Electronic device, method for preparing the same and display device comprising the same

Abstract

The present invention relates to an electronic device comprising at least one layer comprising a borate salt, wherein the borate salt is comprised in the layer comprising the borate salt In an amount, by weight and/or by volume, exceeding the total amount of other components which may additionally be comprised in the layer, a display device comprising the same and a method for preparing the same.

Claims

1. Electronic device comprising at least one layer comprising a borate salt, wherein the electronic device further comprises a first electrode and a second electrode, and the at least one layer comprising the borate salt is arranged between the first electrode and the second electrode, wherein the borate salt is comprised in the layer comprising the borate salt in an amount, by weight and/or by volume, exceeding the total amount of other components which may additionally be comprised in the layer, wherein the borate salt is a metal borate salt, wherein the metal borate salt comprises a metal atom that is positively charged, wherein the layer comprising the borate salt is a charge injection layer, a charge generation layer, or a charge transport layer, and wherein the charge injection layer is a hole injection layer, the charge generation layer is a hole generation layer, and/or the charge transport layer is a hole transport layer, wherein the layer comprising the borate salt comprises the borate salt in an amount of at least 75 wt % with respect to the total weight of the layer comprising the borate salt.

2. Electronic device according to claim 1, wherein the borate salt is comprised in the layer comprising the borate salt in an amount, by weight and by volume, exceeding the total amount of other components which may additionally be comprised in the layer.

3. Electronic device according to claim 1, wherein the metal borate salt consists of at least one metal cation and at least one anionic ligand, wherein the anionic ligand consists of at least six covalently bound atoms and at least one of these covalently bound atoms is a boron atom.

4. Electronic device according to claim 3, wherein the anionic ligand consists of at least 7 covalently bound atoms.

5. Electronic device according to claim 1, wherein the metal borate salt comprises a metal selected from the group consisting of Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, Ba, Al, Ga, In, Tl, Sn, Pb, Bi, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Th, U, and mixtures thereof.

6. Electronic device according to claim 1, wherein the borate salt comprises an anion having the following formula (I): ##STR00023## wherein each of A.sup.1 to A.sup.4 is independently selected from (i) H, (ii) F, (iii) CN, (iv) C.sub.6-C.sub.60 aryl, (v) C.sub.7-C.sub.60 arylalkyl, (vi) C.sub.1-C.sub.60 alkyl, (vii) C.sub.2-C.sub.60 alkenyl, (viii) C.sub.2-C.sub.60 alkynyl, (ix) C.sub.3-C.sub.60 cycloalkyl and (x) C.sub.2-C.sub.60 heteroaryl; wherein the groups (iv), (v), (vi), (vii), (viii), (ix) and (x) may be substituted with at least one substituent of the group consisting of F, Cl, Br, I, CN, unsubstituted or halogenated alkyl, unsubstituted or halogenated (hetero)aryl, unsubstituted or halogenated (hetero)arylalkyl, unsubstituted or halogenated alkylsulfonyl, unsubstituted or halogenated (hetero)arylsulfonyl, unsubstituted or halogenated (hetero)arylalkylsulfonyl, unsubstituted or halogenated boron-containing hydrocarbyl, and unsubstituted and halogenated silicon-containing hydrocarbyl, wherein the overall number of carbon atoms in each of the groups (iv), (v), (vi), (vii), (viii), (ix) and (x) does not exceed 60, respectively.

7. Electronic device according to claim 6, wherein at least one of A.sup.1 to A.sup.4 is selected from the group consisting of F, CN, hydrocarbyl, boron-containing hydrocarbyl, silicon-containing hydrocarbyl and heteroaryl, wherein 50% or more of the hydrogen atoms comprised in the respective hydrocarbyl, boron-containing hydrocarbyl, silicon-containing hydrocarbyl and heteroaryl is replaced by one of the group consisting of F, Cl, Br, I and CN.

8. Electronic device according to claim 1, wherein the electronic device is an electroluminescent device.

9. Display device comprising the electronic device according to claim 8.

10. Method for preparing an electronic device according to claim 1, the method comprising the steps: evaporating a borate salt at an elevated temperature and, optionally, at a reduced pressure; and (ii) depositing the evaporated borate salt on a substrate.

11. Electronic device according to claim 3, wherein the anionic ligand consists of at least 9 covalently bound atoms.

12. Electronic device according to claim 3, wherein the anionic ligand consists of at least 12 covalently bound atoms.

13. Electronic device according to claim 1, wherein the layer comprising the borate salt comprises the borate salt in an amount of at least 90 wt % with respect to the total weight of the layer comprising the borate salt.

14. Electronic device according to claim 1, wherein the layer comprising the borate salt comprises the borate salt in an amount of at least 98 wt % with respect to the total weight of the layer comprising the borate salt.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and/or other aspects and advantages of the present invention will become apparent and more readily appreciated from the following description of the exemplary embodiments, taken in conjunction with the accompanying drawings, of which:

(2) FIG. 1 is a schematic sectional view of an organic light-emitting diode (OLED), according to an exemplary embodiment of the present invention;

(3) FIG. 2 is a schematic sectional view of an OLED, according to an exemplary embodiment of the present invention.

(4) FIG. 3 is a schematic sectional view of a tandem OLED comprising a charge generation layer, according to an exemplary embodiment of the present invention.

EMBODIMENTS OF THE INVENTIVE DEVICE

(5) Reference will now be made in detail to the exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The exemplary embodiments are described below, in order to explain the aspects of the present invention, by referring to the figures.

(6) Herein, when a first element is referred to as being formed or disposed “on” a second element, the first element can be disposed directly on the second element, or one or more other elements may be disposed there between. When a first element is referred to as being formed or disposed “directly on” a second element, no other elements are disposed there between.

(7) FIG. 1 is a schematic sectional view of an organic light-emitting diode (OLED) 100, according to an exemplary embodiment of the present invention. The OLED 100 includes a substrate 110, an anode 120, a hole injection layer (HIL) 130, a hole transport layer (HTL) 140, an emission layer (EML) 150, an electron transport layer (ETL) 160. The electron transport layer (ETL) 160 is formed directly on the EML 150. Onto the electron transport layer (ETL) 160, an electron injection layer (EIL) 180 is disposed. The cathode 190 is disposed directly onto the electron injection layer (EIL) 180.

(8) Instead of a single electron transport layer 160, optionally an electron transport layer stack (ETL) can be used.

(9) FIG. 2 is a schematic sectional view of an OLED 100, according to another exemplary embodiment of the present invention. FIG. 2 differs from FIG. 1 in that the OLED 100 of FIG. 2 comprises an electron blocking layer (EBL) 145 and a hole blocking layer (HBL) 155.

(10) Referring to FIG. 2, the OLED 100 includes a substrate 110, an anode 120, a hole injection layer (HIL) 130, a hole transport layer (HTL) 140, an electron blocking layer (EBL) 145, an emission layer (EML) 150, a hole blocking layer (HBL) 155, an electron transport layer (ETL) 160, an electron injection layer (EIL) 180 and a cathode electrode 190.

(11) FIG. 3 is a schematic sectional view of a tandem OLED 200, according to another exemplary embodiment of the present invention. FIG. 3 differs from FIG. 2 in that the OLED 100 of FIG. 3 further comprises a charge generation layer and a second emission layer.

(12) Referring to FIG. 3, the OLED 200 includes a substrate 110, an anode 120, a first hole injection layer (HIL) 130, a first hole transport layer (HTL) 140, a first electron blocking layer (EBL) 145, a first emission layer (EML) 150, a first hole blocking layer (HBL) 155, a first electron transport layer (ETL) 160, an n-type charge generation layer (n-type CGL) 185, a hole generating layer (p-type charge generation layer; p-type GCL) 135, a second hole transport layer (HTL) 141, a second electron blocking layer (EBL) 146, a second emission layer (EML) 151, a second hole blocking layer (EBL) 156, a second electron transport layer (ETL) 161, a second electron injection layer (EIL) 181 and a cathode 190.

(13) While not shown in FIG. 1, FIG. 2 and FIG. 3, a sealing layer may further be formed on the cathode electrodes 190, in order to seal the OLEDs 100 and 200. In addition, various other modifications may be applied thereto.

(14) Hereinafter, one or more exemplary embodiments of the present invention will be described in detail with, reference to the following examples. However, these examples are not intended to limit the purpose and scope of the one or more exemplary embodiments of the present invention.

EXPERIMENTAL PART

Lithium tris(4,5,6,7-tetrafluoro-3-(trifluoromethyl)-1H-indazol-1-yl)hydroborate (PB-1)

Step 1: 4,5,6,7-tetrafluoro-3-(trifluoromethyl)-1H-indazole

(15) ##STR00009##

(16) 11.09 g (45.1 mmol) perfluoroacetophenone is dissolved in 100 mL toluene. The solution is cooled with an ice bath and 2.3 mL (2.37 g, 47.3 mmol, 1.05 eq) hydrazine-monohydrate is added dropwise. The mixture is heated to reflux for 3 days. After cooling to room temperature, the mixture is washed two times with 100 mL saturated aqueous sodium hydrogen carbonate solution and two times with 100 mL water, dried over magnesium sulfate and the solvent is removed under reduced pressure. The yellow, oily residue is distilled from bulb to bulb at a temperature about 140° C. and pressure about 12 Pa. The crude product is dissolved in hot hexane and the solution stored at −18° C. The precipitated solid is filtered off and the slurry washed two times in to mL hexane. 5.0 g (43%) product is obtained as a slightly yellow solid.

(17) GCMS: confirms the expected M/z (mass/charge) ratio 258

Step 2: lithium tris(4,5,6,7-tetrafluoro-3-(trifluromethyl)-1H-indazol-1-yl)hydroborate

(18) ##STR00010##

(19) 5.1 g (19.8 mmol) 4,5,6,7-tetrafluoro-3-(trifluoromethyl)-1H-indazole is added under Ar counter-flow to an out-baked Schlenk flask and treated with 3 mL toluene. Freshly pulverized lithium borohydride is added to the starting material. The mixture is heated to 100° C., until hydrogen formed ceases (ca. 4 h). After slight cooling, 15 mL hexane are added, the mixture is heated to reflux for 10 min and cooled to room temperature. The precipitated solid is filtered off, washed with 10 mL hot hexane and dried in high vacuum. 2.55 g (49%) product is obtained as an off-white solid.

Lithium tris(3,5-bis(trifluoromethyl)-1H-pyrazol-1-yl)hydroborate (PB-2)

(20) ##STR00011##

(21) 2.0 g (9.8 mmol, 5 eq) 3,5-bis(trifluoromethyl)pyrazole in a baked-out Schlenk flask is dissolved in 5 mL dry toluene. 43 mg (1.96 mmol, 1 eq) freshly pulverized lithium borohydride is added under Ar counter-flow and the mixture is heated to reflux for 3 days. The solvent and excess starting material are removed by distillation under reduced pressure and the residue is crystallized from n-chlorohexane. 0.25 g (20%) product is obtained as a white solid.

Lithium tris(4,5,6,7-tetrafluoro-3-(perfluorophenyl)-1H-indazol-1-yl)hydroborate (PB-3)

Step 1: 4,5,6,7-tetrafluoro-3-(perfluorophenyl)-1H-indazole

(22) ##STR00012##

(23) 20.0 g (54.8 mmol) perfluorobenzophenone are dissolved in 200 mL toluene. 4.0 mL (4.11 g, 82.1 mmol, ca. 1.5 eq) hydrazine-monohydrate is added dropwise to the ice-cooled solution. 40 g sodium sulfate are added and the mixture is heated to reflux for 2 days. After cooling, 10 mL acetone are added to the reaction mixture and the resulting slurry is stirred for 1 h at room temperature. The solid is filtered off, thoroughly washed with 4×50 mL toluene, organic fractions are combined and washed two times with saturated aqueous sodium hydrogen carbonate. The solvent is removed under reduced pressure and the residue purified by column chromatography. 7.92 g (41%) product are obtained as a pale yellow solid.

(24) GC-MS: confirms the expected M/z (mass/charge) ratio 356

Step 2: lithium tris(4,5,6,7-tetrafluoro-3-(perfluorophenyl)-1H-indazol-1-yl)hydroborate

(25) ##STR00013##

(26) 1.02 g (2.86 mmol, 3.0 eq) 4,5,6,7-tetrafluoro-3-(perfluorophenyl)-1H-indazole are dissolved in 5 mL chlorobenzene in a baked-out Schlenk flask. Freshly pulverized lithium borohydride (21 mg, 0.95 mmol, 1.0 eq) is added under Ar counter-flow. The mixture is heated to 150° C. for 2 days and cooled to room temperature. The solvent is removed under reduced pressure and the residue dried in high vacuum. The crude is further purified by drying in a bulb to bulb apparatus at a temperature about 150° C. and a pressure about 12 Pa. 0.57 g (70%) product is obtained as an off white solid.

Lithium tris(3-cyano-5,6-difluoro-1H-indazol-1-yl)hydroborate (PB-4)

(27) ##STR00014##

(28) Freshly pulverized lithium borohydride (15 mg, 0.7 mmol, 1.0 eq) is placed in a baked-out pressure tube, 0.5 g (2.79 mmol, 4.0 eq) 5,6-difluoro-1H-indazole-3-carbonitrile are added under Ar counter-flow and washed down with 1 mL toluene. The pressure tube is closed and heated to a temperature about 160° C. for ca 21 h. After cooling to room temperature, the mixture is treated with 5 mL hexane in an ultra-sonic bath for ca 30 min. The precipitated solid is filtered off and washed with hexane (20 mL in total). After drying, 0.48 g yellowish solid is obtained.

Zinc(II) tris(3,5-bis(trifluoromethyl)-1H-pyrazol-1-yl)hydroborate (PB-5)

(29) ##STR00015##

(30) 0.57 g (0.91 mmol) lithium tris(3,5-bis(trifluoromethyl)-1H-pyrazol-1-yl)hydroborate is dissolved in 6 mL N,N-dimethyl formamide. An aqueous solution of 62 mg zinc dichloride in 1 mL water is added dropwise. 20 mL water is further added and the mixture is treated in an ultra-sonic bath for 2 h. The precipitate is filtered off and dried in high vacuum, 0.485 g (82%) product is obtained as a white solid.

DEVICE EXAMPLES

Example 1 (Tandem OLED, Model for Bottom Emitting White OLED Pixel)

(31) On a glass substrate provided with an ITO anode having thickness 90 nm, there were subsequently deposited 10 nm hole injection layer made of F1 doped with 8 wt % PD-2; 140 nm thick undoped hole transport layer made of neat F1; 20 nm thick first emitting layer formed of ABH113 doped with 3 wt % BD200 (both supplied by SFC, Korea); 25 nm thick first electron transport layer made of neat F2; 10 nm thick electron-generating part of the charge-generating layer (n-CGL) made of F3 doped with 5 wt % Yb; 2 nm thick interlayer made of F4; 30 nm thick hole-generating part of the charge-generating layer (p-CGL) made of PB-1; 10 nm thick second hole transport layer made of neat F1; 20 nm second emitting layer of the same thickness and composition as the first emitting layer; 25 nm thick first electron transport layer made of neat F2; 10 nm thick electron injection layer (EIL) made of F3 doped with 5 wt % Yb; 100 nm A.sup.1 cathode.

(32) All layers were deposited by vacuum thermal evaporation (VTE).

(33) At the current density 10 mA/cm.sup.2, the operational voltage of the device 8 V and the observed luminance were well comparable with the same device comprising a commercial state-of-art p-dopant instead of PB-1. An accurate calibration necessary for efficiency evaluation was omitted within this preliminary experiment.

Example 2 (Bottom Emitting Blue OLED Pixel)

(34) On the same glass substrate provided with an ITO anode as in the Example 1, following layers were subsequently deposited by VTE: to nm hole injection layer made of the compound PB-1; 120 nm thick HTL made of neat F1; 20 nm EML made of ABH113 doped with 3 wt % NUBD370 (both supplied by SFC, Korea), 36 nm EIL/ETL made of F2 doped with 50 wt % LiQ; 100 nm Al cathode.

(35) Comparative device comprised the HIL made of the compound CN-HAT (CAS 105598-27-4) instead of PB-1.

(36) The inventive device achieved current density 15 mA/cm.sup.2 and EQE 5.4% at a voltage 5.2 V, whereas the comparative device operated at 5.4 V with EQE 4-9%.

(37) TABLE-US-00001 TABLE 1 auxiliary materials Compound Structure F1 (CAS 1242056-42-3) F2 (CAS 1440545-225-1) F3 (CAS 597578-38-6) F4 (CAS 1207671-22-4) PD2 2,2′,2″-(cyclopropane-1,2,3-triylidene)-tris[2- (4-cyanoperfluorophenyl)-acetonitrile] (CAS1224447-88-4) 0 LiQ 8-Hydroxyquinolato lithium (CAS 850918-68-2) CN-HAT (CAS 105598-27-4)

(38) The features disclosed in the foregoing description and in the dependent claims may, both separately and in any combination thereof, be material for realizing the aspects of the disclosure made in the independent claims, in diverse forms thereof.

(39) Key symbols and abbreviations used throughout the application: CV cyclic voltammetry DSC differential scanning calorimetry EBL electron blocking layer EIL electron injecting layer EML emitting layer eq. equivalent ETL electron transport layer ETM electron transport matrix Fe ferrocene Fe.sup.+ ferricenium HBL hole blocking layer HIL hole injecting layer HOMO highest occupied molecular orbital HPLC high performance liquid chromatography HTL hole transport layer p-HTL p-doped hole transport layer HTM hole transport matrix ITO indium tin oxide LUMO lowest unoccupied molecular orbital mol % molar percent NMR nuclear magnetic resonance OLED organic light emitting diode OPV organic photovoltaics QE quantum efficiency R.sub.f retardation factor in TLC RGB red-green-blue TCO transparent conductive oxide TFT thin film transistor T.sub.g glass transition temperature TLC thin layer chromatography wt % weight percent