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MATERIALS FOR ELECTRONIC DEVICES

20190040034 ยท 2019-02-07

    Inventors

    Cpc classification

    International classification

    Abstract

    The present application relates to compounds of a formula (I), to the use thereof in electronic devices, and to processes for preparing the compounds.

    Claims

    1.-16. (canceled)

    17. Compound of formula (I) ##STR00211## where the compound is optionally substituted by an R.sup.1 radical at each of the free positions on the spirobifluorene unit, and is optionally substituted by an R.sup.2 radical at each of the free positions on the phenylene unit, and where the variables that occur are: R.sup.1 is the same or different at each instance and is selected from the group consisting of H, D, F, C(?O)R.sup.4, CN, Si(R.sup.4).sub.3, N(R.sup.4).sub.2, P(?O)(R.sup.4).sub.2, OR.sup.4, S(?O)R.sup.4, S(?O).sub.2R.sup.4, straight-chain alkyl or alkoxy groups having 1 to 20 carbon atoms, branched or cyclic alkyl or alkoxy groups having 3 to 20 carbon atoms, alkenyl or alkynyl groups having 2 to 20 carbon atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where two or more R.sup.1 radicals are optionally joined to one another and optionally form a ring; where the alkyl, alkoxy, alkenyl and alkynyl groups mentioned and the aromatic ring systems and heteroaromatic ring systems mentioned are optionally substituted by one or more R.sup.4 radicals; and where one or more CH.sub.2 groups in the alkyl, alkoxy, alkenyl and alkynyl groups mentioned are optionally replaced by R.sup.4C?CR.sup.4, C?C, Si(R.sup.4).sub.2, C?O, C?NR.sup.4, C(?O)O, C(?O)NR.sup.4, NR.sup.4, P(?O)(R.sup.4), O, S, SO or SO.sub.2; R.sup.2 is the same or different at each instance and is selected from the group consisting of H, D, F, C(?O)R.sup.4, CN, Si(R.sup.4).sub.3, P(?O)(R.sup.4).sub.2, OR.sup.4, S(?O)R.sup.4, S(?O).sub.2R.sup.4, straight-chain alkyl or alkoxy groups having 1 to 20 carbon atoms, branched or cyclic alkyl or alkoxy groups having 3 to 20 carbon atoms, alkenyl or alkynyl groups having 2 to 20 carbon atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where two or more R.sup.2 radicals are optionally joined to one another and optionally form a ring; where the alkyl, alkoxy, alkenyl and alkynyl groups mentioned and the aromatic ring systems and heteroaromatic ring systems mentioned are optionally substituted by one or more R.sup.4 radicals; and where one or more CH.sub.2 groups in the alkyl, alkoxy, alkenyl and alkynyl groups mentioned are optionally replaced by R.sup.4C?CR.sup.4, C?C, Si(R.sup.4).sub.2, C?O, C?NR.sup.4, C(?O)O, C(?O)NR.sup.4, NR.sup.4, P(?O)(R.sup.4), O, S, SO or SO.sub.2; Ar.sup.1 is the same or different at each instance and is selected from the group consisting of aromatic ring systems which have 6 to 20 aromatic ring atoms and are optionally substituted by one or more R.sup.3 radicals, and from heteroaromatic ring systems which have 5 to 30 aromatic ring atoms and are optionally substituted by one or more R.sup.3 radicals; R.sup.3 is the same or different at each instance and is selected from the group consisting of H, D, F, C(?O)R.sup.4, CN, Si(R.sup.4).sub.3, N(R.sup.4).sub.2, P(?O)(R.sup.4).sub.2, OR.sup.4, S(?O)R.sup.4, S(?O).sub.2R.sup.4, straight-chain alkyl or alkoxy groups having 1 to 20 carbon atoms, branched or cyclic alkyl or alkoxy groups having 3 to 20 carbon atoms, alkenyl or alkynyl groups having 2 to 20 carbon atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where the alkyl, alkoxy, alkenyl and alkynyl groups mentioned and the aromatic ring systems and heteroaromatic ring systems mentioned are optionally substituted by one or more R.sup.4 radicals; and where one or more CH.sub.2 groups in the alkyl, alkoxy, alkenyl and alkynyl groups mentioned are optionally replaced by R.sup.4C?CR.sup.4, C?C, Si(R.sup.4).sub.2, C?O, C?NR.sup.4, C(?O)O, C(?O)NR.sup.4, NR.sup.4, P(?O)(R.sup.4), O, S, SO or SO.sub.2; R.sup.4 is the same or different at each instance and is selected from the group consisting of H, D, F, C(?O)R.sup.5, CN, Si(R.sup.5).sub.3, N(R.sup.5).sub.2, P(?O)(R.sup.5).sub.2, OR.sup.5, S(?O)R.sup.5, S(?O).sub.2R.sup.5, straight-chain alkyl or alkoxy groups having 1 to 20 carbon atoms, branched or cyclic alkyl or alkoxy groups having 3 to 20 carbon atoms, alkenyl or alkynyl groups having 2 to 20 carbon atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where two or more R.sup.4 radicals may be joined to one another and may form a ring; where the alkyl, alkoxy, alkenyl and alkynyl groups mentioned and the aromatic ring systems and heteroaromatic ring systems mentioned are optionally substituted by one or more R.sup.5 radicals; and where one or more CH.sub.2 groups in the alkyl, alkoxy, alkenyl and alkynyl groups mentioned are optionally replaced by R.sup.5C?CR.sup.5, C?C, Si(R.sup.5).sub.2, C?O, C?NR.sup.5, C(?O)O, C(?O)NR.sup.5, NR.sup.5, P(?O)(R.sup.5), O, S, SO or SO.sub.2; R.sup.5 is the same or different at each instance and is selected from the group consisting of H, D, F, CN, alkyl or alkoxy groups having 1 to 20 carbon atoms, alkenyl or alkynyl groups having 2 to 20 carbon atoms, aromatic ring systems having 6 to 40 aromatic ring atoms and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where two or more R.sup.4 radicals may be joined to one another and may form a ring; and where the alkyl, alkoxy, alkenyl and alkynyl groups, aromatic ring systems and heteroaromatic ring systems mentioned are optionally substituted by F or CN; where the benzene ring is bonded to the spirobifluorene group at one of the positions marked by the # symbol; and where the N(Ar.sup.1).sub.2 group is bonded to the benzene ring at one of the positions marked by the * symbol.

    18. The compound according to claim 17, wherein no R.sup.1 radical is bonded, exactly one R.sup.1 radical other than H is bonded, or exactly two R.sup.1 radicals other than H are bonded to the spirobifluorene base skeleton.

    19. The compound according to claim 17, wherein R.sup.2 is the same or different at each instance and is selected from the group consisting of H, F, methyl, ethyl, propyl, butyl, tert-butyl, phenyl, biphenyl, terphenyl, naphthyl, carbazolyl, benzofuranyl, benzothiophenyl, dibenzofuranyl, dibenzothiophenyl, 9,9-dimethylfluorenyl and 9,9-diphenylfluorenyl.

    20. The compound according to claim 17, wherein no R.sup.2 radical or exactly one R.sup.2 radical other than H is bonded to the phenylene group in formula (I).

    21. The compound according to claim 17, wherein Ar.sup.1, when it is a heteroaromatic ring system, is the same or different at each instance and is selected from the following radicals that are each optionally substituted by one or more R.sup.3 radicals: dibenzofuranyl, dibenzothiophenyl, benzofuranyl, benzothiophenyl, benzofused dibenzofuranyl, benzofused dibenzothiophenyl, indolyl, quinolinyl, pyridyl, pyrimidyl, pyrazinyl, pyridazinyl, triazinyl, triazole, oxazole, oxadiazole, benzoxazole, benzothiazole, phenanthrolyl and azacarbazolyl; and/or in that Ar.sup.1, when it is an aromatic ring system, is the same or different at each instance and is selected from aromatic ring systems which have 6 to 12 aromatic ring atoms and are optionally substituted by one or more R.sup.3 radicals.

    22. The compound according to claim 17, wherein Ar.sup.1 is the same or different at each instance and is selected from the following radicals that are each optionally substituted by one or more R.sup.3 radicals: phenyl, biphenyl, terphenyl, quaterphenyl, naphthyl, fluorenyl, especially 9,9-dimethylfluorenyl and 9,9-diphenylfluorenyl, monobenzofluorenyl, dibenzofluorenyl, indenofluorenyl, dibenzofuranyl, dibenzothiophenyl, benzofuranyl, benzothiophenyl, benzofused dibenzofuranyl, benzofused dibenzothiophenyl, indolyl, quinolinyl, pyridyl, pyrimidyl, pyrazinyl, pyridazinyl and triazinyl.

    23. The compound according to claim 17, wherein R.sup.3 is H.

    24. The compound according to claim 17, wherein the compound of the formula (I) is a compound of one of the formulae (I-1) to (I-4) ##STR00212## where the formula is optionally substituted by an R.sup.1 radical at each of the free positions on the spirobifluorene unit, and is optionally substituted by an R.sup.2 radical at each of the free positions on the phenylene unit.

    25. A process for preparing the compound according to claim 17, comprising reacting a spirobifluorene bearing one reactive group in a first metal-catalysed coupling reaction with a benzene derivative containing two reactive groups, one of which is converted in this coupling reaction, and where an amino group is finally introduced into the compound at the other of the two reactive groups via a second organometallic coupling reaction; or comprising reacting a benzene compound bearing two reactive groups in a first metal-catalysed coupling reaction with an amino compound at one of the two reactive groups, and is reacted in a second metal-catalysed coupling reaction with a spirobifluorene derivative at the other of the two reactive groups.

    26. An oligomer, polymer or dendrimer containing one or more compounds of formula (I) according to claim 17, wherein the bond(s) to the polymer, oligomer or dendrimer may be localized at any desired positions substituted by R.sup.1 or R.sup.2 or R.sup.3 in formula (I).

    27. A formulation comprising at least one compound according to claim 17, and at least one solvent.

    28. An electronic device comprising at least one compound according to claim 17.

    29. The electronic device according to claim 28, wherein the device is an organic electroluminescent device comprising anode, cathode and at least one emitting layer, where it is at least one organic layer of the device, which may be an emitting layer or a hole-transporting layer, especially a hole transport layer, a hole injection layer or an electron-blocking layer, that contains the at least one compound.

    30. The electronic device according to claim 28, wherein the device is an organic electroluminescent device comprising anode, cathode, at least one emitting layer, and exactly two, three or four hole-transporting layers between the anode and emitting layer, where it is at least one of the hole-transporting layers that contains the at least one compound.

    31. The electronic device according to claim 28, wherein the device is an organic electroluminescent device comprising anode, cathode, at least one emitting layer and at least one hole-transporting layer that contains the at least one compound and at least one further compound selected from p-dopants.

    32. Use of a compound according to claim 17 in an electronic device.

    Description

    EXAMPLES

    A) Synthesis Examples

    A1) Example 1

    Synthesis of the compound bis(biphenyl-3-yl)[4-(9,9-spirobifluoren-4-yl)phenyl]amine (1-1) and of compounds (1-2) to (1-17)

    [0117] ##STR00116##

    Synthesis of intermediate I-1: 4-(3-Chlorophenyl)-9,9-spirobifluorene

    [0118] 21.7 g (139 mmol) of 4-chlorobenzeneboronic acid, 50 g (126 mmol) of 4-bromo-9,9-spirobifluorene and 208 ml of an aqueous 2 M K.sub.2CO.sub.3 solution (416 mmol) are suspended in 300 ml of tetrahydrofuran. To this suspension are added 1.45 g (1.26 mmol) of tetrakis(triphenyl)phosphine-palladium(0). The reaction mixture is heated under reflux for 16 h. After cooling, the organic phase is removed, filtered through silica gel, washed three times with 300 ml of water and then concentrated to dryness. After the crude product has been filtered through silica gel with heptane/ethyl acetate (20:1), 48 g (89%) of 4-(3-chlorophenyl)-9,9-spirobifluorene are obtained.

    [0119] The following compounds are prepared in an analogous manner:

    TABLE-US-00002 Reactant 1 Reactant 2 Product Yield I-1 [00117]embedded image [00118]embedded image [00119]embedded image 89% I-2 [00120]embedded image [00121]embedded image [00122]embedded image 88% I-3 [00123]embedded image [00124]embedded image [00125]embedded image 85% I-4 [00126]embedded image [00127]embedded image [00128]embedded image 89% I-5 [00129]embedded image [00130]embedded image [00131]embedded image 89% I-6 [00132]embedded image [00133]embedded image [00134]embedded image 83% I-7 [00135]embedded image [00136]embedded image [00137]embedded image 83%

    Bis(biphenyl-3-yi)[4-(9,9-spirobifluoren-4 yl)phenyl]amine (1-1)

    [0120] 15.1 g of bis(biphenyl-4-yl)amine (46.8 mmol) and 20 g of 4-(3-chlorophenyl)-9,9-spirobifluorene (46.8 mmol) are dissolved in 300 ml of toluene. The solution is degassed and saturated with N.sub.2. Thereafter, 2.34 ml (2.34 mmol) of a 1 M tri-tert-butylphosphine solution and 0.26 g (1.17 mmol) of palladium(II) acetate are added thereto. Subsequently, 11.2 g of sodium tert-butoxide (117 mmol) are added. The reaction mixture is heated to boiling under a protective atmosphere for 4 h. The mixture is subsequently partitioned between toluene and water, and the organic phase is washed three times with water, dried over Na.sub.2SO.sub.4 and concentrated by rotary evaporation. After the crude product has been filtered through silica gel with toluene, the remaining residue is recrystallized from heptane/toluene and finally sublimed under high vacuum. The purity is 99.9%. The yield is 23 g (71% of theory). The following compounds are prepared in an analogous manner:

    TABLE-US-00003 Reactant 1 Reactant 2 Product Yield 1-1 [00138]embedded image [00139]embedded image [00140]embedded image 71% 1-2 [00141]embedded image [00142]embedded image [00143]embedded image 68% 1-3 [00144]embedded image [00145]embedded image [00146]embedded image 80% 1-4 [00147]embedded image [00148]embedded image [00149]embedded image 70% 1-5 [00150]embedded image [00151]embedded image [00152]embedded image 75% 1-6 [00153]embedded image [00154]embedded image [00155]embedded image 70% 1-8 [00156]embedded image [00157]embedded image [00158]embedded image 70% 1-9 [00159]embedded image [00160]embedded image [00161]embedded image 73% 1-10 [00162]embedded image [00163]embedded image [00164]embedded image 73% 1-11 [00165]embedded image [00166]embedded image [00167]embedded image 65% 1-12 [00168]embedded image [00169]embedded image [00170]embedded image 71% 1-13 [00171]embedded image [00172]embedded image [00173]embedded image 68% 1-14 [00174]embedded image [00175]embedded image [00176]embedded image 63% 1-15 [00177]embedded image [00178]embedded image [00179]embedded image 58% 1-16 [00180]embedded image [00181]embedded image [00182]embedded image 50% 1-17 [00183]embedded image [00184]embedded image [00185]embedded image 50% 1-18 [00186]embedded image [00187]embedded image [00188]embedded image 53% 1-19 [00189]embedded image [00190]embedded image [00191]embedded image 45%

    B) Device Examples

    [0121] OLEDs of the invention and OLEDs according to the prior art are produced by a general method according to WO 04/058911, which is adapted to the circumstances described here (e.g. materials, layer thicknesses).

    [0122] In the inventive examples which follow, the data of various OLEDs are presented (see Tables 1 to 4). The substrates used are glass plates coated with structured ITO (indium tin oxide) of thickness 50 nm. The OLEDs have the following general layer structure: substrate/hole injection layer (HIL)/hole transport layer (HTL)/optional second hole transport layer (HTL2)/electron blocker layer (EBL)/emission layer (EML)/electron transport layer (ETL)/electron injection layer (EIL) and finally a cathode. The cathode is formed by an aluminium layer of thickness 100 nm. The exact structure of the OLEDs is shown in Table 1. The materials required for production of the OLEDs are shown in Table 3.

    [0123] All materials are applied by thermal vapour deposition in a vacuum chamber. In this case, the emission layer always consists of at least one matrix material (host material) and an emitting dopant (emitter) which is added to the matrix material(s) in a particular proportion by volume by co-evaporation. Details given in such a form as H1:SEB(5%) mean here that the material H1 is present in the layer in a proportion by volume of 95% and SEB in a proportion by volume of 5%. In an analogous manner, other layers may also consist of a mixture of two or more materials. Details of this are given in Tables 1 and 4.

    [0124] The OLEDs are characterized in a standard manner. For this purpose, the external quantum efficiency (EQE, measured in percent) is determined as a function of luminance, calculated from current-voltage-luminance characteristics (IUL characteristics) assuming Lambertian radiation characteristics, and the lifetime. The parameter EQE @ 10 mA/cm.sup.2 refers to the external quantum efficiency at a current density of 10 mA/cm.sup.2. LD80 @60 mA/cm.sup.2 is the lifetime until the OLED has dropped from its starting brightness of 5000 cd/m.sup.2 to 80% of its starting brightness, i.e. 4000 cd/m.sup.2, without any acceleration factor. The values obtained for the OLEDs of the invention and the comparative OLEDs are summarized in Tables 2a and 2b.

    TABLE-US-00004 TABLE 1 Structure of the OLEDs HTL HTL2 EBL EIL HIL Thickness/ Thickness/ Thickness/ EML ETL Thickness/ Ex. Thickness/nm nm nm nm Thickness/nm Thickness/nm nm C1 HIM: HIM HTMC1 H1:SEB (5%) ETM:LiQ (50%) LiQ F4TCNQ (5%) 180 nm 10 nm 20 nm 30 nm 1 nm 20 nm C2 HIM: HIM HTMC2 H1:SEB (5%) ETM:LiQ (50%) LiQ F4TCNQ (5%) 180 nm 10 nm 20 nm 30 nm 1 nm 20 nm I1 HIM: HIM HTM1 H1:SEB (5%) ETM:LiQ (50%) LiQ F4TCNQ (5%) 180 nm 10 nm 20 nm 30 nm 1 nm 20 nm I3 HIM: HIM HTM2 H1:SEB (5%) ETM:LiQ (50%) LiQ F4TCNQ (5%) 180 nm 10 nm 20 nm 30 nm 1 nm 20 nm I8 HIM: HIM HTM6 H1:SEB (5%) ETM:LiQ (50%) LiQ F4TCNQ (5%) 180 nm 10 nm 20 nm 30 nm 1 nm 20 nm I10 HIM: HIM HTM7 H1:SEB (5%) ETM:LiQ (50%) LiQ F4TCNQ (5%) 180 nm 10 nm 20 nm 30 nm 1 nm 20 nm C3 HTMC3: HTMC3 EBM H1:SEB (5%) ETM:LiQ (50%) LiQ F4TCNQ (5%) 180 nm 10 nm 20 nm 30 nm 1 nm 20 nm I2 HTM3: HTM3 EBM H1:SEB (5%) ETM:LiQ (50%) LiQ F4TCNQ (5%) 180 nm 10 nm 20 nm 30 nm 1 nm 20 nm I4 HTM2: HTM2 EBM H1:SEB (5%) ETM:LiQ (50%) LiQ F4TCNQ (5%) 180 nm 10 nm 20 nm 30 nm 1 nm 20 nm I9 HTM6: HTM6 EBM H1:SEB (5%) ETM:LiQ (50%) LiQ F4TCNQ (5%) 180 nm 10 nm 20 nm 30 nm 1 nm 20 nm C4 HIM: HIM HTMC1: HTMC1 TMM:TEG(10%) ETM:LiQ (50%) LiQ F4TCNQ (5%) 210 nm F4TCNQ (5%) 20 nm 30 nm 40 nm 1 nm 20 nm 20 nm C5 HIM: HIM HTMC2: HTMC2 TMM:TEG(10%) ETM:LiQ (50%) LiQ F4TCNQ (5%) 210 nm F4TCNQ (5%) 20 nm 30 nm 40 nm 1 nm 20 nm 20 nm I7 HIM: HIM HTM2: HTM2 TMM:TEG(10%) ETM:LiQ (50%) LiQ F4TCNQ (5%) 210 nm F4TCNQ (5%) 20 nm 30 nm 40 nm 1 nm 20 nm 20 nm

    TABLE-US-00005 TABLE 2a Data obtained for the OLEDs with singlet blue EML U EQE @ 10 mA/cm.sup.2 [V] [%] C1 3.8 8.0 C2 4.1 8.0 I1 3.8 8.7 I3 4.0 8.6 I8 3.6 8.1 I10 3.8 8.6 C3 7.9 5.5 I2 3.9 8.9 I4 4.0 8.1 I9 3.8 8.7

    TABLE-US-00006 TABLE 2b Data obtained for the OLEDs with triplet green EML U LD80 @ 60 mA/cm.sup.2 C4 4.1 130 C5 3.9 70 I7 4.1 165

    TABLE-US-00007 TABLE 3 Structures of the compounds used [00192]embedded image [00193]embedded image [00194]embedded image [00195]embedded image [00196]embedded image [00197]embedded image [00198]embedded image [00199]embedded image [00200]embedded image [00201]embedded image [00202]embedded image [00203]embedded image [00204]embedded image [00205]embedded image [00206]embedded image [00207]embedded image [00208]embedded image [00209]embedded image [00210]embedded image

    [0125] All the OLEDs tested that contain compounds of the invention exhibit very good values for the measured parameters of lifetime and efficiency, both for singlet blue devices (I1 to I4 and I8 to I10) and for triplet green devices (I7). The compounds of the invention are each used in hole injection layers and/or hole transport layers and/or electron blocker layers in the devices produced.

    [0126] From the results obtained, the following comparisons should be emphasized:

    [0127] A comparison of the devices C1, I1 and I3 that are otherwise of identical structure shows that devices comprising the inventive compounds HTM1 (I1) and HTM2 (I3) show much better values for efficiency than the comparative device comprising the comparative compound HTMC1 (C1). This shows the improvement which is achieved by the introduction of an ortho- or meta-phenylene group compared to a para-phenylene group.

    [0128] A comparison of the devices C2 and I1 that are otherwise of identical structure shows that a device comprising the inventive compound HTM1 (11) shows much better values for efficiency than the comparative device comprising the comparative compound HTMC2 (C2). This shows the improvement which is achieved by 4-substituted spiro compounds compared to 2-substituted spiro compounds.

    [0129] A comparison of the devices C3 and 12 and 19 that are otherwise of identical structure shows that a device comprising the inventive compound HTM3 (I2) and a device comprising the inventive compound HTM6 (I9) show much better values for efficiency than the comparative device comprising the comparative compound HTMC3 (C3). This again shows, for two other examples, the improvement which is achieved by the introduction of a meta-phenylene group compared to a para-phenylene group.

    [0130] A further comparison between the two inventive OLEDs I2 comprising HTM3 and I4 comprising HTM2 that are otherwise of identical structure shows the surprising distinct improvement in efficiency which is obtained through the use of two fluorenyl groups rather than one fluorenyl group and one biphenyl group on the amine.

    [0131] A comparison of the devices C4 and I7 that are otherwise of identical structure shows that a device comprising the inventive compound HTM2 (I7) shows much better values for lifetime than the comparative device comprising the comparative compound HTMC1 (C4). This again shows, for another example, the improvement which is achieved by the introduction of a meta-phenylene group compared to a para-phenylene group.

    [0132] In addition, the following two device constructions are created:

    TABLE-US-00008 TABLE 4 Structure of the OLEDs HTL HIL2 EBL EML EIL HIL Thickness/ Thickness/ Thickness/ Thickness/ ETL Thickness/ Ex. Thickness/nm nm nm nm nm Thickness/nm nm I5 HIM: HIM HTM4 H1:SEB (5%) ETM:LiQ (50%) LiQ F4TCNQ (5%) 180 nm 10 nm 20 nm 30 nm 1 nm 20 nm I6 HIM: HIM HTM5 H1:SEB (5%) ETM:LiQ (50%) LiQ F4TCNQ (5%) 180 nm 10 nm 20 nm 30 nm 1 nm 20 nm

    [0133] In these two examples, the materials HTM4 and HTM5 are used, which are 3-substituted spirobifluorenes according to the present invention. With these two materials too, good results are achieved in OLEDs.