Materials for organic electroluminescent devices

Abstract

The present invention relates to an organic composition which comprises a conjugated polymer as hole-transport compound and a doping compound. The present invention furthermore relates to the use of the composition according to the invention in organic electroluminescent devices, in particular in the so-called buffer layer of such devices. The present invention also relates to a formulation which comprises the composition according to the invention and a solvent and to an organic electroluminescent device which comprises the composition according to the invention.

Claims

1. An electronic device comprising: an anode, a cathode, an active layer, and a buffer layer between the anode and the active layer, wherein the buffer layer comprises at least one organic composition comprising: a) a hole-transport compound, b) an ion-conducting or proton-conducting compound, and c) a doping compound selected from the group consisting of ionic compounds, wherein the hole-transport compound is a conjugated polymer comprising polymer segments of formula (1) and/or polymer segments of a conjugated block co-polymer of formula (2): ##STR00027## ##STR00028## wherein A is a recurring unit selected on each occurrence, identically or differently, from the group consisting of phenylenevinylene, phenanthrene, dehydrophenanthrene, fluorene, spirobifluorene, benzofluorene, dibenzofluorene, indenofluorene, indolocarbazole, and derivatives thereof; B is a recurring unit selected on each occurrence, identically or differently, from the group consisting of amine, triarylamine, thiophene, carbazole, phenanthrene, dehydrophenanthrene, fluorene, spirobifluorene, benzofluorene, dibenzofluorene, indenofluorene, indolocarbazoles, and derivatives thereof; x and y denote that the units A and B are in the form of recurring units in the conjugated polymer; and q denotes that the unit -A-B is a recurring unit in the polymer; and wherein the doping compound is an ionic compound of formula G.sup.+A.sup.?, wherein G.sup.+ is a cation selected from the group consisting of H.sup.+, alkali and alkaline-earth metal ions, ammonium, phosphonium, thiouronium, thioxonium, and guanidinium cations; and A.sup.? is an anion selected from the group consisting of [HSO.sub.4].sup.?, [SO.sub.4].sup.2?, [NO.sub.3].sup.?, [BF.sub.4].sup.?, [(R.sub.F)BF.sub.3].sup.?, [(R.sub.F).sub.2BF.sub.2].sup.?, [(R.sub.F).sub.3BF].sup.?, [(R.sub.F).sub.4B].sup.?, [B(CN).sub.4].sup.?, [PO.sub.4].sup.3?, [HPO.sub.4].sup.2?, [H.sub.2PO.sub.4].sup.?, [alkyl-OPO.sub.3].sup.2?, [(alkyl-O).sub.2PO.sub.2].sup.?, [alkyl-PO.sub.3].sup.2?, [R.sub.FPO.sub.3].sup.2?, [(alkyl).sub.2PO.sub.2].sup.?, [(R.sub.F).sub.2PO.sub.2].sup.?, [R.sub.FSO.sub.3].sup.?, [HOSO.sub.2(CF.sub.2).sub.kSO.sub.2O].sup.?, [OSO.sub.2(CF.sub.2).sub.kSO.sub.2O].sup.2?, [alkyl-SO.sub.3].sup.?, [HOSO.sub.2(CH.sub.2).sub.kSO.sub.2O].sup.?, [OSO.sub.2(CH.sub.2).sub.kSO.sub.2O].sup.2?, [alkyl-OSO.sub.3].sup.?, [alkyl-C(O)O].sup.?, [HO(O)C(CH.sub.2).sub.kC(O)O].sup.?, [R.sub.FC(O)O].sup.?, [HO(O)C(CF.sub.2).sub.kC(O)O].sup.?, [O(O)C(CF.sub.2).sub.kC(O)O].sup.2, [(R.sub.FSO.sub.2).sub.2N].sup.?, [(FSO.sub.2).sub.2N.sup.?, R(R.sub.F).sub.2P(O)).sub.2N].sup.?, [(R.sub.FSO.sub.2).sub.3C].sup.?, [(FSO.sub.2).sub.3C].sup.?, Cl.sup.? and/or Br.sup.?, PF.sub.6.sup.?, [PF.sub.3(C.sub.2F.sub.5).sub.3].sup.?, [PF.sub.3(CF.sub.3).sub.3].sup.?, [B(COOCOO).sub.2].sup.?, [(CF.sub.3SO.sub.2).sub.2N].sup.?, [(C.sub.2F.sub.5SO.sub.2).sub.2N].sup.?, [(CF.sub.3SO.sub.2)(C.sub.4F.sub.9SO.sub.2)N].sup.?, [(CN).sub.2N].sup.?, [CF.sub.3SO.sub.2].sub.3C].sup.?, and [(CN).sub.3C].sup.?; wherein k is an integer from 1 to 8; and R.sub.F is a fluorinated aryl or alkylaryl radical or a fluorinated alkyl radical of formula (C.sub.oF.sub.2o?p+1H.sub.p), wherein o is an integer from 1 to 12 and p is an integer from 0 to 7; and wherein the active layer is an emitting layer or a charge-generation layer.

2. The device of claim 1, wherein the polymer is a crosslinked or uncrosslinked polymer.

3. The device of claim 1, wherein G.sup.+ is selected from the group consisting of R.sup.1(PO.sub.3.sup.2?).sub.n, R.sup.1(PO.sub.2.sup.?).sub.n, R.sup.1(PO.sub.3H.sup.?).sub.n, R.sup.1(BO.sub.2.sup.2?).sub.n, R.sup.1(SO.sub.2.sup.?).sub.n, R.sup.1(SO.sub.3.sup.?).sub.n, R.sup.1(COO.sup.?).sub.r, and R.sup.1(BO.sub.2H.sup.?).sub.n; wherein n is 0, 1, 2, 3, or 4; r is greater than or equal to 1; and R.sup.1 is on each occurrence, identically or differently, an H, an amino group, an alkylamino group, a dialkylamino group, an arylamino group, a diarylamino group, or an alkylarylamino group.

4. The device of claim 1, wherein the recurring unit A is a fluorene, indenofluorene, spirobifluorene, phenanthrene, benzofluorene, dibenzofluorene, or a derivative thereof.

5. The composition of claim 1, wherein the recurring unit B is a triarylamine, a thiophene, a carbazole, a phenanthrene, or a derivative thereof.

6. The composition of claim 1, wherein the recurring unit A or B is a structural unit of formula (3): ##STR00029## wherein X, Y, and Z are on each occurrence, independently of one another, a divalent group selected from the group consisting of CR.sup.2R.sup.3, NR.sup.2, PR.sup.2, O, S, SO.sub.2, CO, CS, CSe, P(?O)R.sup.2, P(?S)R.sup.2, and SiR.sup.2R.sup.3; R.sup.2 and R.sup.3 are on each occurrence, independently of one another, H, halogen, CN, NC, NCO, NCS, OCN, SCN, C(?O)NR.sup.4R.sup.5, C(?O)X, C(?O)R.sup.4, NH.sub.2, NR.sup.4R.sup.5, SH, SR.sup.4, SO.sub.3H, SO.sub.2R.sup.4, OH, NO.sub.2, CF.sub.3, SF, optionally substituted silyl, or an optionally substituted hydrocarbon radical having 1 to 40 C atoms, which optionally comprises one or more heteroatoms, and wherein R.sup.2 and R.sup.3 together optionally define a carbyl radical, or, together with the fluorene radical to which they are bonded, optionally define a spiro group; R.sup.4 and R.sup.5 are on each occurrence, independently of one another, H or an optionally substituted hydrocarbon radical having 1 to 40 C atoms, which optionally comprise one or more heteroatoms, and wherein R.sup.4 and R.sup.5 together optionally define a carbyl radical; g and h are on each occurrence, in each case independently of one another, 0 or 1, wherein each h corresponding to g in the same unit is, differently to g, in each case 0 or 1; X is halogen; m is 0, 1, 2, or 3; Ar.sup.1 and Ar.sup.2 are on each occurrence, identically or differently, a divalent aromatic or heteroaromatic ring system having 5 to 40 ring atoms optionally substituted by one or more groups R.sup.2, and wherein the ring system is optionally condensed onto positions 7,8 or 8,9 of the structural unit of formula (3); and a and b are in each case, independently of one another, 0 or 1.

7. The device of claim 1, wherein the recurring unit A or B in formula (1) is a structural unit of formulae (4-1) or (4-2): ##STR00030## wherein R.sup.6 is on each occurrence, identically or differently, H, a straight-chain, branched, or cyclic alkyl radical having 1 or 3 to 40 C atoms respectively, which are optionally substituted by a group R.sup.7, and wherein one or more non-adjacent C atoms are optionally replaced by NR.sup.7, O, S, OCOO, COO, CR.sup.7?CR.sup.7, or C?C, with the proviso that the heteroatoms are not bonded directly to the phenanthrene unit, and wherein one or more H atoms are optionally replaced by F, Cl, or CN, or an aromatic or heteroaromatic ring system having 6 or 5 to 40 ring atoms respectively, which are optionally substituted by one or more groups R.sup.7; and wherein two R.sup.6 optionally define a further mono- or polycyclic, aromatic or aliphatic ring system with one another; with the proviso that at least one R.sup.6 group is in each case not H; X is on each occurrence, identically or differently, CR.sup.7?CR.sup.7, C?C, or NAr.sup.3; Y is on each occurrence, identically or differently, a divalent aromatic or heteroaromatic ring system having 6 or 5 to 40 ring atoms respectively, which are optionally substituted by one or more R.sup.7 groups; R.sup.7 is on each occurrence, identically or differently, H, a straight-chain, branched, or cyclic alkyl or alkoxy radical having 1 or 3 to 22 C atoms respectively, wherein one or more non-adjacent C atoms are optionally replaced by NR.sup.8, O, S, OCOO, COO, CR.sup.9?CR.sup.9, or C?C, and wherein one or more H atoms are optionally replaced by F, Cl, or CN, or an aryl, heteroaryl, aryloxy, or heteroaryloxy group having 5 to 40 C atoms optionally substituted by one or more non-aromatic R.sup.7 groups; and wherein two or more R.sup.7 groups optionally define a ring system with one another and/or with an R.sup.6 group; or F, Cl, CN, N(R.sup.10).sub.2, Si(R.sup.10).sub.3, or B(R.sup.10).sub.2; R.sup.8 is on each occurrence, identically or differently, H or a hydrocarbon radical having 1 to 20 C atoms; R.sup.9 is on each occurrence, identically or differently, H, a straight-chain, branched, or cyclic alkyl or alkoxy radical having 1 or 3 to 22 C atoms respectively, wherein one or more non-adjacent C atoms are optionally replaced by NR.sup.8, O, S, OCOO, COO, or C?C, and wherein one or more H atoms are optionally replaced by F, Cl, Br, I, or CN, or an aryl or aryloxy radical having 5 to 40 C atoms optionally substituted by one or more non-aromatic R.sup.9 groups; and wherein two or more R.sup.9 groups optionally define a ring system with one another and/or with an R.sup.6 or R.sup.7; or F, Cl, CN, N(R.sup.10).sub.2, Si(R.sup.10).sub.3, or B(R.sup.10).sub.2; R.sup.10 is on each occurrence, identically or differently, H or an aliphatic or aromatic hydrocarbon radical having 1 to 20 C atoms; Ar.sup.3 is on each occurrence, identically or differently, an aromatic or heteroaromatic ring system having 6 or 5 to 40 C atoms respectively, which are optionally substituted by R.sup.7 groups; t is on each occurrence, identically or differently, 0 or 1; s is on each occurrence, identically or differently, 0, 1, or 2; and wherein the dashed bond denotes the linking in the polymer.

8. The device of claim 1, wherein the recurring unit B in formula (1) is a compound of formula (5):
-(T.sup.1).sub.c-(Ar.sup.4).sub.d-(T.sup.2).sub.e-(Ar.sup.5).sub.f (5) wherein T.sup.1 and T.sup.2 are in each case, independently of one another, thiophene, selenophene, thieno[2,3b]thiophene, thieno[3,2b]thiophene, dithienothiophene, or pyrrole, each of which are optionally substituted by one or more R.sup.11 groups; R.sup.11 is on each occurrence, identically or differently, halogen, CN, NC, NCO, NCS, OCN, SCN, C(?O)NR.sup.12R.sup.13, C(?O)X, C(?O)R.sup.12, NH.sub.2, NR.sup.12R.sup.13, SH, SR.sup.12, SO.sub.3H, SO.sub.2R.sup.12, OH, NO.sub.2, CF.sub.3, SF.sub.5, optionally substituted silyl, or a hydrocarbon radical having 1 to 40 C atoms and optionally one or more heteroatoms; wherein two adjacent R.sup.11 groups, together with the atoms/rings to which they are bonded, optionally define a polycyclic ring system; and wherein two R.sup.11 groups together optionally define a carbyl radical; R.sup.12 and R.sup.13 are in each case, independently of one another, H or an optionally substituted hydrocarbon radical having 1 to 40 C atoms and optionally one or more heteroatoms; Ar.sup.4 and Ar.sup.y are in each case, independently of one another, an optionally substituted, divalent, aromatic or heteroaromatic unit, which is optionally bonded to the 2,3-position of one or more adjacent thiophene or selenophene groups; c and e are, independently of one another, 0, 1, 2, 3, or 4, wherein 1<c+e<6; and d and f are, independently of one another, 0, 1, 2, 3, or 4.

9. The device of claim 1, wherein the recurring unit B in formula (1) is a triarylamine compound of formula (6): ##STR00031## wherein L is in each case, independently of one another, N, P, P?O, PF.sub.2, P?S, As, As?O, As?S, Sb, Sb?O, or Sb?S; Ar.sup.6 is on each occurrence, independently of one another, a covalent single bond or a divalent aromatic or heteroaromatic unit; Ar.sup.7 is on each occurrence, independently of one another, a divalent aromatic or heteroaromatic unit; Ar.sup.8 is on each occurrence, independently of one another, an optionally substituted aromatic or heteroaromatic unit, which is optionally substituted by a R.sup.14 group, and/or which is optionally bridged to a further recurring unit of formula (6) via a divalent group; R.sup.14 is a straight-chain, branched, or cyclic alkyl radical having 1 or 3 to 12 C atoms respectively or a straight-chain, branched, or cyclic alkenyl radical having 2 or 3 to 12 C atoms respectively; and w is 1, 2, or 3.

10. The device of claim 1 wherein the at least one composition is in the form of a formulation further comprising a solvent.

11. The electronic device of claim 1, wherein said electronic device is selected from the group consisting of organic electroluminescent devices, polymeric electroluminescent devices, organic field-effect transistors, organic integrated circuits, organic thin-film transistors, organic light-emitting transistors, coating for antistatics, thin layer for antistatics, organic solar cells, dye-sensitised solar cells, organic optical detectors, electroluminescent devices, organic integrated circuits, organic light-emitting transistors, organic solar cells, dye-sensitised solar cells, organic optical detectors, organic laser diodes, light-emitting electrochemical cells, organic plasmon emitting devices, organic photovoltaic elements, organic photovoltaic devices, and organic photoreceptors.

12. The device of claim 1, wherein B, identically or differently on each occurrence, is selected from the group consisting of structural units of formulae (7) through (11): ##STR00032## wherein R.sup.14 is a straight-chain, branched, or cyclic alkyl radical having 1 or 3 to 12 C atoms respectively or a straight-chain, branched, or cyclic alkenyl radical having 2 or 3 to 12 C atoms respectively; R is on each occurrence, independently of one another, H, halogen, CN, NC, NCO, NCS, OCN, SCN, C(?O)NR.sup.4R.sup.5, C(?O)X, C(?O)R.sup.4, NH.sub.2, NR.sup.4R.sup.5, SH, SR.sup.4, SO.sub.3H, SO.sub.2R.sup.4, OH, NO.sub.2, CF.sub.3, SF, optionally substituted silyl, or an optionally substituted hydrocarbon radical having 1 to 40 C atoms, which optionally comprises one or more heteroatoms, and wherein R.sup.2 and R.sup.3 together optionally define a carbyl radical, or, together with the fluorene radical to which they are bonded, optionally define a Spiro group; o is in each case, independently of one another, 0, 1, or 2; and p is in each case, independently of one another, 0, 1, 2, 3, or 4.

13. The device of claim 1, wherein A, identically or differently on each occurrence, is selected from the group consisting of structural units of formulae (42) through (53): ##STR00033## ##STR00034## ##STR00035## wherein R.sub.0 is H, halogen or optionally a fluorinated, linear, or branched alkyl or alkoxy group having 1 to 12 C atoms.

14. The device of claim 1, wherein A, identically or differently on each occurrence, is selected from the group consisting of structural units of formulae (44), (46), (49), (50), (51), and (53): ##STR00036## ##STR00037## wherein R.sub.0 is H, halogen or optionally a fluorinated, linear or branched alkyl or alkoxy group having 1 to 12 C atoms.

Description

(1) The invention is explained in greater detail by the following figures and examples without wishing to restrict it thereby.

(2) FIG. 1 shows the current density as a function of the voltage for OLED1 and Ref1.

(3) FIG. 2 shows the luminous density as a function of the voltage for OLED1 and Ref1.

EXAMPLES

Example 1

Materials Used

(4) For the production of an OLED without an electron-blocking interlayer, the following materials are employed for the production of an emitting layer:

(5) ##STR00021##

(6) H1 and H2 are host materials which can be synthesised in accordance with WO 2009/124627 and DE 102008036982. TG1 is a green triplet emitter which is synthesised in accordance with DE 102009041414.

(7) The following materials are used for the production of the buffer layer:

(8) The ion-conducting material used is poly(ethylene oxide) (PEO, average M.sub.v=1?10.sup.6, Aldrich). Lithium trifluoromethanesulfonate (LiTrf, 99.995% metal basis; Aldrich) is used as ionic compound.

(9) The following hole-transporting polymers are synthesised by SUZUKI coupling in accordance with WO 2003/048225, WO 2010/097155 and WO 2008/009343. The percentages indicated here are mol % of monomers. The molecular weight of all polymers is between 200,000 and 300,000 g/mol (GPC measurements: THF; 1 ml/min, Plgel 10 ?m mixed-B 2?300?7.5 mm.sup.2, 35? C., RI detection calibrated against polystyrene).

(10) ##STR00022## ##STR00023## ##STR00024## ##STR00025## ##STR00026##

Example 2

Preparation the Formulations

(11) 9 different solutions are prepared whose composition are indicated in Table 1. To this end, firstly 100 mg of the constituents indicated in the Composition column in the ratio indicated are dissolved in 10 ml of cyclohexanone (purity 99.90%) and stirred until the solution is clear. The solution is subsequently filtered using a Millipore Millex LS, hydrophobic PTFE 5.0 ?m filter.

(12) TABLE-US-00001 TABLE 1 Composition of the solutions Ratio (based on Solution Composition weight) Concentration 1 Polymer1 + PEO + LiTrf 1:0.1:0.05 10 mg/ml 2 Polymer2 + PEO + LiTrf 1:0.1:0.05 10 mg/ml 3 Polymer3 + PEO + LiTrf 1:0.1:0.05 10 mg/ml 4 Polymer4 + PEO + LiTrf 1:0.1:0.05 10 mg/ml 5 Polymer5 + PEO + LiTrf 1:0.1:0.05 10 mg/ml 6 Polymer6 + PEO + LiTrf 1:0.1:0.05 10 mg/ml 7 Polymer7 + PEO + LiTrf 1:0.1:0.05 10 mg/ml 8 Polymer8 + PEO + LiTrf 1:0.1:0.05 10 mg/ml 9 Polymer9 + PEO + LiTrf 1:0.1:0.05 10 mg/ml

Example 3

Production of the OLEDs

(13) OLEDs 1 to 6 having an anode/buffer layer/EML/cathode structure, are produced as follows using Solutions 1 to 6 prepared under Example 2: 1) coating of an ITO-coated glass substrate with a buffer layer with a thickness of 80 nm by application of the solutions by spin coating in a glove box; 2) drying of the buffer layer by heating at 180? C. for 1 h in a glove box; 3) application of an emitting layer (EML) with a thickness of 80 nm to the buffer layer by spin coating of a solution in toluene of an H1(40 wt %)+H2(40 wt %)+TG1(20 wt %) mixture in a glove box; 4) drying of the device by heating at 180? C. for 10 min. in a glove box; 5) application of a Ba/Al cathode (3 nm+150 nm) by vapour deposition; and 6) encapsulation of the device.

Comparative Example

(14) Reference OLEDs Ref1 to Ref6 are produced in the same way as under Example 3, with the only difference that, besides Polymers1-6, no further compounds are employed for the production of the buffer layer.

(15) Furthermore, a further reference device, Ref0, can be produced using PEDOT as buffer layer. Ref0 is produced analogously to OLED1-6, where steps 1) and 2) are carried out as follows: 1) coating of an ITO-coated glass substrate with a PEDOT layer (Clevios? P VP AI 4083) with a thickness of 80 nm as buffer layer by application of a dispersion by spin coating in a clean room; 2) drying of the buffer layer by heating at 180? C. for 10 min. in a clean room;

Example 4

Characterisation of the OLEDs

(16) The OLEDs obtained in this way are characterised by standard methods which are well known to the person skilled in the art. The following properties are measured here: UIL characteristics, electroluminescence spectrum, efficiency and operating voltage. In particular, the efficiency is compared here at 1000 nits. The results are summarised in Table 2 below, where Ref1-6 serves as comparison, and Ref0 serves in accordance with the prior art.

(17) TABLE-US-00002 TABLE 2 Eff. @ 1 knits V @ 1 knits OLED1 19 9.5 Ref1 0.95 17 OLED2 20.1 9.1 Ref2 1.2 16 OLED3 21.2 9.3 Ref3 1 17 OLED3 23 8.8 Ref3 0.8 16 OLED4 18.5 8.6 Ref4 2.1 19 OLED5 24.3 8.5 Ref5 3 17 OLED6 17 10 Ref6 0.6 16.6

(18) REf0 gives an efficiency about 16 cd/A @ 1 knits.

(19) FIGS. 1 and 2 shows the current density and luminous density of OLED1 and Ref1 as a function of the voltage.

(20) Further optimisations by means of various possibilities can be achieved without inventive step on the basis of the present technical teaching according to the invention. Thus, a further optimisation may consist, for example, in using other ionic compounds, other co-matrices or other emitters.

Example 5

Conductive Layer Comprising Compositions Comprising Polymer7, Polymer8 and Polymer9

(21) Polymer7, Polymer8 and Polymer9 are not crosslinkable polymers and are not incorporated into an OLED as buffer layer. A thin layer of 80 nm is applied to a glass substrate in a clean room by application of the solutions (Solution7-Solution9) by spin coating. For the production of a reference layer (80 nm), no further compounds are employed besides Polymers1-6. The conductivities of the layers is determined by a four-conductor measurement (4-point probes method). In each case, the thin layer comprising the compositions according to the invention is at least an order of magnitude higher than the corresponding reference layer.

(22) Polymer7, Polymer8 and Polymer9 and the like can easily be modified to give crosslinkable polymers, so that they can also be utilised for other electronic device.