ir(t-buppy)3 with varying laser frequencies; FIG. 4 is a graph showing ion intensity of B3PYMPM with varying laser intensity. FIG. 4 is a graph showing the ion intensity of B3PYMPM with varying laser frequencies. FIG. 10 is a diagram showing mass spectra of deposited films of B3PYMPM when laser intensity is changed. FIG. 4 is a diagram showing mass spectra of coating films of B3PYMPM when laser intensity is changed. FIG. 4 is a graph showing the ionic strength of B3PYMPM dimers and trimers with varying laser intensities. FIG. 10 is a graph showing the ion intensity of negative ions of B3PYMPM when the laser frequency is changed. FIG. 10 is a diagram showing mass spectra of negative ions in a deposited film of B3PYMPM when the laser frequency is changed; FIG. 4 is a diagram showing mass spectra of negative ions in a coating film of B3PYMPM when the laser frequency is changed. FIG. 10 is a diagram showing mass spectra of a B3PYMPM deposited film and a coated film when the laser frequency is changed; FIG. 3 is a diagram showing measurement results of a deposited film and a coated film of B3PYMPM by synchrotron radiation soft X-ray absorption spectroscopy. FIG. 4 is a diagram showing measurement results of a B3PYMPM deposited film and a coated film by GI-WAXS. FIG. 4 is a diagram showing measurement results by GI-SAXS of a deposited film and a coated film obtained by mixing TPBi and Ir(t-buppy)3. FIG. 4 is a diagram showing measurement results of an organic multilayer thin film by MALDI-TOFMS;

Embodiments of the present invention are described in detail below, but these are aspects of the present invention, and the present invention is not limited to these contents. Unless otherwise specified in this specification, "A to B" representing a numerical range means "A or more (including A and greater than A) and B or less (including B and less than B)".

An analysis method according to one embodiment of the present invention includes an evaluation step of evaluating the physical structure of a sample based on the ionization behavior of the sample obtained by MALDI-TOFMS.

[1. Evaluation process]
This step is a step of evaluating the physical structure of the sample based on the ionization behavior of the sample obtained by MALDI-TOFMS.

As shown in Examples below, the present inventors have found that when membrane samples obtained by different manufacturing methods using the same material (that is, membrane samples with the same chemical structure) are observed by MALDI-TOFMS, , found that there is a difference in ionization behavior. Since these film samples use the same material, they have the same chemical composition. Therefore, this difference in ionization behavior is considered to reflect the difference in physical structure.

In addition, as shown in Examples below, the inventors of the present invention may actually find differences in physical structures when membrane samples obtained by different manufacturing methods are evaluated by analytical methods other than MALDI-TOFMS. Confirmed. From the above, it is considered that the physical structure of the sample can be evaluated, not the chemical structure of the sample, according to this analytical method.

An analysis method capable of evaluating the physical structure of a sample in this way is very useful as a screening method for film quality evaluation in the development of a coating method, and is useful for improving development speed and development accuracy.

Moreover, according to this analysis method, since MALDI-TOFMS is used, the cost is lower than the techniques using synchrotron radiation X-rays, such as Non-Patent Documents 2 and 3 described above. Moreover, since MALDI-TOFMS is used, differences in the physical structure of samples can be evaluated with high sensitivity, and a plurality of factors can be collectively evaluated.

<1-1. MALDI-TOF MS>
An analysis method according to an embodiment of the present invention uses MALDI-TOFMS. MALDI-TOFMS is an analysis method combining matrix-assisted laser desorption/ionization (MALDI) and time-of-flight mass spectrometer (TOFMS).

In MALDI, first, a mixed crystal of a sample and a matrix (ionization aid) is produced. Then, the mixed crystal is irradiated with a pulse of laser light. This adds protons or metal cations to produce ions. This ion is introduced into the mass spectrometer. Since MALDI uses a matrix, it is possible to perform mass spectrometry of macromolecular components that are easily decomposed by laser irradiation in the conventional ionization method. In the case of components that are difficult to decompose, measurement can be performed without using a matrix.

TOFMS measures the mass-to-charge ratio (m/z) by measuring the time it takes an accelerated charged particle (ion) to fly a certain distance. Ions with a high mass-to-charge ratio fly at low speeds, and ions with low mass-to-charge ratios fly at high speeds. Therefore, ions with a large mass-to-charge ratio reach the ion detector late, and ions with a small mass-to-charge ratio reach the ion detector early. It is possible to measure the mass of the sample from the flight time difference until it reaches the ion detector.

Conventionally, MALDI-TOFMS has been used to evaluate the chemical structure of samples, as described in Non-Patent Document 4. That is, MALDI-TOFMS has been used for qualitative observation of samples. On the other hand, in the analysis method according to one embodiment of the present invention, the physical structure of the sample is evaluated by analyzing the ionization behavior of the sample using MALDI-TOFMS.

In addition, in MALDI-TOFMS, in order to improve the measurement sensitivity of the component to be measured, it is possible to devise a pretreatment to variously change the crystalline state of the sample. In particular, for trace amounts of components or components that are difficult to ionize, a slight difference in the crystal state may significantly change the sensitivity of detection. The present inventors focused on this point and found that the physical structure can be evaluated with high sensitivity using MALDI-TOFMS. In other words, the physical structure of the sample affects the direction and degree of transmission of the laser energy irradiated during ionization to each component constituting the sample. One embodiment of the present invention is an invention that utilizes the fact that the difference in the way of propagation is reflected in the generation rate of ions detected by TOFMS.

<1-2. Sample>
The sample to be analyzed is not particularly limited as long as it contains an ionizable substance, and may be an organic substance, an inorganic substance, or a mixture thereof. The organic substance may be a single organic substance or a mixture of two or more different organic substances. Further, the inorganic substance may be a single inorganic substance or a mixture of two or more different inorganic substances. That is, the sample may be composed of multiple components. In this case, each component may be evaluated by the analysis method according to one embodiment of the present invention. As described above, in the prior art, it was sometimes difficult to evaluate a plurality of components for each component, but according to the analysis method according to one embodiment of the present invention, evaluation for each component is possible.

Examples of organic substances include compounds derived from aliphatic hydrocarbons, aromatic hydrocarbons, polycyclic aromatic hydrocarbons, heteroaromatic hydrocarbons, or heteropolycyclic aromatic hydrocarbons, and the rings are covalently bonded to each other. Linked compounds, compounds containing fullerene in the skeleton, compounds containing porphyrin or phthalocyanine in the skeleton, metal complex compounds containing these structures, oligomers and polymers containing these structures, and the like.

Examples of inorganic substances include those containing at least one of the following elements: [alkali metal elements] Li, Na, K, Rb, Cs; [alkaline earth metal elements] Be, Mg, Ca, Sr, Ba; [Lanthanoid elements] La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu; [Actinoid elements] Th, U; [Transition metal elements] Sc , Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt , Au; [boron group element] B, Al, Ga, In, Tl; [carbon group element] Si, Ge, Sn, Pb; [nictogen element] P, As, Sb, Bi; [chalcogen element] S, Se , Te; [halogen element] F, Cl, Br, I;

The shape of the sample is also not particularly limited, and may be, for example, a powder sample or a film sample (hereinafter also referred to as a film sample). Also, in this specification, a film sample containing an organic substance may be referred to as an organic film. Note that the organic film may contain an inorganic substance in addition to the organic substance. Further, the film sample may be a single-layer film or a multilayer film composed of two or more layers. That is, the sample may be composed of multiple layers. In this case, each layer may be evaluated by the analysis method according to one embodiment of the present invention. As described above, in the prior art, it was sometimes difficult to evaluate a plurality of layers for each layer. As described in Non-Patent Document 5, according to LDI-TOFMS, ablation occurs on the sample surface by irradiating the sample with a laser. Therefore, according to the analysis method according to one embodiment of the present invention, it is possible to evaluate each layer by repeatedly irradiating a laser using MALDI-TOFMS and measuring.

As described above, according to the analysis method according to one embodiment of the present invention, differences in the physical structure of the entire sample can be quickly evaluated regardless of the number and layer structure of the constituent components of the sample.

Moreover, the sample may consist of an organic film, or may comprise an organic film and other members. That is, the sample may contain an organic film. For example, the sample may have a member made of an inorganic substance such as an electrode and/or a solid sealing film.

The thickness of the film sample is not particularly limited, and may be 1 nm or less, 1 to 10 nm, 10 to 100 nm, 100 to 1000 nm, or 1 to 2 μm. It may be 2 μm or more. In this specification, a film sample having a thickness of 0.1 nm to 2 μm is also referred to as a thin film. The organic film may have a thickness of 0.1 nm to 2 μm. In this specification, a sample that is both an organic film and a thin film is also referred to as an organic thin film.

The sample may be one used in the field of organic electronics. In this specification, materials used in the field of organic electronics mean materials used in, for example, organic EL, organic solar cells, organic transistors, and the like. Organic thin films as described above are included in materials used in the field of organic electronics.

In addition, the sample may contain, for example, the following components as components that can be used in the field of organic electronics: 2,2′,2″-(1,3,5-benzenetriyl)- Tris(1-phenyl-1H-benzimidazole) (hereinafter also referred to as TPBi), iridium (III) tris(2-(4′-tert-butylphenyl)pyridinato) (hereinafter also referred to as Ir(t-buppy)3 ), bis-4,6-(3,5-di-3-pyridylphenyl)-2-methylpyrimidine (hereinafter also referred to as B3PYMPM), tris(8-quinolinolato)aluminum (hereinafter also referred to as Alq3), 4, 4′-bis(9H-carbazol-9-yl)biphenyl (hereinafter also referred to as CBP), N,N′-diphenyl-N,N′-di(m-tolyl)benzidine (hereinafter also referred to as TPD) and tris (2-phenylpyridinato)iridium (III) (hereinafter also referred to as Ir(ppy)3);

B3PYMPM, Alq3, CBP, TPD and Ir(ppy)3 are compounds represented by the following formulas (1) to (5), respectively.

The field in which the physical structure of the sample greatly affects the performance of the product is not limited to the field of organic electronics. That is, the sample that is the target of the analysis method according to one embodiment of the present invention is not limited to those used in the field of organic electronics. As well as organic electronics, the field of batteries such as accumulators and fuel cells in which a flow of electrons or ions is generated also applies. In addition, films, resins, rubbers, carbon materials and metals whose physical structure affects gas permeability such as water vapor and oxygen, and mechanical strength against tension, tear, twist, pressure, pressure reduction, temperature, etc., and those This also applies to fields using composite materials, etc.

When the sample is a film sample, the manufacturing method is not particularly limited. According to the analysis method according to one embodiment of the present invention, differences in physical structure between samples obtained by different manufacturing methods can be evaluated. For example, the film sample may be at least one of a coated film and a deposited film.

By vapor-deposited film is intended a film produced by a vapor deposition method. Vapor deposition methods include physical vapor deposition (PVD) and chemical vapor deposition (CVD). PVD includes a vacuum deposition method, a sputtering method, an ion plating method, a molecular beam epitaxy method (MBE), a laser ablation method, and the like. CVD includes thermal CVD, optical CVD, plasma CVD, metal organic chemical vapor deposition (MOCVD), and the like.

By coated film is intended a film produced by a coating method. Examples of coating methods include an inkjet method, a spin coating method, a die coating method, a spray method and a screen printing method.

Alternatively, the film sample may be produced by a plating method, anodization, a sol-gel method, or the like.

<1-3. Physical Structure>
An analytical method according to one embodiment of the present invention evaluates the physical structure of a sample. As used herein, the physical structure of a sample is intended to be a property that can differ between samples made of the same material. For example, the physical structure of a sample includes properties that may differ between samples made of the same material and obtained by different manufacturing methods. The physical structure excludes the chemical structure (eg, structure of polymer end groups, molecular weight distribution, copolymer composition, etc.).

The physical structure includes, for example, any one or more selected from the group consisting of molecular orientation, density, degree of mixing, crystallinity, radical generation state, charge trap state, and interface state. good too. If these physical structures are different, the way energy is transmitted by the laser in MALDI-TOFMS can be different. Therefore, it is conjectured that these physical structures can be evaluated by the analytical method according to one embodiment of the present invention. These physical structures are important, for example, as the film quality of organic films. That is, the analysis method according to one embodiment of the present invention can collectively evaluate a plurality of factors.

Molecular orientation refers to whether the molecules constituting the sample are randomly oriented or oriented in a specific direction (for example, parallel or perpendicular to the substrate on which the film is formed).

Density is an index of whether or not molecules are packed as an average for the entire sample. In other words, the density is an index representing whether or not there is a gap. Cohesiveness is an index that indicates whether or not there is a state in which molecules are attracted to each other and aggregated in a certain portion of the sample as a whole, or whether the amount of such portion is large or small. becomes. The cohesiveness also includes whether there are gaps (low-density areas) and no gaps (high-density areas) in the sample (whether the density is uneven in the sample). It means to

The degree of mixing represents, for example, whether or not a plurality of components contained in the sample are uniformly mixed in the sample as a whole. "Whether or not they are uniformly mixed" means that there are locations where the component ratio is constant and locations where the component ratio is not constant in the sample.

Crystallinity represents whether or not it is crystallized. Physical structure also includes the degree of molecular packing in a crystal.

The state of radical generation represents the presence or absence and distribution of radical generation in a sample.

The charge trap state indicates the presence or absence and distribution of trapped charges.

In the case of a sample composed of multiple components or composed of multiple layers (multilayer film), the state of the interface is the degree of distance, amount, and attractive force between one component and another component. to indicate whether they are in close contact with each other. In the case of a sample composed of a multilayer film, the interface of each layer also includes a state in which an upper layer component and a lower layer component are mixed during or after sample preparation.

Physical structure also includes whether or not molecules are weakly bound and whether or not molecules are solvated.

Such physical structures may differ between the interior and surface of the sample. In some cases, a difference is observed between the upper layer and the lower layer (interface) of the film sample.

In addition, depending on whether or not the coated film is dried, the degree of residual solvent varies, which may affect packing. Furthermore, in the multilayer film obtained by the coating method, the vicinity of the interface between each layer may dissolve due to the influence of the residual solvent. On the other hand, this does not occur in multilayer films obtained by vapor deposition. This may cause a difference in physical structure between the deposited film and the coated film.

Conventional analysis methods can only evaluate a limited number of the physical structures described above per analysis method. In contrast, an analysis method according to an embodiment of the present invention can evaluate various physical structures as described above.

<1-4. Ionization Behavior>
An analysis method according to an embodiment of the present invention utilizes the ionization behavior of a sample obtained by MALDI-TOFMS. In this specification, the ionization behavior means the behavior of ions when the components contained in the sample are ionized. The index of ionization behavior includes, for example, ion intensity or ion production ratio obtained by MALDI-TOFMS.

The ions to be focused on in the analysis of ionization behavior are not particularly limited as long as they are ions of components contained in the sample. Since the analysis method according to one embodiment of the present invention uses MALDI-TOFMS, even if the sample is a mixture of a plurality of components, the ionization behavior of a specific component in the sample is focused on based on the mass-to-charge ratio. can be analyzed as The ions of interest may, for example, be ions of constituents that may be used in the field of organic electronics as described above.

In addition, ions of interest are, for example, molecular ions (M ⁺ and M ⁻ ) of components contained in the sample, protonated molecules ([M+H] ⁺ ), sodium ion adduct molecules ([M+Na] ⁺ ), dehydrated molecules ([M−H] ⁺ ), multivalent protonated molecules ([M+nH] ⁿ⁺ ), deprotonated molecules ([M−H] ⁻ ) and multivalent deprotonated molecules ([M−nH] ⁿ⁻ ), etc. is mentioned. Furthermore, the ions of interest may be other adduct ions, fragment ions, monomers, dimers, trimers, tetramers, or higher multimers. may Those ions may be added. In the case of a sample containing a plurality of components, ions derived from the components may be added to each other. Ions derived from the solvent remaining in the sample prepared by the coating method may be added to ions derived from components derived from the sample. During or after preparation of the sample, ions derived from unintentionally mixed impurities may be added to ions derived from components derived from the sample. In the case of a sample containing inorganic substances and organic substances, ions corresponding to their complexes may be used. Also included are ions that have been altered by heat, light, and/or electricity after sample preparation. The ions may be positive ions or negative ions.

The ion intensity of each of these ions or the production ratio of each ion may be used as an index of ionization behavior. For example, the indicator of ionization behavior is preferably ionic strength, fragment ion generation ratio, adduct ion generation ratio, positive ion to negative ion generation ratio, or protonated molecule to molecular ion generation ratio. These indexes can be suitably used for evaluating the physical structure.

The above ionization behavior may be obtained under certain specific conditions, or may be obtained under a plurality of conditions. Preferably, the ionization behavior is obtained under a plurality of conditions, for example, by changing certain conditions stepwise (or continuously). Specifically, the ionization behavior is preferably obtained by changing any one or more selected from the group consisting of laser intensity, laser frequency, laser wavelength, temperature and measurement atmosphere. Those skilled in the art will appreciate that these conditions can be varied in the analysis by MALDI-TOF MS, and that the ionization behavior can change as these conditions vary. The physical structure of the sample can be evaluated by analyzing the change in the index of ionization behavior that accompanies changes in these conditions. The range in which these conditions are changed is not particularly limited, and may be appropriately selected depending on the type of sample and the type of ions of interest. Examples are shown below.

The laser intensity may be 0.1 to 10%, 10 to 60%, 20 to 55%, or 35 to 45%, with the maximum intensity of the oscillating laser being 100%. %, or 40 to 55%. The laser intensity is not limited as long as the laser can oscillate. In general, the higher the laser intensity, the higher the energy received by the sample and the easier it is to ionize, resulting in a higher ion intensity. When changing the laser intensity, it may be changed by 1% or by 10%.

The laser frequency may be 0.1-1000000 Hz, or 10-1000 Hz. When changing the laser frequency, it may be changed by 10 Hz or by 100 Hz. The laser frequency is not limited as long as the laser can oscillate.

The laser wavelength may be 200-380 nm, 10-200 nm, 10-121 nm, 380-780 nm, 780-1400 nm, 1400 It may be ~3000 nm. The laser wavelength is not limited as long as it is a wavelength at which the laser can oscillate. When changing the laser wavelength, it may be changed by 5 nm or by 50 nm.

The temperature may be from absolute zero to -196°C, may be from -196 to 0°C, may be from 0 to 25°C, may be from 25 to 40°C, may be from 40 to 100°C. or 100° C. or higher. When changing the temperature, it may be changed by 5°C or by 10°C.

The measurement atmosphere may be nitrogen, argon, helium, air, oxygen or hydrogen.

According to the analysis method according to one embodiment of the present invention, since MALDI-TOFMS is used, various indicators of ionization behavior can be used as described above. Also, similarly, the ionization behavior can be evaluated when various conditions are changed. Therefore, it is possible to evaluate the sample from various viewpoints. In other words, compared with the conventional technique that can evaluate only limited factors, the analysis method according to one embodiment of the present invention is considered to be able to evaluate various factors that affect the physical structure of the sample.

The ionization behavior may be represented graphically or as a mass spectrum. This makes it easy to visually understand the ionization behavior.

The ionization behavior is preferably represented by a graph showing changes in ion intensity accompanying changes in any one selected from the group consisting of laser intensity, laser frequency, laser wavelength, temperature, and measurement atmosphere. This makes it easier to visually understand the effect of ionization behavior on the physical structure of the sample. As a graph, for example, the vertical axis represents ion intensity, and the horizontal axis represents laser intensity, laser frequency, laser wavelength, temperature, measurement atmosphere, or the like. In this case, the vertical axis may be the ion intensity of the specific ion described above or the integrated ion intensity of the entire mass spectrum.

Further, as a mass spectrum, there is a spectrum in which the ion intensity is plotted on the vertical axis and the mass-to-charge ratio is plotted on the horizontal axis. A plurality of mass spectra obtained when changing the above-described laser intensity, laser frequency, laser wavelength, temperature, or measurement atmosphere may be used.

[2. Comparison process]
The analysis method according to one embodiment of the present invention may include a comparison step of performing the evaluation step on a plurality of samples and comparing the results. The plurality of samples may be samples for which it is desired to examine whether or not there is a difference in physical structure. This allows comparison of differences in physical structure between samples based on their ionization behavior.

For example, the plurality of samples may be samples obtained by different manufacturing methods. This makes it possible to compare differences in physical structure due to manufacturing methods. Specifically, the plurality of samples may be a deposited film and a coated film.

Further, the plurality of samples may be samples obtained by altering properties by any one selected from the group consisting of cooling, heat, light, electricity, under pressure, under reduced pressure, and left in the environment after production. . This allows comparison of differences in physical structure due to cooling, heat, light, electricity and/or environmental exposure after fabrication. In this specification, "environmental exposure" means to leave the sample in a specific environment. A specific environment refers to certain environmental conditions, for example, an environment of atmospheric pressure and constant temperature and humidity.

The results of the evaluation process may be represented graphically or as a mass spectrum as described above. This makes it possible to visually compare differences in physical structure.

The present invention is not limited to the above-described embodiments, but can be modified in various ways within the scope of the claims, and can be obtained by appropriately combining technical means disclosed in different embodiments. is also included in the technical scope of the present invention.

EXAMPLES The present invention will be described in more detail below based on examples, but the present invention is not limited to the following examples.

[1. Preparation of sample]
A deposited film was produced by a vacuum deposition method using materials described later. Further, a coating film was produced by a spin coating method using the same material. Specifically, after dissolving the materials in a solvent, a coating film was produced at a rotation speed of 2000 rpm. In addition, about the coating film, what dried (baked) for 30 minutes at 110 degreeC was produced. Both the deposited film and the coated film were produced on silicon substrates.

[2. Measurement by MALDI-TOFMS]
The ionic strength of the deposited film and coated film prepared as described above was measured using MALDI-TOFMS. Here, the following [3. Ionization Behavior Accompanying Changes in Laser Intensity (1)] Conditions common to measurements by MALDI-TOFMS performed thereafter will be described.

The deposited film and the coated film were placed on a measurement plate, and the measurement plate was installed in a MALDI-TOFMS apparatus. As the MALDI-TOFMS apparatus, JMS-S3000 manufactured by JEOL Ltd. was used.

For more detailed conditions, see [3. Ionization Behavior Accompanying Change in Laser Intensity (1)] will be described later.

[3. Ionization Behavior with Changes in Laser Intensity (1)]
Using MALDI-TOFMS, the ion intensity was measured with a laser frequency of 10 Hz and a laser intensity varying from 19% to 40%. Measurement was performed on a sample formed to a thickness of 25 nm using 85% by weight of TPBi and 15% by weight of Ir(t-buppy)3 as materials. Note that toluene was used as a solvent for dissolving the materials used in forming the coating film. Also, the ionic strength is the average value of measurements obtained from multiple locations on each sample.

FIG. 1 is a graph showing the ion intensity of molecular ions of TPBi and Ir(t-buppy)3 when the laser intensity is varied. The vertical axis represents ion intensity and the horizontal axis represents laser intensity. A diamond represents a deposited film, and a triangle represents a coated film.

FIG. 1(a) is a graph showing the ionic strength of the molecular ion of TPBi at m/z 653. FIG. As can be seen from FIG. 1(a), when focusing on TPBi, the ionic strength of the deposited film was higher than that of the coated film in the range where the laser intensity was high.

FIG. 1(b) is a graph showing the ionic strength of the molecular ion of Ir(t-buppy)3 with m/z 821. FIG. As can be seen from FIG. 1(b), when focusing on Ir(t-buppy)3, the difference between the deposited film and the coated film was smaller than that of TPBi.

As described above, the difference between the deposited film and the coated film can be detected by analyzing the ionization behavior when the laser intensity is changed by the analysis method according to one embodiment of the present invention. Since the vapor-deposited film and the coated film use the same material, it is believed that the difference between them is due to the physical structure rather than the chemical structure. That is, according to the analysis method according to one embodiment of the present invention, the physical structure of a sample can be evaluated using MALDI-TOFMS.

Moreover, the analysis method according to one embodiment of the present invention can also be applied when a sample is composed of a plurality of components. Moreover, according to the analysis method according to one embodiment of the present invention, it is possible to analyze each component. For example, this time we found a difference in ionization behavior between TPBi and Ir(t-buppy)3. Therefore, it is considered that the physical structure of each target component can be evaluated with high sensitivity.

[4. Ionization behavior with change in laser frequency (1)]
Using MALDI-TOFMS, the ion intensity was measured by changing the laser frequency from 10 Hz to 1000 Hz with a laser intensity of 21%. As a sample, [3. The same ionization behavior as in (1)] with changes in laser intensity was used. Also, the ionic strength is the average value of measurements obtained from multiple locations on each sample.

FIG. 2 is a graph showing the ion intensity of molecular ions of TPBi and Ir(t-buppy)3 when the laser frequency is varied. The vertical axis represents ion intensity and the horizontal axis represents laser frequency. Diamonds represent deposited films, and triangles represent coated films.

FIG. 2(a) is a graph showing the ionic strength of the molecular ion of TPBi at m/z 653. FIG. As can be seen from FIG. 2(a), when focusing on TPBi, the deposited film had a higher ionic strength than the coated film.

FIG. 2(b) is a graph showing the ionic strength of the molecular ion of Ir(t-buppy)3 with m/z 821. FIG. As can be seen from FIG. 2(b), the deposited film had a higher ionic strength than the coated film.

From the above, it is possible to evaluate the difference in the physical structure of the sample also by analyzing the ionization behavior when the laser frequency is changed by the analysis method according to one embodiment of the present invention. That is, according to the analysis method according to one embodiment of the present invention, the physical structure can be evaluated using various parameters.

In addition, focusing on the tendency of ion intensity with respect to frequency change, in (b) of FIG. indicates On the other hand, in (a) of FIG. 2 corresponding to TPBi, the ion intensity shows a positive correlation up to 500 Hz, but greatly decreases at 1000 Hz. In other words, it appears that different compounds are affected differently by changes in frequency. Therefore, by changing the type of compound to be focused on, it is possible to evaluate the factors affecting the film quality (physical structure) from different viewpoints.

In addition, when focusing on Ir(t-buppy)3 in FIG. Also when paying attention, the difference between the deposited film and the coated film was found. Since different results were obtained between FIG. 1 and FIG. 2, it is considered that evaluation can be made from different viewpoints depending on whether the laser intensity is changed or the laser frequency is changed.

[5. Ionization Behavior with Changes in Laser Intensity (2)]
Using MALDI-TOFMS, the ion intensity was measured with the laser frequency set to 10 Hz and the laser intensity varied from 35% to 54%. Measurement was performed on a sample formed into a film of 30 nm using B3PYMPM as a material. Chloroform was used as a solvent for dissolving the materials used in the preparation of the coating film. Also, the ionic strength is the average value of measurements obtained from multiple locations on each sample.

FIG. 3 shows a graph representing the ionic strength of B3PYMPM at m/z 555 ([M+H] ⁺ ). The vertical axis represents ion intensity and the horizontal axis represents laser intensity. Diamonds represent deposited films and squares represent coated films. From FIG. 3, when focusing on B3PYMPM, although the difference between the deposited film and the coated film was small, a difference was observed in the laser intensity range of 41 to 44%. In addition, it can be seen from this that the ionization behavior of B3PYMPM exhibits a tendency different from that of TPBi described above. Therefore, by changing the type of compound of interest, it is possible to evaluate the factors affecting the film quality from different viewpoints.

[6. Ionization behavior with change in laser frequency (2)]
In FIG. 3 described above, a slight difference in ion intensity was observed between the evaporated film and the coated film in the laser intensity range of 41 to 44%. Therefore, using MALDI-TOFMS, the ion intensity was measured by setting the laser intensity to 44% and varying the laser frequency from 10 Hz to 1000 Hz. As a sample, [5. The same ionization behavior as in (2)] with changes in laser intensity was used. Also, the ionic strength is the average value of measurements obtained from multiple locations on each sample.

FIG. 4 shows a graph representing the ionic strength of B3PYMPM at m/z 554 (M ⁺ ). The vertical axis represents ion intensity and the horizontal axis represents laser frequency. Diamonds represent deposited films and squares represent coated films. In FIG. 4, the coated film had a higher ionic strength than the deposited film. This also indicates that the ionization behavior of B3PYMPM exhibits a tendency different from that of TPBi described above.

In addition, while the ionic strength of the deposited film is almost constant with respect to the change in frequency, the ionic strength of the coated film is high up to 100 Hz, the ionic strength is greatly reduced at 250 Hz, and the ionic strength is almost constant up to 1000 Hz. rice field. These results show a tendency different from the ionization behavior of TPBi and Ir(t-buppy)3 described above. In other words, it is considered that factors affecting film quality can be evaluated from different viewpoints by changing the type of compound to be focused on.

[7. Ionization behavior with changes in laser intensity (3)]
Using MALDI-TOFMS, the ion intensity was measured with a laser frequency of 10 Hz and a laser intensity varying from 40% to 44%. As a sample, [5. The same ionization behavior as in (2)] with changes in laser intensity was used.

FIG. 5 is a diagram showing mass spectra of deposited films of B3PYMPM when the laser intensity is varied. (a) to (c) of FIG. 5 represent cases where the laser intensity is 40%, 41% and 44%, respectively.

FIG. 6 is a diagram showing the mass spectrum of the coating film of B3PYMPM when the laser intensity is changed. (a) to (c) of FIG. 6 represent cases where the laser intensity is 40%, 41% and 44%, respectively.

In Figures 5 and 6, the peaks of macromolecules appeared as the laser intensity increased. Specifically, peaks of macromolecules such as dimers and trimers appeared. In addition, in FIG. 6, as the laser intensity increased, the low-molecular decomposition peak (fragment ion peak) increased. In other words, it is considered that the use of the mass spectrum makes it possible to evaluate the factors affecting the film quality from a viewpoint different from that of the above-described examples.

5 and 6, the peaks enclosed by dotted lines represent peaks that were not observed in the powder measurements (data not shown). In addition, in FIG. 6, the peaks enclosed by the dashed-dotted line represent peaks that were not seen in FIG. 5 (ie, the deposited film). In this way, the difference between the deposited film and the coated film can also be detected from the mass spectrum of the film sample.

[8. Ionization Behavior of Dimers and Trimers]
Using MALDI-TOFMS, the ion intensity was measured with the laser frequency set to 10 Hz and the laser intensity varied from 35% to 54%. As a sample, [5. The same ionization behavior as in (2)] with changes in laser intensity was used. Also, the ionic strength is the average value of measurements obtained from multiple locations on each sample.

FIG. 7 is a graph showing the ion intensity of B3PYMPM dimers and trimers when laser intensity is varied. The vertical axis represents ion intensity and the horizontal axis represents laser intensity. Diamonds represent deposited films and squares represent coated films.

FIG. 7(a) is a graph representing the ionic strength of the B3PYMPM dimer with m/z 1107 ([2M+H] ⁺ ). FIG. 7(b) is a graph representing the ionic strength of the trimer of B3PYMPM at m/z 1659 ([3M+H] ⁺ ).

In both (a) and (b) of FIG. 7, in the high laser intensity range (for example, the laser intensity range of 45% or more), the deposited film had a higher ion intensity than the coated film. This result is different from the results for molecular ions where the difference between the deposited film and the coated film was small as shown in FIG. Moreover, the difference was larger in the trimer than in the dimer. In other words, by paying attention to dimers, trimers, and the like, factors affecting film quality can be evaluated from a viewpoint different from that of the above-described examples.

[9. Behavior of Negative Ions]
Using MALDI-TOFMS, the ion intensity was measured by changing the laser frequency from 10 Hz to 1000 Hz with a laser intensity of 44%. As a sample, [5. The same ionization behavior as in (2)] with changes in laser intensity was used. Also, the ionic strength is the average value of measurements obtained from multiple locations on each sample.

FIG. 8 shows a graph representing the ion intensity of negative ions of B3PYMPM at m/z 554 (M ⁻ ).

Here, FIG. 4 described above represents the ion intensity of positive ions. In FIG. 4, the difference between the deposited film and the coated film was large in the low laser frequency range, whereas in FIG. 8, the difference between the deposited film and the coated film was large in the high laser frequency range. Also, as can be seen from FIGS. 4 and 8, the difference is greater for negative ions than for positive ions. Therefore, when focusing on the negative ions of B3PYMPM, it is considered possible to evaluate the difference in physical structure with higher sensitivity than when focusing on the positive ions.

FIG. 9 is a diagram showing mass spectra of negative ions in a deposited film of B3PYMPM when the laser frequency is changed with the laser intensity set at 41%. (a) to (c) of FIG. 9 represent cases where the laser frequency is 10 Hz, 100 Hz and 1000 Hz, respectively.

FIG. 10 is a diagram showing mass spectra of negative ions in the coating film of B3PYMPM when the laser intensity is 41% and the laser frequency is changed. FIGS. 10(a) to 10(c) represent cases where the laser frequency is 10 Hz, 100 Hz and 1000 Hz, respectively.

In both FIGS. 9 and 10, the low-molecular-weight fragment peaks decrease as the laser frequency increases, and at 1000 Hz, a clean mass spectral pattern is shown. Here, the applied film sample in FIG. 10 has a smaller intensity of low-molecular fragment fragments than the deposited film sample in FIG. 9 at any frequency, showing a clear pattern. Also when focusing on the mass spectrum in this way, the difference in physical structure can be evaluated.

[10. molecular ion]
Using MALDI-TOFMS, the ion intensity was measured by changing the laser frequency from 20 Hz to 250 Hz with a laser intensity of 41%. As a sample, [5. The same ionization behavior as in (2)] with changes in laser intensity was used. FIG. 11 is a diagram showing mass spectra of a deposited film and a coated film of B3PYMPM when the laser frequency is changed.

FIGS. 11(a) and 11(b) represent the mass spectrum of the deposited film at laser frequencies of 20 Hz and 250 Hz, respectively.

(c) and (d) of FIG. 11 represent the mass spectrum of the coating film at laser frequencies of 20 Hz and 250 Hz, respectively.

In both the deposited film and the coated film, the increase in ion intensity with increasing laser frequency was greater for M ⁺ than for [M+H] ⁺ , and the degree of increase was more pronounced for the deposited film than for the coated film. This change is thought to involve the presence or absence of intramolecular or intermolecular protons. By paying attention to the type of ions, it is considered that the factors affecting the film quality can be evaluated from a viewpoint different from that of the above-described examples.

[11. Confirmation of molecular orientation]
The molecular orientation of the vapor-deposited film and the coated film was evaluated using synchrotron radiation soft X-ray absorption spectroscopy. Using B3PYMPM as a material, a deposited film (vacuum deposition method, thickness 50 nm) and a coating film (spin coating method, 1000 rpm, thickness 10 nm) were each formed on a silicon substrate, and these films were used as samples. Advanced Light Source (ALS) BL6.3.2 was used as a measuring device, and the total electron yield method was used. In the measurement, the incident angle of soft X-rays was varied from 30 to 90 degrees. The evaluation was performed in the NK absorption edge region. Thus, an anisotropic evaluation focusing on N atoms was performed.

FIG. 12 is a diagram showing measurement results of a deposited film and a coated film of B3PYMPM by synchrotron radiation soft X-ray absorption spectroscopy. Note that the vertical axis in FIG. 12 represents the intensity normalized with the intensity of σ* as a reference.

FIG. 12(a) represents the measurement results of the deposited film. In FIG. 12(a), the relative intensity of π* decreased as the soft X-ray incident angle approached 90 degrees. From this, it is considered that the π orbital extends perpendicularly to the substrate in the deposited film. That is, the deposited film exhibits horizontal orientation.

(b) of FIG. 12 represents the measurement result of the coating film. In FIG. 12(b), even if the incident angle of the soft X-rays was changed, no change was observed in the spectral shape. That is, the coating film exhibits random orientation.

As described above, it has been clarified that the deposited film and the coated film have different molecular orientations even if the materials are the same. That is, the deposited film and the coated film have different physical structures, as observed in the above MALDI-TOFMS.

[12. Confirmation of crystallinity]
GI-WAXS (grazing-incidence wide-angle X-ray scattering) was used to evaluate the crystallinity of the deposited film and the coated film. Using B3PYMPM as a material, a vapor deposition film (vacuum vapor deposition method) and a coating film (spin coating method, 1000 rpm) each having a thickness of 30 nm were formed on a silicon substrate, and these films were used as samples. SPring-8's BL08B2 was used as the measuring apparatus, and the wavelength was 1.0 Å, the camera length (the distance between the sample and the detector) was 125.4 mm, the incident angle was 0.1 degrees, and the exposure time was 10 seconds.

FIG. 13 is a diagram showing the measurement results of the B3PYMPM deposited film and coated film by GI-WAXS. If the peaks match in the measurement results by GI-WAXS, it can be determined that they have similar crystallinity. According to FIG. 13, the evaporated film shows peaks at ˜3.7 Å and ˜3.2 Å, which is considered to correspond to π-stacking. On the other hand, no such peak is observed in the coated film.

Therefore, it has been clarified that the deposited film and the coated film have different crystallinities even if the materials are the same. That is, the deposited film and the coated film have different physical structures, as observed in the above MALDI-TOFMS.

[13. Confirmation of physical structure of mixed film sample]
GI-SAXS (grazing incidence small angle X-ray scattering) was used to evaluate the crystallinity of the deposited film and the coated film. As a sample, [3. The same ionization behavior as in (1)] with changes in laser intensity was used.

FIG. 14 is a diagram showing measurement results by GI-SAXS of a deposited film and a coated film obtained by mixing TPBi and Ir(t-buppy)3. From FIG. 14, different curves are obtained for the deposited film and the coated film. Therefore, it can be seen from FIG. 14 that the deposited film and the coated film have different physical structures.

More specifically, the deposited film and the coated film have different densities or uniformities, different orientations, different molecular structures (intramolecular bond angles or bond lengths), or differences in intermolecular distance and uniformity. are different. In addition, since the curve of the deposited film has fringes, it is considered that the periodic structure is uniform (high uniformity).

[14. Evaluation of Organic Multilayer Thin Film]
A sample (that is, an organic multilayer thin film) in which a TPD film, a mixed film of CBP and Ir(ppy)3, an Alq3 film, and an Al film (electrode) were formed in this order on a glass substrate was measured by MALDI-TOFMS. rice field.

FIG. 15 is a diagram showing measurement results (mass spectrum) of an organic multilayer thin film by MALDI-TOFMS. From FIG. 15, it can be seen that all the components used can be detected even when the sample is composed of multiple layers. That is, the analysis method according to one embodiment of the present invention can be applied regardless of the layer structure of the sample.

One aspect of the present invention can be used to analyze the physical structure of samples in various fields such as organic electronics.

Claims (7)

An evaluation step of evaluating the physical structure of the sample based on the ionization behavior of the sample obtained by MALDI-TOFM S ;
The index of the ionization behavior is the ionic strength or ion generation ratio obtained by MALDI-TOFM S ,
The physical structure is any one or more selected from the group consisting of molecular orientation, density, degree of mixing, crystallinity, radical generation state, charge trap state and interface state,
The ionization behavior is obtained by changing any one or more selected from the group consisting of laser intensity, laser frequency, laser wavelength, temperature and measurement atmosphere,
The sample includes an organic film,
An analysis method comprising a comparison step of performing the evaluation step on a plurality of samples and comparing the results. 2. The analysis method according to claim 1, wherein the sample is composed of a plurality of components, and each component is evaluated. 3. The analysis method according to claim 1, wherein the sample is composed of a plurality of layers, and each layer is evaluated. The analysis method according to any one of claims 1 to 3, wherein the sample is used in the field of organic electronics. The ionization behavior is represented by a graph showing changes in ion intensity accompanying changes in any one selected from the group consisting of laser intensity, laser frequency, laser wavelength, temperature, and measurement atmosphere. The analysis method according to any one of 1 to 4. The analysis method according to any one of claims 1 to 5, wherein the plurality of samples are samples obtained by different manufacturing methods. The plurality of samples are characterized in that they are samples obtained by altering properties after production by any one selected from the group consisting of cooling, heat, light, electricity, under pressure, under reduced pressure, and left in an environment. The analysis method according to any one of claims 1 to 6.

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