Patent Publication Number: US-2021184137-A1

Title: Organic electroluminescent compound and organic electroluminescent device comprising the same

Description:
TECHNICAL FIELD 
     The present disclosure relates to an organic electroluminescent compound and an organic electroluminescent device comprising the same. 
     BACKGROUND ART 
     An electroluminescent (EL) device is a self-light-emitting device which has advantages in that it provides a wider viewing angle, a greater contrast ratio, and a faster response time. An organic EL device was first developed by Eastman Kodak in 1987, by using small aromatic diamine molecules and aluminum complexes as materials for forming a light-emitting layer [Appl. Phys. Lett. 51, 913, 1987]. 
     The most important factor determining luminous efficiency in the organic electroluminescent device is light-emitting materials. Until now, fluorescent materials have been widely used as light-emitting materials. However, in view of electroluminescent mechanisms, since phosphorescent light-emitting materials theoretically enhance luminous efficiency by four (4) times compared to fluorescent light-emitting materials, phosphorescent light-emitting materials have been widely researched. Iridium(III) complexes have been widely known as phosphorescent light-emitting materials, including bis(2-(2′-benzothienyl)-pyridinato-N,C-3′)iridium(acetylacetonate) ((acac)Ir(btp) 2 ), tris(2-phenylpyridine)iridium (Ir(ppy) 3 ) and bis(4,6-difluorophenylpyridinato-N,C2)picolinate iridium (Firpic) as red-, green-, and blue-emitting materials, respectively. 
     At present, 4,4′-N,N′-dicarbazol-biphenyl (CBP) is the most widely known phosphorescent host material. Recently, Pioneer (Japan) et al., developed a high performance organic electroluminescent device using bathocuproine (BCP) and aluminum(III) bis(2-methyl-8-quinolinate)(4-phenylphenolate) (BAlq), etc., as host materials, which were known as hole blocking materials. 
     Although these materials provide good luminous characteristics, they have the following disadvantages: (1) Due to their low glass transition temperature and poor thermal stability, their degradation may occur during a high-temperature deposition process in a vacuum, and the lifespan of the device decreases. (2) The power efficiency of the organic electroluminescent device is given by [(π/voltage)×current efficiency], and the power efficiency is inversely proportional to the voltage. Although the organic electroluminescent device comprising phosphorescent host materials provides higher current efficiency (cd/A) than one comprising fluorescent materials, a significantly high driving voltage is necessary. Thus, there is no merit in terms of power efficiency (lm/W). (3) Further, when these materials are used in an organic electroluminescent device, the operational lifespan of an organic electroluminescent device is short and luminous efficiency is still required to be improved. 
     In order to enhance luminous efficiency, driving voltage, and/or lifespan, various materials or concepts for an organic layer of an organic electroluminescent device have been proposed, but they have not been satisfactory in practical use. 
     Korean Patent Application Laying-Open Nos. 10-2012-0033017 and 10-2016-0038006 disclose an organic electroluminescent compound in which a nitrogen-containing heteroaryl group is bonded to a dibenzofuran or dibenzothiophene structure. However, it is still required to be improved in terms of driving voltage, luminous efficiency, and/or lifespan characteristics. 
     DISCLOSURE OF INVENTION 
     Technical Problem 
     The objective of the present disclosure is firstly, to provide an organic electroluminescent compound effective for producing an organic electroluminescent device having high luminescent efficiency and/or excellent lifespan characteristic, and secondly, to provide an organic electroluminescent device comprising the organic electroluminescent compound. 
     Solution to Problem 
     The present inventors have found that the above objective can be achieved by the organic electroluminescent compound represented by the following formula 1: 
     
       
         
         
             
             
         
       
     
     wherein 
     X represents —O— or —S—; 
     L represents a single bond, a substituted or unsubstituted (C6-C30)arylene, or a substituted or unsubstituted (3- to 30-membered)heteroarylene; 
     R 1  and R 2 , each independently, represent hydrogen, deuterium, a halogen, a cyano, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C3-C30)cycloalkyl, a substituted or unsubstituted (C3-C30)cycloalkenyl, a substituted or unsubstituted (3- to 7-membered)heterocycloalkyl, a substituted or unsubstituted (C6-C30)aryl, a substituted or unsubstituted (3- to 30-membered)heteroaryl, —NR 5 R 6 , or —SiR 7 R 8 R 9 ; or may be linked to an adjacent substituent to form a ring; 
     R 5  to R 9 , each independently, represent a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (3- to 30-membered)heteroaryl; 
     HAr represents a substituted or unsubstituted (7- to 30-membered)heteroaryl containing at least one nitrogen atom, with the proviso that, if -L-HAr is bonded to one of * positions in 
     
       
         
         
             
             
         
       
     
     HAr is not 
     
       
         
         
             
             
         
       
     
     Y represents N or CH: 
     R represents a substituted or unsubstituted hydroxyl, a substituted or unsubstituted thiol, a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (3- to 30-membered)heteroaryl; and 
     a represents an integer of 1 to 4; and b represents an integer of 1 to 3; in which, if a and b, each independently, are 2 or more, each of R 1  and each of R 2  may be the same or different. 
     Advantageous Effects of Invention 
     By using the organic electroluminescent compound according to the present disclosure, it is possible to produce an organic electroluminescent device having high luminescent efficiency and/or excellent lifespan characteristic. 
    
    
     MODE FOR THE INVENTION 
     Hereinafter, the present disclosure will be described in detail. However, the following description is intended to explain the invention, and is not meant in any way to restrict the scope of the invention. 
     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 layer constituting an organic electroluminescent device, as necessary. 
     The term “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, an electron buffer material, a hole blocking material, an electron transport material, an electron injection material, etc. 
     The organic electroluminescent material of the present disclosure may comprise at least one compound represented by formula 1. The compound represented by formula 1 may be comprised in a light-emitting layer, but is not limited thereto. When comprised in the light-emitting layer, the compound represented by formula 1 may be comprised as a host. Further, the compound represented by formula 1 may be comprised in an electron transport layer, an electron injection layer, an electron buffer layer, and/or a hole blocking layer, but is not limited thereto. When comprised in the the electron transport layer, the electron injection layer, the electron buffer layer, and/or the hole blocking layer, the compound represented by formula 1 may be comprised as an electron transport material, an electron injection material, an electron buffer material, and/or a hole blocking material, respectively. 
     Hereinafter, the compound represented by formula 1 will be described in more detail. 
     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 20, and more preferably 1 to 10. The above alkyl may include methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl, etc. The term “(C2-C30)alkenyl” is meant to be a linear or branched alkenyl having 2 to 30 carbon atoms constituting the chain, in which the number of carbon atoms is preferably 2 to 20, and more preferably 2 to 10. The above alkenyl may include vinyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 2-methylbut-2-enyl, etc. The term “(C2-C30)alkynyl” is meant to be a linear or branched alkynyl having 2 to 30 carbon atoms constituting the chain, in which the number of carbon atoms is preferably 2 to 20, and more preferably 2 to 10. The above alkynyl may include ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 3-butynyl, 1-methylpent-2-ynyl, 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, etc. The term “(3- to 7-membered)heterocycloalkyl” is meant to be a cycloalkyl having 3 to 7, preferably 5 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(ene)” is meant to be a monocyclic or fused ring radical derived from an aromatic hydrocarbon having 6 to 30 ring backbone carbon atoms, in which the number of the ring backbone carbon atoms is preferably 6 to 25, more preferably 6 to 18. The above aryl may be partially saturated, and may comprise a spiro structure. The above aryl may include phenyl, biphenyl, terphenyl, naphthyl, binaphthyl, phenylnaphthyl, naphthylphenyl, phenylterphenyl, fluorenyl, phenylfluorenyl, benzofluorenyl, dibenzofluorenyl, phenanthrenyl, phenylphenanthrenyl, anthracenyl, indenyl, triphenylenyl, pyrenyl, tetracenyl, perylenyl, chrysenyl, naphthacenyl, fluoranthenyl, spirobifluorenyl, etc. More specifically, the aryl may include a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 1-anthryl group, a 2-anthryl group, a 9-anthryl group, a benzanthryl group, a 1-phenanthryl group, a 2-phenanthryl group, a 3-phenanthryl group, a 4-phenanthryl group, a 9-phenanthryl group, a naphthacenyl group, a pyrenyl group, a 1-chrysenyl group, a 2-chrysenyl group, a 3-chrysenyl group, a 4-chrysenyl group, a 5-chrysenyl group, a 6-chrysenyl group, a benzo[c]phenanthryl group, a benzo[g]chrysenyl group, a 1-triphenylenyl group, a 2-triphenylenyl group, a 3-triphenylenyl group, a 4-triphenylenyl group, a 1-fluorenyl group, a 2-fluorenyl group, a 3-fluorenyl group, a 4-fluorenyl group, a 9-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a 2-biphenylyl group, a 3-biphenylyl group, a 4-biphenylyl group, an o-terphenyl group, an m-terphenyl-4-yl group, an m-terphenyl-3-yl group, an m-terphenyl-2-yl group, a p-terphenyl-4-yl group, a p-terphenyl-3-yl group, a p-terphenyl-2-yl group, an m-quaterphenyl group, a 3-fluoranthenyl group, a 4-fluoranthenyl group, an 8-fluoranthenyl group, a 9-fluoranthenyl group, a benzofluoranthenyl group, an o-tolyl group, an m-tolyl group, a p-tolyl group, a 2,3-xylyl group, a 3,4-xylyl group, a 2,5-xylyl group, a mesityl group, an o-cumenyl group, an m-cumenyl group, a p-cumenyl group, a p-t-butylphenyl group, a p-(2-phenylpropyl)phenyl group, a 4′-methylbiphenylyl group, a 4″-t-butyl-p-terphenyl-4-yl group, a 9,9-dimethyl-1-fluorenyl group, a 9,9-dimethyl-2-fluorenyl group, a 9,9-dimethyl-3-fluorenyl group, a 9,9-dimethyl-4-fluorenyl group, a 9,9-diphenyl-1-fluorenyl group, a 9,9-diphenyl-2-fluorenyl group, a 9,9-diphenyl-3-fluorenyl group, a 9,9-diphenyl-4-fluorenyl group, etc. 
     Herein, the term “(3- to 30-membered)heteroaryl(ene)” is an aryl group having 3 to 30 ring backbone atoms, and including at least one, preferably 1 to 4 heteroatoms selected from the group consisting of B, N, O, S, Si, and P. The above heteroaryl may be a monocyclic ring, or a fused ring condensed with at least one benzene ring; may be partially saturated; 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, benzimidazolyl, benzothiazolyl, benzoisothiazolyl, benzoisoxazolyl, benzoxazolyl, isoindolyl, indolyl, benzoindolyl, indazolyl, benzothiadiazolyl, quinolyl, isoquinolyl, cinnolinyl, quinazolinyl, benzoquinazolinyl, quinoxalinyl, benzoquinoxalinyl, naphthyridinyl, carbazolyl, benzocarbazolyl, dibenzocarbazolyl, phenoxazinyl, phenothiazinyl, phenanthridinyl, benzodioxolyl, dihydroacridinyl, etc. More specifically, the heteroaryl may include a 1-pyrrolyl group, a 2-pyrrolyl group, a 3-pyrrolyl group, a pyrazinyl group, a 2-pyridinyl group, a 2-pyrimidinyl group, a 4-pyrimidinyl group, a 5-pyrimidinyl group, a 6-pyrimidinyl group, a 1,2,3-triazin-4-yl group, a 1,2,4-triazin-3-yl group, a 1,3,5-triazin-2-yl group, a 1-imidazolyl group, a 2-imidazolyl group, a 1-pyrazolyl group, a 1-indolidinyl group, a 2-indolidinyl group, a 3-indolidinyl group, a 5-indolidinyl group, a 6-indolidinyl group, a 7-indolidinyl group, an 8-indolidinyl group, a 2-imidazopyridinyl group, a 3-imidazopyridinyl group, a 5-imidazopyridinyl group, a 6-imidazopyridinyl group, a 7-imidazopyridinyl group, an 8-imidazopyridinyl group, a 3-pyridinyl group, a 4-pyridinyl group, a 1-indolyl group, a 2-indolyl group, a 3-indolyl group, a 4-indolyl group, a 5-indolyl group, a 6-indolyl group, a 7-indolyl group, a 1-isoindolyl group, a 2-isoindolyl group, a 3-isoindolyl group, a 4-isoindolyl group, a 5-isoindolyl group, a 6-isoindolyl group, a 7-isoindolyl group, a 2-furyl group, a 3-furyl group, a 2-benzofuranyl group, a 3-benzofuranyl group, a 4-benzofuranyl group, a 5-benzofuranyl group, a 6-benzofuranyl group, a 7-benzofuranyl group, a 1-isobenzofuranyl group, a 3-isobenzofuranyl group, a 4-isobenzofuranyl group, a 5-isobenzofuranyl group, a 6-isobenzofuranyl group, a 7-isobenzofuranyl group, a 2-quinolyl group, a 3-quinolyl group, a 4-quinolyl group, a 5-quinolyl group, a 6-quinolyl group, a 7-quinolyl group, an 8-quinolyl group, a 1-isoquinolyl group, a 3-isoquinolyl group, a 4-isoquinolyl group, a 5-isoquinolyl group, a 6-isoquinolyl group, a 7-isoquinolyl group, an 8-isoquinolyl group, a 2-quinoxalinyl group, a 5-quinoxalinyl group, a 6-quinoxalinyl group, a 1-carbazolyl group, a 2-carbazolyl group, a 3-carbazolyl group, a 4-carbazolyl group, a 9-carbazolyl group, an azacarbazolyl-1-yl group, an azacarbazolyl-2-yl group, an azacarbazolyl-3-yl group, an azacarbazolyl-4-yl group, an azacarbazolyl-5-yl group, an azacarbazolyl-6-yl group, an azacarbazolyl-7-yl group, an azacarbazolyl-8-yl group, an azacarbazolyl-9-yl group, a 1-phenanthridinyl group, a 2-phenanthridinyl group, a 3-phenanthridinyl group, a 4-phenanthridinyl group, a 6-phenanthridinyl group, a 7-phenanthridinyl group, an 8-phenanthridinyl group, a 9-phenanthridinyl group, a 10-phenanthridinyl group, a 1-acridinyl group, a 2-acridinyl group, a 3-acridinyl group, a 4-acridinyl group, a 9-acridinyl group, a 2-oxazolyl group, a 4-oxazolyl group, a 5-oxazolyl group, a 2-oxadiazolyl group, a 5-oxadiazolyl group, a 3-furazanyl group, a 2-thienyl group, a 3-thienyl group, a 2-methylpyrrol-1-yl group, a 2-methylpyrrol-3-yl group, a 2-methylpyrrol-4-yl group, a 2-methylpyrrol-5-yl group, a 3-methylpyrrol-1-yl group, a 3-methylpyrrol-2-yl group, a 3-methylpyrrol-4-yl group, a 3-methylpyrrol-5-yl group, a 2-t-butylpyrrol-4-yl group, a 3-(2-phenylpropyl)pyrrol-1-yl group, a 2-methyl-1-indolyl group, a 4-methyl-1-indolyl group, a 2-methyl-3-indolyl group, a 4-methyl-3-indolyl group, a 2-t-butyl-1-indolyl group, a 4-t-butyl-1-indolyl group, a 2-t-butyl-3-indolyl group, a 4-t-butyl-3-indolyl group, a 1-dibenzofuranyl group, a 2-dibenzofuranyl group, a 3-dibenzofuranyl group, a 4-dibenzofuranyl group, a 1-dibenzothiophenyl group, a 2-dibenzothiophenyl group, a 3-dibenzothiophenyl group, a 4-dibenzothiophenyl group, a 1-silafluorenyl group, a 2-silafluorenyl group, a 3-silafluorenyl group, a 4-silafluorenyl group, a 1-germafluorenyl group, a 2-germafluorenyl group, a 3-germafluorenyl group, a 4-germafluorenyl group, etc. “Halogen” includes F, Cl, Br, and I. 
     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. The substituents of the substituted alkyl, the substituted aryl(ene), the substituted heteroaryl(ene), the substituted cycloalkyl, the substituted cycloalkenyl, and the substituted heterocycloalkyl in L, R, R 1 , R 2 , R 5  to R 9 , R 12  to R 25 , and HAr, each independently, are at least one selected from the group consisting of deuterium; a halogen; a cyano; a carboxyl; a nitro; a hydroxyl; a (C1-C30)alkyl; 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; a (C6-C30)aryl unsubstituted or substituted with at least one of a (C1-C30)alkyl, a (3- to 30-membered)heteroaryl, and a di(C6-C30)arylamino; a tri(C1-C30)alkylsilyl; a tri(C6-C30)arylsilyl; a di(C1-C30)alkyl(C6-C30)arylsilyl; a (C1-C30)alkyldi(C6-C30)arylsilyl; an amino; a mono- or di-(C1-C30)alkylamino; a mono- or di-(C6-C30)arylamino; a (C1-C30)alkyl(C6-C30)arylamino; a (C1-C30)alkylcarbonyl; a (C1-C30)alkoxycarbonyl; a (C6-C30)arylcarbonyl; a di(C6-C30)arylboronyl; 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. According to one embodiment of the present disclosure, the substituents, each independently, are at least one selected from the group consisting of a (C1-C6)alkyl; a (C6-C20)aryl unsubstituted or substituted with at least one of a (C1-C6)alkyl, a (5- to 20-membered)heteroaryl, and a di(C6-C12)arylamino; a (5- to 15-membered)heteroaryl unsubstituted or substituted with at least one (C6-C12)aryl; and a di(C6-C12)arylamino. Specifically, the substituents, each independently, may be at least one selected from the group consisting of a methyl, a phenyl, a naphthyl, a biphenyl, a phenanthrenyl, a terphenyl, a triphenylenyl, a naphthylphenyl, a phenylnaphthyl, a dimethylfluorenyl, a dimethylbenzofluorenyl, a phenyl substituted with a phenylquinoxalinyl, a phenyl substituted with a carbazolyl, a phenyl substituted with a dibenzofuranyl, a phenyl substituted with a diphenylamino, a carbazolyl, a carbazolyl substituted with a phenyl, a dibenzofuranyl, a quinoxalinyl substituted with a phenyl, and a diphenylamino. 
     The compound represented by formula 1 may be represented by any one of the following formulas 1-1 to 1-4: 
     
       
         
         
             
             
         
       
     
     wherein X, L, HAr, R 1 , R 2 , a, and b are as defined in formula 1. 
     In formula 1, HAr may be represented by any one of the following formulas 2-1 to 2-7: 
     
       
         
         
             
             
         
       
     
     wherein 
     ring A represents a naphthalene ring; 
     R 12  to R 25 , each independently, represent hydrogen, deuterium, a halogen, a cyano, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C3-C30)cycloalkyl, a substituted or unsubstituted (C3-C30)cycloalkenyl, a substituted or unsubstituted (3- to 7-membered)heterocycloalkyl, a substituted or unsubstituted (C6-C30)aryl, a substituted or unsubstituted (3- to 30-membered)heteroaryl, —NR 5 R 6 , or —SiR 7 R 8 R 9 ; 
     R 5  to R 9 , each independently, represent a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (3- to 30-membered)heteroaryl; 
     d represents an integer of 1 to 4; e, f, h, j, and l, each independently, represent an integer of 1 to 3; c, g, i, k, m, and o, each independently, represent 1 or 2; and n and p, each independently, represent an integer of 1 to 6; in which, if c to p, each independently, are 2 or more, each of R 13  to each of R 25  may be the same or different. 
     In formula 1, X represents —O— or —S—. 
     In formula 1, L represents a single bond, a substituted or unsubstituted (C6-C30)arylene, or a substituted or unsubstituted (3- to 30-membered)heteroarylene. In one embodiment of the present disclosure. L represents a single bond, or a substituted or unsubstituted (C6-C15)arylene. In another embodiment of the present disclosure, L represents a single bond, or an unsubstituted (C6-C15)arylene. Specifically, L may represent a single bond, a phenylene, a naphthylene, a biphenylene, etc. 
     In formula 1, R 1  and R 2 , each independently, represent hydrogen, deuterium, a halogen, a cyano, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C3-C30)cycloalkyl, a substituted or unsubstituted (C3-C30)cycloalkenyl, a substituted or unsubstituted (3- to 7-membered)heterocycloalkyl, a substituted or unsubstituted (C6-C30)aryl, a substituted or unsubstituted (3- to 30-membered)heteroaryl, —NR 5 R 6 , or —SiR 7 R 8 R 9 ; or may be linked to an adjacent substituent to form a ring. In one embodiment of the present disclosure, R 1  and R 2 , each independently, represent hydrogen. 
     In formula 1, HAr represents a substituted or unsubstituted (7- to 30-membered)heteroaryl containing at least one nitrogen atom, with the proviso that the (7- to 30-membered)heteroaryl is not a carbazole, a benzocarbazole, a dibenzocarbazole, and an indolocarbazole, and, if -L-HAr is bonded to one of * positions in 
     
       
         
         
             
             
         
       
     
     HAr is not 
     
       
         
         
             
             
         
       
     
     in which Y represents N or CH, and R represents a substituted or unsubstituted hydroxyl, a substituted or unsubstituted thiol, a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (3- to 30-membered)heteroaryl. In one embodiment of the present disclosure, HAr represents a substituted or unsubstituted quinoxalinyl, a substituted or unsubstituted benzoquinoxalinyl, a substituted or unsubstituted quinazolinyl, a substituted or unsubstituted benzoquinazolinyl, a substituted or unsubstituted naphthyridinyl, or a substituted or unsubstituted pyridopyrazinyl. 
     In formulas 2-1 to 2-7, R 12  to R 25 , each independently, represent hydrogen, deuterium, a halogen, a cyano, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C3-C30)cycloalkyl, a substituted or unsubstituted (C3-C30)cycloalkenyl, a substituted or unsubstituted (3- to 7-membered)heterocycloalkyl, a substituted or unsubstituted (C6-C30)aryl, a substituted or unsubstituted (3- to 30-membered)heteroaryl, —NR 5 R 6 , or —SiR 7 R 8 R 9 , in which R 5  to R 9 , each independently, represent a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (3- to 30-membered)heteroaryl. 
     In one embodiment of the present disclosure, R 12  to R 25 , each independently, represent hydrogen, a substituted or unsubstituted (C6-C20)aryl, or a substituted or unsubstituted (5- to 15-membered)heteroaryl. In another embodiment of the present disclosure, R 12  to R 25 , each independently, represent hydrogen; a (C6-C20)aryl unsubstituted or substituted with at least one of a (C1-C6)alkyl, a (5- to 20-membered)heteroaryl, and di(C6-C12)arylamino; or a (5- to 15-membered)heteroaryl unsubstituted or substituted with at least one (C6-C12)aryl. Specifically, R 12  to R 25 , each independently, may represent hydrogen, a phenyl, a naphthyl, a biphenyl, a phenanthrenyl, a terphenyl, a triphenylenyl, a naphthylphenyl, a phenylnaphthyl, a dimethylfluorenyl, a dimethylbenzofluorenyl, a phenyl substituted with a phenylquinoxalinyl, a phenyl substituted with a carbazolyl, a phenyl substituted with a dibenzofuranyl, a phenyl substituted with a diphenylamino, a carbazolyl substituted with a phenyl, a dibenzofuranyl, etc. 
     In formula 1, a represents an integer of 1 to 4, and b represents an integer of 1 to 3. If a and b, each independently, are 2 or more, each of R 1  and each of R 2  may be the same or different. 
     In the formulas of the present disclosure, if adjacent substituents are linked to each other to form a ring, the ring may be a substituted or unsubstituted mono- or polycyclic (3- to 30-membered) alicyclic or aromatic ring, or the combination thereof, in which the formed ring may contain at least one heteroatom selected from nitrogen, oxygen, and sulfur. For example, the fused ring may be a substituted or unsubstituted dibenzothiophene ring, a substituted or unsubstituted dibenzofuran ring, a substituted or unsubstituted naphthalene ring, a substituted or unsubstituted phenanthrene ring, a substituted or unsubstituted fluorene ring, a substituted or unsubstituted benzothiophene ring, a substituted or unsubstituted benzofuran ring, a substituted or unsubstituted indole ring, a substituted or unsubstituted indene ring, a substituted or unsubstituted benzene ring, or a substituted or unsubstituted carbazole ring. 
     In the formulas of the present disclosure, the heteroaryl(ene), each independently, may contain at least one heteroatom selected from 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 (5- 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-(C6-C30)arylamino, and a substituted or unsubstituted (C1-C30)alkyl(C6-C30)arylamino. 
     The compound represented by formula 1 includes the following compounds, but is not limited thereto. 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     The compound of formula 1 according to the present disclosure may be prepared by a synthetic method known to one skilled in the art, and for example, as shown in the following reaction scheme, but is not limited thereto. 
     
       
         
         
             
             
         
       
     
     In reaction scheme 1, X, L, R 1 , R 2 , HAr, a, and b are as defined in formula 1. 
     The present disclosure provides an organic electroluminescent material comprising the organic electroluminescent compound represented by formula 1, and an organic electroluminescent device comprising the organic electroluminescent material. The material may consist of the organic electroluminescent compound according to the present disclosure alone, or may further comprise conventional materials included in the organic electroluminescent material. 
     In addition, the present disclosure provides a plurality of organic electroluminescent compounds comprising the compound represented by formula 1 and at least one organic electroluminescent compound. 
     The organic electroluminescent device according to the present disclosure comprises a first electrode, a second electrode, and at least one organic layer between the first and second electrodes, in which the organic layer may comprise at least one organic electroluminescent compound represented by formula 1. 
     One of the first and second electrodes may be an anode, and the other may be a 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. 
     The organic electroluminescent compound represented by formula 1 of the present disclosure may be comprised in at least one of a light-emitting layer, 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, preferably, may be comprised in a light-emitting layer. When used in the light-emitting layer, the organic electroluminescent compound represented by formula 1 of the present disclosure may be comprised as a host material. Preferably, the light-emitting layer may further comprise at least one dopant. If necessary, the organic electroluminescent compound of the present disclosure may be used as a co-host material. That is, the light-emitting layer may further include a compound other than the organic electroluminescent compound represented by formula 1 of the present disclosure (first host material) as a second host material. The weight ratio between the first host material and the second host material is in the range of 1:99 to 99:1. 
     The dopant comprised in the organic electroluminescent device of the present disclosure is at least one phosphorescent or fluorescent dopant, preferably at least one phosphorescent dopant. The phosphorescent dopant material applied to the organic electroluminescent device of the present disclosure is not particularly limited, but may be preferably selected from the metallated complex compounds of iridium (Ir), osmium (Os), copper (Cu), and platinum (Pt), more preferably selected from ortho-metallated complex compounds of iridium (Ir), osmium (Os), copper (Cu), and platinum (Pt), and even more preferably ortho-metallated iridium complex compounds. 
     The dopant comprised in the organic electroluminescent device of the present disclosure may comprise the compound represented by the following formula 101, but is not limited thereto. 
     
       
         
         
             
             
         
       
     
     In formula 101, L′ is selected from the following structures 1 and 2: 
     
       
         
         
             
             
         
       
     
     R 100  to R 103 , each independently, represent hydrogen, deuterium, a halogen, a (C1-C30)alkyl unsubstituted or substituted with a halogen, 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, to form a ring with the pyridine, e.g., a substituted or unsubstituted quinoline, a substituted or unsubstituted isoquinoline, 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, with the pyridine; 
     R 104  to R 107 , each independently, represent hydrogen, deuterium, a halogen, a (C1-C30)alkyl unsubstituted or substituted with a halogen, 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 to form a ring with the benzene, 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, with the benzene; 
     R 201  to R 211 , each independently, represent hydrogen, deuterium, a halogen, a (C1-C30)alkyl unsubstituted or substituted with a halogen, a substituted or unsubstituted (C3-C30)cycloalkyl, or a substituted or unsubstituted (C6-C30)aryl; or may be linked to an adjacent substituent to form a ring; and 
     n represents an integer of 1 to 3. 
     The specific examples of the dopant compound are as follows, but are not limited thereto. 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     According to one embodiment of the present disclosure, the organic electroluminescent device of the present disclosure may further comprise azine-based compounds besides the organic electroluminescent compound of the present disclosure as at least one of an electron transport material, an electron injection material, an electron buffer material, and a hole blocking material. 
     The organic layer may further comprise at least one compound selected from the group consisting of arylamine-based compounds and styrylarylamine-based compounds. 
     In addition, 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 d-transition elements of the Periodic Table, or at least one complex compound comprising said metal. 
     The organic electroluminescent device of the present disclosure may emit white light by further including at least one light-emitting layer containing a blue, red, or green light-emitting compound, which is known in the art, besides the organic electroluminescent compound of the present disclosure. In addition, it may further include a yellow or orange light-emitting layer, if necessary. 
     In the organic electroluminescent device of the present disclosure, at least one layer selected from a chalcogenide layer, a metal halide layer and a metal oxide layer (hereinafter, “a surface layer”) may be preferably placed on an inner surface(s) of one or both electrodes. 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. The surface layer may provide 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, or an electron blocking layer, or a combination thereof may be used between the anode and the light-emitting layer. The hole injection layer may be multilayers 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 multilayers may use two compounds simultaneously. The hole transport layer or the electron blocking layer may also be multilayers. 
     An electron buffer layer, a hole blocking layer, an electron transport layer, or 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 multilayers 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 multilayers may use two compounds simultaneously. The hole blocking layer or the electron transport layer may also be multilayers, wherein each of the multilayers 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 the 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 the electron transport, or for preventing the overflow of holes. In addition, 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 the 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 may block overflowing electrons from the light-emitting layer and confine the excitons in the light-emitting layer to prevent light 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 hole auxiliary layer and the electron blocking layer may have an effect of improving the efficiency and/or the lifespan of the organic electroluminescent device. 
     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 is preferably 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 an electroluminescent medium. Further, 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 electroluminescent 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. A reductive dopant layer may be employed as a charge-generating layer to prepare an organic electroluminescent device having two or more light-emitting layers, which emits white light. 
     In addition, the organic electroluminescent compound or the plurality of host materials according to the present disclosure may also be used in the 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, etc., or wet film-forming methods such as ink jet printing, spin coating, dip coating, flow coating, etc., can be used. 
     When using a wet film-forming method, a thin film can be formed by dissolving or diffusing the materials forming each layer into any suitable solvent such as ethanol, chloroform, tetrahydrofuran, dioxane, etc. The solvent is not specifically limited as long as the material forming each layer is soluble or dispersible in the solvents, which do not cause any problems in forming a film. 
     It is possible to produce a display system, e.g., a display system for smartphones, tablets, notebooks, PCs, TVs, or cars, or a lighting system, e.g., an outdoor or indoor lighting system, by using the organic electroluminescent device of the present disclosure. 
     Hereinafter, the preparation method of the compound of the present disclosure, and the properties thereof, and the luminous property of the organic electroluminescent device comprising the same will be explained in detail with reference to the representative compounds of the present disclosure. However, the present disclosure is not limited to the following examples. 
     Example 1: Preparation of Compound C-84 
     
       
         
         
             
             
         
       
     
     Synthesis of Compound 1 
     40.0 g of dibenzo[b,d]furan-1-yl boronic acid (189 mmol), 80.06 g of 1-bromo-4-iodobenzene (283 mmol), 10.90 g of Pd(PPh 3 ) 4  (9 mmol), 49.99 g of Na 2 CO 3  (472 mmol), and a mixed solvent of 550 mL of toluene, 200 mL of ethanol, and 200 mL of water were introduced into a flask, and the mixture was stirred under reflux at 150° C. for 2 hours. After completion of the reaction, the organic layer was extracted with ethyl acetate (EA) and dried with MgSO 4 . The residue was separated by column chromatography and methanol was added thereto. The resulting solid was filtered under reduced pressure to obtain 30.1 g of compound 1 (yield: 49.3%). 
     Synthesis of Compound 2 
     9.0 g of compound 1 (28 mmol), 10.61 g of 4,4,4′,4′,5,5,5′,5′-octamethyl-2,2′-bi(1,3,2-dioxaborolane) (42 mmol), 0.977 g of PdCl 2 (PPh 3 ) 2  (1 mmol), 6.832 g of KOAc (70 mmol), and 150 mL of 1,4-dioxane were introduced into a flask, and the mixture was stirred under reflux at 140° C. for 1 hour. After completion of the reaction, the organic layer was extracted with EA and dried with MgSO 4 . The residue was separated by column chromatography and methanol was added thereto. The resulting solid was filtered under reduced pressure to obtain 10.2 g of compound 2 (yield: 98.93%). 
     Synthesis of Compound C-84 
     2.50 g of 2,3-dichloroquinoxaline (13 mmol), 10.23 g of compound 2 (28 mmol), 1.451 g of Pd(PPh) 4  (1 mmol), 8.680 g of K 2 CO 3  (63 mmol), and a mixed solvent of 10 mL of toluene, 3 mL of ethanol, and 3 mL of water were introduced into a flask, and the mixture was stirred under reflux at 150° C. for 2 hours. After completion of the reaction, the organic layer was extracted with EA and dried with MgSO 4 . The residue was separated by column chromatography and methanol was added thereto. The resulting solid was filtered under reduced pressure to obtain 1.6 g of compound C-84 (yield: 20.0%). 
       1 H NMR (600 MHz, DMSO-d6, δ) 8.28 (dd, J=6.3, 3.4 Hz, 2H), 7.98 (dd, J=6.3, 3.4 Hz, 2H), 7.85-7.80 (m, 4H), 7.77 (dd, J=8.3, 0.9 Hz, 2H), 7.73-7.68 (m, 4H), 7.66 (d, J=8.1 Hz, 2H), 7.63 (dd, J=8.2, 7.4 Hz, 2H), 7.42 (dt, J=7.9, 0.9 Hz, 2H), 7.37 (dd, J=7.4, 0.9 Hz, 2H), 7.30 (ddd, J=8.4, 7.2, 1.3 Hz, 2H), 6.91 (td, J=7.6, 1.0 Hz, 2H) 
     
       
         
           
               
               
               
               
             
               
                   
                   
               
               
                   
                 Compound 
                 MW 
                 M.P. 
               
               
                   
                   
               
             
            
               
                   
                 C-84 
                 614.70 
                 231° C. 
               
               
                   
                   
               
            
           
         
       
     
     Example 2: Preparation of Compound C-3 
     
       
         
         
             
             
         
       
     
     8.38 g of compound 3 (20 mmol), 4.0 g of 2-chloro-3-phenylquinoxaline (17 mmol), 0.960 g of Pd(PPh 3 ) 4  (0.83 mmol), 6.89 g of K 2 CO 3  (50 mmol), and a mixed solvent of 50 mL of toluene, 20 mL of ethanol, and 20 mL of water were introduced into a flask, and the mixture was stirred under reflux at 140° C. for 2 hours. After completion of the reaction, the organic layer was extracted with EA and dried with MgSO 4 . The residue was separated by column chromatography and methanol was added thereto. The resulting solid was filtered under reduced pressure to obtain 3.2 g of compound C-3 (yield: 38.6%). 
       1 H NMR (600 MHz, DMSO-d6, δ) 8.34-8.29 (m, 1H), 8.25 (d, J=7.8 Hz, 1H), 8.04-7.95 (m, 2H), 7.87 (dd, J=8.3, 0.9 Hz, 1H), 7.76-7.69 (m, 4H), 7.62 (d, J=7.2 Hz, 1H), 7.54 (d, J=7.5 Hz, 2H), 7.48-7.39 (m, 4H), 7.37 (s, 1H), 7.30 (dt, J=26.1, 7.6 Hz, 3H), 7.19 (s, 1H), 7.03 (t, J=7.5 Hz, 1H) 
     
       
         
           
               
               
               
               
             
               
                   
                   
               
               
                   
                 Compound 
                 MW 
                 M.P. 
               
               
                   
                   
               
             
            
               
                   
                 C-3 
                 498.59 
                 245° C. 
               
               
                   
                   
               
            
           
         
       
     
     Example 3: Preparation of Compound C-29 
     
       
         
         
             
             
         
       
     
     Synthesis of Compound 1 
     80.0 g of dibenzo[b,d]furan-1-yl boronic acid (377 mmol), 60.13 g of 1-bromo-4-iodobenzene (566 mmol), 21.80 g of Pd(PPh 3 ) 4  (19 mmol), 99.99 g of Na 2 CO 3  (943 mmol), and a mixed solvent of 550 mL of toluene, 200 mL of ethanol, and 200 mL of water were introduced into a flask, and the mixture was stirred under reflux at 150° C. for 2.5 hours. After completion of the reaction, the organic layer was extracted with EA and dried with MgSO 4 . The residue was separated by column chromatography and methanol was added thereto. The resulting solid was filtered under reduced pressure to obtain 51.8 g of compound 1 (yield: 42.5%). 
     Synthesis of Compound 2 
     30.0 g of compound 1 (93 mmol), 35.4 g of 4,4,4′,4′,5,5,5′,5′-octamethyl-2,2′-bi(1,3,2-dioxaborolane) (139 mmol), 3.26 g of PdCl 2 (PPh 3 ) 2  (5 mmol), 22.77 g of KOAc (232 mmol), and 150 mL of 1,4-dioxane were introduced into a flask, and the mixture was stirred under reflux at 140° C. for 1 hour. After completion of the reaction, the organic layer was extracted with EA and dried with MgSO 4 . The residue was separated by column chromatography and methanol was added thereto. The resulting solid was filtered under reduced pressure to obtain 23.3 g of compound 2 (yield: 67.8%). 
     Synthesis of Compound C-29 
     4.28 g of 6-chloro-2,4-diphenylquinazoline (14 mmol), 6.00 g of compound 2 (16 mmol), 0.780 g of Pd(PPh 3 ) 4  (0.675 mmol), 4.67 g of K 2 CO 3  (34 mmol), and a mixed solvent of 40 mL of toluene, 15 mL of ethanol, and 15 mL of water were introduced into a flask, and the mixture was stirred under reflux at 150° C. for 2 hours. After completion of the reaction, the organic layer was extracted with EA and dried with MgSO 4 . The residue was separated by column chromatography, and methanol was added thereto. The resulting solid was filtered under reduced pressure to obtain 4.3 g of compound C-29 (yield: 60.7%). 
       1 H NMR (600 MHz, DMSO-d6, δ) 8.69-8.64 (m, 2H), 8.54 (dd, J=8.7, 2.0 Hz, 1H), 8.42 (d, J=2.0 Hz, 1H), 8.31 (d, J=8.7 Hz, 1H), 8.03 (dd, J=21.1, 7.3 Hz, 4H), 7.83-7.69 (m, 7H), 7.66-7.56 (m, 5H), 7.51 (t, J=7.7 Hz, 1H), 7.37 (d, J=7.4 Hz, 1H), 7.25 (t, J=7.6 Hz, 1H) 
     
       
         
           
               
               
               
               
             
               
                   
                   
               
               
                   
                 Compound 
                 MW 
                 M.P. 
               
               
                   
                   
               
             
            
               
                   
                 C-29 
                 524.62 
                 242° C. 
               
               
                   
                   
               
            
           
         
       
     
     Example 4: Preparation of Compound C-20 
     
       
         
         
             
             
         
       
     
     4.28 g of 6-chloro-2,3-diphenylquinoxaline (14 mmol), 6.00 g of 2-(4-dibenzo[b,d]furan-1-yl)phenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (16 mmol), 0.618 g of Pd 2 (dba) 3  (0.83 mmol), 0.554 g of 2-dichlorohexylphosphin-2′,6′-dimethoxybiphenyl (sphos) (1 mmol), 3.24 g of NaOt-Bu (34 mmol), and 70 mL of o-xylene were introduced into a flask, and the mixture was stirred under reflux at 140° C. for 2 hours. After completion of the reaction, the organic layer was extracted with EA and dried with MgSO 4 . The residue was separated by column chromatography and methanol was added thereto. The resulting solid was filtered under reduced pressure to obtain 4.6 g of compound C-20 (yield: 64.9%). 
       1 H NMR (600 MHz, DMSO-d6, δ) 8.59 (d, J=2.1 Hz, 1H), 8.41 (dd, J=8.7, 2.1 Hz, 1H), 8.30 (d, J=8.7 Hz, 1H), 8.21 (d, J=8.2 Hz, 2H), 7.87-7.83 (m, 2H), 7.81-7.74 (m, 2H), 7.68-7.62 (m, 2H), 7.57-7.50 (m, 5H), 7.45-7.36 (m, 7H), 7.27 (t, J=7.6 Hz, 1H) 
     
       
         
           
               
               
               
               
             
               
                   
                   
               
               
                   
                 Compound 
                 MW 
                 M.P. 
               
               
                   
                   
               
             
            
               
                   
                 C-20 
                 524.62 
                 225° C. 
               
               
                   
                   
               
            
           
         
       
     
     Device Examples 1 to 4: Producing an OLED Deposited with a Compound According to the Present Disclosure as a Host 
     An OLED comprising a compound according to the present disclosure was produced as follows: 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, ethanol, and distilled water, sequentially, and then was stored in isopropanol. The ITO substrate was 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 the pressure in the chamber of the apparatus was then controlled to 10 −8  torr. Thereafter, an electric current was applied to the cell to evaporate the above-introduced material, thereby forming a first hole injection layer having a thickness of 80 nm on the ITO substrate. Next, compound HI-2 was 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 injection layer having a thickness of 5 nm on the first hole injection layer. Compound HT-1 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 first hole transport layer having a thickness of 10 nm on the second hole injection layer. 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 layers and the hole transport layers, a light-emitting layer was formed thereon as follows: The compound shown in Table 1 was introduced into one cell of the vacuum vapor depositing apparatus as a host, and compound D-39 was introduced into another cell as a dopant. The two materials were evaporated at different rates and the dopant was deposited in a doping amount of 3 wt % based on the total amount of the host and 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 were evaporated at a rate of 1:1 in two other cells to deposit 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. 
     Comparative Example 1: Producing an OLED Deposited with a Conventional Compound as a Host 
     An OLED was produced in the same manner as in Device Example 1, except that compound X shown in Table 2 was used as the host. 
     The results such as luminous efficiency, luminance, etc., of the produced OLEDs are provided in Table 1 below. 
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                 Lumunous 
                   
                 Light- 
               
               
                   
                   
                 Efficiency 
                 Luminance 
                 Emitting 
               
               
                   
                 Host 
                 (cd/A) 
                 (nit) 
                 Color 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 Device Example 1 
                 C-3 
                 28.5 
                 1000 
                 Red 
               
               
                 Device Example 2 
                 C-84 
                 27.2 
                 1000 
                 Red 
               
               
                 Device Example 3 
                 C-29 
                 25.8 
                 1000 
                 Red 
               
               
                 Device Example 4 
                 C-20 
                 23.2 
                 1000 
                 Red 
               
               
                 Comparative 
                 X 
                 17.0 
                 1000 
                 Red 
               
               
                 Example 1 
               
               
                   
               
            
           
         
       
     
     The times taken to be reduced from 100% to 50% of the luminance (lifespan; T50) based on a luminance of 5,000 nit in Device Example 3 and Comparative Example 1 were 178 hours and 137 hours, respectively. 
     It can be seen from Device Examples 1 to 4 and Comparative Example 1 that the OLED produced by using the organic electroluminescent compound according to the present disclosure as a host exhibited higher luminous efficiency and/or longer lifespan property than the OLED produced by using the conventional organic electroluminescent compound as a host. 
     The compounds used in the Device Examples and the Comparative Example are shown in Table 2 below. 
     
       
         
           
               
               
             
               
                 TABLE 2 
               
               
                   
               
             
            
               
                 Hole Injection Layer/ Hole Transport Layer 
                 
                   
                     
                     
                         
                         
                     
                   
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                 Light-Emitting Layer 
                 
                   
                     
                     
                         
                         
                     
                   
                   
                     
                     
                         
                         
                     
                   
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                   
                     
                     
                         
                         
                     
                   
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                 Electron Transport Layer/ Electron Injection Layer