Organic solid-state laser materials and organic semiconductor laser devices

Abstract

Providing an organic solid laser material that oscillates in the short wavelength region. 【Solution means】An organic solid laser material containing a compound represented by the general formula (1). R 1 and R 2 , R 2 and R 3 , or R 3 and R 4 are bonded to each other to form a spirofluorene indeno structure, or any one of R 1 ~R 4 is a spirobifluorene-1-yl group, a spirobifluorene-2-yl group, a spirobifluorene-3-yl group, or a spirobifluorene-4-yl group. The remaining R 1 ~R 4 and R 5 ~R 16 represent H, D or a substituent. JPEG2026046930000013.jpg50170

Description

[Technical Field]

[0001] This invention relates to an organic solid-state laser material that oscillates in the short-wavelength region, and an organic semiconductor laser element using the organic solid-state laser material. [Background technology]

[0002] Organic semiconductor laser devices, which use organic materials as gain media, are being actively researched and developed because they offer advantages such as the potential to control the oscillation wavelength over a wide range through molecular design of the organic material, ease of imparting flexibility to the device, and lower manufacturing costs compared to inorganic semiconductor lasers. In particular, regarding the gain media, the development of solid organic laser materials that oscillate at relatively short wavelengths within the ultraviolet region (10-400 nm) is expected, as they are useful for laser treatment of skin diseases and other conditions. However, the organic solid-state laser materials reported so far have been limited to the ultraviolet region close to visible light, even at the shortest oscillation wavelengths, thus limiting their applications.

[0003] For example, spiroterphenyl and CBP are known as organic solid-state laser materials with relatively short ASE (Amplified Spontaneous Emission) oscillation wavelengths (see Non-Patent Literature 1). However, the ASE oscillation wavelength of spiroterphenyl is 381 nm and that of CBP is 393 nm, both of which are long wavelengths close to visible light within the ultraviolet region.

[0004] [ka] [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] J. Mater. Chem. C, 8, 14665-14694 (2019) [Overview of the project] [Problems that the invention aims to solve]

[0006] As described above, the oscillation wavelengths of organic solid-state laser materials reported to date are long wavelengths in the ultraviolet region, close to visible light. Furthermore, regarding the oscillation wavelengths of organic solid-state laser materials, only reports of specific organic compounds exhibiting ASE oscillation at relatively short wavelengths have been made, and systematic studies, such as finding common structures among laser materials exhibiting short-wavelength oscillation, have not been sufficiently conducted. Under these circumstances, the inventors diligently pursued research with the aim of discovering a new organic solid-state laser material that oscillates in the short-wavelength region. [Means for solving the problem]

[0007] As a result of diligent research, the inventors have discovered that compounds having a structure in which a spirofluorene indeno structure is condensed onto a spirobifluorene structure, and compounds having a structure in which a spirobifluorenyl group is bonded to a spirobifluorene structure (dispirobifluorene structure), exhibit ASE oscillation in the short wavelength region and are useful as organic solid-state laser materials. Furthermore, they have found that some of these compounds exhibit ASE oscillation at extremely short wavelengths of 370 nm or less. There have been no previous reports of organic laser materials exhibiting ASE oscillation at 370 nm or less in a solid state. The present invention was proposed based on these findings and specifically has the following configuration.

[0008] [1] Organic solid-state laser material containing a compound represented by the following general formula (1). [ka] [In general formula (1), R 1 ~R 4 The following conditions (A) or (B) are met. The remaining R that are not involved in the following conditions (A) or (B) 1 ~R 4 and R5 ~R 16 each independently represents a hydrogen atom, a deuterium atom, or a substituent. Condition (A) R 1 and R 2 are bonded to each other to form a substituted or unsubstituted spirofluorene indeno structure, R 2 and R 3 are bonded to each other to form a substituted or unsubstituted spirofluorene indeno structure, or, R 3 and R 4 are bonded to each other to form a substituted or unsubstituted spirofluorene indeno structure. Condition (B) R 1 ~R 4 Any one of them is a substituted or unsubstituted spirobifluorene-1-yl group, a substituted or unsubstituted spirobifluorene-2-yl group, a substituted or unsubstituted spirobifluorene-3-yl group, or a substituted or unsubstituted spirobifluorene-4-yl group. [2] The remaining R 1 ~R 4 and R 5 ~R 16 are each independently a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group, the organic solid laser material according to [1]. [3] The organic solid laser material according to [1], which satisfies the condition (A). [4] The organic solid laser material according to [3], wherein the spirofluorene indeno structure formed by the condition (A) is substituted with a deuterium atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group. [5] Among the condition (A), the organic solid laser material according to [3] or [4], which satisfies that R 1 and R 2 are bonded to each other to form a substituted or unsubstituted spirofluorene indeno structure. [6] The organic solid-state laser material described in [1] that satisfies the above condition (B). [7] The organic solid-state laser material according to [6], wherein the spirobifluoren-1-yl group, the spirobifluoren-2-yl group, the spirobifluoren-3-yl group, and the spirobifluoren-4-yl group are substituted with a deuterium atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group. [8] R 1 ~R 4 The organic solid-state laser material according to [6] or [7], wherein one of the groups is a substituted or unsubstituted spirobifluoren-3-yl group, or a substituted or unsubstituted spirobifluoren-4-yl group. [9] An organic gas laser material according to any one of [1] to [8], comprising a compound represented by general formula (1) and a matrix material, wherein the content of the compound represented by general formula (1) is 20% by weight or less.

[10] An organic semiconductor laser device having a laser oscillation wavelength of 380 nm or less.

[11] The organic semiconductor laser element according to

[10] , having an organic solid-state laser material according to any one of [1] to [9]. [Effects of the Invention]

[0009] The organic solid-state laser material of the present invention exhibits ASE oscillation in the short-wavelength region, making it useful as a gain medium for ultraviolet organic lasers. By using the organic solid-state laser material of the present invention, an organic semiconductor laser element with a laser oscillation wavelength of 380 nm or less can be realized. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic cross-sectional view showing an example of the layer configuration of the organic semiconductor laser element of the present invention. [Figure 2] This is the absorption spectrum of a 5 wt% PMMA dispersion film of compound 1. [Figure 3] This is the fluorescence spectrum of a 5 wt% PMMA dispersion film of compound 1. [Figure 4]This is the ASE spectrum of a 5 wt% PMMA dispersion film of compound 1. [Figure 5] This is an ASE plot for a 5 wt% PMMA dispersion of compound 1, with the excitation light intensity per unit area (considering absorption) on the x-axis and the peak intensity and full width at half maximum (FWHM) of the emission spectrum on the y-axis. [Figure 6] This is the absorption spectrum of compound 2 dispersed in a 5 wt% PMMA film. [Figure 7] This is the fluorescence spectrum of a 5 wt% PMMA dispersion film of compound 2. [Figure 8] This is the ASE spectrum of compound 2 dispersed in a 5 wt% PMMA film. [Figure 9] This is an ASE plot for a 5 wt% PMMA dispersion of compound 2, with the excitation light intensity per unit area (considering absorptivity) on the x-axis and the peak intensity and full width at half maximum (FWHM) of the emission spectrum on the y-axis. [Modes for carrying out the invention]

[0011] The present invention will be described in detail below. The following descriptions of constituent elements may be based on representative embodiments and specific examples of the present invention, but the present invention is not limited to such embodiments and specific examples. In this specification, numerical ranges represented by "~" mean a range that includes the numbers written before and after "~" as the lower and upper limits. Furthermore, the isotopes of hydrogen atoms present in the molecule of the compound used in the present invention are not particularly limited; for example, all hydrogen atoms in the molecule 1 H is fine, or part or all of it 2It may also be H (deuterium D). In the chemical structural formulas herein, hydrogen atoms are either represented as H or omitted. For example, when the representation of an atom bonded to a carbon atom in the ring skeleton of a benzene ring is omitted, it is assumed that H is bonded to the carbon atom in the ring skeleton where the representation is omitted. In this specification, the term "substituent" means an atom or group of atoms other than hydrogen atoms and deuterium atoms. On the other hand, the term "substituted or unsubstituted" means that the hydrogen atom may be substituted with a deuterium atom or a substituent. In this specification, the term "short wavelength region" as used in relation to ASE oscillation wavelength and laser oscillation wavelength refers to the wavelength region in the range of 10 to 380 nm.

[0012] <Organic Solid State Laser Materials> The organic solid-state laser material of the present invention includes a compound represented by the following general formula (1). The compound represented by general formula (1) has a structure in which a spirofluorene indeno structure is condensed onto a spirobifluorene structure, or a structure in which a spirobifluorenyl group is bonded to a spirobifluorene structure. Due to the rigid molecular structure resulting from the spiro structure and the discontinuation of the π-conjugated system by multiple spiro carbon atoms, a population inversion can occur between the ground state and the excited state, and it is presumed that the energy gap between the ground level and the excited level in which the population inversion occurs is large. Therefore, the compound represented by general formula (1) can produce amplified spontaneous emission (ASE) in the short wavelength region and is highly useful as an organic solid-state laser material.

[0013] [Compounds represented by general formula (1)] The chemical structure of the compound represented by general formula (1) will be described below.

[0014] [ka]

[0015] In general formula (1), R 1 ~R 4It satisfies either condition (A) or condition (B) below. Condition (A) R 1 and R 2 They bind to each other to form a substituted or unsubstituted spirofluoreneindeno structure, R 2 and R 3 They bind to each other to form a substituted or unsubstituted spirofluoreneindeno structure, or R 3 and R 4 These molecules combine with each other to form substituted or unsubstituted spirofluoreneindeno structures. Condition (B) R 1 ~R 4 One of the following is a substituted or unsubstituted spirobifluoren-1-yl group, a substituted or unsubstituted spirobifluoren-2-yl group, a substituted or unsubstituted spirobifluoren-3-yl group, or a substituted or unsubstituted spirobifluoren-4-yl group.

[0016] The substituted or unsubstituted spirofluoreneindeno structure referred to in condition (A) is the structure represented by the following general formula (2).

[0017] [ka]

[0018] The α carbon atom and the β carbon atom in general formula (2) are the same as R in general formula (1). 1 ~R 4 These are adjacent carbon atoms to which R is bonded. 1 and R 2 When these atoms bond to each other to form a substituted or unsubstituted spirofluorene indeno structure, the carbon atom of α is R 1 The carbon atom to which it is bonded is R 2 Is the carbon atom to which it is bonded, or is the carbon atom of α R 2 The carbon atom to which it is bonded is R1 It is the carbon atom to which it is bonded. 2 and R 3 When these atoms bond to each other to form a substituted or unsubstituted spirofluorene indeno structure, the carbon atom of α is R 2 The carbon atom to which it is bonded is R 3 Is the carbon atom to which it is bonded, or is the carbon atom of α R 3 The carbon atom to which it is bonded is R 2 It is the carbon atom to which it is bonded. 3 and R 4 When these atoms bond to each other to form a substituted or unsubstituted spirofluorene indeno structure, the carbon atom of α is R 3 The carbon atom to which it is bonded is R 4 Is the carbon atom to which it is bonded, or is the carbon atom of α R 4 The carbon atom to which it is bonded is R 3 It is a carbon atom to which it is bonded. R 21 ~R 32 Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent. 21 ~R 32 They may be the same or different from each other. Preferably, R 21 ~R 32 Each of these is independently a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group. 21 ~R 32 If at least one of is a substituent (preferably a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group), then at least R 26 Preferably, the substituent is at least R 26 and R 31 It is preferable that each of them be an independent substituent. For example, R 21 ~R 32 Of these, those with substituents (preferably substituted or unsubstituted alkyl groups, or substituted or unsubstituted alkoxy groups) are R 26 and R 31 That alone is fine. In this case, R 26 and R 31They may be the same or different. Here, R 21 ~R 32 If the alkyl group in the "substituted or unsubstituted alkyl group" that can be formed is substituted, it is preferable that it is substituted with a deuterium atom or an alkoxy group which may be substituted with a deuterium atom. 21 ~R 32 If the "alkoxy group" in the "substituted or unsubstituted alkoxy group" that can be formed is substituted, it is preferable that it is substituted with a deuterium atom, or an alkoxy group that may be substituted with a deuterium atom.

[0019] Specific examples of ring-shaped skeletal structures of general formula (1) that satisfy condition (A) are given below. However, in the present invention, ring-shaped skeletal structures of general formula (1) that satisfy general formula (A) should not be interpreted as being limited by these specific examples.

[0020] [ka]

[0021] In condition (B), the substituted or unsubstituted spirobifluoren-1-yl group, substituted or unsubstituted spirobifluoren-2-yl group, substituted or unsubstituted spirobifluoren-3-yl group, or substituted or unsubstituted spirobifluoren-4-yl group refers to the structure represented by the following general formula (3).

[0022] [ka]

[0023] In general formula (3), R 45 ~R 48 One of them is R in general formula (1) 1 ~R 4 One of these represents a single bond to the carbon atom to which it is bonded. The remaining three Rs 45 ~R 48 and R 41 ~R 44 and R49 ~R 56 each independently represents a hydrogen atom, a deuterium atom, or a substituent. That is, when R 48 is a single bond, the structure represented by the general formula (3) is a substituted or unsubstituted spirobifluorene-1-yl group, and when R 47 is a single bond, the structure represented by the general formula (3) is a substituted or unsubstituted spirobifluorene-2-yl group, and when R 46 is a single bond, the structure represented by the general formula (3) is a substituted or unsubstituted spirobifluorene-3-yl group, and when R 45 is a single bond, the structure represented by the general formula (3) is a substituted or unsubstituted spirobifluorene-4-yl group. The remaining three R 45 ~R 48 and R 41 ~R 44 and R 49 ~R 56 may be the same as or different from each other. The remaining three R 45 ~R 48 and R 41 ~R 44 and R 49 ~R 56 are preferably each independently a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group. When at least one of the remaining three R 45 ~R 48 and R 41 ~R 44 and R 49 ~R 56 is a substituent (preferably a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group), it is preferable that at least R 50 is a substituent, and it is preferable that at least R 50 and R 55 are each independently a substituent. For example, the remaining three R 45 ~R 48 and R 41 ~R 44 and R 49 ~R 56Of these, those that are substituents (preferably substituted or unsubstituted alkyl groups, or substituted or unsubstituted alkoxy groups) are R 50 and R 55 That alone is fine. In this case, R 50 and R 55 They may be the same or different. The remaining three R's 45 ~R 48 and R 41 ~R 44 and R 49 ~R 56 If the alkyl group in the possible "substituted or unsubstituted alkyl group" is substituted, it is preferable that it is substituted with a deuterium atom or an alkoxy group which may be substituted with a deuterium atom. The remaining three R 45 ~R 48 and R 41 ~R 44 and R 49 ~R 56 In the case where the "substituted or unsubstituted alkoxy group" in is substituted, it is preferable that the "alkoxy group" is substituted with a deuterium atom, or an alkoxy group that may be substituted with a deuterium atom.

[0024] Specific examples of ring-shaped skeletal structures of general formula (1) that satisfy condition (B) are given below. However, in the present invention, ring-shaped skeletal structures of general formula (1) that satisfy condition (B) should not be interpreted as being limited by these specific examples.

[0025] [ka]

[0026] In general formula (1), the remaining R that is not involved in condition (A) or condition (B) 1 ~R 4 and R 5 ~R 16 Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent. The remaining R 1 ~R 4 and R 5 ~R 16They may be the same or different from each other. Preferably, the remaining R 1 ~R 4 and R 5 ~R 16 Each of these is independently a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group. The remaining R 1 ~R 4 and R 5 ~R 16 When at least one of is a substituent (preferably a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group), at least R 10 Preferably, the substituent is at least R 10 and R 15 It is preferable that each of them be an independent substituent. For example, the remaining R 1 ~R 4 and R 5 ~R 16 Of these, those that are substituents (preferably substituted or unsubstituted alkyl groups, or substituted or unsubstituted alkoxy groups) are R 10 and R 15 That alone is fine. In this case, R 10 and R 15 They may be the same or different. The remaining R 1 ~R 4 and R 5 ~R 16 If the alkyl group in the "substituted or unsubstituted alkyl group" that can be formed is substituted, it is preferable that it is substituted with a deuterium atom or an alkoxy group which may be substituted with a deuterium atom. 1 ~R 4 and R 5 ~R 16 If the "alkoxy group" in the "substituted or unsubstituted alkoxy group" that can be formed is substituted, it is preferable that it is substituted with a deuterium atom, or an alkoxy group that may be substituted with a deuterium atom.

[0027] In one aspect of the present invention, R of general formula (1) 1 ~R 4This satisfies condition (A). In this case, it is preferable that at least one hydrogen atom of the spirofluoreneindeno structure formed by condition (A) is substituted with a deuterium atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group. In one preferred embodiment of the present invention, R of general formula (1) 1 ~R 4 It satisfies condition (A) and R in general formula (2) 21 ~R 30 Of these, at least R 26 The remaining R is a substituent (preferably a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group) and does not participate in condition (A) of general formula (1). 1 ~R 4 and R 5 ~R 16 Of these, at least R 10 R is a substituent (preferably a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group). In a preferred embodiment of the present invention, R of general formula (1) 1 ~R 4 It satisfies condition (A) and R in general formula (2) 21 ~R 30 Of these, at least R 26 and R 31 The remaining R is a substituent (preferably a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group) and does not participate in condition (A) of general formula (1). 1 ~R 4 and R 5 ~R 16 Of these, at least R 10 and R 15 The substituent is (preferably a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group). In one preferred embodiment of the present invention, R of general formula (1) 1 ~R 4 Of the conditions (A), "R 1 and R 2 The condition is satisfied that the atoms bond to each other to form a spirofluorene indeno structure. In this case, preferably the carbon atom of α in general formula (2) is R 1 The carbon atom to which it is bonded is R2 It is a carbon atom to which is bonded. In one aspect of the present invention, R of general formula (1) 1 ~R 4 Of the conditions (A), "R 2 and R 3 The condition is satisfied that the atoms bond to each other to form a spirofluorene indeno structure. In this case, preferably the carbon atom of α in general formula (2) is R 3 The carbon atom to which it is bonded is R 2 It is a carbon atom to which it is bonded.

[0028] In one aspect of the present invention, R of general formula (1) 1 ~R 4 This satisfies condition (B). In one aspect of the present invention, at least one hydrogen atom of the spirobifluoren-1-yl group, spirobifluoren-2-yl group, spirobifluoren-3-yl group, and spirobifluoren-4-yl group in condition (B) is substituted with a deuterium atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group. In one aspect of the present invention, R of general formula (1) 1 ~R 4 Of the conditions (B), R 2 The group satisfies the condition that it is a substituted or unsubstituted spirobifluoren-1-yl group, a substituted or unsubstituted spirobifluoren-2-yl group, a substituted or unsubstituted spirobifluoren-3-yl group, or a substituted or unsubstituted spirobifluoren-4-yl group, preferably R 2 is a substituted or unsubstituted spirobifluoren-3-yl group or a substituted or unsubstituted spirobifluoren-4-yl group. In one aspect of the present invention, R of general formula (1) 1 ~R 4 Of the conditions (B), R 1 ~R 4 The condition is met that one of the groups is a substituted or unsubstituted spirobifluoren-3-yl group, or a substituted or unsubstituted spirobifluoren-4-yl group.

[0029] R in general formula (1) 1 ~R 16 , R in general formula (2)21 ~R 32 , R of general formula (3) 41 ~R 56 In the context of "substituents" and "substituted or unsubstituted," the substituents may be selected from, for example, substituent group A, substituent group B, substituent group C, substituent group D, or substituent group E. For "alkyl group" in "substituted or unsubstituted alkyl group" and "alkoxy group" in "substituted or unsubstituted alkoxy group," please refer to the explanations of "alkyl group" and "alkoxy group" below.

[0030] Specific examples of compounds represented by general formula (1) are given below. However, the compounds represented by general formula (1) that can be used in the present invention should not be interpreted as being limited by these specific examples. In the following structural formula, tbu represents a tert-butyl group.

[0031] [ka]

[0032] Definition of chemical structure In this specification, "alkyl group" may be linear, branched, or cyclic. Furthermore, two or more of the linear, cyclic, and branched portions may be mixed. The number of carbon atoms in an alkyl group can be, for example, 1 or more, 2 or more, or 4 or more. Also, the number of carbon atoms can be 30 or less, 20 or less, 10 or less, 6 or less, or 4 or less. Specific examples of alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, n-hexyl group, isohexyl group, 2-ethylhexyl group, n-heptyl group, isoheptyl group, n-octyl group, isooctyl group, n-nonyl group, isononyl group, n-decanyl group, isodecanyl group, cyclopentyl group, cyclohexyl group, and cycloheptyl group. In this specification, the "alkoxy group" may be linear, branched, or cyclic. Furthermore, two or more of the linear, cyclic, and branched portions may be mixed. The number of carbon atoms in the alkoxy group can be, for example, 1 or more, 2 or more, or 4 or more. Alternatively, the number of carbon atoms can be 30 or less, 20 or less, 10 or less, 6 or less, or 4 or less. Specific examples of alkoxy groups include those having an alkyl group bonded to oxygen, as listed above as a specific example of an "alkyl group." For example, alkoxy groups having a structure in which a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, or tert-butyl group bonded to oxygen are, respectively, methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, and tert-butoxy group.

[0033] In this specification, "substituent group A" refers to a hydroxyl group, halogen atom (e.g., fluorine atom, chlorine atom, bromine atom, iodine atom), alkyl group (e.g., C1-40), alkoxy group (e.g., C1-40), alkylthio group (e.g., C1-40), aryl group (e.g., C6-30), aryloxy group (e.g., C6-30), arylthio group (e.g., C6-30), heteroaryl group (e.g., C5-30), heteroaryloxy group (e.g., C5-30), and This refers to one or more groups selected from the group consisting of teloarylthio groups (e.g., 5-30 ring skeleton atoms), acyl groups (e.g., 1-40 carbon atoms), alkenyl groups (e.g., 1-40 carbon atoms), alkynyl groups (e.g., 1-40 carbon atoms), alkoxycarbonyl groups (e.g., 1-40 carbon atoms), aryloxycarbonyl groups (e.g., 1-40 carbon atoms), heteroaryloxycarbonyl groups (e.g., 1-40 carbon atoms), silyl groups (e.g., trialkylsilyl groups with 1-40 carbon atoms), and nitro groups. In this specification, "substituent group B" means one or more groups selected from the group consisting of alkyl groups (e.g., 1 to 40 carbon atoms), alkoxy groups (e.g., 1 to 40 carbon atoms), aryl groups (e.g., 6 to 30 carbon atoms), aryloxy groups (e.g., 6 to 30 carbon atoms), heteroaryl groups (e.g., 5 to 30 atoms in the ring skeleton), heteroaryloxy groups (e.g., 5 to 30 atoms in the ring skeleton), and diarylaminoamino groups (e.g., 0 to 20 carbon atoms). In this specification, "substituent group C" means one or more groups selected from the group consisting of alkyl groups (e.g., 1 to 20 carbon atoms), aryl groups (e.g., 6 to 22 carbon atoms), heteroaryl groups (e.g., 5 to 20 atoms in the ring skeleton), and diarylamino groups (e.g., 12 to 20 carbon atoms). In this specification, "substituent group D" means one or more groups selected from the group consisting of alkyl groups (e.g., 1 to 20 carbon atoms), aryl groups (e.g., 6 to 22 carbon atoms), and heteroaryl groups (e.g., 5 to 20 atoms in the ring skeleton). In this specification, "substituent group E" means one group or a combination of two or more groups selected from the group consisting of alkyl groups (e.g., C1 to C20) and aryl groups (e.g., C6 to C22). In this specification, when a substituent is described as "substituent" or "substituted or unsubstituted," it may be selected from, for example, substituent group A, substituent group B, substituent group C, substituent group D, or substituent group E.

[0034] [Method for synthesizing compounds represented by general formula (1)] Compounds represented by general formula (1) can be synthesized by combining known reactions. Among the compounds represented by general formula (1), R 1 ~R 4Compounds that satisfy condition (A) can be synthesized, for example, by coupling reactions of terphenyl halides with fluorenone or its derivatives, and by cyclization reactions that form spiro structures. 1 ~R 4 Compounds that satisfy condition (B) can be synthesized, for example, by a coupling reaction between a spirobifluorene halide and a spirobifluorene derivative to which a dioxaborolane group has been introduced.

[0035] [Conditions for Organic Solid State Laser Materials] The organic solid-state laser material of the present invention is an organic laser material that is in a solid state at room temperature (25°C). The fact that it is a laser material can be determined, for example, by the observation of an ASE oscillation threshold. The organic solid-state laser material of the present invention contains one or more compounds selected from the group of compounds represented by general formula (1). The organic solid-state laser material may contain only one compound represented by general formula (1) or two or more compounds. Furthermore, the organic solid-state laser material of the present invention may contain components other than the compound represented by general formula (1). Examples of components other than the compound represented by general formula (1) include matrix materials. Here, "matrix material" can refer to a host material or a matrix resin, which can be included in the organic solid-state laser material in an amount of more than 50% by weight. For a description of the host material, refer to the description of host materials that can be used in the "emissive layer" of the "organic semiconductor laser element" below. As the matrix resin, a polymer that is in a solid state at room temperature (25°C) (usually a polymer compound having 30 or more constituent units derived from monomers) can be used. The type of polymer is not particularly limited, but acrylic (e.g., polyalkyl acrylate, polyalkyl methacrylate) or vinyl polymers can be preferably used.

[0036] When the organic solid-state laser material of the present invention contains components other than the compound represented by general formula (1), the content of the compound represented by general formula (1) in the organic solid-state laser material is preferably 0.1% by weight or more, more preferably 1% by weight or more, preferably 50% by weight or less, more preferably 25% by weight or less, even more preferably 20% by weight or less, and particularly preferably 15% by weight or less.

[0037] The organic solid-state laser material of the present invention is characterized by exhibiting ASE oscillation in the short-wavelength region. The ASE oscillation wavelength of the organic solid-state laser material of the present invention is, for example, 380 nm or less, and may be less than 380 nm, or for example, 375 nm or less or 370 nm or less. [ASE vibration threshold] In this specification, the "ASE oscillation threshold" refers to the excitation light intensity at which the slope of the linear function obtained by irradiating a target thin film with excitation light and measuring the dependence of the emission intensity on the excitation light intensity changes when the relationship between the excitation light intensity and the emission intensity is considered as a linear function. The target thin film may be an emission layer of a current-excited organic semiconductor laser element or an emission layer of a photo-excited organic laser element. Furthermore, the emission layer may consist only of the compound represented by general formula (1), or it may contain the compound represented by general formula (1) and a matrix material. For specific measurement conditions of the "ASE oscillation threshold," please refer to the Examples section. The light-emitting layer of the organic semiconductor laser element has an ASE oscillation threshold of 20 μJ / cm². 2 Preferably, it is 10 μJ / cm 2 More preferably, the following is true: 5 μJ / cm 2 The following is even more preferable:

[0038] [Usefulness of Organic Solid State Laser Materials] The organic solid-state laser material of the present invention exhibits oscillation in the short-wavelength region. Furthermore, because the organic solid-state laser material of the present invention is an organic material, using it as a material for an element can provide flexibility to the element, and enable the element to be made thinner and less expensive. For this reason, the organic solid-state laser material of the present invention is useful as a gain medium for organic laser elements, and can be used particularly effectively as a gain medium for ultraviolet organic lasers. For example, an ultraviolet organic laser using the organic solid-state laser material of the present invention can be effectively used for laser treatment of skin diseases such as atopic dermatitis and vitiligo. Furthermore, the organic solid-state laser material of the present invention can also be applied to wearable medical devices that enable laser skin treatment simply by being applied like a bandage. Furthermore, the ultraviolet light emitted by the organic solid-state laser material of the present invention can be absorbed by materials with high reflectivity and transmittance. For example, during laser processing, it is not necessary to irradiate the workpiece with excessive power, thus suppressing thermal damage to the workpiece. Therefore, the organic solid-state laser material of the present invention can be effectively used as a gain medium for laser elements for laser processing, such as for forming fine patterns by laser ablation in the semiconductor field, cold marking in the printing field, and cutting and solidifying cells in the biotechnology field. In particular, since the organic solid-state laser material of the present invention is also advantageous for miniaturizing elements, it can be suitably used for laser elements for processing in the biotechnology field, which is often carried out on a small scale. Furthermore, the compound represented by general formula (1) included in the organic solid-state laser material of the present invention allows for control of the oscillation wavelength by changing its chemical structure. Therefore, by using the organic solid-state laser material of the present invention, it is possible to manufacture multiple laser elements with slightly different oscillation wavelengths. This makes it possible, for example, in the biotechnology field to observe cell behavior by slightly changing the irradiation wavelength, or in the photochemistry field to excite materials by slightly changing the excitation light wavelength, thereby greatly contributing to the progress of research and development in various fields.

[0039] <Organic semiconductor laser element> Next, the organic semiconductor laser element of the present invention will be described. The organic semiconductor laser element of the present invention is characterized by having a laser oscillation wavelength of 380 nm or less. An organic semiconductor laser element with a laser oscillation wavelength of 380 nm or less can be realized by using an organic solid-state laser material containing a compound represented by general formula (1) as the light-emitting layer (gain medium). For a description of the organic solid-state laser material, please refer to the "Organic Solid-State Laser Material" section above. An organic semiconductor laser element has a structure in which at least an anode, a cathode, and an organic layer formed between the anode and the cathode. The organic layer has at least an emissive layer, and may consist only of an emissive layer, or it may have one or more organic layers in addition to the emissive layer. Examples of other such organic layers include hole transport layers, hole injection layers, electron blocking layers, hole blocking layers, electron injection layers, electron transport layers, and exciton blocking layers. The hole transport layer may be a hole injection transport layer with hole injection function, and the electron transport layer may be an electron injection transport layer with electron injection function. A specific example of the structure of an organic semiconductor laser element is shown in Figure 1. In Figure 1, 1 represents the substrate, 2 is the anode, 3 is the hole injection layer, 4 is the hole transport layer, 5 is the emissive layer, 6 is the electron transport layer, and 7 is the cathode. In a current-excited organic semiconductor laser element, the laser light generated in the emissive layer may be extracted to the outside by passing through the anode, by passing through the cathode, or by passing through both the anode and the cathode. Furthermore, the laser light generated in the light-emitting layer may be extracted to the outside from the edge of the organic layer. The following describes each component and layer of the organic semiconductor laser device.

[0040] (substrate) The organic semiconductor laser element of the present invention is preferably supported by a substrate. If the organic semiconductor laser element is configured to extract laser light from the substrate side, a substrate that is transparent to laser light is used, and it is preferable to use a transparent substrate made of glass, transparent plastic, quartz, etc. On the other hand, if the organic semiconductor laser element is configured to extract laser light from the opposite side of the substrate, the substrate is not particularly limited, and in addition to the transparent substrates mentioned above, substrates made of silicon, paper, cloth, etc., can also be used.

[0041] (anode) For the anode in an organic semiconductor laser device, metals, alloys, electrically conductive compounds, and mixtures thereof with a large work function (4 eV or more) are preferably used as electrode materials. Specific examples of such electrode materials include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO2, ZnO, and TiN. Amorphous materials capable of producing transparent conductive films, such as IDIXO (In2O3-ZnO), may also be used. The anode can be formed by depositing these electrode materials by methods such as vapor deposition or sputtering. Alternatively, a pattern of a desired shape may be formed on the formed thin film using photolithography, or, if pattern accuracy is not required (around 100 μm or more), the pattern may be formed via a mask of the desired shape during vapor deposition or sputtering of the electrode material. In the case of coating materials such as organic conductive compounds, wet film formation methods such as printing or coating can also be used. However, if the organic semiconductor laser element is configured to extract laser light by transmitting light through the anode, the anode must be transparent to the laser light, and it is preferable that the anode be configured such that the transmittance of the laser light is greater than 1%, and more preferably greater than 10%. Specifically, it is preferable to use the above-mentioned conductive transparent material as the anode, or to use a thin film formed of a metal or alloy with a thickness of 10 to 100 nm as the anode. The sheet resistance of the anode is preferably several hundred ohms / square or less. Furthermore, the film thickness is usually selected in the range of 10 to 1000 nm, preferably 10 to 200 nm, although this depends on the material.

[0042] (cathode) On the other hand, for the cathode, materials such as metals with a lower work function than the material used for the anode (referred to as electron-injection metals), alloys, electrically conductive compounds, and mixtures thereof are used as electrode materials. Specific examples of such electrode materials include sodium, sodium-potassium alloys, magnesium, lithium, magnesium / copper mixtures, magnesium / silver mixtures, magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al2O3) mixtures, indium, lithium / aluminum mixtures, and rare earth metals. Among these, from the viewpoint of electron injection and durability against oxidation, mixtures of electron-injection metals and metalloids with a higher work function and greater stability, such as magnesium / silver mixtures, magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al2O3) mixtures, lithium / aluminum mixtures, and aluminum, are preferred. The cathode can be formed by depositing these electrode materials into a film by methods such as vapor deposition or sputtering. However, if the organic semiconductor laser element is configured to extract laser light by transmitting light through a cathode, the cathode must be transparent to the laser light, and it is preferable that the transmittance of the laser light be greater than 1%, and more preferably greater than 10%. Specifically, it is preferable to use a thin film formed of the above electrode material with a thickness of 10 to 100 nm as the cathode. The sheet resistance of the cathode is preferably several hundred ohms / square or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm.

[0043] (Emitting layer) The light-emitting layer is a layer that emits laser light after excitons are generated by the recombination of holes and electrons injected from the anode and cathode, respectively, forming a population inversion. In the present invention, the light-emitting layer is preferably formed of an organic solid-state laser material containing a compound represented by general formula (1). The organic solid-state laser material used for the light-emitting layer may consist only of the compound represented by general formula (1), or it may contain the compound represented by general formula (1) and a host material. The light-emitting layer may contain one or more compounds selected from the group of compounds represented by general formula (1). In order to further lower the threshold current density of the organic semiconductor laser element of the present invention, it is important to confine at least one of the singlet excitons and triplet excitons generated in the compound represented by general formula (1) within the light-emitting material. Therefore, it is preferable that the organic solid-state laser material used for the light-emitting layer contains a host material in addition to the compound represented by general formula (1). As the host material, an organic compound having at least one of the excitation singlet energy and excitation triplet energy higher than that of the compound represented by general formula (1) can be used. As a result, it becomes possible to confine the singlet and triplet excitons generated in the compound represented by general formula (1) within the molecule of the compound, thereby lowering the threshold current density required to produce the laser light emission. However, even if the singlet and triplet excitons cannot be sufficiently confined, it may still contribute to lowering the threshold current and improving the laser characteristics. Therefore, any host material capable of achieving lower threshold current and improved laser characteristics can be used in the present invention without any particular restrictions. In the organic semiconductor laser element of the present invention, the laser light is emitted from the compound represented by general formula (1). The light emitted by the compound represented by general formula (1) may include spontaneously radiated amplified light (ASE). In addition, the light from the light-emitting layer may include light emitted from the host material. When a host material is used, the amount of the compound represented by general formula (1) contained in the light-emitting layer is preferably 0.1% by weight or more, more preferably 1% by weight or more, preferably 50% by weight or less, more preferably 25% by weight or less, even more preferably 20% by weight or less, and particularly preferably 15% by weight or less. The host material in the light-emitting layer is preferably an organic compound that has hole transport ability, electron transport ability, prevents the emission from becoming longer wavelengths, and has a high glass transition temperature. The following compounds are specific examples of organic compounds that can be used as host materials. However, the organic compounds that can be used as host materials in the present invention should not be interpreted as being limited by these specific examples.

[0044] JPEG2026046930000009.jpg41170

[0045] (Injection layer) An injection layer is a layer provided between the electrode and the organic layer to reduce the driving voltage and improve the luminescence brightness. There are hole injection layers and electron injection layers, and they may be present between the anode and the light-emitting layer or hole transport layer, and between the cathode and the light-emitting layer or electron transport layer. The injection layer can be provided as needed.

[0046] (blocking layer) A blocking layer is a layer that can prevent the diffusion of charges (electrons or holes) and / or excitons present in the light-emitting layer out of the light-emitting layer. An electron blocking layer can be placed between the light-emitting layer and the hole transport layer to prevent electrons from passing through the light-emitting layer toward the hole transport layer. Similarly, a hole blocking layer can be placed between the light-emitting layer and the electron transport layer to prevent holes from passing through the light-emitting layer toward the electron transport layer. Blocking layers can also be used to prevent excitons from diffusing out of the light-emitting layer. That is, electron blocking layers and hole blocking layers can also function as exciton blocking layers. In this specification, the terms electron blocking layer or exciton blocking layer are used to mean a layer that has the functions of both an electron blocking layer and an exciton blocking layer in a single layer.

[0047] (Hole blocking layer) In a broad sense, a hole blocking layer functions as an electron transport layer. The hole blocking layer transports electrons while preventing holes from reaching the electron transport layer, thereby improving the probability of electron-hole recombination in the light-emitting layer. The materials used for the hole blocking layer can be the same as those used for the electron transport layer, as described later, as needed.

[0048] (electron blocking layer) In a broad sense, an electron blocking layer has the function of transporting holes. The electron blocking layer transports holes while preventing electrons from reaching the hole transport layer, thereby increasing the probability of electrons and holes recombining in the light-emitting layer.

[0049] (Exciton blocking layer) An exciton blocking layer is a layer designed to prevent excitons, generated by the recombination of holes and electrons within the light-emitting layer, from diffusing into the charge transport layer. By inserting this layer, excitons can be efficiently confined within the light-emitting layer, thereby improving the luminescence efficiency of the device. The exciton blocking layer can be inserted adjacent to the light-emitting layer on either the anode or cathode side, and it is also possible to insert it on both sides simultaneously. That is, when the exciton blocking layer is on the anode side, it can be inserted between the hole transport layer and the light-emitting layer, adjacent to the light-emitting layer. When it is inserted on the cathode side, it can be inserted between the light-emitting layer and the cathode, adjacent to the light-emitting layer. Furthermore, a hole injection layer or electron blocking layer can be provided between the anode and the exciton blocking layer adjacent to the anode side of the light-emitting layer, and an electron injection layer, electron transport layer, hole blocking layer, etc., can be provided between the cathode and the exciton blocking layer adjacent to the cathode side of the light-emitting layer. When a blocking layer is provided, it is preferable that at least one of the excitation singlet energy and excitation triplet energy of the material used as the blocking layer is higher than the excitation singlet energy and excitation triplet energy of the light-emitting material.

[0050] (Hole transport layer) A hole transport layer consists of a hole transport material that has the function of transporting holes, and the hole transport layer can be a single layer or multiple layers. The hole transport material can be any material that either injects or transports holes or acts as an electron barrier, and may be either organic or inorganic. Known hole transport materials that can be used include, for example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, carbazole derivatives, indrocarbazole derivatives, polyarylalkane derivatives, pyrazoline and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, aminosubstituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers. However, it is preferable to use porphyrin compounds, aromatic tertiary amine compounds, and styrylamine compounds, and it is more preferable to use aromatic tertiary amine compounds.

[0051] (electron transport layer) An electron transport layer consists of a material that has the function of transporting electrons, and the electron transport layer can consist of a single layer or multiple layers. As an electron transport material (which may also serve as a hole-blocking material), it is sufficient that it has the function of transferring electrons injected from the cathode to the light-emitting layer. Examples of usable electron transport layers include nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyrandioxide derivatives, carbodiimide, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, and oxadiazole derivatives. Furthermore, thiadiazole derivatives in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and quinoxaline derivatives having a quinoxaline ring known as an electron-withdrawing group, can also be used as electron transport materials. Moreover, polymer materials can be used in which these materials are incorporated into polymer chains, or in which these materials are used as the main chain of the polymer.

[0052] (resonator structure) The organic semiconductor laser element of the present invention may further have a resonator structure. A "resonator structure" is a structure that causes light emitted by a light-emitting material to travel back and forth within the light-emitting layer. This causes the light to repeatedly travel through the light-emitting layer and induce stimulated emission, thereby enabling the acquisition of laser light of higher intensity. Specifically, the resonator structure is composed of a pair of reflectors, one of which preferably has a reflectivity of 100%, and the other reflector preferably has a reflectivity of 50 to 95%. By setting the reflectivity of the other reflector to be relatively low, it becomes possible to transmit the laser light through this reflector and extract it to the outside. Hereinafter, the reflector on the side from which the laser light is extracted will be referred to as the "output mirror". The reflectors and output mirrors may be provided separately from each layer and part that constitutes the organic semiconductor laser element described above, or the anode and cathode may also function as reflectors or output mirrors.

[0053] For example, when the anode also functions as a reflector or output mirror, it is preferable that the anode be made of a metal film that has low visible light absorption, high reflectivity, and a relatively large work function (4.0 eV or more). Examples of such metal films include metal films of Ag, Pt, Au, etc., or alloy films containing these metals. The reflectivity and transmittance of the anode can be adjusted to desired values ​​by controlling the thickness of the metal film, for example, in a range of several tens of nanometers or more. When the cathode also functions as a reflector or output mirror, it is preferable that the cathode be made of a metal film that has low visible light absorption, high reflectivity, and a relatively small work function. Examples of such metal films include Al, Mg, or alloy films containing these metals. The reflectivity and transmittance of the cathode can be adjusted to desired values ​​by controlling the thickness of the metal film, for example, in a range of several tens of nanometers or more. When a reflector or output mirror is provided separately from each of the above layers and parts, it is preferable to form a reflective film between the anode and the organic layer, or between the substrate and the anode, so that it functions as a reflector or output mirror. When a reflector or output mirror is provided between the anode and the organic layer, it is preferable to use a conductive material that has low visible light absorption, high reflectivity, and a large work function (work function of 4.0 eV or more) as the material for the reflector or output mirror. Specifically, a metal film made of metals such as Ag, Pt, Au, or alloys containing these metals can be used as a reflector or output mirror. The reflectivity and transmittance of this reflector or output mirror can be adjusted to desired values ​​by controlling the thickness of the metal film, for example, in a range of several tens of nanometers or more. Here, when such a reflector or output mirror is provided between the anode and the organic layer, the anode material does not need to have a large work function, and a wide range of known electrode materials can be used. When a reflector or output mirror is provided between the substrate and the anode, it is preferable to use a material that has low visible light absorption and high reflectivity. Specifically, metal films made of metals such as Al, Ag, and Pt, or alloys containing these metals, multilayer films in which a Ti film is laminated on an Al and Si alloy film, and dielectric multilayer films in which silicon oxide and titanium oxide are alternately deposited can be used as reflectors or output mirrors. Of these, the reflectivity and transmittance of the metal film can be adjusted to desired values ​​by controlling the film thickness, for example, in a range of several tens of nanometers or more. The reflectivity and transmittance of the dielectric multilayer film can also be adjusted to desired values ​​by controlling the film thickness and number of layers of silicon oxide and titanium oxide. Combinations of a reflector and an output mirror include: a combination where the output mirror is the anode and the reflector is the cathode; a combination where the output mirror is a reflective film placed between the anode and the organic layer or between the substrate and the anode, and the reflector is the cathode; a combination where the reflector is the anode and the output mirror is the cathode; and a combination where the reflector is a reflective film placed between the anode and the organic layer or between the substrate and the anode, and the output mirror is the cathode. In such a resonator structure, it is preferable to design the layer structure of the element such that the sum of the optical thicknesses of the layers interposed between the reflector and the output mirror (the sum of the values ​​obtained by multiplying the thickness of each layer by its refractive index) is an integer multiple of half the wavelength of the laser light. This allows for the formation of standing waves between the reflector and the output mirror, which amplifies the light and allows for the acquisition of a higher intensity laser beam.

[0054] Furthermore, while the above-described resonator structure oscillates the laser beam back and forth perpendicular to the main surface of the substrate, the resonator structure may also oscillate the laser beam back and forth horizontally to the main surface of the substrate. Such a resonator structure can utilize reflection due to the refractive index difference between the organic layer and air, and the edge face of the organic layer can be configured as a reflector or output mirror. Alternatively, a diffraction grating may be provided near the light-emitting layer with a period that satisfies the Bragg equation below, so that the light generated in the light-emitting layer is periodically reflected by the grating spacing of the diffraction grating. This enables the realization of a single longitudinal mode, allowing a laser beam with good monochromaticity to be emitted from the edge face of the organic layer. Bragg's equation: mλ = 2n eff Λ m Here, m is the diffraction order, λ is the oscillation wavelength, and n eff Λ is the effective refractive index. m This is the period of the diffraction grating.

[0055] When fabricating the organic semiconductor laser element of the present invention, the method for depositing the organic layer constituting the element is not particularly limited, and either a dry process or a wet process may be used. Furthermore, the method for fabricating parts other than the organic layer is not particularly limited, and known electrode formation techniques and resonator fabrication techniques can be used.

[0056] The organic semiconductor laser element described above emits laser light by passing a current exceeding a threshold current density between the anode and cathode. In this case, the organic semiconductor laser element of the present invention has an emissive layer formed of an organic solid-state laser material containing a compound represented by general formula (1), and since it oscillates in the wavelength region of 380 nm or less, it can be effectively used as an ultraviolet organic laser. [Examples]

[0057] The features of the present invention will be described in more detail below with reference to examples. The materials, processing content, processing procedures, etc. shown below can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the specific examples shown below. The luminescence characteristics were evaluated using a fluorescence spectrophotometer (JASCO Corporation: FP-8600), an absolute PL quantum yield analyzer (Hamamatsu Photonics Ltd.: C11347-01), a multichannel spectrometer (Hamamatsu Photonics Ltd.: PMA-12), and a fluorescence lifetime analyzer (Hamamatsu Photonics Ltd.: Quantaurus-Tau C11367-03).

[0058] The ASE spectrum and ASE oscillation threshold were measured using the following method. [Measurement of ASE spectrum] The sample to be measured was photoexcited by irradiating it with excitation light (nitrogen gas laser, pulse width 0.9 ns) with a wavelength of 337 nm at an intensity above the ASE oscillation threshold. At this time, the excitation light was focused into a stripe shape with a size of 0.1 cm × 0.5 cm. The ASE emission from the sample to be measured was observed from the edge side of the thin film using a multi-channel spectrometer (Hamamatsu Photonics: PMA-12) to obtain the ASE spectrum.

[0059] [Measurement of ASE oscillation threshold] The emission spectrum was measured using the same procedure as described in "Measurement of ASE Spectra" above, by changing the incident light intensity of the excitation light using a neutral density (ND) filter. The intensity at the emission maximum wavelength (peak intensity) and the full width at half maximum (FWHM) of the peak were measured for each emission spectrum. The measured values ​​were plotted on a log-log graph with the absorbed energy density (Absorbed Energy Density) on the x-axis and the peak intensity on the y-axis, and on a semi-log graph with the absorbed energy density (Absorbed Energy Density) on the x-axis and the FWHM on the y-axis, to create an ASE plot. For the peak intensity plot, two approximate lines were drawn on the left and right sides of the horizontal axis position where the intensity changes abruptly, and the ASE oscillation threshold was determined from their intersection. 2 The following formula was used to calculate it. Excitation light intensity (μJ) × Absorption rate at excitation wavelength 337 nm / Area of ​​excited region (cm²) 2 ) Here, the excitation light intensity was measured using a light intensity meter, and the area of ​​the excited region was measured using a CCD camera. The light absorption rate was calculated using absorbance A with the following formula. Absorption rate = 1-10 -A

[0060] [Compounds represented by general formula (1) used in the examples] The compound represented by general formula (1) used in the examples is shown below. In the following structural formula, tbu represents a tert-butyl group.

[0061] [ka]

[0062] (Example 1) Preparation and evaluation of a thin film containing compound 1 Thin films (neat films) of compound 1 and polymethyl methacrylate (PMMA) dispersion films of compound 1 were prepared using the spin-coating method as follows. A chloroform solution of compound 1 at a 1% by weight was supplied onto a 1.1 mm thick glass substrate using a filtered syringe, and a thin film with a thickness of 100 nm (a neat film of compound 1) was fabricated by spin coating while rotating at 1000 rpm for 60 seconds. Compound 1 was added to an anisole solution of PMMA (495PMMA A6 Resists: Microchem Co., Ltd.) and stirred with a stirrer for 1 hour to prepare a dispersion. At this time, the concentration of compound 1 was 5% by weight relative to the weight of PMMA. This dispersion was supplied onto a quartz substrate (20 × 30 mm, 1.1 mm thick) and spin-coated by rotating at 1000 rpm for 60 seconds to produce a thin film with a thickness of 540 nm (a 5% by weight PMMA dispersion of compound 1). Furthermore, the concentration of compound 1 added to the dispersion was set to 10% by weight relative to the weight of PMMA, and a 10% by weight PMMA dispersion membrane of compound 1 was prepared using the same procedure. For each fabricated thin film, the absorption spectrum, fluorescence spectrum, ASE characteristics, and fluorescence lifetime were measured. The absorption maximum wavelength, fluorescence emission maximum wavelength, ASE oscillation wavelength, fluorescence lifetime, and ASE oscillation threshold for each thin film are shown in Table 1 below. In Table 1, "-" indicates that the measurement was not performed. As a representative example, the absorption spectrum of a 5 wt% PMMA dispersion film of compound 1 is shown in Figure 2, the fluorescence spectrum in Figure 3, the ASE spectrum in Figure 4, and the ASE plot in Figure 5. Furthermore, using a quartz substrate (10 × 15 mm, 1.1 mm thick), and changing the spin-coating substrate rotation speed to 3000 rpm, 5 wt% PMMA dispersion films of compound 1 and 10 wt% PMMA dispersion films of compound 1 were prepared using the same procedure. The fluorescence quantum yields of these PMMA dispersion films and the neat films described above were also measured and are shown in Table 1 below.

[0063] (Example 2) Preparation and evaluation of a thin film containing compound 2 Using compound 2 instead of compound 1, neat membranes, 5 wt% PMMA-dispersed membranes, and 10 wt% PMMA-dispersed membranes of compound 2 were prepared using the same procedure. For each fabricated thin film, the absorption spectrum, fluorescence spectrum, ASE characteristics, and fluorescence lifetime were measured. The absorption maximum wavelength, fluorescence emission maximum wavelength, ASE oscillation wavelength, fluorescence quantum yield, fluorescence lifetime, and ASE oscillation threshold for each thin film are shown in Table 1 below. As a representative example, the absorption spectrum of a 5 wt% PMMA dispersion film of compound 2 is shown in Figure 6, the fluorescence spectrum in Figure 7, the ASE spectrum in Figure 8, and the ASE plot in Figure 9.

[0064] [Table 1]

[0065] As shown in Table 1, the ASE oscillation wavelengths of each thin film containing compound 1 and the PMMA dispersion film containing compound 2 were all 370 nm or less. Furthermore, it was confirmed that the neat film of compound 3 (2,3''-dispirobifluorene) exhibited a sharp emission peak characteristic of ASE at 376 nm. Since ASE oscillation and laser oscillation are both light emission induced by the incidence of light in a population inversion state, materials exhibiting ASE oscillation can be considered laser materials. Therefore, these results indicate that compounds having a spirobifluorene structure and a spirofluorene indeno structure are useful as organic solid-state laser materials and can be used as gain media for ultraviolet organic lasers. [Industrial applicability]

[0066] The organic solid-state laser material of the present invention exhibits ASE oscillation in the short-wavelength region, making it effective as a material for organic semiconductor laser elements, thereby enabling laser oscillation of 380 nm or less. Such short-wavelength laser light can be effectively used for laser treatment of skin diseases and laser processing in the biotechnology field. For this reason, the present invention has high industrial applicability. [Explanation of symbols]

[0067] 1 circuit board 2 Anode 3. Hole injection layer 4. Hole transport layer 5. Emitting layer 6 Electron transport layer 7 Cathode

Claims

1. An organic solid-state laser material containing a compound represented by the following general formula (1). 【Chemistry 1】 [In general formula (1), R １ ~R ４ The following conditions (A) or (B) are met. The remaining R that are not involved in the following conditions (A) or (B) １ ~R ４ and R ５ ~R １６ Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent. Condition (A) R １ and R ２ They bind to each other to form a substituted or unsubstituted spirofluoreneindeno structure, R ２ and R ３ are combined with each other to form a substituted or unsubstituted spirofluorene indeno structure, or or R ３ and R ４ These molecules combine with each other to form substituted or unsubstituted spirofluoreneindeno structures. Condition (B) R １ ~R ４ One of these groups is a substituted or unsubstituted spirobifluoren-1-yl group, a substituted or unsubstituted spirobifluoren-2-yl group, a substituted or unsubstituted spirobifluoren-3-yl group, or a substituted or unsubstituted spirobifluoren-4-yl group.

2. The remaining R １ ~R ４ and R ５ ~R １６ The organic solid-state laser material according to claim 1, wherein each is independently a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group.

3. The organic solid-state laser material according to claim 1, satisfying the above condition (A).

4. The organic solid-state laser material according to claim 3, wherein the spirofluorene indeno structure formed by the above condition (A) is substituted with a deuterium atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group.

5. Of the above conditions (A), R １ and R ２ The organic solid-state laser material according to claim 3, wherein the elements bond to each other to form a substituted or unsubstituted spirofluorene indeno structure.

6. The organic solid-state laser material according to claim 1, satisfying the above condition (B).

7. The organic solid-state laser material according to claim 6, wherein the spirobifluoren-1-yl group, the spirobifluoren-2-yl group, the spirobifluoren-3-yl group, and the spirobifluoren-4-yl group are substituted with a deuterium atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group.

8. R １ ~R ４ The organic solid-state laser material according to claim 6, wherein one of the groups is a substituted or unsubstituted spirobifluoren-3-yl group, or a substituted or unsubstituted spirobifluoren-4-yl group.

9. The organic gas laser material according to claim 1, comprising a compound represented by general formula (1) and a matrix material, wherein the content of the compound represented by general formula (1) is 20% by weight or less.

10. An organic semiconductor laser element with a laser oscillation wavelength of 380 nm or less.

11. The organic semiconductor laser element according to claim 10, comprising the organic solid-state laser material according to any one of claims 1 to 9.

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