Electronic Semiconducting Device, Method for Preparing the Electronic Semiconducting Device and Compound

Abstract

The present invention relates to an electronic device comprising between a first electrode and a second electrode at least one first semiconducting layer comprising (i) at least one first hole transport matrix compound consisting of covalently bound atoms and (ii) at least one electrical p-dopant selected from metal borate complexes, wherein the metal borate complex consists of at least one metal cation and at least one anionic ligand consisting of at least six covalently bound atoms which comprises at least one boron atom,
wherein the first semiconducting layer is a hole injection layer, a hole-injecting part of a charge generating layer or a hole transport layer, a method for preparing the same and a respective metal borate compound.

Claims

1. Electronic device comprising between a first electrode and a second electrode at least one first semiconducting layer comprising (i) at least one first hole transport matrix compound consisting of covalently bound atoms and (ii) at least one electrical p-dopant selected from metal borate complexes, wherein the metal borate complex consists of at least one metal cation and at least one anionic ligand consisting of at least six covalently bound atoms which comprises at least one boron atom, wherein the first semiconducting layer is a hole injection layer, a hole-injecting part of a charge generating layer or a hole transport layer.

2. Electronic device according to claim 1, further comprising at least one light emit ting layer or at least one light absorbing layer between the first electrode and the second electrode, wherein the first electrode is an anode and the first semiconducting layer is arranged between the anode and the light emitting layer or between the anode and the light absorbing layer.

3. Electronic device according to claim 2, wherein the first semiconducting layer is adjacent to the anode.

4. Electronic device according to claim 1, wherein the anionic ligand consists of at least 7, preferably at least 8, more preferably at least 9, even more preferably at least 10, even more preferably at least 11, most preferably at least 12 covalently bound atoms.

5. Electronic device according to claim 1, wherein the metal borate complex has formula (I) ##STR00024## wherein M is a metal ion, each of A.sup.1-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, with proviso that the overall count of carbon atoms in a carbon-containing group will not exceed 60, any hydrogen atom in any carbon containing group selected from (iv), (v), (vi), (vii), (viii), (ix) and (x) may be replaced with a substituent independently selected from 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, unsubstituted or halogenated silicon-containing hydrocarbyl; n is valence of the metal ion; and at least one of A.sup.1-A.sup.4 is F, CN, or an electron-withdrawing carbon group, wherein the electron-withdrawing carbon group is a carbon group selected from hydrocarbyl, boron-containing hydrocarbyl, silicon-containing hydrocarbyl and heteroaryl and having at least one half of its hydrogen atoms replaced with F, Cl, Br, I and/or CN.

6. Electronic device according to claim 5, wherein M is selected from alkali metals, alkaline earth metals, rare earth metals, transition metals except silver, Al, Ga, In, Tl, Sn, Pb, Bi or mixtures thereof and n is 1, 2 or 3; preferably, M is selected from Li, Na, K, Rb, Cs, Cu, or mixtures thereof and n is 1; also preferably, M is selected from Be, Mg, Ca, Sr, Ba, Mn, Fe, Co, Ni, Cu, Zn, Cd or mixtures thereof and n is 2; more preferably, M is selected from Li, Na, Cu, or mixtures thereof and n is 1; also more preferably, M is selected from Mg, Ca, Mn, Zn, Cu or mixtures thereof and n is 2; most preferably, M is Li and n is 1 or M is selected from Mg, Mn, Zn or mixtures thereof and n is 2.

7. Electronic device according to claim 1, wherein the electrical p-dopant has an energy level of its lowest unoccupied molecular orbital computed by standard quantum chemical method and expressed in absolute vacuum scale of at least 0.5 eV, preferably at least 0.6 eV, more preferably at least 0.8 eV, even more preferably at least 1.0 eV, most preferably at least 1.2 eV less negative than the energy level of the highest occupied orbital of the first hole transport compound computed by the standard quantum chemical method.

8. Electronic device according to claim 1, wherein the first hole transport matrix compound has an energy level of its highest occupied molecular orbital computed by standard quantum chemical method and expressed in absolute vacuum scale more negative than −3.0 eV, preferably more negative than −3.5 eV, more prefer ably more negative than −4.0 eV, even more preferably more negative than −4.5 eV and most preferably more negative than −5.0 eV.

9. Electronic device according to claim 1, wherein in the first semiconducting layer, the p-dopant and the first hole transport matrix compound form two adjacent sub-layers.

10. Electronic device according to claim 1, wherein the first hole transport matrix compound is an organic compound, preferably an organic compound comprising a conjugated system of at least 6, preferably at least 10 delocalized electrons, also preferably an organic compound comprising at least one triaryl amine structural moiety, more preferably comprising at least two triaryl amine structural moieties.

11. Electronic device according to claim 1, wherein all layers between the first and second electrode as well as the electrode deposited on top of the last organic layer are preparable by vacuum deposition at a pressure below 1×10.sup.−3 Pa, preferably at a pressure below 5×10.sup.−4 Pa, more preferably at a pressure below 1×10.sup.−4 Pa.

12. Method for preparation of the electronic device of claim 1, the method comprising at least one step wherein the first hole transport matrix compound and the electrical p-dopant are in mutual contact exposed to a temperature above 50° C.

13. Method according to claim 12, further comprising a step, wherein the p-dopant is evaporated at a reduced pressure, preferably at a pressure below 1×10.sup.−2 Pa and at a temperature above 50° C., more preferably at a pressure below 5×10.sup.−2 Pa and at a temperature above 80° C., even more preferably at a pressure below 1×10.sup.−3 Pa and at a temperature above 120° C., most preferably at a pressure below 5×10.sup.−4 Pa and at a temperature above 150° C.

14. Compound having formula (Ia) ##STR00025## wherein A.sup.1 is H, A.sup.2-A.sup.4 are independently selected from perfluorinated indazolyl having formula IIa or IIb ##STR00026## wherein the dashed bond does represent the attachment to the boron atom in formula (Ia) and R.sup.1 is a perfluorinated C.sub.1-C.sub.20 hydrocarbyl group; M is Li and n is 1, or M is a divalent metal and n is 2.

15. Compound according to claim 14, wherein the divalent metal M is selected from Mg or Mn, and n is 2.

16. Compound according to claim 14, wherein the divalent metal M is Zn, and n is 2.

17. Compound having formula (Ib) ##STR00027## wherein A.sup.1 is H, A.sup.2-A.sup.4 are independently selected from fluorinated pyrazolyl having formula III ##STR00028## wherein the dashed bond does represent the attachment to the boron atom in formula (Ib), R.sup.2 and R.sup.4 are independently selected from a perfluorinated C.sub.1-C.sub.20 hydrocarbyl group, R.sup.3 is selected from H, F, CN and from a perfluorinated C.sub.1-C.sub.20 hydrocarbyl group; M is Li and n is 1, or M is a divalent metal and n is 2.

18. Compound according to claim 17, wherein R.sup.2 and/or R.sup.4 are trifluoromethyl.

19. Compound according to claim 17, wherein M is a divalent metal selected from Mg or Mn, and n is 2.

20. Compound according to claim 17, wherein M is Zn, and n is 2.

Description

DESCRIPTION OF EMBODIMENTS

[0107] In the following, further embodiments will be described in further detail, by way of example, with reference to figures. In the FIGURES show:

[0108] FIG. 1 a schematic representation of an active OLED display, the display having a plurality of OLED pixels,

[0109] FIG. 1 shows a schematic representation of an active OLED display 1 having a plurality of OLED pixels 2, 3, 4 provided in an OLED display 1. In the OLED display 1, each pixel 2, 3, 4 is provided with an anode 2a, 3a, 4a being connected to a driving circuit (not shown). Various equipment able to serve as a driving circuit for an active matrix display is known in the art. In one embodiment, the anodes 2a, 3a, 4a are made of a TCO, for example of ITO.

[0110] A cathode 6 is provided on top of an organic stack comprising an electrically doped hole transport layer (HTL) 7, an electron blocking layer (EBL) 5, a light emitting layer (EML) having sub-regions 2b, 3b, 4b assigned to the pixels 2, 3, 4 and being provided separately in an electron transport layer (ETL) 9. For example, the sub-regions 2b, 3b, 4b can provide an RGB combi nation for a color display (R—red, G—green, B—blue). By applying individual drive currents to the pixels 2, 3, 4 via the anodes 2a, 3a, 4a and the cathode 6, the display pixels 2, 3, 4 are operated independently.

SYNTHESIS EXAMPLES

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

[0111] ##STR00010##

[0112] 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 10 mL hexane. 5.0 g (43%) product is obtained as a slightly yellow solid.

[0113] GCMS: confirms the expected M/z (mass/charge) ratio 258

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

[0114] ##STR00011##

[0115] 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)

[0116] ##STR00012##

[0117] 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

[0118] ##STR00013##

[0119] 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.

[0120] 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

[0121] ##STR00014##

[0122] 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)

[0123] ##STR00015##

[0124] 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)

[0125] ##STR00016##

[0126] 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)

[0127] 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 Al cathode.

[0128] All layers were deposited by vacuum thermal evaporation (VTE).

[0129] 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)

[0130] On the same glass substrate provided with an ITO anode as in the Example 1, following layers were subsequently deposited by VTE: 10 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.

[0131] Comparative device comprised the HIL made of the compound CN-HAT (CAS 105598-27-4) instead of PB-1.

[0132] 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%.

Example 3 (Device Comprising a Homogeneous Injection Layer Consisting of a Hole Transport Matrix Doped with a Borate Complex)

[0133] On the same glass substrate provided with an ITO anode as in the Example 2, following layers were subsequently deposited by VTE: 10 nm hole injection layer made of the matrix compound F2 doped with 8 weight 5 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.

[0134] The inventive device achieved current density 15 mA/cm.sup.2 and EQE 5.6% at a voltage 5.6 V, LT97 (operational time necessary for luminance decrease to 97% of ist initial value at the cur rent density 15 mA/cm.sup.2) was 135 hours.

Example 4 (Tandem Device Comprising a Homogeneous Charge Generating Layer Consisting of a Hole Transport Matrix Doped with a Borate Complex)

[0135] In the device prepared analogously as in Example 1, the neat PB-1 layer was replaced with a layer of the same thickness, consisting of F2 doped with 35 weight % PB-1.

TABLE-US-00001 TABLE 1 auxiliary materials Compound Structure F.sub.1 (CAS 1242056-42-3) [00017] F.sub.2 (CAS 1440545-225-1) [00018] F.sub.3 (CAS 597578-38-6) [00019] F.sub.4 (CAS 1207671-22-4) [00020] PD.sub.2 2,2′,2″-(cyclopropane-1,2,3-triylidene)-tris[2- (4-cyanoperfluorophenyl)-acetonitrile] (CAS1224447-88-4) [00021] LiQ 8-Hydroxyquinolato lithium (CAS 850918-68-2) [00022] CN-HAT (CAS 105598-27-4) [00023]

[0136] 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.

[0137] Key Symbols and Abbreviations Used Throughout the Application: [0138] CV cyclic voltammetry [0139] DSC differential scanning calorimentry [0140] EBL electron blocking layer [0141] EIL electron injecting layer [0142] EML emitting layer [0143] eq. equivalent [0144] ETL electron transport layer [0145] ETM electron transport matrix [0146] Fc ferrocene [0147] Fc.sup.+ ferricenium [0148] HBL hole blocking layer [0149] HIL hole injecting layer [0150] HOMO highest occupied molecular orbital [0151] HPLC high performance liquid chromatography [0152] HTL hole transport layer [0153] p-HTL p-doped hole transport layer [0154] HTM hole transport matrix [0155] ITO indium tin oxide [0156] LUMO lowest unoccupied molecular orbital [0157] mol % molar percent [0158] NMR nuclear magnetic resonance [0159] OLED organic light emitting diode [0160] OPV organic photovoltaics [0161] QE quantum efficiency [0162] R.sub.f retardation factor in TLC [0163] RGB red-green-blue [0164] TCO transparent conductive oxide [0165] TFT thin film transistor [0166] T.sub.g glass transition temperature [0167] TLC thin layer chromatography [0168] wt % weight percent