Light-emitting device comprising semiconductor nanocrystal layer free of voids and method for producing the same

Abstract

A light-emitting device including a semiconductor nanocrystal layer and a method for producing the light-emitting device are provided. The light-emitting device includes a semiconductor nanocrystal layer whose voids are filled with a filling material. According to the light-emitting device, since voids formed between nanocrystal particles of the semiconductor nanocrystal layer are filled with a filling material, the occurrence of a current leakage through the voids is minimized, which enables the device to have extended service life, high luminescence efficiency, and improved stability.

1 . A light-emitting device, comprising: 
 a first electrode;    a second electrode arranged opposite to the first electrode; and    a semiconductor nanocrystal layer positioned between the first and second electrodes,    wherein voids formed between nanocrystal particles of the semiconductor nanocrystal layer are filled with a filling material.    
     
     
         2 . The light-emitting device of  claim 1 , wherein the first electrode is a hole injecting electrode and the second electrode is an electron injecting electrode.  
     
     
         3 . The light-emitting device according to  claim 1 , further comprising a hole transport layer in contact with the first electrode and an electron transport layer in contact with the second electrode.  
     
     
         4 . The light-emitting device according to  claim 3 , wherein the semiconductor nanocrystal layer includes a material selected from Group II-VI compounds, Group III-V compounds, Group IV-VI compounds, Group IV compounds, and mixtures thereof.  
     
     
         5 . The light-emitting device according to  claim 3 , wherein the semiconductor nanocrystal layer further includes an overcoating made of at least one material selected from Group II-VI compounds, Group III-V compounds, Group IV-VI compounds, Group IV compounds, and mixtures thereof.  
     
     
         6 . The light-emitting device according to  claim 3 , wherein the filling material is an inorganic or organic insulating material.  
     
     
         7 . The light-emitting device according to  claim 3 , wherein the filling material has a resistivity of 10 4  Ω·cm or more.  
     
     
         8 . The light-emitting device according to  claim 3 , wherein the semiconductor nanocrystal layer has a monolayer structure in which the nanocrystal particles are arranged in a single layer.  
     
     
         9 . The light-emitting device according to  claim 3 , wherein the hole transport layer is composed of material selected from the group consisting of poly(3,4-ethylenedioxythiophene (PEDOT)/polystyrene parasulfonate (PSS) derivatives, poly-N-vinylcarbazole derivatives, polyphenylenevinylene derivatives, polyparaphenylene derivatives, polymethaacrylate derivatives, poly(9,9-octylfluorene) derivatives, poly(spiro-fluorene) derivatives, N,N′-diphenyl-N,N′-bis 3-methylphenyl-1,1′-biphenyl-4,4′-diamine(TPD), N,N′-di(naphthalen-1-yl)-N—N′-diphenyl-benzidine, tris(3-methylphenylphenylamino)-triphenylamine (m-MTDATA), poly 9,9′-dioctylfluorene-co-N-(4-butylphenyl)diphenylamine (TFB), copper phthalocyanine, metal oxides, including TiO 2 , ZnO, SiO 2 , SnO 2 , WO 3 , ZrO 2 , HfO 2 , Ta 2 O 5 , BaTiO 3 , BaZrO 3 , Al 2 O 3 , Y 2 O 3  and ZrSiO 4 , and semiconductors having a bandgap of 2.4 eV or higher, including CdS, ZnSe and ZnS.  
     
     
         10 . The light-emitting device according to  claim 3 , wherein the electron transport layer is composed of a material selected from the group consisting of oxazole compounds, isooxazole compounds, triazole compounds, isothiazole compounds, oxidiazole compounds, thiadiazole compounds, perylene compounds, aluminum complexes, metal oxides, including TiO 2 , ZnO, SiO 2 , SnO 2 , WO 3 , ZrO 2 , HfO 2 , Ta 2 O 5 , BaTiO 3 , BaZrO 3 , Al 2 O 3 , Y 2 O 3  and ZrSiO 4 , and semiconductors having a bandgap 2.4 eV or higher, such as CdS, ZnSe and ZnS.  
     
     
         11 . The light-emitting device according to  claim 1 , wherein the semiconductor nanocrystal layer includes a material selected from Group II-VI compounds, Group III-V compounds, Group IV-VI compounds, Group IV compounds, and mixtures thereof.  
     
     
         12 . The light-emitting device according to  claim 11 , wherein the Group II-VI compounds are selected from the group consisting of binary compounds, including CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe and HgTe, ternary compounds, including CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgznS and HgznSe, and quaternary compounds, including CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe; the Group III-V compounds are selected from the group consisting of binary compounds, including GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs and InSb, ternary compounds, including GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb and GaAlNP, and quaternary compounds, including GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs and InAlPSb; the Group IV-VI compounds are selected from the group consisting of binary compounds, including SnS, SnSe, SnTe, PbS, PbSe and PbTe, ternary compounds, including SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe and SnPbTe, and quaternary compounds, including SnPbSSe, SnPbSeTe and SnPbSTe; and the Group IV compounds are selected from the group consisting of unary compounds, including Si and Ge, and binary compounds, including SiC and SiGe.  
     
     
         13 . The light-emitting device according to  claim 1 , wherein the semiconductor nanocrystal layer further includes an overcoating made of at least one material selected from Group II-VI compounds, Group III-V compounds, Group IV-VI compounds, Group IV compounds, and mixtures thereof.  
     
     
         14 . The light-emitting device according to  claim 13 , wherein the Group II-VI compounds are selected from the group consisting of binary compounds, including CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe and HgTe, ternary compounds, including CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgznS and HgZnSe, and quaternary compounds, including CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe; the Group III-V compounds are selected from the group consisting of binary compounds, including GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs and InSb, ternary compounds, including GANP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb and GaAlNP, and quaternary compounds, including GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs and InAlPSb; the Group IV-VI compounds are selected from the group consisting of binary compounds, including SnS, SnSe, SnTe, PbS, PbSe and PbTe, ternary compound, including SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe and SnPbTe, and quaternary compound, including SnPbSSe, SnPbSeTe and SnPbSTe, and the Group IV compounds are selected from the group consisting of unary compounds, including Si and Ge, and binary compounds, including SiC and SiGe.  
     
     
         15 . The light-emitting device according to  claim 1 , wherein the filling material is an inorganic or organic insulating material.  
     
     
         16 . The light-emitting device according to  claim 15 , wherein the inorganic insulating material is at least one material selected from the group consisting of metal oxides, including TiO 2 , ZnO, SiO 2 , SnO 2 , WO 3 , ZrO 2 , HfO 2 , Ta 2 O 5 , BaTiO 3 , BaZrO 3 , Al 2 O 3 , Y 2 O 3  and ZrSiO 4 , Si 3 N 4 , and TiN; and the organic insulating material is at least one material selected from the group consisting of polymers, including epoxy resins and phenolic resins, 3-(4-biphenylyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole (TAZ), 3,4,5-triphenyl-1,2,4-triazole, and 3,5-bis(4-tert-butylphenyl)-4-phenyl-1,2,4-triazole.  
     
     
         17 . The light-emitting device according to  claim 1 , wherein the filling material has a resistivity of 10 4  Ω≠cm or more.  
     
     
         18 . The light-emitting device according to  claim 1 , wherein the semiconductor nanocrystal layer has a monolayer structure in which the nanocrystal particles are arranged in a single layer.  
     
     
         19 . The light-emitting device according to  claim 1 , wherein the semiconductor nanocrystal layer has a multilayer structure comprising a plurality of monolayers, each monolayer having a plurality of the nanocrystal particles arranged in a single layer.  
     
     
         20 . The light-emitting device according to  claim 1 , wherein the first electrode is composed of at least one material selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), nickel (Ni), platinum (Pt), gold (Au), silver (Ag), iridium (Ir), and oxides thereof.  
     
     
         21 . The light-emitting device according to  claim 1 , wherein the second electrode is composed of at least one material selected from the group consisting of I, Ca, Ba, Ca/Al, LiF/Ca, BaF 2 /Al, BaF 2 /Ca/Al, Al, Mg, and Ag/Mg alloys.  
     
     
         22 . An illuminatable device comprising: 
 a light-emitting device, the light emitting device including    a first electrode;    a second electrode arranged opposite to the first electrode; and    a semiconductor nanocrystal layer positioned between the first and second electrodes,    wherein voids formed between nanocrystal particles of the semiconductor nanocrystal layer are filled with a filling material.    
     
     
         23 . The device of  claim 22 , wherein the device is a display device.  
     
     
         24 . The device of  claim 22 , wherein the device is an illuminator  
     
     
         25 . The device of  claim 22 , wherein the device is a backlight unit  
     
     
         26 . A method for producing a light-emitting device having a semiconductor nanocrystal layer positioned between a pair of electrodes, the method comprising filling voids of the semiconductor nanocrystal layer with a filling material.  
     
     
         27 . The method according to  claim 26 , wherein filling voids includes mixing a semiconductor nanocrystal and a filling material to form the semiconductor nanocrystal layer.  
     
     
         28 . The method according to  claim 26 , wherein filling voids includes filling voids formed between semiconductor nanocrystal particles in the semiconductor nanocrystal layer with a filling material by surfactant pretreatment.  
     
     
         29 . The method according to  claim 26 , wherein filling voids includes preparing a semiconductor nanocrystal, and then filling with a filling material.  
     
     
         30 . The method according to  claim 29 , wherein filling with a filling material includes physical vapor deposition or chemical vapor deposition.  
     
     
         31 . The method according to  claim 26 , further comprising selecting a filling material to be an inorganic or organic insulating material.  
     
     
         32 . The method according to  claim 31 , wherein the inorganic insulating material is a material selected from the group consisting of metal oxides, including TiO 2 , ZnO, SiO 2 , SnO 2 , WO 3 , ZrO 2 , HfO 2 , Ta 2 O 5 , BaTiO 3 , BaZrO 3 , Al 2 O 3 , Y 2 O 3  and ZrSiO 4 , Si 3 N 4 , and TiN; and the organic insulating material is a material selected from the group consisting of polymers, including epoxy resins and phenolic resins, 3-(4-biphenylyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole (TAZ), 3,4,5-triphenyl-1,2,4-triazole, and 3,5-bis(4-tert-butylphenyl)-4-phenyl-1,2,4-triazole.  
     
     
         33 . The method according to  claim 26 , further comprising selecting a filling material having a resistivity of 10 4  Ω·cm or more.  
     
     
         34 . A semiconductor nanocrystal layer having a monolayer structure, the semiconductor nanocrystal layer comprising: 
 a plurality of nanocrystal particles arranged in a single layer; and,    a filling material filling voids between the nanocrystal particles.    
     
     
         35 . The semiconductor nanocrystal layer of  claim 34 , wherein a height of the filling material is substantially same as a height of the nanocrystal particles.  
     
     
         36 . The semiconductor nanocrystal layer of  claim 34 , wherein a surface of the semiconductor nanocrystal layer is substantially uniform to improve interfacing with adjacent layers.