Patent Publication Number: US-2023157168-A1

Title: Plurality of host materials, organic electroluminescent compound, and organic electroluminescent device comprising the same

Description:
TECHNICAL FIELD 
     The present disclosure relates to a plurality of host materials, an organic electroluminescent compound, and an organic electroluminescent device comprising the same. 
     BACKGROUND ART 
     A small molecular green organic electroluminescent device (OLED) was first developed by Tang, et al., of Eastman Kodak in 1987 by using TPD/ALq3 bi-layer consisting of a light-emitting layer and a charge transport layer. Thereafter, the development of OLEDs was rapidly effected and OLEDs have been commercialized. At present, OLEDs primarily use phosphorescent materials having excellent luminous efficiency in panel implementation. In many applications such as TVs and lightings, the lifetime of OLEDs is insufficient and higher efficiency of OLEDs is still required. Typically, the higher the luminance of an OLED, the shorter the lifetime that the OLED has. Thus, an OLED which has high luminous efficiency and/or long lifetime is required for long time uses and high resolution of displays. 
     In order to enhance luminous efficiency, driving voltage and/or lifetime, various materials or concepts for an organic layer of an OLED have been proposed. However, they were not satisfactory in practical use. In addition, there has been a need to develop a light-emitting material having more improved performances, for example, improved driving voltage, luminous efficiency, power efficiency, and/or lifetime properties compared to a combination of specific compounds previously disclosed. 
     Meanwhile, Korean Patent Application Laying-Open No. 2018-0022574 discloses a compound having a nitrogen-containing hetero ring bonded to a condensed dibenzo moiety, and Korean Patent Application Laying-Open No. 2017-0022865 discloses a compound having a 5-membered heteroaryl condensed with a phenanthrene. However, the aforementioned references do not specifically disclose a specific compound or a specific combination of host materials claimed in the present disclosure. 
     DISCLOSURE OF INVENTION 
     Technical Problem 
     The objective of the present disclosure is to provide a plurality of host materials capable of providing an organic electroluminescent device having improved driving voltage, luminous efficiency and/or lifetime properties. Another objective of the present disclosure is to provide an organic electroluminescent compound having a new structure suitable for applying to an organic electroluminescent device. Still another objective of the present disclosure is to provide an organic electroluminescent device having improved driving voltage, luminous efficiency and/or lifetime properties by comprising a specific combination of compounds according to the present disclosure. 
     Solution to Problem 
     As a result of intensive studies to solve the technical problems, the present inventors found that the above objective can be achieved by a plurality of host materials comprising a first host material comprising a compound represented by the following formula 1 and a second host material comprising a compound represented by the following formula 2, or by a compound represented by the following formula 3. 
     
       
         
         
             
             
         
       
     
     In formula 1, 
     Y represents O or S; 
     R 1  to R 3 , each independently, represent hydrogen, deuterium, a halogen, a cyano, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, a substituted or unsubstituted (3- to 30-membered)heteroaryl, a substituted or unsubstituted tri(C1-C30)alkylsilyl, a substituted or unsubstituted di(C1-C30)alkyl(C6-C30)arylsilyl, a substituted or unsubstituted (C1-C30)alkyldi(C6-C30)arylsilyl, a substituted or unsubstituted tri(C6-C30)arylsilyl, a substituted or unsubstituted mono- or di-(C1-C30)alkylamino, a substituted or unsubstituted (C1-C30)alkyl(C6-C30)arylamino, a substituted or unsubstituted mono- or di-(C6-C30)arylamino, a substituted or unsubstituted mono- or di-(3- to 30-membered)heteroarylamino, or a substituted or unsubstituted (C6-C30)aryl(3- to 30-membered)heteroarylamino; or may be linked to an adjacent substituent(s) to form a ring(s); 
     with the proviso that at least one of R 1  represents -(L 1 ) d -Ar 1 ; 
     L 1 , each independently, represents a single bond, a substituted or unsubstituted (C6-C30)arylene, or a substituted or unsubstituted (3- to 30-membered)heteroarylene; 
     Ar 1 , each independently, represents a substituted or unsubstituted (3- to 30-membered)heteroaryl containing at least one nitrogen; and 
     a and c, each independently, represent an integer of 1 to 4, and b and d, each independently, represent an integer of 1 or 2, where if a to d are each an integer of 2 or more, each of R 1 , each of R 2 , each of R 3 , and each of L 1  may be the same or different; 
     
       
         
         
             
             
         
       
     
     in formula 2, 
     X 1  and Y 1 , each independently, represent —N═, —NR 67 —, —O— or —S—, with the proviso that any one of X 1  and Y 1  represents —N═, and the other of X 1  and Y 1  represents —NR 67 —, —O— or —S—; 
     R 61  represents a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (3- to 30-membered)heteroaryl; 
     R 62  to R 64  and R 67 , each independently, represent hydrogen, deuterium, a halogen, a cyano, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, a substituted or unsubstituted (3- to 30-membered)heteroaryl, a substituted or unsubstituted (C3-C30)cycloalkyl, a substituted or unsubstituted (C1-C30)alkoxy, a substituted or unsubstituted tri(C1-C30)alkylsilyl, a substituted or unsubstituted di(C1-C30)alkyl(C6-C30)arylsilyl, a substituted or unsubstituted (C1-C30)alkyldi(C6-C30)arylsilyl, a substituted or unsubstituted tri(C6-C30)arylsilyl, a substituted or unsubstituted fused ring group of a (C3-C30) aliphatic ring(s) and a (C6-C30) aromatic ring(s), or -L 3 ″-N(Ar 3 ″)(Ar 4 ″); or may be linked to an adjacent substituent(s) to form a ring(s); 
     L 3 ″, each independently, represents a single bond, a substituted or unsubstituted (C6-C30)arylene, or a substituted or unsubstituted (3- to 30-membered)heteroarylene; 
     Ar 3 ″ and Ar 4 ″, each independently, represent hydrogen, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C2-C30)alkenyl, a substituted or unsubstituted fused ring group of a (C3-C30) aliphatic ring(s) and a (C6-C30) aromatic ring(s), a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (3- to 30-membered)heteroaryl; 
     L 4  represents a single bond, a substituted or unsubstituted (C6-C30)arylene, or a substituted or unsubstituted (3- to 30-membered)heteroarylene; 
     R 65  and R 66 , each independently, represent a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (3- to 30-membered)heteroaryl; and 
     a′ represents 1, b′ and c′, each independently, represent 1 or 2, and d′ represents an integer of 1 to 4, where if b′ to d′ are each an integer of 2 or more, each of R 62  to each of R 64  may be the same or different. 
     
       
         
         
             
             
         
       
     
     In formula 3, 
     X 1  and Y 1 , each independently, represent —N═, —NR 67 —, —O— or —S—, with the proviso that any one of X 1  and Y 1  represents —N═, and the other of X 1  and Y 1  represents —NR 67 —, —O— or —S—; 
     R 61  represents a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (3- to 30-membered)heteroaryl; 
     R 62  to R 64  and R 67 , each independently, represent hydrogen, deuterium, a halogen, a cyano, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, a substituted or unsubstituted (3- to 30-membered)heteroaryl, a substituted or unsubstituted (C3-C30)cycloalkyl, a substituted or unsubstituted (C1-C30)alkoxy, a substituted or unsubstituted tri(C1-C30)alkylsilyl, a substituted or unsubstituted di(C1-C30)alkyl(C6-C30)arylsilyl, a substituted or unsubstituted (C1-C30)alkyldi(C6-C30)arylsiyl, a substituted or unsubstituted tri(C6-C30)arylsilyl, a substituted or unsubstituted fused ring group of a (C3-C30) aliphatic ring(s) and a (C6-C30) aromatic ring(s), or -L 3 ″-N(Ar 3 ″)(Ar 4 ″); or may be linked to an adjacent substituent(s) to form a ring(s); 
     L 3 ″, each independently, represents a single bond, a substituted or unsubstituted (C6-C30)arylene, or a substituted or unsubstituted (3- to 30-membered)heteroarylene; 
     Ar 3 ″ and Ar 4 ″, each independently, represent hydrogen, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C2-C30)alkenyl, a substituted or unsubstituted fused ring group of a (C3-C30) aliphatic ring(s) and a (C6-C30) aromatic ring(s), a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (3- to 30-membered)heteroaryl; 
     L 4  represents a single bond, a substituted or unsubstituted (C6-C30)arylene, or a substituted or unsubstituted (3- to 30-membered)heteroarylene; 
     R 65  and R 66 , each independently, represent a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (3- to 30-membered)heteroaryl; and 
     a′ represents 1, b′ and c′, each independently, represent 1 or 2, and d′ represents an integer of 1 to 4, where if b′ to d′ are each an integer of 2 or more, each of R 62  to each of R 64  may be the same or different; 
     with the proviso that at least one of R 61  to R 67 , Ar 3 ″ and Ar 4 ″ comprises the following formula 3-1: 
     
       
         
         
             
             
         
       
     
     in formula 3-1, 
     A represents Si or C; 
     L 3  represents a substituted or unsubstituted (C6-C30)arylene, or a substituted or unsubstituted (3- to 30-membered)heteroarylene; and 
     R′, R″, and R′″, each independently, represent a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (3- to 30-membered)heteroaryl. 
     Advantageous Effects of Invention 
     An organic electroluminescent device having lower driving voltage, higher luminous efficiency, and/or improved lifespan properties compared to the conventional organic electroluminescent device is provided by comprising a specific combination of compounds according to the present disclosure as a plurality of host materials, or by comprising the compound according to the present disclosure, and it is possible to produce a display system or lighting system using the same. 
    
    
     MODE FOR THE INVENTION 
     Hereinafter, the present disclosure will be described in detail. However, the following description is intended to explain the present disclosure and is not meant in any way to restrict the scope of the present disclosure. 
     The term “organic electroluminescent compound” in the present disclosure means a compound that may be used in an organic electroluminescent device, and may be comprised in any material layer constituting an organic electroluminescent device, as necessary. 
     The term “an organic electroluminescent material” in the present disclosure means a material that may be used in an organic electroluminescent device, and may comprise at least one compound. The organic electroluminescent material may be comprised in any layer constituting an organic electroluminescent device, as necessary. For example, the organic electroluminescent material may be a hole injection material, a hole transport material, a hole auxiliary material, a light-emitting auxiliary material, an electron blocking material, a light-emitting material (including a host material and a dopant material), an electron buffer material, a hole blocking material, an electron transport material, an electron injection material, etc. 
     The term “a plurality of host materials” in the present disclosure means a host material comprising a combination of at least two compounds, which may be comprised in any light-emitting layer constituting an organic electroluminescent device. It may mean both a material before being comprised in an organic electroluminescent device (for example, before vapor deposition) and a material after being comprised in an organic electroluminescent device (for example, after vapor deposition). For example, the plurality of host materials of the present disclosure may be a combination of at least two compounds, which, optionally, may further comprise conventional materials included in the organic electroluminescent material. At least two compounds comprised in the plurality of host materials may be comprised together in one light-emitting layer, or each may be comprised in different light-emitting layers. For example, the at least two host materials may be mixture-evaporated or co-evaporated, or may be separately evaporated. 
     Herein, the term “(C1-C30)alkyl” is meant to be a linear or branched alkyl having 1 to 30 carbon atoms constituting the chain, in which the number of carbon atoms is preferably 1 to 10, and more preferably 1 to 6. The above alkyl may include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, etc. The term “(C3-C30)cycloalkyl” is meant to be a mono- or polycyclic hydrocarbon having 3 to 30 ring backbone carbon atoms, in which the number of carbon atoms is preferably 3 to 20, and more preferably 3 to 7. The above cycloalkyl may include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclohexylmethyl, etc. The term “(3- to 7-membered)heterocycloalkyl” is meant to be a cycloalkyl having 3 to 7 ring backbone atoms and including at least one heteroatom selected from the group consisting of B, N, O, S, Si, and P, and preferably the group consisting of O, S, and N. The above heterocycloalkyl may include tetrahydrofuran, pyrrolidine, thiolan, tetrahydropyran, etc. The term “(C6-C30)aryl” or “(C6-C30)arylene” is meant to be a monocyclic or fused ring radical derived from an aromatic hydrocarbon having 6 to 30 ring backbone carbon atoms, and may be partially saturated. The above aryl may comprise a spiro structure. The above aryl may include phenyl, biphenyl, terphenyl, naphthyl, binaphthyl, phenylnaphthyl, naphthylphenyl, fluorenyl, phenylfluorenyl, diphenylfluorenyl, benzofluorenyl, dibenzofluorenyl, phenanthrenyl, phenylphenanthrenyl, benzophenanthrenyl, anthracenyl, indenyl, triphenylenyl, pyrenyl, tetracenyl, perylenyl, chrysenyl, naphthacenyl, fluoranthenyl, spirobifluorenyl, spiro[fluorene-benzofluorene]yl, spiro[cyclopentane-fluorene]yl, spiro[dihydroindene-fluorene]yl, azulenyl, tetramethyl-dihydrophenanthrenyl, etc. Specifically, the above aryl may include phenyl, 1-naphthyl, 2-naphthyl, 1-anthryl, 2-anthryl, 9-anthryl, benzanthryl, 1-phenanthryl, 2-phenanthryl, 3-phenanthryl, 4-phenanthryl, 9-phenanthryl, naphthacenyl, pyrenyl, 1-chrysenyl, 2-chrysenyl, 3-chrysenyl, 4-chrysenyl, 5-chrysenyl, 6-chrysenyl, benzo[c]phenanthryl, benzo[g]chrysenyl, 1-triphenylenyl, 2-triphenylenyl, 3-triphenylenyl, 4-triphenylenyl, 1-fluorenyl, 2-fluorenyl, 3-fluorenyl, 4-fluorenyl, 9-fluorenyl, benzo[a]fluorenyl, benzo[b]fluorenyl, benzo[c]fluorenyl, dibenzofluorenyl, 2-biphenylyl, 3-biphenylyl, 4-biphenylyl, o-terphenyl, m-terphenyl-4-yl, m-terphenyl-3-yl, m-terphenyl-2-yl, p-terphenyl-4-yl, p-terphenyl-3-yl, p-terphenyl-2-yl, m-quaterphenyl, 3-fluoranthenyl, 4-fluoranthenyl, 8-fluoranthenyl, 9-fluoranthenyl, benzofluoranthenyl, o-tolyl, m-tolyl, p-tolyl, 2,3-xylyl, 3,4-xylyl, 2,5-xylyl, mesityl, o-cumenyl, m-cumenyl, p-cumenyl, p-tert-butylphenyl, p-(2-phenylpropyl)phenyl, 4′-methylbiphenyl, 4″-tert-butyl-p-terphenyl-4-yl, 9,9-dimethyl-1-fluorenyl, 9,9-dimethyl-2-fluorenyl, 9,9-dimethyl-3-fluorenyl, 9,9-dimethyl-4-fluorenyl, 9,9-diphenyl-1-fluorenyl, 9,9-diphenyl-2-fluorenyl, 9,9-diphenyl-3-fluorenyl, 9,9-diphenyl-4-fluorenyl, 11,11-dimethyl-1-benzo[a]fluorenyl, 11,11-dimethyl-2-benzo[a]fluorenyl, 11,11-dimethyl-3-benzo[a]fluorenyl, 11,11-dimethyl-4-benzo[a]fluorenyl, 11,11-dimethyl-5-benzo[a]fluorenyl, 11,11-dimethyl-6-benzo[a]fluorenyl, 11,11-dimethyl-7-benzo[a]fluorenyl, 11,11-dimethyl-8-benzo[a]fluorenyl, 11,11-dimethyl-9-benzo[a]fluorenyl, 11,11-dimethyl-10-benzo[a]fluorenyl, 11,11-dimethyl-1-benzo[b]fluorenyl, 11,11-dimethyl-2-benzo[b]fluorenyl, 11,11-dimethyl-3-benzo[b]fluorenyl, 11,11-dimethyl-4-benzo[b]fluorenyl, 11,11-dimethyl-5-benzo[b]fluorenyl, 11,11-dimethyl-6-benzo[b]fluorenyl, 11,11-dimethyl-7-benzo[b]fluorenyl, 11,11-dimethyl-8-benzo[b]fluorenyl, 11,11-dimethyl-9-benzo[b]fluorenyl, 11,11-dimethyl-10-benzo[b]fluorenyl, 11,11-dimethyl-1-benzo[c]fluorenyl, 11,11-dimethyl-2-benzo[c]fluorenyl, 11,11-dimethyl-3-benzo[c]fluorenyl, 11,11-dimethyl-4-benzo[c]fluorenyl, 11,11-dimethyl-5-benzo[c]fluorenyl, 11,11-dimethyl-6-benzo[c]fluorenyl, 11,11-dimethyl-7-benzo[c]fluorenyl, 11,11-dimethyl-8-benzo[c]fluorenyl, 11,11-dimethyl-9-benzo[c]fluorenyl, 11,11-dimethyl-10-benzo[c]fluorenyl, 11,11-diphenyl-1-benzo[a]fluorenyl, 11,11-diphenyl-2-benzo[a]fluorenyl, 11,11-diphenyl-3-benzo[a]fluorenyl, 11,11-diphenyl-4-benzo[a]fluorenyl, 11,11-diphenyl-5-benzo[a]fluorenyl, 11,11-diphenyl-6-benzo[a]fluorenyl, 11,11-diphenyl-7-benzo[a]fluorenyl, 11,11-diphenyl-8-benzo[a]fluorenyl, 11,11-diphenyl-9-benzo[a]fluorenyl, 11,11-diphenyl-10-benzo[a]fluorenyl, 11,11-diphenyl-1-benzo[b]fluorenyl, 11,11-diphenyl-2-benzo[b]fluorenyl, 11,11-diphenyl-3-benzo[b]fluorenyl, 11,11-diphenyl-4-benzo[b]fluorenyl, 11,11-diphenyl-5-benzo[b]fluorenyl, 11,11-diphenyl-6-benzo[b]fluorenyl, 11,11-diphenyl-7-benzo[b]fluorenyl, 11,11-diphenyl-8-benzo[b]fluorenyl, 11,11-diphenyl-9-benzo[b]fluorenyl, 11,11-diphenyl-10-benzo[b]fluorenyl, 11,11-diphenyl-1-benzo[c]fluorenyl, 11,11-diphenyl-2-benzo[c]fluorenyl, 11,11-diphenyl-3-benzo[c]fluorenyl, 11,11-diphenyl-4-benzo[c]fluorenyl, 11,11-diphenyl-5-benzo[c]fluorenyl, 11,11-diphenyl-6-benzo[c]fluorenyl, 11,11-diphenyl-7-benzo[c]fluorenyl, 11,11-diphenyl-8-benzo[c]fluorenyl, 11,11-diphenyl-9-benzo[c]fluorenyl, 11,11-diphenyl-10-benzo[c]fluorenyl, 9,9,10,10-tetramethyl-9,10-dihydro-1-phenanthrenyl, 9,9,10,10-tetramethyl-9,10-dihydro-2-phenanthrenyl, 9,9,10,10-tetramethyl-9,10-dihydro-3-phenanthrenyl, 9,9,10,10-tetramethyl-9,10-dihydro-4-phenanthrenyl, etc. 
     The term “(3- to 30-membered)heteroaryl” or “(3- to 30-membered)heteroarylene” is meant to be an aryl or arylene having 3 to 30 ring backbone atoms, and including at least one heteroatom selected from the group consisting of B, N, O, S, Si, and P. The number of heteroatoms is preferably 1 to 4. The above heteroaryl or heteroarylene may be a monocyclic ring, or a fused ring condensed with at least one benzene ring; and may be partially saturated. In addition, the above heteroaryl or heteroarylene may be one formed by linking at least one heteroaryl or aryl group to a heteroaryl group via a single bond(s); and may comprise a spiro structure. The above heteroaryl may include a monocyclic ring-type heteroaryl such as furyl, thiophenyl, pyrrolyl, imidazolyl, pyrazolyl, thiazolyl, thiadiazolyl, isothiazolyl, isoxazolyl, oxazolyl, oxadiazolyl, triazinyl, tetrazinyl, triazolyl, tetrazolyl, furazanyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, etc., and a fused ring-type heteroaryl such as benzofuranyl, benzothiophenyl, isobenzofuranyl, dibenzofuranyl, dibenzothiophenyl, dibenzoselenophenyl, naphthobenzofuranyl, naphthobenzothiophenyl, benzofuroquinolyl, benzofuroquinazolinyl, benzofuronaphthyridinyl, benzofuropyrimidinyl, naphthofuropyrimidinyl, benzothienoquinolyl, benzothienoquinazolinyl, naphthyridinyl, benzothienonaphthyridinyl, benzothienopyrimidinyl, naphthothienopyrimidinyl, pyrimidoindolyl, benzopyrimidoindolyl, benzofuropyrazinyl, naphthofuropyrazinyl, benzothienopyrazinyl, naphthothienopyrazinyl, pyrazinoindolyl, benzopyrazinoindolyl, benzoimidazolyl, benzothiazolyl, benzoisothiazolyl, benzoisoxazolyl, benzoxazolyl, isoindolyl, indolyl, indazolyl, benzothiadiazolyl, quinolyl, isoquinolyl, cinnolinyl, quinazolinyl, benzoquinazolinyl, quinoxalinyl, benzoquinoxalinyl, carbazolyl, benzocarbazolyl, dibenzocarbazolyl, phenoxazinyl, phenanthridinyl, benzodioxolyl, dihydroacridinyl, benzotriazolyl, phenazinyl, imidazopyridyl, chromenoquinazolinyl, thiochromenoquinazolinyl, dimethylbenzopyrimidinyl, indolocarbazolyl, indenocarbazolyl, etc. More specifically, the above heteroaryl may include 1-pyrrolyl, 2-pyrrolyl, 3-pyrrolyl, pyrazinyl, 2-pyridinyl, 2-pyrimidinyl, 4-pyrimidinyl, 5-pyrimidinyl, 6-pyrimidinyl, 1,2,3-triazin-4-yl, 1,2,4-triazin-3-yi, 1,3,5-triazin-2-yl, 1-imidazolyl, 2-imidazolyl, 1-pyrazolyl, 1-indolidinyl, 2-indolidinyl, 3-indolidinyl, 5-indolidinyl, 6-indolidinyl, 7-indolidinyl, 8-indolidinyl, 2-imidazopyridinyl, 3-imidazopyridinyl, 5-imidazopyridinyl, 6-imidazopyridinyl, 7-imidazopyridinyl, 8-imidazopyridinyl, 3-pyridinyl, 4-pyridinyl, 1-indolyl, 2-indolyl, 3-indolyl, 4-indolyl, 5-indolyl, 6-indolyl, 7-indolyl, 1-isoindolyl, 2-isoindolyl, 3-isoindolyl, 4-isoindolyl, 5-isoindolyl, 6-isoindolyl, 7-isoindolyl, 2-furyl, 3-furyl, 2-benzofuranyl, 3-benzofuranyl, 4-benzofuranyl, 5-benzofuranyl, 6-benzofuranyl, 7-benzofuranyl, 1-isobenzofuranyl, 3-isobenzofuranyl, 4-isobenzofuranyl, 5-isobenzofuranyl, 6-isobenzofuranyl, 7-isobenzofuranyl, 2-quinolyl, 3-quinolyl, 4-quinolyl, 5-quinolyl, 6-quinolyl, 7-quinolyl, 8-quinolyl, 1-isoquinolyl, 3-isoquinolyl, 4-isoquinolyl, 5-isoquinolyl, 6-isoquinolyl, 7-isoquinolyl, 8-isoquinolyl, 2-quinoxalinyl, 5-quinoxalinyl, 6-quinoxalinyl, 1-carbazolyl, 2-carbazolyl, 3-carbazolyl, 4-carbazolyl, 9-carbazolyl, azacarbazol-1-yl, azacarbazol-2-yl, azacarbazol-3-yl, azacarbazol-4-yl, azacarbazol-5-yl, azacarbazol-6-yl, azacarbazol-7-yl, azacarbazol-8-yl, azacarbazol-9-yl, 1-phenanthridinyl, 2-phenanthridinyl, 3-phenanthridinyl, 4-phenanthridinyl, 6-phenanthridinyl, 7-phenanthridinyl, 8-phenanthridinyl, 9-phenanthridinyl, I-phenanthridinyl, 1-acridinyl, 2-acridinyl, 3-acridinyl, 4-acridinyl, 9-acridinyl, 2-oxazolyl, 4-oxazolyl, 5-oxazolyl, 2-oxadiazolyl, 5-oxadiazolyl, 3-furazanyl, 2-thienyl, 3-thienyl, 2-methylpyrrol-1-yl, 2-methylpyrrol-3-yl, 2-methylpyrrol-4-yl, 2-methylpyrrol-5-yl, 3-methylpyrrol-1-yl, 3-methylpyrrol-2-yl, 3-methylpyrrol-4-yl, 3-methylpyrrol-5-yl, 2-tert-butylpyrrol-4-yl, 3-(2-phenylpropyl)pyrrol-1-yl, 2-methyl-1-indolyl, 4-methyl-1-indolyl, 2-methyl-3-indolyl, 4-methyl-3-indolyl, 2-tert-butyl-1-indolyl, 4-tert-butyl-1-indolyl, 2-tert-butyl-3-indolyl, 4-tert-butyl-3-indolyl, 1-dibenzofuranyl, 2-dibenzofuranyl, 3-dibenzofuranyl, 4-dibenzofuranyl, 1-dibenzothiophenyl, 2-dibenzothiophenyl, 3-dibenzothiophenyl, 4-dibenzothiophenyl, 1-naphtho-[1,2-b]-benzofuranyl, 2-naphtho-[1,2-b]-benzofuranyl, 3-naphtho-[1,2-b]-benzofuranyl, 4-naphtho-[1,2-b]-benzofuranyl, 5-naphtho-[1,2-b]-benzofuranyl, 6-naphtho-[1,2-b]-benzofuranyl, 7-naphtho-[1,2-b]-benzofuranyl, 8-naphtho-[1,2-b]-benzofuranyl, 9-naphtho-[1,2-b]-benzofuranyl, 10-naphtho-[1,2-b]-benzofuranyl, 1-naphtho-[2,3-b]-benzofuranyl, 2-naphtho-[2,3-b]-benzofuranyl, 3-naphtho-[2,3-b]-benzofuranyl, 4-naphtho-[2,3-b]-benzofuranyl, 5-naphtho-[2,3-b]-benzofuranyl, 6-naphtho-[2,3-b]-benzofuranyl, 7-naphtho-[2,3-b]-benzofuranyl, 8-naphtho-[2,3-b]-benzofuranyl, 9-naphtho-[2,3-b]-benzofuranyl, 10-naphtho-[2,3-b]-benzofuranyl, 1-naphtho-[2,1-b]-benzofuranyl, 2-naphtho-[2,1-b]-benzofuranyl, 3-naphtho-[2,1-b]-benzofuranyl, 4-naphtho-[2,1-b]-benzofuranyl, 5-naphtho-[2,1-b]-benzofuranyl, 6-naphtho-[2,1-b]-benzofuranyl, 7-naphtho-[2,1-b]-benzofuranyl, 8-naphtho-[2,1-b]-benzofuranyl, 9-naphtho-[2,1-b]-benzofuranyl, 10-naphtho-[2,1-b]-benzofuranyl, 1-naphtho-[1,2-b]-benzothiophenyl, 2-naphtho-[1,2-b]-benzothiophenyl, 3-naphtho-[1,2-b]-benzothiophenyl, 4-naphtho-[1,2-b]-benzothiophenyl, 5-naphtho-[1,2-b]-benzothiophenyl, 6-naphtho-[1,2-b]-benzothiophenyl, 7-naphtho-[1,2-b]-benzothiophenyl, 8-naphtho-[1,2-b]-benzothiophenyl, 9-naphtho-[1,2-b]-benzothiophenyl, 10-naphtho-[1,2-b]-benzothiophenyl, 1-naphtho-[2,3-b]-benzothiophenyl, 2-naphtho-[2,3-b]-benzothiophenyl, 3-naphtho-[2,3-b]-benzothiophenyl, 4-naphtho-[2,3-b]-benzothiophenyl, 5-naphtho-[2,3-b]-benzothiophenyl, 1-naphtho-[2,1-b]-benzothiophenyl, 2-naphtho-[2,1-b]-benzothiophenyl, 3-naphtho-[2,1-b]-benzothiophenyl, 4-naphtho-[2,1-b]-benzothiophenyl, 5-naphtho-[2,1-b]-benzothiophenyl, 6-naphtho-[2,1-b]-benzothiophenyl, 7-naphtho-[2,1-b]-benzothiophenyl, 8-naphtho-[2,1-b]-benzothiophenyl, 9-naphtho-[2,1-b]-benzothiophenyl, 10-naphtho-[2,1-b]-benzothiophenyl, 2-benzofuro[3,2-d]pyrimidinyl, 6-benzofuro[3,2-d]pyrimidinyl, 7-benzofuro[3,2-d]pyrimidinyl, 8-benzofuro[3,2-d]pyrimidinyl, 9-benzofuro[3,2-d]pyrimidinyl, 2-benzothio[3,2-d]pyrimidinyl, 6-benzothio[3,2-d]pyrimidinyl, 7-benzothio[3,2-d]pyrimidinyl, 8-benzothio[3,2-d]pyrimidinyl, 9-benzothio[3,2-d]pyrimidinyl, 2-benzofuro[3,2-d]pyrazinyl, 6-benzofuro[3,2-d]pyrazinyl, 7-benzofuro[3,2-d]pyrazinyl, 8-benzofuro[3,2-d]pyrazinyl, 9-benzofuro[3,2-d]pyrazinyl, 2-benzothio[3,2-d]pyrazinyl, 6-benzothio[3,2-d]pyrazinyl, 7-benzothio[3,2-d]pyrazinyl, 8-benzothio[3,2-d]pyrazinyl, 9-benzothio[3,2-d]pyrazinyl, 1-silafluorenyl, 2-silafluorenyl, 3-silafluorenyl, 4-silafluorenyl, 1-germafluorenyl, 2-germafluorenyl, 3-germafluorenyl, 4-germafluorenyl, 1-dibenzoselenophenyl, 2-dibenzoselenophenyl, 3-dibenzoselenophenyl, 4-dibenzoselenophenyl, etc. Furthermore, “halogen” includes F, Cl, Br, and I. 
     In addition, “ortho (o-),” “meta (m-),” and “para (p-)” are prefixes, which represent the relative positions of substituents respectively. Ortho indicates that two substituents are adjacent to each other, and for example, when two substituents in a benzene derivative occupy positions 1 and 2, it is called an ortho position. Meta indicates that two substituents are at positions 1 and 3, and for example, when two substituents in a benzene derivative occupy positions 1 and 3, it is called a meta position. Para indicates that two substituents are at positions 1 and 4, and for example, when two substituents in a benzene derivative occupy positions 1 and 4, it is called a para position. 
     Herein, “substituted” in the expression “substituted or unsubstituted” means that a hydrogen atom in a certain functional group is replaced with another atom or another functional group, i.e., a substituent, and also includes that the hydrogen atom is replaced with a group formed by a linkage of two or more substituents of the above substituents. For example, the “group formed by a linkage of two or more substituents” may be pyridine-triazine. That is, pyridine-triazine may be interpreted as a heteroaryl substituent, or as substituents in which two heteroaryl substituents are linked. Herein, the substituent(s) of the substituted alkyl, the substituted alkenyl, the substituted aryl, the substituted arylene, the substituted heteroaryl, the substituted heteroarylene, the substituted cycloalkyl, the substituted alkoxy, the substituted trialkylsilyl, the substituted dialkylarylsilyl, the substituted alkyldiarylsilyl, the substituted triarylsilyl, the substituted mono- or di-alkylamino, the substituted alkylarylamino, the substituted mono- or di-arylamino, the substituted mono- or di-heteroarylamino, the substituted arylheteroarylamino, and the substituted fused ring group of an aliphatic ring(s) and an aromatic ring(s), each independently, are at least one selected from the group consisting of deuterium; a halogen; a cyano; a carboxyl; a nitro; a hydroxyl; a phosphine oxide; a (C1-C30)alkyl unsubstituted or substituted with a (C6-C30)aryl(s); a halo(C1-C30)alkyl; a (C2-C30)alkenyl; a (C2-C30)alkynyl; a (C1-C30)alkoxy; a (C1-C30)alkylthio; a (C3-C30)cycloalkyl; a (C3-C30)cycloalkenyl; a (3- to 7-membered)heterocycloalkyl; a (C6-C30)aryloxy; a (C6-C30)arylthio; a (3- to 30-membered)heteroaryl unsubstituted or substituted with a (C6-C30)aryl(s); a (C6-C30)aryl unsubstituted or substituted with at least one of deuterium, a halogen(s), a cyano(s), a (C1-C30)alkyl(s), a (C6-C30)aryl(s), a (3- to 30-membered)heteroaryl(s), and a tri(C6-C30)arylsilyl(s); a tri(C1-C30)alkylsilyl; a tri(C6-C30)arylsilyl; a di(C1-C30)alkyl(C6-C30)arylsilyl; a (C1-C30)alkyldi(C6-C30)arylsiyl; a (C6-C30)aryldi(3- to 30-membered)heteroarylsilyl; a di(C6-C30)aryl(3- to 30-membered)heteroarylsilyl; a tri(3- to 30-membered)heteroarylsilyl; an amino; a mono- or di-(C1-C30)alkylamino; a mono- or di-(C2-C30)alkenylamino; a mono- or di-(C6-C30)arylamino unsubstituted or substituted with a (C1-C30)alkyl(s); a mono- or di-(3- to 30-membered)heteroarylamino; a (C1-C30)alkyl(C2-C30)alkenylamino; a (C1-C30)alkyl(C6-C30)arylamino; a (C1-C30)alkyl(3- to 30-membered)heteroarylamino; a (C2-C30)alkenyl(C6-C30)arylamino; a (C2-C30)alkenyl(3- to 30-membered)heteroarylamino; a (C6-C30)aryl(3- to 30-membered)heteroarylamino; a (C1-C30)alkylcarbonyl; a (C1-C30)alkoxycarbonyl; a (C6-C30)arylcarbonyl; a di(C6-C30)arylboronyl; a (C6-C30)arylphosphine; a di(C1-C30)alkylboronyl; a (C1-C30)alkyl(C6-C30)arylboronyl; a (C6-C30)aryl(C1-C30)alkyl; and a (C1-C30)alkyl(C6-C30)aryl, or a combination thereof. According to one embodiment of the present disclosure, the substituent(s), each independently, are at least one selected from the group consisting of deuterium; a halogen; a cyano; a (C1-C20)alkyl unsubstituted or substituted with a (C6-C25)aryl(s); a (C6-C25)cycloalkyl; a (C6-C25)aryl unsubstituted or substituted with at least one of deuterium, a halogen(s), a cyano(s), a (C1-C20)alkyl(s), a (C6-C25)aryl(s), a (5- to 25-membered)heteroaryl(s), and a tri(C6-C25)arylsilyl(s); a (5- to 25-membered)heteroaryl unsubstituted or substituted with a (C6-C25)aryl(s); a mono- or di-(C6-C25)arylamino; a tri(C6-C25)arylsilyl; and a di(C6-C25)aryl(5- to 25-membered)heteroarylsilyl, or a combination thereof. According to another embodiment of the present disclosure, the substituent(s), each independently, are at least one selected from the group consisting of deuterium; a halogen; a cyano; a (C1-C10)alkyl unsubstituted or substituted with a (C6-C18)aryl(s); a (C6-C20)cycloalkyl; a (C6-C25)aryl unsubstituted or substituted with at least one of deuterium, a halogen(s), a cyano(s), a (C1-C10)alkyl(s), a (C6-C18)aryl(s), a (5- to 20-membered)heteroaryl(s), and a tri(C6-C18)arylsilyl(s); a (5- to 20-membered)heteroaryl unsubstituted or substituted with a (C6-C18)aryl(s); a di-(C6-C18)arylamino; a tri(C6-C18)arylsilyl; and a di(C6-C18)aryl(5- to 20-membered)heteroarylsilyl, or a combination thereof. For example, the substituent(s), each independently, may be at least one selected from the group consisting of deuterium; a fluoro; a cyano; a methyl unsubstituted or substituted with a phenyl(s); a tert-butyl; a cyclohexyl; a phenyl unsubstituted or substituted with at least one of deuterium, a fluoro(s), a cyano(s), a methyl(s), a tert-butyl(s), a naphthyl(s), a dimethylfluorenyl(s), a dibenzothiophenyl(s), a dibenzofuranyl(s), and a triphenylsilyl(s); a naphthyl unsubstituted or substituted with at least one of deuterium, a phenyl(s), a dibenzofuranyl(s), and a dibenzothiophenyl(s); a biphenyl unsubstituted or substituted with at least one of a naphthyl(s) and a dibenzofuranyl(s); a phenanthrenyl; a fluoranthenyl; a dimethylfluorenyl; a phenylfluorenyl; an anthracenyl; a terphenyl; a triphenylenyl; a triphenylbenzyl; a pyridyl substituted with a phenyl(s); a benzoimidazolyl substituted with a phenyl(s); a dibenzothiophenyl; a dibenzofuranyl unsubstituted or substituted with at least one of a phenyl(s), a naphthyl(s), and a phenanthrenyl(s); a carbazolyl substituted with a phenyl(s); a phenoxazinyl; a benzonaphthofuranyl; a benzonaphthothiophenyl; a diphenylamino; a triphenylsilyl; a diphenylbiphenylsilyl; a diphenylnaphthylsilyl; a diphenyldibenzofuranylsilyl; a diphenylpyridylsilyl; and a diphenylquinolylsilyl. 
     In the present disclosure, “a ring formed by a linkage of adjacent substituents” means that at least two adjacent substituents are linked or fused to each other to form a substituted or unsubstituted, mono- or polycyclic, (3- to 30-membered) alicyclic or aromatic ring, or the combination thereof. The ring may be preferably a substituted or unsubstituted, mono- or polycyclic, (3- to 26-membered) alicyclic or aromatic ring, or the combination thereof, and more preferably a mono- or polycyclic, (5- to 25-membered) aromatic ring unsubstituted or substituted with at least one of a (C1-C6)alkyl(s), a (C6-C18)aryl(s), and a (3- to 20-membered)heteroaryl(s). In addition, the formed ring may contain at least one heteroatom selected from B, N, O, S, Si, and P, preferably at least one heteroatom selected from N, O, and S. For example, the ring may be a benzene ring, a cyclopentane ring, an indene ring, an indane ring, a fluorene ring, a phenanthrene ring, an indole ring, a benzofuran ring, a xanthene ring, etc., in which these rings may be substituted with a methyl(s). 
     In the present disclosure, heteroaryl, heteroarylene, and heterocycloalkyl may, each independently, contain at least one heteroatom selected from the group consisting of B, N, O, S, Si, and P. In addition, the heteroatom may be bonded to at least one selected from the group consisting of hydrogen, deuterium, a halogen, a cyano, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, a substituted or unsubstituted (3 to 30-membered)heteroaryl, a substituted or unsubstituted (C3-C30)cycloalkyl, a substituted or unsubstituted (C1-C30)alkoxy, a substituted or unsubstituted tri(C1-C30)alkylsilyl, a substituted or unsubstituted di(C1-C30)alkyl(C6-C30)arylsilyl, a substituted or unsubstituted (C1-C30)alkyldi(C6-C30)arylsilyl, a substituted or unsubstituted tri(C6-C30)arylsilyl, a substituted or unsubstituted mono- or di-(C1-C30)alkylamino, a substituted or unsubstituted mono- or di-(C2-C30)alkenylamino, a substituted or unsubstituted mono- or di-(C6-C30)arylamino, a substituted or unsubstituted mono- or di-(3- to 30-membered)heteroarylamino, a substituted or unsubstituted (C1-C30)alkyl(C2-C30)alkenylamino, a substituted or unsubstituted (C1-C30)alkyl(C6-C30)arylamino, a substituted or unsubstituted (C1-C30)alkyl(3- to 30-membered)heteroarylamino, a substituted or unsubstituted (C2-C30)alkenyl(C6-C30)arylamino, a substituted or unsubstituted (C2-C30)alkenyl(3- to 30-membered)heteroarylamino, and a substituted or unsubstituted (C6-C30)aryl(3- to 30-membered)heteroarylamino. 
     A plurality of host materials of the present disclosure comprise a first host material and a second host material, wherein the first host material comprises at least one compound represented by formula 1 and the second host material comprises at least one compound represented by formula 2. According to one embodiment of the present disclosure, the compound represented by formula 1 and the compound represented by formula 2 are different from each other. 
     In formula 1, Y represents O or S. 
     In formula 1, R 1  to R 3 , each independently, represent hydrogen, deuterium, a halogen, a cyano, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, a substituted or unsubstituted (3- to 30-membered)heteroaryl, a substituted or unsubstituted tri(C1-C30)alkylsilyl, a substituted or unsubstituted di(C1-C30)alkyl(C6-C30)arylsilyl, a substituted or unsubstituted (C1-C30)alkyldi(C6-C30)arylsilyl, a substituted or unsubstituted tri(C6-C30)arylsilyl, a substituted or unsubstituted mono- or di-(C1-C30)alkylamino, a substituted or unsubstituted (C1-C30)alkyl(C6-C30)arylamino, a substituted or unsubstituted mono- or di-(C6-C30)arylamino, a substituted or unsubstituted mono- or di-(3- to 30-membered)heteroarylamino, a substituted or unsubstituted (C6-C30)aryl(3- to 30-membered)heteroarylamino, or -(L 1 ) d -Ar 1 ; or may be linked to an adjacent substituent(s) to form a ring(s). According to one embodiment of the present disclosure, R 1  to R 3 , each independently, represent hydrogen, deuterium, a substituted or unsubstituted (C6-C25)aryl, a substituted or unsubstituted (5- to 25-membered)heteroaryl, or -(L 1 ) d -Ar 1 . According to another embodiment of the present disclosure, R 1 , each independently, represents hydrogen; deuterium; a (C6-C18)aryl unsubstituted or substituted with deuterium; or -(L 1 ) d -Ar 1 , and R 2  and R 3 , each independently, represent hydrogen, deuterium, or an unsubstituted (5- to 25-membered)heteroaryl. At least one of R 1  represents -(L 1 ) d -Ar 1 , for example, any one or any two of R 1  represent -(L 1 ) d -Ar 1 . For example, R 1  to R 3 , each independently, may be hydrogen; deuterium; a phenyl unsubstituted or substituted with deuterium; a naphthyl; a biphenyl; a benzocarbazolyl; or -(L 1 ) d -Ar 1 . 
     L 1 , each independently, represents a single bond, a substituted or unsubstituted (C6-C30)arylene, or a substituted or unsubstituted (3- to 30-membered)heteroarylene. According to one embodiment of the present disclosure, L 1 , each independently, represents a single bond, a substituted or unsubstituted (C6-C25)arylene, or a substituted or unsubstituted (5- to 25-membered)heteroarylene. According to another embodiment of the present disclosure, L 1 , each independently, represents a single bond; a (C6-C18)arylene unsubstituted or substituted with deuterium or a (C6-C18)aryl(s); or an unsubstituted (5- to 20-membered)heteroarylene. For example, L 1 , each independently, may be a single bond; a phenylene unsubstituted or substituted with deuterium or a phenyl(s); a naphthylene; a biphenylene; a dibenzothiophenylene; a dibenzofuranylene; or a benzonaphthofuranylene. 
     Ar 1 , each independently, represents a substituted or unsubstituted (3- to 30-membered)heteroaryl containing at least one nitrogen. According to one embodiment of the present disclosure, Ar 1 , each independently, represents a substituted (5- to 25-membered)heteroaryl containing at least one nitrogen. According to another embodiment of the present disclosure, Ar 1 , each independently, represents a substituted (5- to 20-membered)heteroaryl containing one to three nitrogens. Specifically, Ar 1 , each independently, may be a substituted or unsubstituted pyridyl, a substituted or unsubstituted pyrimidinyl, a substituted or unsubstituted triazinyl, a substituted or unsubstituted pyrazinyl, a substituted or unsubstituted pyridazinyl, a substituted or unsubstituted quinazolinyl, a substituted or unsubstituted benzoquinazolinyl, a substituted or unsubstituted quinoxalinyl, a substituted or unsubstituted benzoquinoxalinyl, a substituted or unsubstituted quinolyl, a substituted or unsubstituted benzoquinolyl, a substituted or unsubstituted isoquinolyl, a substituted or unsubstituted benzoisoquinolyl, a substituted or unsubstituted triazolyl, a substituted or unsubstituted pyrazolyl, a substituted or unsubstituted naphthyridinyl, a substituted or unsubstituted benzofuropyrimidinyl, or a substituted or unsubstituted benzothienopyrimidinyl. For example, Ar 1 , each independently, may be a substituted triazinyl, a substituted pyrimidinyl, a substituted pyridyl, a substituted benzofuropyrimidinyl, a substituted quinoxalinyl, a substituted quinazolinyl, a substituted benzoquinoxalinyl, etc. The substituent(s) of the substituted heteroaryl in Ar 1 , may be at least one selected from the group consisting of deuterium, a halogen, a cyano, a (C1-C30)alkyl, a (C3-C30)cycloalkyl, a (C6-C30)aryl, a (3- to 30-membered)heteroaryl, and a tri(C6-C30)arylsilyl. For example, The substituent(s) of the substituted heteroaryl in Ar 1 , may be at least one selected from the group consisting of a cyclohexyl; a phenyl unsubstituted or substituted with at least one of deuterium, a fluoro(s), a cyano(s), a naphthyl(s), a dimethylfluorenyl(s), a dibenzofuranyl(s), a dibenzothiophenyl(s), and a triphenylsilyl(s); a naphthyl unsubstituted or substituted with at least one of deuterium, a phenyl(s), a dibenzofuranyl(s), and a dibenzothiophenyl(s); a biphenyl unsubstituted or substituted with a dibenzofuranyl(s) or a naphthyl(s); a phenanthrenyl; a dimethylfluorenyl; a terphenyl; a triphenylenyl; a triphenylbenzyl; a dibenzothiophenyl; a dibenzofuranyl unsubstituted or substituted with a phenyl(s), a naphthyl(s), or a phenanthrenyl(s); a carbazolyl substituted with a phenyl(s); a benzonaphthofuranyl; and a benzonaphthothiophenyl. 
     a and c, each independently, represent an integer of 1 to 4, and b and d, each independently, represent an integer of 1 or 2, where if a to d are each an integer of 2 or more, each of R 1 , each of R 2 , each of R 3 , and each of L 1  may be the same or different. 
     According to one embodiment of the present disclosure, formula 1 is represented by at least one of the following formulas 1-1 to 1-3. 
     
       
         
         
             
             
         
       
     
     In formulas 1-1 to 1-3, Y, L 1 , Ar 1 , R 1  to R 3 , and b to d are as defined in formula 1; and a represents an integer of 1 to 3. 
     In formula 2, X 1  and Y 1 , each independently, represent —N═, —NR 67 —, —O— or —S—, with the proviso that any one of X 1  and Y 1  represents —N═, and the other of X 1  and Y 1  represents —NR 67 —, —O— or —S—. According to one embodiment of the present disclosure, any one of X 1  and Y 1  represents —N═, and the other of X 1  and Y 1  represents —O— or —S—. 
     In formula 2, R 61  represents a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (3- to 30-membered)heteroaryl. According to one embodiment of the present disclosure, R 61  represents a substituted or unsubstituted (C6-C25)aryl, or a substituted or unsubstituted (5- to 25-membered)heteroaryl. According to another embodiment of the present disclosure, R 61  represents an unsubstituted (C6-C18)aryl, or an unsubstituted (5- to 20-membered)heteroaryl. For example, R 61  may be a phenyl, a naphthyl, a biphenyl, or a pyridyl. 
     In formula 2, R 62  to R 64  and R 67 , each independently, represent hydrogen, deuterium, a halogen, a cyano, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, a substituted or unsubstituted (3- to 30-membered)heteroaryl, a substituted or unsubstituted (C3-C30)cycloalkyl, a substituted or unsubstituted (C1-C30)alkoxy, a substituted or unsubstituted tri(C1-C30)alkylsilyl, a substituted or unsubstituted di(C1-C30)alkyl(C6-C30)arylsilyl, a substituted or unsubstituted (C1-C30)alkyldi(C6-C30)arylsilyl, a substituted or unsubstituted tri(C6-C30)arylsilyl, a substituted or unsubstituted fused ring group of a (C3-C30) aliphatic ring(s) and a (C6-C30) aromatic ring(s), or -L 3 ″-N(Ar 3 ″)(Ar 4 ″); or may be linked to an adjacent substituent(s) to form a ring(s). According to one embodiment of the present disclosure, R 62  to R 64  and R 67 , each independently, represent hydrogen, deuterium, or a substituted or unsubstituted (C6-C25)aryl. According to another embodiment of the present disclosure, R 62  to R 64 , each independently, represent hydrogen, deuterium, or an unsubstituted (C6-C18)aryl. For example, R 62  to R 64 , each independently, may be hydrogen, deuterium, or a phenyl. 
     L 3 ″, each independently, represents a single bond, a substituted or unsubstituted (C6-C30)arylene, or a substituted or unsubstituted (3- to 30-membered)heteroarylene. 
     Ar 3 ″ and Ar 4 ″, each independently, represent hydrogen, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C2-C30)alkenyl, a substituted or unsubstituted fused ring group of a (C3-C30) aliphatic ring(s) and a (C6-C30) aromatic ring(s), a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (3- to 30-membered)heteroaryl. 
     L 4  represents a single bond, a substituted or unsubstituted (C6-C30)arylene, or a substituted or unsubstituted (3- to 30-membered)heteroarylene. According to one embodiment of the present disclosure, L 4  represents a single bond, or a substituted or unsubstituted (C6-C25)arylene. According to another embodiment of the present disclosure, L 4  represents a single bond, or an unsubstituted (C6-C18)arylene. For example, L 4  may be a single bond, a phenylene, or a naphthylene, etc. 
     R 65  and R 66 , each independently, represent a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (3- to 30-membered)heteroaryl. According to one embodiment of the present disclosure, R 65  and R 66 , each independently, represent a substituted or unsubstituted (C6-C25)aryl, or a substituted or unsubstituted (5- to 25-membered)heteroaryl. Specifically, R 65  and R 66 , each independently, may be a substituted or unsubstituted phenyl, a substituted or unsubstituted naphthyl, a substituted or unsubstituted o-biphenyl, a substituted or unsubstituted m-biphenyl, a substituted or unsubstituted p-biphenyl, a substituted or unsubstituted o-terphenyl, a substituted or unsubstituted m-terphenyl, a substituted or unsubstituted p-terphenyl, a substituted or unsubstituted triphenylenyl, a substituted or unsubstituted phenanthrenyl, a substituted or unsubstituted chrysenyl, a substituted or unsubstituted fluoranthenyl, a substituted or unsubstituted fluorenyl, a substituted or unsubstituted benzofluorenyl, a substituted or unsubstituted spirobifluorenyl, a substituted or unsubstituted spiro[cyclopentane-fluorene]yl, a substituted or unsubstituted spiro[dihydroindene-fluorene]yl, a substituted or unsubstituted spiro[benzofluorene-fluorene]yl, a substituted or unsubstituted carbazolyl, a substituted or unsubstituted benzocarbazolyl, a substituted or unsubstituted dibenzocarbazolyl, a substituted or unsubstituted dibenzothiophenyl, a substituted or unsubstituted benzothiophenyl, a substituted or unsubstituted benzonaphthothiophenyl, a substituted or unsubstituted dibenzofuranyl, a substituted or unsubstituted benzofuranyl, a substituted or unsubstituted benzonaphthofuranyl, a substituted or unsubstituted benzofuropyridyl, or may be a combination of two or more selected from a phenyl, a naphthyl, a naphthylphenyl, a phenylnaphthyl, an o-biphenyl, an m-biphenyl, a p-biphenyl, an o-terphenyl, an m-terphenyl, a p-terphenyl, a fluorenyl, a benzofluorenyl, a phenanthrenyl, a benzonaphthofuranyl, a dibenzothiophenyl, and a dibenzofuranyl. In R 65  and R 66 , the substituent(s) of the substituted aryl and the substituted heteroaryl, each independently, may be at least one selected from the group consisting of deuterium, a (C1-C10)alkyl, a (5- to 25-membered)heteroaryl, a di(C6-C18)arylamino, a (C6-C18)aryl, and a tri(C6-C18)arylsilyl. For example, R 65  and R 66 , each independently, may be a substituted or unsubstituted phenyl, a substituted or unsubstituted naphthyl, a substituted or unsubstituted biphenyl, a phenanthrenyl, a terphenyl, a dimethylfluorenyl, a diphenylfluorenyl, a dimethylbenzofluorenyl, a spirobifluorenyl, a (C22)aryl, a benzothiophenyl, a substituted or unsubstituted dibenzofuranyl, a substituted or unsubstituted dibenzothiophenyl, a carbazolyl substituted with a phenyl(s), a benzofuropyridyl, a benzonaphthofuranyl, or a benzonaphthothiophenyl, etc., in which the substituent(s) of the substituted phenyl, the substituted naphthyl, the substituted biphenyl, the substituted dibenzofuranyl, and the substituted dibenzothiophenyl, each independently, may be at least one selected from the group consisting of a triphenylmethyl; a phenyl unsubstituted or substituted with at least one of deuterium, a methyl(s), and a tert-butyl(s); a naphthyl; an anthracenyl; a fluoranthenyl; a fluorenyl substituted with a phenyl(s); a pyridyl unsubstituted or substituted with a phenyl(s); a benzoimidazolyl substituted with a phenyl(s); a phenoxazinyl; a diphenylamino; a triphenylsilyl; a diphenylbiphenylsilyl; a diphenylnaphthylsilyl; a diphenyldibenzofuranylsilyl; a diphenylpyridylsilyl; and a diphenylquinolylsilyl. 
     a′ represents 1, b′ and c′, each independently, represent 1 or 2, and d′ represents an integer of 1 to 4, where if b′ to d′ are each an integer of 2 or more, each of R 62  to each of R 64  may be the same or different. 
     According to one embodiment of the present disclosure, formula 2 is represented by at least one of the following formulas 2-1 to 2-3. 
     
       
         
         
             
             
         
       
     
     In formulas 2-1 to 2-3, X 1 , Y 1 , L 4 , R 61  to R 66 , and a′ to d′ are as defined in formula 2; and d″ represents an integer of 1 to 3. 
     The compound represented by formula 1 may be at least one selected from the group consisting of the following compounds, but is not limited thereto. 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     The compound represented by formula 2 may be at least one selected from the group consisting of the following compounds, but is not limited thereto. 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     The combination of at least one of compounds C-1 to C-209 and at least one of compounds H1-1 to H1-186 may be used in an organic electroluminescent device. 
     The present disclosure provides the compounds represented by formulas 1 to 3. The present disclosure may provide an organic electroluminescent material or an organic electroluminescent device comprising the organic electroluminescent compound, in which the organic electroluminescent compound may be comprised as a host of a light-emitting layer, a hole transport material of a hole transport layer, etc. According to one embodiment of the present disclosure, the organic electroluminescent device of the present disclosure comprises at least one or at least two hole transport layers, in which the organic electroluminescent compound may be comprised as a hole transport material of the at least one or at least two hole transport layers. 
     The present disclosure provides an organic electroluminescent compound represented by the following formula 3. 
     
       
         
         
             
             
         
       
     
     In formula 3, 
     X 1  and Y 1 , each independently, represent —N═, —NR 67 —, —O— or —S—, with the proviso that any one of X 1  and Y 1  represents —N═, and the other of X 1  and Y 1  represents —NR 67 —, —O— or —S—; 
     R 61  represents a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (3- to 30-membered)heteroaryl; 
     R 62  to R 64  and R 67 , each independently, represent hydrogen, deuterium, a halogen, a cyano, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, a substituted or unsubstituted (3- to 30-membered)heteroaryl, a substituted or unsubstituted (C3-C30)cycloalkyl, a substituted or unsubstituted (C1-C30)alkoxy, a substituted or unsubstituted tri(C1-C30)alkylsilyl, a substituted or unsubstituted di(C1-C30)alkyl(C6-C30)arylsilyl, a substituted or unsubstituted (C1-C30)alkyldi(C6-C30)arylsilyl, a substituted or unsubstituted tri(C6-C30)arylsilyl, a substituted or unsubstituted fused ring group of a (C3-C30) aliphatic ring(s) and a (C6-C30) aromatic ring(s), or -L 3 ″-N(Ar 3 ″)(Ar 4 ″); or may be linked to an adjacent substituent(s) to form a ring(s); 
     L 3 ″, each independently, represents a single bond, a substituted or unsubstituted (C6-C30)arylene, or a substituted or unsubstituted (3- to 30-membered)heteroarylene; 
     Ar 3 ″ and Ar 4 ″, each independently, represent hydrogen, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C2-C30)alkenyl, a substituted or unsubstituted fused ring group of a (C3-C30) aliphatic ring(s) and a (C6-C30) aromatic ring(s), a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (3- to 30-membered)heteroaryl; 
     L 4  represents a single bond, a substituted or unsubstituted (C6-C30)arylene, or a substituted or unsubstituted (3- to 30-membered)heteroarylene; 
     R 65  and R 66 , each independently, represent a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (3- to 30-membered)heteroaryl; and 
     a′ represents 1, b′ and c′, each independently, represent 1 or 2, and d′ represents an integer of 1 to 4, where if b′ to d′ are each an integer of 2 or more, each of R 62  to each of R 64  may be the same or different; 
     with the proviso that at least one of R 61  to R 67 , Ar 3 ″ and Ar 4 ″ comprises the following formula 3-1: 
     
       
         
         
             
             
         
       
     
     in formula 3-1, 
     A represents Si or C; 
     L 3  represents a substituted or unsubstituted (C6-C30)arylene, or a substituted or unsubstituted (3- to 30-membered)heteroarylene; and 
     R′, R″, and R′″, each independently, represent a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (3- to 30-membered)heteroaryl. 
     In formula 3, the preferred embodiment of X 1 , Y 1 , R 61  to R 67 , L 3 ″, Ar 3 ″, Ar 4 ″, L 4 , and a′ to d′ are as described in formula 2 above. 
     In formula 3, according to one embodiment of the present disclosure, at least one of R 65  and R 66  comprises formula 3-1. According to another embodiment of the present disclosure, any one of R 65  and R 66  comprises formula 3-1. 
     In formula 3-1, according to one embodiment of the present disclosure, L 3  represents a substituted or unsubstituted (C6-C25)arylene. According to another embodiment of the present disclosure, L 3  represents an unsubstituted (C6-C18)arylene. For example, L 3  may be a phenylene, a naphthylene, a biphenylene, etc. 
     In formula 3-1, according to one embodiment of the present disclosure, R′, R″, and R′″, each independently, represent a substituted or unsubstituted (C6-C25)aryl, or a substituted or unsubstituted (5- to 25-membered)heteroaryl. According to another embodiment of the present disclosure. R′, R″, and R′″, each independently, represent an unsubstituted (C6-C18)aryl, or an unsubstituted (5- to 20-membered)heteroaryl. For example, R′, R″, and R′″, each independently, may be a phenyl, a naphthyl, a biphenyl, a pyridyl, a quinolyl, a dibenzofuranyl, etc. 
     The compound represented by formula 3 may be at least one selected from the group consisting of compounds H1-132 to H1-185, but is not limited thereto. 
     The compounds represented by formulas 1 to 3 according to the present disclosure may be produced by synthetic methods known to one skilled in the art. For example, the compound represented by formula 1 of the present disclosure may be produced by referring to Korean Patent Application Laid-Open No. 2018-0022574 (published on Mar. 6, 2018), etc., and the compound represented by formula 2 of the present disclosure may be produced by referring to Korean Patent Application Laid-Open No. 2017-0022865 (published on Mar. 2, 2017), etc., but is not limited thereto. The compound represented by formula 3 of the present disclosure may be produced by referring to the following reaction schemes 1 and 2, but is not limited thereto. 
     
       
         
         
             
             
         
       
     
     
       
         
         
             
             
         
       
     
     In reaction schemes 1 and 2, the substituents are as defined in formula 3, and Hal represents a halogen. 
     The present disclosure provides an organic electroluminescent device comprising an anode, a cathode, and at least one light-emitting layer between the anode and the cathode, wherein the at least one light-emitting layer comprises the plurality of host materials of the present disclosure. The first host material and the second host material of the present disclosure may be comprised in one light-emitting layer, or may be comprised in respective different light-emitting layers. The plurality of host materials of the present disclosure may comprise the compound represented by formula 1 and the compound represented by formula 2 in a ratio of about 1:99 to about 99:1, preferably in a ratio of about 10:90 to about 90:10, more preferably in a ratio of about 30:70 to about 70:30. Also, the compound represented by formula 1 and the compound represented by formula 2 in a desired ratio may be combined by mixing them in a shaker, by dissolving them in a glass tube by heat, or by dissolving them in a solvent, etc. 
     The present disclosure provides an organic electroluminescent device comprising an anode, a cathode, and at least one hole transport layer between the anode and the cathode, wherein the at least one hole transport layer comprises the organic electroluminescent compound represented by formula 3 of the present disclosure. According to one embodiment of the present disclosure, the organic electroluminescent device comprises a first hole transport layer and a second hole transport layer, in which the second hole transport layer comprises the organic electroluminescent compound represented by formula 3. 
     According to one embodiment of the present disclosure, the doping concentration of a dopant compound with respect to a host compound in the light-emitting layer is less than about 20 wt %. The dopant comprised in the organic electroluminescent device of the present disclosure may be at least one phosphorescent or fluorescent dopant, and is preferably a phosphorescent dopant. The phosphorescent dopant material applied to the organic electroluminescent device of the present disclosure is not particularly limited, but may be a complex compound of a metal atom selected from indium (Ir), osmium (Os), copper (Cu) and platinum (Pt), and preferably ortho-metallated complex compounds of a metal atom selected from iridium (Ir), osmium (Os), copper (Cu), and platinum (Pt), and more preferably ortho-metallated iridium complex compounds. 
     The dopant comprised in the organic electroluminescent device of the present disclosure may comprise a compound represented by the following formula 101, but is not limited thereto. 
     
       
         
         
             
             
         
       
     
     In formula 101, 
     L is selected from the following structures 1 to 3: 
     
       
         
         
             
             
         
       
     
     R 100  to R 103 , each independently, represent hydrogen, deuterium, a halogen, a (C1-C30)alkyl unsubstituted or substituted with deuterium and/or a halogen(s), a substituted or unsubstituted (C3-C30)cycloalkyl, a substituted or unsubstituted (C6-C30)aryl, a cyano, a substituted or unsubstituted (3- to 30-membered)heteroaryl, or a substituted or unsubstituted (C1-C30)alkoxy; or may be linked to an adjacent substituent(s) to form a ring(s), e.g., a substituted or unsubstituted quinoline, a substituted or unsubstituted benzofuropyridine, a substituted or unsubstituted benzothienopyridine, a substituted or unsubstituted indenopyridine, a substituted or unsubstituted benzofuroquinoline, a substituted or unsubstituted benzothienoquinoline, or a substituted or unsubstituted indenoquinoline, together with pyridine; 
     R 104  to R 107 , each independently, represent hydrogen, deuterium, a halogen, a (C1-C30)alkyl unsubstituted or substituted with deuterium and/or a halogen(s), a substituted or unsubstituted (C3-C30)cycloalkyl, a substituted or unsubstituted (C6-C30)aryl, a substituted or unsubstituted (3- to 30-membered)heteroaryl, a cyano, or a substituted or unsubstituted (C1-C30)alkoxy; or may be linked to an adjacent substituent(s) to form a substituted or unsubstituted ring(s), e.g., a substituted or unsubstituted naphthalene, a substituted or unsubstituted fluorene, a substituted or unsubstituted dibenzothiophene, a substituted or unsubstituted dibenzofuran, a substituted or unsubstituted indenopyridine, a substituted or unsubstituted benzofuropyridine, or a substituted or unsubstituted benzothienopyridine, together with benzene; 
     R 201  to R 220 , each independently, represent hydrogen, deuterium, a halogen, a (C1-C30)alkyl unsubstituted or substituted with deuterium and/or a halogen(s), a substituted or unsubstituted (C3-C30)cycloalkyl, or a substituted or unsubstituted (C6-C30)aryl; or may be linked to an adjacent substituent(s) to form a substituted or unsubstituted ring(s); and 
     s represents an integer of 1 to 3. 
     The specific examples of the dopant compound are as follows, but are not limited thereto. 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     The organic electroluminescent device according to the present disclosure has an anode, a cathode, and at least one organic layer between the anode and the cathode. The organic layer may comprise a light-emitting layer, and may further comprise at least one layer selected from a hole injection layer, a hole transport layer, a hole auxiliary layer, a light-emitting auxiliary layer, an electron transport layer, an electron buffer layer, an electron injection layer, an interlayer, a hole blocking layer, and an electron blocking layer. Each of the layers may be further configured as a plurality of layers. 
     The anode and the cathode may be respectively formed with a transparent conductive material, or a transflective or reflective conductive material. The organic electroluminescent device may be a top emission type, a bottom emission type, or a both-sides emission type, depending on the materials forming the anode and the cathode. In addition, the hole injection layer may be further doped with a p-dopant(s), and the electron injection layer may be further doped with an n-dopant(s). 
     The organic layer may further comprise at least one compound selected from the group consisting of arylamine-based compounds and styrylarylamine-based compounds. 
     Further, in the organic electroluminescent device of the present disclosure, the organic layer may further comprise at least one metal selected from the group consisting of metals of Group 1, metals of Group 2, transition metals of the 4 th  period, transition metals of the 5 th  period, lanthanides, and organic metals of the d-transition elements of the Periodic Table, or at least one complex compound comprising the metal. 
     In addition, the organic electroluminescent device of the present disclosure may emit white light by further comprising at least one light-emitting layer, which comprises a blue, a red, or a green electroluminescent compound known in the field, besides the compound of the present disclosure. If necessary, it may further comprise a yellow or an orange light-emitting layer. 
     In the organic electroluminescent device of the present disclosure, preferably, at least one layer selected from the group consisting of a chalcogenide layer, a metal halide layer, and a metal oxide layer (hereinafter, “a surface layer”) may be placed on an inner surface(s) of one or both electrode(s). Specifically, a chalcogenide (including oxides) layer of silicon or aluminum is preferably placed on an anode surface of an electroluminescent medium layer, and a metal halide layer or a metal oxide layer is preferably placed on a cathode surface of an electroluminescent medium layer. Such a surface layer provides operation stability for the organic electroluminescent device. Preferably, the chalcogenide includes SiO X (1≤X≤2), AlO X (1≤X≤1.5), SiON, SiAlON, etc.; the metal halide includes LiF, MgF 2 , CaF 2 , a rare earth metal fluoride, etc.; and the metal oxide includes Cs 2 O, Li 2 O, MgO, SrO, BaO, CaO, etc. 
     A hole injection layer, a hole transport layer, an electron blocking layer, or a combination thereof can be used between the anode and the light-emitting layer. The hole injection layer may be multi-layers in order to lower the hole injection barrier (or hole injection voltage) from the anode to the hole transport layer or the electron blocking layer, wherein each of the multi-layers may use two compounds simultaneously. The hole transport layer or the electron blocking layer may also be multi-layers. 
     An electron buffer layer, a hole blocking layer, an electron transport layer, an electron injection layer, or a combination thereof can be used between the light-emitting layer and the cathode. The electron buffer layer may be multi-layers in order to control the injection of the electron and improve the interfacial properties between the light-emitting layer and the electron injection layer, wherein each of the multi-layers may use two compounds simultaneously. The hole blocking layer or the electron transport layer may also be multi-layers, wherein each of the multi-layers may use a plurality of compounds. 
     The light-emitting auxiliary layer may be placed between the anode and the light-emitting layer, or between the cathode and the light-emitting layer. When the light-emitting auxiliary layer is placed between the anode and the light-emitting layer, it can be used for promoting the hole injection and/or hole transport, or for preventing the overflow of electrons. When the light-emitting auxiliary layer is placed between the cathode and the light-emitting layer, it can be used for promoting the electron injection and/or electron transport, or for preventing the overflow of holes. Also, the hole auxiliary layer may be placed between the hole transport layer (or hole injection layer) and the light-emitting layer, and may be effective to promote or block the hole transport rate (or hole injection rate), thereby enabling the charge balance to be controlled. Further, the electron blocking layer may be placed between the hole transport layer (or hole injection layer) and the light-emitting layer, and can confine the excitons within the light-emitting layer by blocking the overflow of electrons from the light-emitting layer to prevent a light-emitting leakage. When an organic electroluminescent device includes two or more hole transport layers, the hole transport layer, which is further included, may be used as a hole auxiliary layer or an electron blocking layer. The light-emitting auxiliary layer, the hole auxiliary layer or the electron blocking layer may have an effect of improving the efficiency and/or the lifetime of the organic electroluminescent device. 
     In addition, in the organic electroluminescent device of the present disclosure, a mixed region of an electron transport compound and a reductive dopant, or a mixed region of a hole transport compound and an oxidative dopant may be placed on at least one surface of a pair of electrodes. In this case, the electron transport compound is reduced to an anion, and thus it becomes easier to inject and transport electrons from the mixed region to the light-emitting medium. Furthermore, the hole transport compound is oxidized to a cation, and thus it becomes easier to inject and transport holes from the mixed region to the light-emitting medium. Preferably, the oxidative dopant includes various Lewis acids and acceptor compounds; and the reductive dopant includes alkali metals, alkali metal compounds, alkaline earth metals, rare-earth metals, and mixtures thereof. The reductive dopant layer may be employed as a charge-generating layer to produce an organic electroluminescent device having two or more light-emitting layers and emitting white light. 
     The organic electroluminescent compound or the organic electroluminescent material according to one embodiment of the present disclosure may be used as a light-emitting material for a white organic light-emitting device. The white organic light-emitting device has been suggested to have various structures such as a side-by-side structure or a stacking structure depending on the arrangement of R (red), G (green) or YG (yellow green), and B (blue) light-emitting parts, or color conversion material (CCM) method, etc. The organic electroluminescent material according to one embodiment of the present disclosure may also be used in an organic electroluminescent device comprising a quantum dot (QD). 
     In order to form each layer of the organic electroluminescent device of the present disclosure, dry film-forming methods such as vacuum evaporation, sputtering, plasma, ion plating methods, etc., or wet film-forming methods such as ink jet printing, nozzle printing, slot coating, spin coating, dip coating, flow coating methods, etc., can be used. When the first and second host compounds of the present disclosure are used to form a film, a co-evaporation process or a mixture-evaporation process is carried out. 
     When using a wet film-forming method, a thin film can be formed by dissolving or diffusing materials forming each layer into any suitable solvent such as ethanol, chloroform, tetrahydrofuran, dioxane, etc. The solvent can be any one where the materials forming each layer can be dissolved or diffused, and where there are no problems in film-formation capability. 
     In addition, it is possible to produce a display system, for example, a display system for smart phones, tablets, notebooks, PCs, TVs, or cars; or a lighting system, for example an outdoor or indoor lighting system, by using the organic electroluminescent device of the present disclosure. 
     Hereinafter, the preparation method of the compounds according to the present disclosure and the properties thereof, and luminous efficiency and lifetime properties of an organic electroluminescent device (OLED) comprising a plurality of host materials according to the present disclosure will be explained in detail with reference to the representative compounds of the present disclosure. The following examples only describe the properties of the OLED comprising the compound according to the present disclosure, but the present disclosure is not limited to the following examples. 
     Example 1: Preparation of Compound C-68 
     
       
         
         
             
             
         
       
     
     In a flask, 15 g of 2-(4-bromophenyl)-4,6-diphenyl-1,3,5-triazine (38.6 mmol), 11.3 g of naphtho[2,3-b]benzofuran-1-yl boronic acid (42.5 mmol), 2.2 g of Pd(pph 3 ) 4  (1.93 mmol), 10.6 g of K 2 CO 3  (77.2 mmol), 200 mL of toluene, 40 mL of EtOH, and 40 mL of H 2 O were added and the mixture was stirred at 160° C. After completion of the reaction, methanol (MeOH) and water were added and stirred. Thereafter, the mixture was filtered under reduced pressure to remove the solvent, and separated by column chromatography. After adding MeOH, the resulting solid was filtered under reduced pressure to obtain 14.7 g of compound C-68 (yield: 72.7%). 
     
       
         
           
               
               
               
               
               
             
               
                   
                   
               
               
                   
                   
                 MW 
                 Color 
                 M.R 
               
               
                   
                   
               
             
            
               
                   
                 C-68 
                 525.61 
                 White 
                 255.3° C. 
               
               
                   
                   
               
            
           
         
       
     
     Example 2: Preparation of Compound C-137 
     
       
         
         
             
             
         
       
     
     Compound 2 (5 g, 11.89 mmol), compound 3 (4.1 g, 11.89 mmol), Pd(PPh 3 ) 4  (0.68 g, 0.594 mmol), and K 2 CO 3  (4.9 g, 35.68 mmol) were added to 80 mL of toluene, 20 mL of EtOH, and 20 mL of distilled water, and the mixture was stirred under reflux at 130° C. for 2 hours. After completion of the reaction, the mixture was cooled to room temperature and extracted with distilled water and EA. The organic layer was distilled under reduced pressure, and then separated with silica filter to obtain 4 g of compound C-137 (yield: 55%). 
     
       
         
           
               
               
               
               
             
               
                   
                   
               
               
                   
                   
                 MW 
                 M.P. 
               
               
                   
                   
               
             
            
               
                   
                 C-137 
                 801.6 
                 243.7° C. 
               
               
                   
                   
               
            
           
         
       
     
     Example 3: Preparation of Compound C-172 
     
       
         
         
             
             
         
       
     
     Compound 2 (5 g, 11.89 mmol), compound 4 (3.8 g, 11.89 mmol), Pd(PPh 3 ) 4  (0.68 g, 0.594 mmol), and K 2 CO 3  (4.9 g, 35.68 mmol) were added to 80 mL of toluene, 20 mL of EtOH, and 20 mL of distilled water, and the mixture was stirred under reflux at 130° C. for 2 hours. After completion of the reaction, the mixture was cooled to room temperature and extracted with distilled water and EA. The organic layer was distilled under reduced pressure, and then separated with silica filter to obtain 3.1 g of compound C-172 (yield: 41%). 
     
       
         
           
               
               
               
               
             
               
                   
                   
               
               
                   
                   
                 MW 
                 M.R 
               
               
                   
                   
               
             
            
               
                   
                 C-172 
                 575.6 
                 284.2° C. 
               
               
                   
                   
               
            
           
         
       
     
     Example 4: Preparation of Compound H1-102 
     
       
         
         
             
             
         
       
     
     Compound A (5 g, 15.16 mmol), compound B (5.8 g, 16.67 mmol), Pd 2 (dba) 3  (0.64 g, 0.758 mmol), t-BuONa (2.18 g, 22.74 mmol) and S-Phos (0.62 g, 0.5 mmol) were dissolved in 75.8 mL of o-xylene, and then stirred under reflux at 180° C. for 12 hours. The reaction mixture was cooled to room temperature, and layers were separated using MC/H 2 O as a work-up process. After adding MgSO 4 , the mixture was separated with celite filter to produce a solid form. The produced solid was separated with silica filter to obtain 6 g of compound H1-102 (yield: 60%). 
     
       
         
           
               
               
               
               
             
               
                   
                   
               
               
                   
                   
                 MW 
                 M.P. 
               
               
                   
                   
               
             
            
               
                   
                 H1-102 
                 842.1 
                 277.7° C. 
               
               
                   
                   
               
            
           
         
       
     
     Example 5: Preparation of Compound H1-141 
     
       
         
         
             
             
         
       
     
     Synthesis of Compound 7-2 
     Compound 7-1 (15.0 g, 45.48 mmol), dibenzo[b,d]furan-3-amine (12.5 g, 68.23 mmol), PdCl 2 (Amphos) 2  (3.2 g, 4.55 mmol), and NaOt-Bu (6.5 g, 68.22 mmol) were dissolved in 230 mL of o-xylene, and stirred under reflux for 24 hours. The reaction mixture was cooled to room temperature. After adding H 2 O, the mixture was filtered. The filtrate was separated with silica filter to produce a solid form. The produced solid was filtered, and recrystallized with toluene and dichlorobenzene (DCB) to obtain 6.3 g of compound 7-2 (yield: 29.1%). 
     Synthesis of compound H1-141 
     In a reaction vessel, compound 7-2 (3.8 g, 8.02 mmol), (3-bromophenyl)triphenylsilane (4.0 g, 9.62 mmol), Pd 2 (dba) 3  (400 mg, 0.40 mmol), S-Phos (300 mg, 0.80 mmol), and NaOt-Bu (2.0 g, 20.05 mmol) were dissolved in 54 mL of o-xylene, and stirred under reflux for 3 hours. The reaction mixture was cooled to room temperature, and filtered with celite to produce a solid form. The produced solid was separated with silica filter, and recrystallized with toluene to obtain 4.1 g of compound H1-141 (yield: 63.0%). 
     
       
         
           
               
               
               
               
             
               
                   
                   
               
               
                   
                   
                 MW 
                 M.P. 
               
               
                   
                   
               
             
            
               
                   
                 H1-141 
                 811.0 
                 197° C. 
               
               
                   
                   
               
            
           
         
       
     
     Example 6: Preparation of Compound H1-155 
     
       
         
         
             
             
         
       
     
     Synthesis of Compound 8-1 
     (3-chlorophenyl)triphenylsilane (15.0 g, 40 mmol), dibenzo[b,d]furan-2-amine (7.7 g, 42 mmol), Pd(OAc) 2  (0.09 g, 0.4 mmol), t-BuONa (5.8 g, 60.3 mmol), and X-Phos (0.47 g, 0.98 mmol) were dissolved in 300 mL of o-xylene, and stirred under reflux at 130° C. for 3 hours. The reaction mixture was cooled to room temperature, and layers were separated using MC/H 2 O as a work-up process. After adding MgSO 4 , the mixture was separated with celite filter to produce a solid form. The produced solid was separated with silica filter and recrystallized with toluene to obtain compound 8-1 (14.2 g, yield: 70.8%). 
     Synthesis of Compound H1-155 
     Compound 8-1 (14.2 g, 27.4 mmol), compound A (8.6 g, 26.07 mmol), Pd(OAc) 2  (0.06 g, 0.2 mmol), t-BuONa (5.0 g, 52.0 mmol), and S-Phos (0.21 g, 0.5 mmol) were dissolved in 710 mL of toluene, and stirred under reflux at 110° C. for 8 hours. The reaction mixture was cooled to room temperature, and layers were separated using MC/H 2 O as a work-up process. After adding MgSO 4 , the mixture was separated with celite filter to produce a solid form. The produced solid was separated with silica filter and recrystallized with toluene to obtain compound H1-155 (12.7 g, yield: 57.3%). 
     
       
         
           
               
               
               
               
             
               
                   
                   
               
               
                   
                   
                 MW 
                 M.R 
               
               
                   
                   
               
             
            
               
                   
                 H1-155 
                 811.03 
                 242° C. 
               
               
                   
                   
               
            
           
         
       
     
     Device Examples 1 to 5: Producing an OLED Co-Deposited with the First Host Compound and the Second Host Compound According to the Present Disclosure 
     An OLED according to the present disclosure was produced. A transparent electrode indium tin oxide (ITO) thin film (10 Ω/sq) on a glass substrate for an OLED (GEOMATEC CO., LTD., Japan) was subjected to an ultrasonic washing with acetone and isopropyl alcohol, sequentially, and then was stored in isopropyl alcohol. The ITO substrate was then mounted on a substrate holder of a vacuum vapor deposition apparatus. Compound HI-1 was introduced into a cell of the vacuum vapor deposition apparatus, and compound HT-1 was introduced into another cell of the vacuum vapor deposition apparatus. The two materials were evaporated at different rates, and compound HI-1 was deposited in a doping amount of 3 wt % based on the total amount of compound HI-1 and compound HT-1 to form a hole injection layer having a thickness of 10 nm. Next, compound HT-1 was deposited on the hole injection layer to form a first hole transport layer having a thickness of 80 nm. Compound HT-2 was then introduced into another cell of the vacuum vapor deposition apparatus and was evaporated by applying an electric current to the cell, thereby forming a second hole transport layer having a thickness of 60 nm on the first hole transport layer. After forming the hole injection layer and the hole transport layers, a light-emitting layer was formed thereon as follows: the first host compound and the second host compound shown in Table 1 below were introduced into two cells of the vacuum vapor deposition apparatus as hosts, and compound D-39 was introduced into another cell as a dopant. The two host materials were evaporated at a rate of 1:1 and the dopant material was simultaneously evaporated at a different rate, and the dopant was deposited in a doping amount of 3 wt % based on the total amount of the hosts and the dopant to form a light-emitting layer having a thickness of 40 nm on the second hole transport layer. Next, compound ET-1 and compound EI-1 as electron transport materials were deposited in a weight ratio of 50:50 to form an electron transport layer having a thickness of 35 nm on the light-emitting layer. After depositing compound EI-1 as an electron injection layer having a thickness of 2 nm on the electron transport layer, an Al cathode having a thickness of 80 nm was deposited on the electron injection layer by another vacuum vapor deposition apparatus. Thus, an OLED was produced. All the materials used for producing the OLED were purified by vacuum sublimation at 10 −6  torr. 
     Comparative Examples 1 to 3: Producing an OLED Comprising a Comparative Compound as a Host 
     OLEDs were produced in the same manner as in Device Example 1, except that the first host compound or the second host compound as shown in Table 1 below was used alone as the host of the light-emitting layer. 
     Comparative Examples 4 and 5: Producing an OLED Comprising a Comparative Compound as a Host 
     OLEDs were produced in the same manner as in Device Example 1, except that the first host compound and the second host compound as shown in Table 1 below were used as the hosts of the light-emitting layer. 
     The driving voltage, luminous efficiency, and light-emitting color at a luminance of 1,000 nit, and the time taken for luminance to decrease from 100% to 95% at a luminance of 10,000 nit (lifetime; T95) of the OLEDs produced in Device Examples 1 to 5 and Comparative Examples 1 to 5 are provided in Table 1 below. 
     
       
         
           
               
               
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                   
                 Driving 
                 Luminous 
                 Light- 
                   
               
               
                   
                 First 
                 Second 
                 Voltage 
                 Efficiency 
                 Emitting 
                 Lifetime 
               
               
                   
                 Host 
                 Host 
                 [V] 
                 [cd/A] 
                 Color 
                 (T95, hr) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Comparative 
                 C-68 
                 — 
                 3.6 
                 31.1 
                 Red 
                 15 
               
               
                 Example 1 
               
               
                 Comparative 
                 — 
                 H1-9 
                 3.7 
                 9.5 
                 Red 
                 3.3 
               
               
                 Example 2 
               
               
                 Comparative 
                 — 
                 H1-129 
                 4.3 
                 7.8 
                 Red 
                 2.3 
               
               
                 Example 3 
               
               
                 Comparative 
                 C-68 
                 R-1 
                 3.3 
                 34.8 
                 Red 
                 64 
               
               
                 Example 4 
               
               
                 Comparative 
                 C-68 
                 R-2 
                 3.2 
                 33.2 
                 Red 
                 61 
               
               
                 Example 5 
               
               
                 Device 
                 C-68 
                 H1-15 
                 3.2 
                 36.7 
                 Red 
                 240 
               
               
                 Example 1 
               
               
                 Device 
                 C-68 
                 H1-1 
                 2.9 
                 35.7 
                 Red 
                 192 
               
               
                 Example 2 
               
               
                 Device 
                 C-68 
                 H1-9 
                 3.0 
                 37.3 
                 Red 
                 360 
               
               
                 Example 3 
               
               
                 Device 
                 C-137 
                 H1-129 
                 2.9 
                 35.7 
                 Red 
                 157 
               
               
                 Example 4 
               
               
                 Device 
                 C-172 
                 H1-129 
                 3.0 
                 36.6 
                 Red 
                 190 
               
               
                 Example 5 
               
               
                   
               
            
           
         
       
     
     From Table 1 above, it can be seen that the OLEDs comprising a specific combination of compounds according to the present disclosure as host materials exhibit equivalent or lower driving voltage and higher luminous efficiency, and in particular significantly improved lifetime properties, compared to the OLEDs comprising a single host material (Comparative Example 1 to 3) or comprising a comparative compound (Comparative Examples 4 and 5). 
     Device Examples 6 and 7: Producing an OLED Co-Deposited with the First Host Compound and the Second Host Compound According to the Present Disclosure 
     OLEDs were produced in the same manner as in Device Example 1, except that the second host compound as shown in Table 2 below was used as a host of the light-emitting layer. 
     
       
         
           
               
               
               
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                   
                   
                   
                 Driving 
                 Luminous 
                 Light- 
               
               
                   
                   
                   
                 Voltage 
                 Efficiency 
                 Emitting 
               
               
                   
                 First Host 
                 Second Host 
                 [V] 
                 [cd/A] 
                 Color 
               
               
                   
               
             
            
               
                 Device Example 
                 C-68 
                 H1-102 
                 3.4 
                 33.1 
                 Red 
               
               
                 6 
                   
                   
                   
                   
                   
               
               
                 Device Example 
                 C-68 
                 H1-141 
                 3.2 
                 36.6 
                 Red 
               
               
                 7 
               
               
                   
               
            
           
         
       
     
     Device Examples 8 and 9: Producing an OLED Comprising the Compound According to the Present Disclosure as the Material of the Second Hole Transport Laver 
     OLEDs were produced in the same manner as in Device Example 1, except that the compounds as shown in Table 3 below were used as the material of the second hole transport layer and as the first and second host materials of the light-emitting layer. 
     Comparative Examples 6 and 7: Producing an OLED Comprising a Comparative Compound as the Material of the Second Hole Transport Layer 
     OLEDs were produced in the same manner as in Device Examples 8 and 9, except that the compounds as shown in Table 3 below were used as the material of the second hole transport layer. 
     
       
         
           
               
               
               
               
               
               
               
             
               
                   
                 TABLE 3 
               
               
                   
                   
               
               
                   
                 Second Hole 
                   
                   
                 Driving 
                 Luminous 
                 Light- 
               
               
                   
                 Transport 
                 First 
                 Second 
                 Voltage 
                 Efficiency 
                 Emitting 
               
               
                   
                 Layer 
                 Host 
                 Host 
                 [V] 
                 [cd/A] 
                 Color 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Comparative 
                 H1-129 
                 B 
                 H1-129 
                 3.0 
                 32.9 
                 Red 
               
               
                 Example 6 
               
               
                 Comparative 
                 H1-46 
                   
                   
                 3.1 
                 30.1 
                 Red 
               
               
                 Example 7 
               
               
                 Device 
                 H1-155 
                   
                   
                 3.1 
                 35.7 
                 Red 
               
               
                 Example 8 
               
               
                 Device 
                 H1-141 
                   
                   
                 3.0 
                 34.8 
                 Red 
               
               
                 Example 9 
               
               
                   
               
            
           
         
       
     
     From Table 3 above, it can be seen that the OLED comprising the organic electroluminescent compound according to the present disclosure (formula 3) as the second hole transport material exhibits equivalent driving voltage and higher luminous efficiency, compared to the OLED comprising a comparative compound (formula 1). 
     The compounds used in the Device Examples and the Comparative Examples are shown in Table 4 below. 
     
       
         
           
               
               
             
               
                 TABLE 4 
               
               
                   
               
             
            
               
                 Hole Injection Layer/ Hole Transport Layer 
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                 Light- Emitting Layer 
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                 Electron Transport Layer/ Electron Injection Layer