Light-emitting devices

Abstract

A light-emitting device (1) comprises a light-emitting element (3), a first inorganic film (40) that covers the light-emitting element, a hydrophobic organic film (41) located outside the first inorganic film, and a hygroscopic film (42) located outside the hydrophobic organic film.

Description

[Technical Field]

[0001] The present disclosure relates to a light-emitting device comprising a light-emitting element. [Background technology]

[0002] Patent Document 1 discloses an organic light-emitting display device having an organic light-emitting element sealed with a sealing thin film having a hydrophilic polymer film and an inorganic protective film. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2011-113967 Summary of the Invention [Problem to be solved by the invention]

[0004] In the organic light-emitting display device described in Patent Document 1, foreign matter such as moisture that has passed through pinholes in the inorganic protective film and been absorbed into the hydrophilic polymer film may be released toward the organic light-emitting element, which may cause deterioration of the organic light-emitting element. [Means for solving the problem]

[0005] A light-emitting device according to one embodiment of the present disclosure comprises a light-emitting element, a first inorganic film covering the light-emitting element, a hydrophobic organic film positioned outside the first inorganic film, and a moisture-absorbing film positioned outside the hydrophobic organic film. [Effects of the Invention]

[0006] The moisture absorption film reduces the release of foreign matter such as moisture absorbed by the film toward the light emitting element, thereby reducing deterioration of the light emitting element. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic cross-sectional view of a light-emitting device according to a first embodiment. [Figure 2] 1 is a schematic enlarged view of a cross section of a light-emitting device according to Embodiment 1. FIG. [Figure 3] FIG. 10 is a schematic cross-sectional view of a light-emitting device according to a second embodiment. [Figure 4] FIG. 10 is a schematic cross-sectional view of a light-emitting device according to a third embodiment. [Figure 5] FIG. 10 is a schematic cross-sectional view of a light-emitting device according to a fourth embodiment. [Figure 6] FIG. 10 is a schematic cross-sectional view of a light-emitting device according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] [Embodiment 1] <Light-emitting devices: Overview> In this embodiment, a light emitting device including a field injection type light emitting element will be described as an example.

[0009] 1 is a schematic cross-sectional view of a light-emitting device 1 according to this embodiment. Note that all schematic cross-sectional views of the light-emitting device 1 in this specification show a cross section passing through a light-emitting element (described later) and in a direction substantially parallel to the stacking direction of the light-emitting element.

[0010] 1, the light-emitting device 1 includes a substrate 2, a light-emitting element 3, a sealing layer 4, and a cover film 5. In particular, the light-emitting device 1 includes the light-emitting element 3 on the substrate 2, and the sealing layer 4 that covers the light-emitting element 3 and seals the light-emitting element 3 between the substrate 2 and the light-emitting element 3. In addition, the cover film 5 may be attached to the side of the sealing layer 4 opposite the substrate 2.

[0011] Each part of the light-emitting device 1 may be a flexible material that is flexible enough to be bent, or may have a thickness that is thick enough to be bent, in which case the light-emitting device 1 may be configured as a flexible device.

[0012] <Light-emitting device: substrate> The substrate 2 may be, for example, a glass substrate or a resin film substrate having a drive circuit capable of individually driving any of the electrodes of the light-emitting elements 3 (described later). For example, the substrate 2 may have a drive circuit including a metal material or a transparent material having conductivity.

[0013] <Light-emitting device: light-emitting element> The light-emitting element 3 is an element that emits light when driven by the drive circuit of the substrate 2 described above, and is, for example, a stacked field injection type light-emitting element having a light-emitting layer containing a light-emitting material between electrodes. For example, the light-emitting element 3 may be a quantum dot light-emitting element having semiconductor nanoparticles (quantum dots) as the light-emitting material in the light-emitting layer, or an organic light-emitting element (e.g., an OLED element) having an organic fluorescent material or an organic phosphorescent material in the light-emitting layer. The light-emitting element 3 may contain a mixture of a host material and a dopant material in the light-emitting layer.

[0014] The light-emitting material of the light-emitting element 3 may include a light-emitting material that emits light of any of red, green, and blue, or may include at least two or more of these light-emitting materials. In this specification, red light refers to light having a central emission wavelength in a wavelength band of, for example, more than 600 nm and not more than 780 nm. Green light refers to light having a central emission wavelength in a wavelength band of, for example, more than 500 nm and not more than 600 nm. Blue light refers to light having a central emission wavelength in a wavelength band of, for example, 400 nm or more and not more than 500 nm.

[0015] More specifically, the light-emitting element 3 may have, for example, an anode, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode, in this order from the substrate 2 side. However, the stacking order of the layers of the light-emitting element 3 may be reversed from the above-mentioned order.

[0016] When the light-emitting element 3 is driven by the drive circuit of the substrate 2, holes and electrons may be injected from the anode and cathode of the light-emitting element 3, respectively, toward the light-emitting layer. The hole injection layer, hole transport layer, and electron blocking layer may have the function of transporting holes from the anode to the light-emitting layer. The electron injection layer, electron transport layer, and hole blocking layer may have the function of transporting electrons from the cathode to the light-emitting layer. The electron blocking layer may have the function of inhibiting the transport of electrons from the light-emitting layer to the anode, and the hole blocking layer may have the function of inhibiting the transport of holes from the light-emitting layer to the cathode.

[0017] The light-emitting material contained in the light-emitting layer of the light-emitting element 3 may be a material that emits light by excitons generated by recombination of holes from the anode and electrons from the cathode. Thus, the light-emitting device 1 may obtain light from the light-emitting layer of the light-emitting element 3 by driving the light-emitting element 3 with a drive circuit on the substrate 2. The light emitted from the light-emitting layer of the light-emitting element 3 may be extracted from the light-emitting element 3 to the cover film 5 side. In this case, the light-emitting device 1 may include a capping layer between the light-emitting element 3 and the sealing layer 4, which will be described later, to control light reflection between the light-emitting element 3 and the sealing layer 4 and increase the extraction efficiency of the light emitted from the light-emitting element 3. Alternatively, when the substrate 2 is a transparent substrate, the light emitted from the light-emitting layer of the light-emitting element 3 may be extracted from the light-emitting element 3 to the substrate 2 side.

[0018] <Light-emitting devices: Encapsulating layers: Overview> The sealing layer 4 seals the light-emitting element 3 between itself and the substrate 2, thereby reducing the penetration of foreign substances such as moisture into the light-emitting element 3 from the outside of the sealing layer 4 side of the light-emitting device 1. As shown in Fig. 1 , the sealing layer 4 includes, in order from the substrate 2 and light-emitting element 3 side, a first inorganic film 40 covering at least the light-emitting element 3, a hydrophobic organic film 41 located outside the first inorganic film 40, and a hygroscopic film 42 located outside the hydrophobic organic film 41. In this embodiment, the sealing layer 4 further includes a second inorganic film 43 located outside the hygroscopic film 42 and covering the hygroscopic film 42.

[0019] <Light-emitting device: Sealing layer: First inorganic film> The first inorganic film 40 may include at least one selected from the group consisting of, for example, silicon oxide, silicon nitride, magnesium oxide, magnesium nitride, aluminum oxide, aluminum nitride, zinc oxide, and zinc nitride. In particular, the first inorganic film 40 may include silicon oxide or silicon nitride.

[0020] In order for the first inorganic film 40 to sufficiently reduce the penetration of foreign matter such as moisture into the light-emitting element 3 or to sufficiently reduce the formation of pinholes, which will be described later, the film thickness of the first inorganic film 40 may be 100 nm or more. Furthermore, when the light-emitting device 1 is a flexible device, the film thickness of the first inorganic film 40 may be 2000 nm or less in order to ensure sufficient flexibility of the first inorganic film 40.

[0021] <Light-emitting device: Sealing layer: Hydrophobic organic film> The hydrophobic organic film 41 is an organic sealing film containing a hydrophobic organic material, such as an acrylic resin. For example, the polarity of the organic material of the hydrophobic organic film 41 may be lower than the polarity of water. Alternatively, the contact angle between the hydrophobic organic film 41 and water may be 25 degrees or more.

[0022] The thickness T1 of the hydrophobic organic film 41 may be 50 nm or more, 100 nm or more, or 200 nm or more. The thicker the hydrophobic organic film 41, the more hygroscopic the hydrophobic organic film 41 of the light-emitting device 1 can be, and the more the penetration of foreign matter such as moisture from the outside of the light-emitting device 1 into the light-emitting element 3 can be reduced.

[0023] The moisture permeability of the hydrophobic organic film 41 is 60 g / (m 2 ·24h) or more 1000g / (m 2 The moisture permeability of the hydrophobic organic film 41 may be 60 g / (m 2 24h) or more, the moisture absorption of the hydrophobic organic film 41 of the light-emitting device 1 can be increased, and the penetration of foreign matter such as moisture from the outside of the light-emitting device 1 into the light-emitting element 3 can be reduced. 2By keeping the storage time (24 hours) or less, the light-emitting device 1 can reduce the amount of moisture absorbed by the hydrophobic organic film 41 that passes through the hydrophobic organic film 41 and reaches the first inorganic film 40 side.

[0024] <Light-emitting device: Sealing layer: Moisture-absorbing film> The moisture absorbing film 42 is an organic sealing film having moisture absorption properties, and in particular has the function of absorbing foreign matter such as moisture from the outside of the sealing layer 4 side of the light emitting device 1 to the light emitting element 3, and delaying the penetration of the foreign matter into the light emitting element 3. For example, the moisture absorbing film 42 may have a moisture absorbing organic polymer.

[0025] In this embodiment, the hydrophobic organic film 41 and the hygroscopic film 42 may be adjacent to each other. In this case, the hygroscopic film 42 may include an organic polymer that has both hygroscopicity and adhesion to the hydrophobic organic film 41. In other words, the hygroscopic film 42 may include an organic polymer that has both hydrophilic and hydrophobic properties. In particular, the hygroscopic film 42 may be formed at a position that covers the hydrophobic organic film 41.

[0026] <Light-emitting device: Sealing layer: Moisture-absorbing polymer film> For example, the moisture-absorbing film 42 may include a first organic polymer having a hydrophilic functional group and at least a part of the molecular skeleton being hydrophobic, as an organic polymer having both hydrophilic and hydrophobic properties. In particular, the first organic polymer does not need to have a hydrophobic functional group.

[0027] In this specification, the term "hydrophilic functional group" may refer to a functional group that forms a contact angle between the surface of a polymer film having the hydrophilic functional group and water of less than 25 degrees. Alternatively, the term "hydrophilic functional group" may refer to a functional group that has a polarity equal to or greater than that of a water molecule. Meanwhile, in this specification, the term "hydrophobic functional group" may refer to a functional group that forms a contact angle between the surface of a polymer film having the hydrophobic functional group and water of 25 degrees or greater. Alternatively, the term "hydrophilic functional group" may refer to a functional group that has a polarity less than that of a water molecule.

[0028] The hydrophilic functional group of the first organic polymer may include at least one selected from the group consisting of an amide group and a carboxylic acid group. In particular, the first organic polymer may include at least one selected from the group consisting of polyamic acid, polyamic acid, polyimide acid, partially imidized polyamic acid, and polyacrylic acid. Specifically, the first organic polymer may include at least one selected from the group consisting of polymers represented by the following general formula (1):

[0029] [ka] In the above general formula (1), X represents any one of the following:

[0030] [ka] In the general formula (1), Y represents any one of the following:

[0031] [ka] In other words, the polymer represented by general formula (1) contains a polyamic acid containing an amide group and a carboxylic acid group as hydrophilic functional groups. Furthermore, X and Y of the polymer represented by general formula (1) are part of a molecular skeleton having hydrophobic properties.

[0032] The first organic polymer may also be a polymer obtained by polymerizing a monomer having a hydrophilic functional group. In particular, the first organic polymer may include at least one selected from the group consisting of polymers represented by the following chemical formula: In other words, the polymer represented by the following chemical formula may be obtained by polymerizing a monomer having a hydrophilic functional group and a hydrophobic molecular skeleton.

[0033] [ka] Alternatively, the moisture absorbing film 42 may include a second organic polymer having a hydrophilic functional group and a hydrophobic functional group as an organic polymer having both hydrophilic and hydrophobic properties.

[0034] In particular, the hydrophilic functional group of the second organic polymer may include at least one selected from the group consisting of an amide group and a carboxylic acid group. Furthermore, the hydrophobic functional group of the second organic polymer may include at least one selected from the group consisting of an alkyl group and a functional group having an aromatic ring. In particular, the second organic polymer may include at least one selected from the group consisting of polyamic acid, polyamic acid, polyimide acid, partially imidized polyamic acid, and polyacrylic acid. Specifically, the second organic polymer may include at least one selected from the group consisting of polymers represented by the following general formula (2):

[0035] [ka] In the above general formula (2), X represents any one of the following:

[0036] [ka] In the general formula (2), Y represents any one of the following:

[0037] [ka] Furthermore, in the above general formula (2), Z represents any one of the following:

[0038] [ka] In other words, the polymer represented by general formula (2) contains a polyamic acid containing an amide group and a carboxylic acid group as hydrophilic functional groups. In addition, X and Y of the polymer represented by general formula (2) are part of a molecular skeleton having hydrophobic properties, and Z is a hydrophobic functional group.

[0039] The second organic polymer may also be a polymer obtained by polymerizing a monomer having a hydrophilic functional group and a hydrophobic functional group. For example, the second organic polymer may be a polymer obtained by polymerizing a monomer in which a portion of a monomer having a hydrophilic functional group has been substituted with a hydrophobic functional group. Specifically, the second organic polymer may include at least one selected from the group consisting of polymers represented by the following chemical formula, where X is an alkyl group that is a hydrophobic functional group:

[0040] [ka] The moisture-absorbing film 42 may include both the first organic polymer and the second organic polymer described above. In this case, the molecular skeleton of the first organic polymer may be the same as the molecular skeleton of the second organic polymer. In other words, the moisture-absorbing film 42 may be formed by substituting a hydrophobic functional group for a portion of the terminal or side chain of the first organic polymer. To ensure sufficient moisture absorption and adhesion to the hydrophobic organic film 41 in the moisture-absorbing film 42, the ratio of the amount of substance of the second organic polymer to the amount of substance of the first organic polymer in the moisture-absorbing film 42 may be 0.05 or more and 20 or less.

[0041] The concentration of the second organic polymer in the portion of the hygroscopic film 42 facing the hydrophobic organic film 41 may be higher than the concentration of the second organic polymer in the portion of the hygroscopic film 42 on the opposite side to the hydrophobic organic film 41. In other words, when the direction from the substrate 2 to the cover film 5 in the light-emitting device 1 is defined as the upward direction, the concentration of the second organic polymer in the upper portion of the hygroscopic film 42 may be higher than the concentration of the second organic polymer in the lower portion of the hygroscopic film 42. In this case, the adhesion between the hydrophobic organic film 41 and the hygroscopic film 42 is improved on the hydrophobic organic film 41 side of the hygroscopic film 42. Furthermore, the hygroscopicity is improved on the side of the hygroscopic film 42 opposite to the hydrophobic organic film 41 side, in other words, on the external side of the light-emitting device 1, and the penetration of foreign matter such as moisture from the outside of the light-emitting device 1 to the light-emitting element 3 can be reduced.

[0042] <Light-emitting device: Sealing layer: Properties of moisture-absorbing film> In order to prevent the moisture absorbed by the moisture absorbing film 42 from directly passing through the moisture absorbing film 42 and reaching the hydrophobic organic film 41 side, the moisture permeability of the moisture absorbing film 42 is set to 30 g / (m 2 24h) or less, 20g / (m 2 In order to ensure sufficient moisture absorption of the hygroscopic film 42 with respect to the hydrophobic organic film 41, the moisture permeability of the hygroscopic film 42 may be 1 / 3 or 1 / 2 of the moisture permeability of the hydrophobic organic film 41.

[0043] The thickness T2 of the moisture absorbing film 42 may be 50 nm or more, 100 nm or more, or 200 nm or more. The thicker the moisture absorbing film 42, the more moisture absorbing the moisture absorbing film 42 of the light emitting device 1 can be, and the more the penetration of foreign matter such as moisture from the outside of the light emitting device 1 into the light emitting element 3 can be reduced.

[0044] In order to enhance the hygroscopicity of both the hydrophobic organic film 41 and the hygroscopic film 42, the total thickness T3 of the hydrophobic organic film 41 and the hygroscopic film 42 may be 500 nm or more. In order to achieve both the hygroscopicity of the hydrophobic organic film 41 and the hygroscopic film 42 and the adhesion between the hydrophobic organic film 41 and the hygroscopic film 42, the ratio of the thickness T2 to the thickness T1 may be 0.05 or more and 20 or less.

[0045] <Light-emitting device: Sealing layer: Second inorganic film> The second inorganic film 43 may have the same configuration as the first inorganic film 40, except for the formation position. In particular, the second inorganic film 43 may be formed in a position that covers the hygroscopic film 42. Here, the first inorganic film 40 may be formed on the substrate 2, extending beyond the hydrophobic organic film 41 and the hygroscopic film 42 to the outer periphery of the light-emitting device 1. In this case, the second inorganic film 43 may be in direct contact with the peripheral portion 44 of the first inorganic film 40. As a result, the outer periphery of the sealing layer 4 facing the light-emitting device 1 is covered by the inorganic sealing film. Therefore, with the above configuration, the sealing layer 4 can reduce the penetration of foreign matter such as moisture from the periphery of the light-emitting device 1.

[0046] <Light-emitting device: cover film> The cover film 5 is attached to the side of the sealing layer 4 opposite to the substrate 2. The cover film 5 may contain, for example, a light-transmitting resin material. The cover film 5 may be formed to protect the light-emitting element 3 and the sealing layer 4 of the light-emitting device 1. The cover film 5 may have a transparent electrode having conductivity, such as an electrode of a touch panel.

[0047] <Moisture-proofing mechanism of light-emitting element by sealing layer> The mechanism by which the sealing layer 4 reduces the penetration of foreign matter such as moisture from the outside of the light-emitting device 1 into the light-emitting element 3 will be described in detail with reference to Fig. 2. Fig. 2 is an enlarged schematic view of region A in the cross section of the light-emitting device 1 shown in Fig. 1. In other words, Fig. 2 is an enlarged schematic view of a portion of the cross section of the light-emitting device 1 shown in Fig. 1, from near the end of the light-emitting element 3 on the sealing layer 4 side to near the end of the second inorganic film 43 on the moisture-absorbing film 42 side.

[0048] Moisture from outside the light-emitting device 1 may permeate toward the light-emitting element 3, for example, by passing through the cover film 5 or between the cover film 5 and the sealing layer 4. In this embodiment, the second inorganic film 43 mainly reduces the permeation of moisture that has permeated from the cover film 5 side of the sealing layer 4 into the light-emitting element 3.

[0049] 2, a plurality of fine pinholes H penetrating in the film thickness direction may be formed in the first inorganic film 40 and the second inorganic film 43. Such pinholes H may be generated, for example, by the inclusion of foreign matter during the manufacturing process of the first inorganic film 40 and the second inorganic film 43, or by the occurrence of uneven film thicknesses of the first inorganic film 40 and the second inorganic film 43.

[0050] 2, moisture that has penetrated from the cover film 5 side of the sealing layer 4 may penetrate to the moisture absorbing film 42 through pinholes H formed in the second inorganic film 43. Even in this case, the moisture absorbing film 42 absorbs the moisture using a hydrophilic polymer, and therefore the sealing layer 4 can delay the penetration of moisture from the outside of the light emitting device 1 into the light emitting element 3.

[0051] As the moisture absorption by the moisture absorptive film 42 progresses and the moisture content of the moisture absorptive film 42 becomes saturated, moisture may be released from the moisture absorptive film 42. The release of moisture from the moisture absorptive film 42 occurs in a release direction D2 or a permeation direction D3, as shown in FIG. 2 . The release direction D2 is the direction in which moisture is released from the moisture absorptive film 42 to the outside of the light-emitting device 1 through the pinhole H in the second inorganic film 43. The permeation direction D3 is the direction in which moisture permeates from the moisture absorptive film 42 toward the hydrophobic organic film 41, in other words, toward the light-emitting element 3.

[0052] Moisture from the hygroscopic film 42 is preferentially released into the pinholes H, which are voids in the second inorganic film 43, rather than penetrating into the hydrophobic organic film 41, which is hydrophobic and solid. In other words, moisture is released from the hygroscopic film 42 preferentially in the release direction D2 rather than in the penetration direction D3.

[0053] For example, suppose that the light-emitting device 1 does not include the second inorganic film 43. In this case, the cover film 5 is attached onto the hygroscopic film 42, and in this case, a minute gap may be formed in a portion between the hygroscopic film 42 and the cover film 5. Therefore, even in the above case, moisture from the hygroscopic film 42 is preferentially released into the gap between the hygroscopic film 42 and the cover film 5 rather than permeating into the hydrophobic organic film 41, which is hydrophobic and solid.

[0054] Therefore, the proportion of moisture absorbed by the moisture absorbing film 42 that is released toward the outside of the light emitting device 1 is greater than the proportion that penetrates toward the light emitting element 3. As a result, the sealing layer 4 efficiently releases the moisture absorbed by the moisture absorbing film 42 toward the outside of the light emitting device 1, thereby reducing the penetration of moisture into the light emitting element 3.

[0055] Furthermore, since the hydrophobic organic film 41 also has a certain degree of thickness and hygroscopicity, even if moisture penetrates from the hygroscopic film 42 into the hydrophobic organic film 41, the hydrophobic organic film 41 can delay the penetration of moisture into the light-emitting element 3. In addition, the release of moisture from the hydrophobic organic film 41 to the light-emitting element 3 is reduced by the first inorganic film 40.

[0056] As a result, the sealing layer 4 can more effectively reduce the penetration of moisture from the outside of the light-emitting device 1 into the light-emitting element 3. Note that, by the same mechanism as above, the sealing layer 4 can also reduce the penetration of liquid foreign matter, in addition to moisture, from the outside of the light-emitting device 1 into the light-emitting element 3.

[0057] As described above, the hygroscopic film 42 has a polymer having a hydrophobic functional group or a polymer including a molecular skeleton having hydrophobic properties. This allows the hygroscopic film 42 to have improved adhesion to the hydrophobic organic film 41. The closer adhesion between the hydrophobic organic film 41 and the hygroscopic film 42 allows the sealing layer 4 to further reduce the penetration of foreign matter such as moisture between the two layers.

[0058] <Evaluation of Light-Emitting Device Characteristics: Example 1> A light-emitting device according to Example 1 was manufactured in which a light-emitting element was sealed with a sealing layer having the same configuration as the sealing layer 4 according to the above-described embodiment, and its characteristics were compared with those of a light-emitting device according to Comparative Example 1. A light-emitting device according to Example 1 was manufactured by the following procedure.

[0059] First, a substrate 2 having Ag and ITO was prepared as the driving circuit and the anode of the light-emitting element 3. Next, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode were formed on the anode formed on the substrate 2 by vapor deposition under predetermined vapor deposition conditions. Here, an organic fluorescent material that emits blue light was used as the light-emitting material for the light-emitting layer. The electron injection layer was formed by vapor deposition of LiF, and the cathode was formed by vapor deposition of a metal material containing Mg and Ag. In this way, a top-emission blue OLED element was formed on the substrate 2 as the light-emitting element 3. In Example 1, a capping layer made of an organic material was formed on the blue OLED element.

[0060] Next, a SiN film was formed by sputtering on the substrate 2 and the light-emitting element 3 to a thickness of 0.1 μm, thereby forming a first inorganic film 40. Next, a film of a photocurable acrylic resin material was formed on the first inorganic film 40, and then the acrylic resin material was irradiated with light, thereby forming a hydrophobic organic film 41 with a thickness of 0.5 μm.

[0061] Next, a moisture absorbing film 42 was formed by the following method. First, a polymer material containing a polyamic acid containing an alkyl group in the side chain and a polyamic acid not containing an alkyl group in the side chain in a weight ratio of 20:80 was synthesized. Next, the polymer material was applied to form a film and heated at 200°C. In this way, a moisture absorbing film 42 having a film thickness of 0.5 μm was formed. Furthermore, a SiN film was formed to a film thickness of 0.1 μm by sputtering to form a second inorganic film 43, and thus a sealing layer 4 was formed. In this way, the light emitting device according to Example 1 was completed. In the light emitting device according to Example 1, the moisture permeability of the hydrophobic organic film 41 was 60 g / (m 2 ·24h), and the moisture permeability of the moisture-absorbing film 42 is 25 g / (m 2 24h).

[0062] <Evaluation of Light-Emitting Device Characteristics: Comparative Examples 1 to 4> In order to evaluate the characteristics of the light-emitting device according to Example 1, light-emitting devices according to each of Comparative Examples 1 to 4 were also manufactured. The light-emitting devices according to each Comparative Example were manufactured by changing the configuration of the sealing layer 4 of the light-emitting device according to Example 1 described above as follows. In the sealing layer of each Comparative Example, the film thickness and material of the first inorganic film 40 and the second inorganic film 43 are the same as the film thickness and material of the first inorganic film 40 and the second inorganic film 43 according to Example 1. In addition, in the sealing layer of each Comparative Example, the material of the hydrophobic organic film 41 and the hygroscopic film 42 is the same as the material of the hydrophobic organic film 41 and the hygroscopic film 42 according to Example 1.

[0063] The sealing layer of the light-emitting device according to Comparative Example 1 has, from the light-emitting element 3 side, a first inorganic film 40, a 1 μm-thick hydrophobic organic film 41, and a second inorganic film 43. The sealing layer of the light-emitting device according to Comparative Example 2 has, from the light-emitting element 3 side, a first inorganic film 40, a 20 nm-thick hygroscopic film 42, a 1 μm-thick hydrophobic organic film 41, and a second inorganic film 43. The sealing layer of the light-emitting device according to Comparative Example 3 has, from the light-emitting element 3 side, a first inorganic film 40, a 1 μm-thick hygroscopic film 42, and a second inorganic film 43. The sealing layer of the light-emitting device according to Comparative Example 4 has, from the light-emitting element 3 side, a first inorganic film 40, a 0.13 μm-thick hygroscopic film 42, a 0.2 μm-thick hydrophobic organic film 41, and a second inorganic film 43.

[0064] <Evaluation of light-emitting device characteristics: Evaluation results> The characteristics of the light emitting devices according to Example 1 and each of the comparative examples were measured and are summarized in Table 1 below.

[0065] [Table 1] In the tables in this specification, including Table 1, the column "External quantum efficiency (%)" indicates the external quantum efficiency of the light-emitting element 3 of each light-emitting device. The column "Chromaticity (x, y)" indicates the coordinates on the chromaticity coordinates of light having a central wavelength among the light emitted from each light-emitting device. The column "Lifespan (h)" indicates the lifespan of 50 mA / cm under an environment with a temperature of 45°C and a humidity of 90%. 2This shows the time it takes for the luminance of each light-emitting device to reach 90% of its initial luminance when a current drive test is performed.

[0066] As is clear from Table 1, there was almost no difference between Example 1 and each of the comparative examples in the external quantum efficiency of the light-emitting element 3 and the chromaticity of the light from the light-emitting element 3. In other words, the above indicates that the sealing layer 4 in Example 1 has only a slight effect on the luminous efficiency and luminous color of the light-emitting device.

[0067] Furthermore, as is clear from Table 1, the lifespan of the light-emitting device according to Example 1 is longer than that of the light-emitting devices according to each of the comparative examples. This is thought to be because, in the light-emitting device according to Example 1, the sealing layer 4 more effectively reduces the penetration of foreign matter such as moisture from the outside of the light-emitting device into the light-emitting element 3, thereby reducing deterioration of the light-emitting element 3, compared to the light-emitting devices according to each of the comparative examples.

[0068] <Evaluation of Light-Emitting Device Characteristics: Example 2> A light-emitting device according to another example was manufactured in which a light-emitting element was sealed with a sealing layer having the same configuration as sealing layer 4 according to the above-described embodiment, and its characteristics were compared with those of the light-emitting device according to the comparative example. A light-emitting device according to example 2 was manufactured by the following procedure.

[0069] First, the substrate 2 and the light-emitting element 3 were manufactured by the same method as the method for manufacturing the substrate 2 and the light-emitting element 3 in Example 1, except for the following. In this example, an organic fluorescent material that emits green light was used as the light-emitting material for the light-emitting layer. In Example 2, a capping layer made of an organic material was formed on the green OLED element.

[0070] Next, a SiN film was formed by sputtering on the substrate 2 and the light-emitting element 3 to a thickness of 0.1 μm, thereby forming a first inorganic film 40. Next, a film of a photocurable acrylic resin material was formed on the first inorganic film 40, and then the acrylic resin material was irradiated with light, thereby forming a hydrophobic organic film 41 with a thickness of 0.6 μm.

[0071] Next, the moisture absorbing film 42 was formed by the following method: First, a resin material having an amide bond, made of a monomer represented by the following chemical formula, was formed into a film, and then cured by ultraviolet irradiation.

[0072] [ka] This resulted in the formation of a moisture absorbing film 42 with a thickness of 0.4 μm. Furthermore, a SiN film was formed by sputtering to a thickness of 0.1 μm to form a second inorganic film 43, and thus a sealing layer 4 was formed. In this way, the light emitting device according to Example 2 was completed. In the light emitting device according to Example 2, the moisture permeability of the hydrophobic organic film 41 was 65 g / (m 2 ·24h), and the moisture permeability of the moisture-absorbing film 42 is 30 g / (m 2 24h).

[0073] <Evaluation of Light-Emitting Device Characteristics: Comparative Examples 5 to 7> In order to evaluate the characteristics of the light-emitting device according to Example 2, light-emitting devices according to each of Comparative Examples 5 to 7 were also manufactured. The light-emitting devices according to each Comparative Example were manufactured by changing the configuration of the sealing layer 4 of the light-emitting device according to Example 2 described above as follows. In the sealing layer of each Comparative Example, the film thickness and material of the first inorganic film 40 and the second inorganic film 43 are the same as the film thickness and material of the first inorganic film 40 and the second inorganic film 43 according to Example 2. In the sealing layer of each Comparative Example, the material of the hydrophobic organic film 41 and the hygroscopic film 42 are the same as the material of the hydrophobic organic film 41 and the hygroscopic film 42 according to Example 2.

[0074] The sealing layer of the light-emitting device according to Comparative Example 5 has, from the light-emitting element 3 side, a first inorganic film 40, a 1 μm-thick hydrophobic organic film 41, and a second inorganic film 43. The sealing layer of the light-emitting device according to Comparative Example 6 has, from the light-emitting element 3 side, a first inorganic film 40, a 20 nm-thick hygroscopic film 42, a 1 μm-thick hydrophobic organic film 41, and a second inorganic film 43. The sealing layer of the light-emitting device according to Comparative Example 7 has, from the light-emitting element 3 side, a first inorganic film 40, a 1 μm-thick hygroscopic film 42, and a second inorganic film 43.

[0075] <Evaluation of light-emitting device characteristics: Evaluation results> The characteristics of the light emitting devices according to Example 2 and each of the comparative examples were measured and are summarized in Table 2 below.

[0076] [Table 2] As is clear from Table 2, there was almost no difference between Example 2 and each of the comparative examples in the external quantum efficiency of the light-emitting element 3 and the chromaticity of the light from the light-emitting element 3. In other words, the above indicates that the sealing layer 4 in Example 2 has only a slight effect on the luminous efficiency and luminous color of the light-emitting device.

[0077] Furthermore, as is clear from Table 2, the lifespan of the light-emitting device according to Example 2 is longer than that of the light-emitting devices according to each of the comparative examples. This is thought to be because the sealing layer 4 in the light-emitting device according to Example 2 more effectively reduces the penetration of foreign matter such as moisture from the outside of the light-emitting device into the light-emitting element 3 than in the light-emitting devices according to each of the comparative examples.

[0078] [Embodiment 2] Other embodiments of the present disclosure will be described below. Hereinafter, for the sake of convenience, in this specification, components having the same functions as those described in the previous embodiments will be denoted by the same reference numerals, and the description thereof will not be repeated.

[0079] <Light-emitting device with tandem light-emitting elements> 3 is a schematic cross-sectional view of the light-emitting device 1 according to this embodiment. The light-emitting device 1 according to this embodiment differs in configuration from the light-emitting device 1 according to the previous embodiment only in that it includes a tandem light-emitting element 6 as the light-emitting element instead of the light-emitting element 3. Therefore, the first inorganic film 40 of the sealing layer 4 covers the tandem light-emitting element 6.

[0080] The tandem light-emitting element 6 includes a first portion 60, a charge generating layer 61, and a second portion 62, in this order, on a substrate 2. In particular, the tandem light-emitting element 6 includes light-emitting layers in the first portion 60 and the second portion 62, each of which corresponds to the light-emitting layer of the light-emitting element 3 described above. In other words, the tandem light-emitting element 6 includes a plurality of light-emitting layers.

[0081] For example, the first portion 60 includes an anode, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, and an electron transport layer, in this order, on the substrate 2. The tandem light-emitting element 6 includes a charge generation layer 61 on the electron transport layer of the first portion 60. The second portion 62 includes a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode, in this order, on the charge generation layer 61. The layers of the first portion 60 and the second portion 62 have the same configuration as the layers of the light-emitting element 3 described above.

[0082] The charge generation layer 61 is a layer for injecting electrons into the first portion 60 and holes into the second portion 62 when the tandem light emitting element 6 is driven. The charge generation layer 61 includes, for example, an n-type charge generation layer on the first portion 60 side and a p-type charge generation layer on the second portion 62 side. The n-type charge generation layer may include, for example, a mixed material of an organic material having electron transport properties and Yb, or a mixed material of an organic or inorganic material having electron transport properties and Li. The p-type charge generation layer may include, for example, an organic material having electron accepting properties. In this case, when a potential difference is generated between the anode of the first portion 60 and the cathode of the second portion 60, electrons are injected from the n-type charge generation layer of the charge generation layer 61 into the first portion 60, and holes are injected from the p-type charge generation layer of the charge generation layer 61 into the second portion 62. The charge generation layer 61 may be a layer that generates charges by being driven, for example, by a circuit board formed on the substrate 2. Alternatively, the charge generating layer 61 may be a layer that generates the above-mentioned charges due to a potential difference between the anode of the first portion 60 and the cathode of the second portion 62.

[0083] Therefore, holes from the anode of the first portion 60 and electrons from the charge generation layer 61 are injected into the light-emitting layer of the first portion 60. Furthermore, electrons from the cathode of the second portion 62 and holes from the charge generation layer 61 are injected into the light-emitting layer of the second portion 62. As a result, the light-emitting device 1 according to this embodiment can obtain light emission from the light-emitting layers of the first portion 60 and the second portion 62 by driving the tandem light-emitting element 6.

[0084] Like the light-emitting device 1 according to the previous embodiment, the light-emitting device 1 according to this embodiment also includes a sealing layer 4 that seals the tandem light-emitting element 6. Therefore, the sealing layer 4 according to this embodiment can more effectively reduce the penetration of moisture from the outside of the light-emitting device 1 into the tandem light-emitting element 6.

[0085] <Evaluation of Light-Emitting Device Characteristics: Example 3> A light-emitting device according to another example was manufactured in which a tandem light-emitting element was sealed with a sealing layer having the same configuration as sealing layer 4 according to the above-described embodiment, and its characteristics were compared with those of the light-emitting device according to the comparative example. A light-emitting device according to example 3 was manufactured by the following procedure.

[0086] First, the substrate 2 and the tandem light-emitting element 6 were manufactured by the same method as the method for manufacturing the substrate 2 and the light-emitting element 3 according to Example 1, except for the following.

[0087] In this example, after preparing the substrate 2, a hole injection layer, a hole transport layer, an electron blocking layer, an emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer were formed by vapor deposition on the anode formed on the substrate 2 to form a first portion 60. Next, a charge generation layer 61 having a predetermined film thickness was formed on the electron injection layer of the first portion 60 under predetermined vapor deposition conditions. Next, a hole injection layer, a hole transport layer, an electron blocking layer, an emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode were formed by vapor deposition on the charge generation layer 61 to form a second portion 62. The materials, vapor deposition conditions, and film thicknesses of the layers of the first portion 60 and the second portion 62 were the same as those of the light-emitting element 3 in Example 1. In Example 3, a capping layer made of an organic material was formed on the tandem light-emitting element 6.

[0088] Next, a SiN film was formed on the substrate 2 and the tandem light-emitting element 6 by sputtering to a thickness of 0.1 μm, thereby forming a first inorganic film 40. Next, a photocurable acrylic resin material was formed on the first inorganic film 40, and then the acrylic resin material was irradiated with light to form a hydrophobic organic film 41 with a thickness of 0.3 μm. Next, a moisture-absorbing film 42 containing the same material as in Example 1 and having a thickness of 0.6 μm was formed by the same method as described in Example 1. Furthermore, a SiN film was formed on the substrate 2 by sputtering to a thickness of 0.1 μm, thereby forming a second inorganic film 43 and a sealing layer 4. In this way, the light-emitting device according to Example 3 was completed. In the light-emitting device according to Example 3, the moisture permeability of the hydrophobic organic film 41 was 60 g / (m2 ·24h), and the moisture permeability of the moisture-absorbing film 42 is 25 g / (m 2 24h).

[0089] <Evaluation of Light-Emitting Device Characteristics: Comparative Examples 8 to 11> In order to evaluate the characteristics of the light-emitting device according to Example 3, light-emitting devices according to Comparative Examples 8 to 11 were also manufactured. The light-emitting devices according to Comparative Examples 8 to 11 were manufactured by changing the configuration of the sealing layer 4 of the light-emitting device according to Example 3 described above to the configuration of the sealing layer according to Comparative Examples 1 to 4, respectively.

[0090] <Evaluation of light-emitting device characteristics: Evaluation results> The characteristics of the light emitting devices according to Example 3 and each of the comparative examples were measured and are summarized in Table 3 below.

[0091] [Table 3] As is clear from Table 3, there was almost no difference between Example 3 and each of the comparative examples in the external quantum efficiency of the tandem light-emitting device 6 and the chromaticity of the light from the tandem light-emitting device 6. In other words, the above indicates that the sealing layer 4 in Example 3 has only a slight effect on the luminous efficiency and luminous color of the tandem light-emitting device.

[0092] Furthermore, as is clear from Table 3, the lifetime of the light-emitting device according to Example 3 is longer than that of the light-emitting devices according to each of the comparative examples. This is thought to be because, in the light-emitting device according to Example 3, the sealing layer 4 more effectively reduces the penetration of foreign matter such as moisture from the outside of the light-emitting device into the tandem light-emitting element 6 than in the light-emitting devices according to each of the comparative examples.

[0093] [Embodiment 3] <Buffer layer> 4 is a schematic cross-sectional view of the light-emitting device 1 according to this embodiment. The light-emitting device 1 according to this embodiment differs from the light-emitting device 1 according to embodiment 1 only in that the sealing layer 4 has a buffer layer 45 between the hydrophobic organic film 41 and the moisture-absorbing film 42.

[0094] The buffer layer 45 is, for example, an organic sealing film having hygroscopic properties, similar to the hygroscopic film 42, and in particular has the function of absorbing foreign matter such as moisture from the outside of the sealing layer 4 side of the light-emitting device 1 to the light-emitting element 3, and delaying the penetration of the foreign matter into the light-emitting element 3. In particular, the buffer layer 45 may be formed in a position covering the hydrophobic organic film 41, and the hygroscopic film 42 may be formed in a position covering the buffer layer 45.

[0095] In this embodiment, the buffer layer 45 may have a hydrophobicity higher than that of the hygroscopic film 42 and lower than that of the hydrophobic organic film 41. The buffer layer 45 may include, for example, an organic polymer that is more hydrophobic than the hygroscopic film 42.

[0096] The buffer layer 45 may have at least one of a first organic polymer and a second organic polymer, for example, similar to the moisture-absorbing film 42. In this case, the buffer layer 45 may have, for example, a first organic polymer having a lower concentration of hydrophilic functional groups relative to a hydrophobic molecular skeleton than the first organic polymer in the moisture-absorbing film 42. Alternatively, the buffer layer 45 may have, for example, a second organic polymer having a lower ratio of hydrophilic functional groups relative to hydrophobic functional groups than the second organic polymer in the moisture-absorbing film 42.

[0097] The buffer layer 45 may be formed by coating a material containing an organic polymer, for example, in the same manner as the moisture absorbing film 42. In particular, the buffer layer 45 and the moisture absorbing film 42 may be formed by separate coating processes, or may be formed in the same coating process.

[0098] For example, in the process of forming the buffer layer 45 and the hygroscopic film 42, a coating material containing organic polymers with different hydrophobicities may be applied onto the hydrophobic organic film 41. In this case, the more hydrophobic organic polymer in the coating material may move toward the hydrophobic organic film 41 due to its own weight or attraction by the hydrophobic organic film 41. In this state, the coating material may be cured to simultaneously form the buffer layer 45 and the hygroscopic film 42.

[0099] In this embodiment, as described above, the buffer layer 45 has higher hydrophobicity than the hygroscopic film 42. Therefore, as described above, moisture absorbed into the hygroscopic film 42 through the pinholes H in the second inorganic film 43 is preferentially released into the pinholes H in the second inorganic film 43 rather than penetrating into the buffer layer 45, which is hydrophobic and solid.

[0100] Furthermore, in this embodiment, as described above, the buffer layer 45 has lower hydrophobicity than the hydrophobic organic film 41. Therefore, even if moisture permeates into the buffer layer 45 through the hygroscopic film 42, the moisture will preferentially permeate into the hygroscopic film 42, which has high hydrophilicity, rather than into the hydrophobic organic film 41, which has high hydrophobicity.

[0101] Therefore, the proportion of moisture absorbed by the moisture absorbing film 42 or the buffer layer 45 that is released toward the outside of the light emitting device 1 is greater than the proportion that penetrates toward the light emitting element 3. As a result, the sealing layer 4 efficiently releases the moisture absorbed by the moisture absorbing film 42 or the buffer layer 45 toward the outside of the light emitting device 1, thereby reducing the penetration of moisture into the light emitting element 3.

[0102] Furthermore, the buffer layer 45 has a hydrophobicity higher than that of the hygroscopic film 42 and lower than that of the hydrophobic organic film 41. Therefore, the adhesion between the hydrophobic organic film 41 and the buffer layer 45 and the adhesion between the buffer layer 45 and the hygroscopic film 42 are both higher than the adhesion between the hydrophobic organic film 41 and the hygroscopic film 42. Therefore, the light-emitting device 1 according to this embodiment can further reduce the penetration of foreign matter such as moisture between the sealing layer 4.

[0103] [Embodiment 4] <Inorganic interlayer film> 5 is a schematic cross-sectional view of the light-emitting device 1 according to this embodiment. The light-emitting device 1 according to this embodiment differs from the light-emitting device 1 according to embodiment 1 only in that the sealing layer 4 has an inorganic intermediate film 46 between the hydrophobic organic film 41 and the moisture-absorbing film 42.

[0104] Except for the formation position, the inorganic intermediate film 46 may have the same configuration as the first inorganic film 40 or the second inorganic film 43. In particular, the inorganic intermediate film 46 may be formed in a position covering the hydrophobic organic film 41, and the moisture-absorbing film 42 may be formed in a position covering the inorganic intermediate film 46.

[0105] The inorganic intermediate film 46 reduces the penetration of moisture from the hygroscopic film 42 into the hydrophobic organic film 41. Therefore, the sealing layer 4 more efficiently releases the moisture absorbed by the hygroscopic film 42 to the outside of the light-emitting device 1, thereby reducing the penetration of moisture into the light-emitting element 3.

[0106] Furthermore, even when the pinhole H described above is formed in the inorganic interlayer 46, the hygroscopic film 42, which is formed after the formation of the inorganic interlayer 46, is formed in the pinhole H. Therefore, the hygroscopic film 42 contacts the hydrophobic organic film 41 at the pinhole H in the inorganic interlayer 46. Therefore, moisture from the hygroscopic film 42 is preferentially released to the outside of the light-emitting device 1 through the pinhole H in the second inorganic film 43, rather than penetrating into the hydrophobic organic film 41 through the pinhole H in the inorganic interlayer 46. Therefore, the sealing layer 4 more efficiently releases moisture absorbed by the hygroscopic film 42 to the outside of the light-emitting device 1, thereby reducing the penetration of moisture into the light-emitting element 3.

[0107] [Embodiment 5] <Color light-emitting device> 6 is a schematic cross-sectional view of the light-emitting device 1 according to this embodiment. The light-emitting device 1 according to this embodiment differs from the light-emitting device 1 according to embodiment 1 only in that, instead of the light-emitting element 3, the light-emitting device 1 includes a plurality of light-emitting elements, including a red light-emitting element 7R, a green light-emitting element 7G, and a blue light-emitting element 7B.

[0108] The red light emitting element 7R, the green light emitting element 7G, and the blue light emitting element 7B have light emitting layers that emit red, green, and blue light, respectively. Except for the colors of light emitted by the light emitting layers, the red light emitting element 7R, the green light emitting element 7G, and the blue light emitting element 7B have the same configuration as the light emitting element 3 described above.

[0109] The anodes of the red light-emitting element 7R, the green light-emitting element 7G, and the blue light-emitting element 7B may all be electrically connected to a circuit board formed on the substrate 2 and may be driven individually. Therefore, the light-emitting device 1 according to this embodiment may individually emit at least one of red light, green light, and blue light. Therefore, the light-emitting device 1 according to this embodiment may be a color light-emitting device.

[0110] The light-emitting device 1 may include a plurality of sets of light-emitting elements, each of which includes a red light-emitting element 7R, a green light-emitting element 7G, and a blue light-emitting element 7B, arranged two-dimensionally on the substrate 2. In this case, the light-emitting device 1 may function as a color display device by individually driving each of the sets of light-emitting elements, each of which includes the red light-emitting element 7R, the green light-emitting element 7G, and the blue light-emitting element 7B.

[0111] In this embodiment, the first inorganic film 40 is formed in a position that covers the red light-emitting element 7R, the green light-emitting element 7G, and the blue light-emitting element 7B. Therefore, the sealing layer 4 seals the red light-emitting element 7R, the green light-emitting element 7G, and the blue light-emitting element 7B. Therefore, the sealing layer 4 according to this embodiment can more effectively reduce the penetration of moisture from the outside of the light-emitting device 1 into the red light-emitting element 7R, the green light-emitting element 7G, and the blue light-emitting element 7B.

[0112] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment. [Explanation of symbols]

[0113] 1 Light-emitting devices 3 Light-emitting element 4. Sealing layer 6 Tandem light-emitting element 7B Blue light-emitting element 7G Green light emitting element 7R Red light emitting element 40 1st inorganic membrane 41 Hydrophobic organic membranes 42 Moisture absorption membrane 43 Second inorganic membrane 44 Periphery 46 Inorganic interlayer

Claims

1. A light-emitting element; a first inorganic film covering the light-emitting element; a hydrophobic organic film located outside the first inorganic film; a moisture-absorbing film located outside the hydrophobic organic film, the moisture-absorbing film covers the top and side surfaces of the hydrophobic organic film; The moisture-absorbing film is a first organic polymer having a hydrophilic functional group and at least a part of the molecular skeleton of which is hydrophobic; a second organic polymer having a hydrophilic functional group and a hydrophobic functional group; 1. A light emitting device comprising:

2. The light-emitting device of claim 1 , further comprising a second inorganic film covering the moisture-absorbing film.

3. The light-emitting device according to claim 2 , wherein the second inorganic film is in direct contact with a peripheral edge of the first inorganic film.

4. The light-emitting device of claim 1 , wherein the hydrophobic organic film and the hygroscopic film are adjacent to each other.

5. The light-emitting device of claim 1 , further comprising an inorganic intermediate film located between the hydrophobic organic film and the moisture-absorbing film.

6. The light emitting elements include a red light emitting element that emits red light and a green light emitting element that emits green light. The light-emitting device according to claim 1 , further comprising: a blue light-emitting element that emits blue light.

7. 10. The light emitting device of claim 1, wherein the light emitting element comprises a tandem light emitting element having multiple light emitting layers.

8. The light emitting device of claim 1 , wherein the light emitting element comprises a quantum dot light emitting element comprising quantum dots as a light emitting material.

9. The light-emitting device of claim 1 , wherein the molecular skeleton of the first organic polymer is the same as the molecular skeleton of the second organic polymer.

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