Electronic device and compound

Abstract

The invention relates to an electronic device comprising a compound having Formula (1): AB.sub.x (1), wherein A is a structural moiety that consists of at least two atoms and comprises a conjugated system of delocalized electrons, each B is independently selected from an imine functional group (1a), wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4 are independently selected from C.sub.1-C.sub.30 alkyl, C.sub.2-C.sub.30 alkenyl, C.sub.2-C.sub.3 alkinyl, C.sub.3-C.sub.30 cycloalkyl, C.sub.6-C.sub.30 aryl, C.sub.2-C.sub.30 heteroaryl, C.sub.7-C.sub.30 arylalkyl, C.sub.3-C.sub.30 heteroarylalkyl, the wave line represents a covalent bond to the imine nitrogen atom, G is in each group (1a) independently selected from a quarternary carbon atom and from a cyclopropenylidene structural moiety, x is an integer equal one or higher, preferably equal two or higher, and the lone electron pair of the imine nitrogen atom and/or the pi-electrons of the imine double bond of at least one group B is conjugated with the conjugated system of delocalized electrons comprised in the structural moiety A, with the proviso that two or more of the substituents R.sup.1, R.sup.2, R.sup.3, R.sup.4 may be connected to form a ring that may contain also unsaturation and, if any of the substituents R.sup.1, R.sup.2, R.sup.3, R.sup.4 comprises two or more carbon atoms, up to one third of the overall count of the carbon atoms in the substituent or in any ring formed by two connected substituents can be replaced with heteroatoms independently selected from O, S, N and B as well as to an electrically semiconducting material and a compound for use in the electronic device. ##STR00001##

Claims

1. Organic electronic device comprising a compound having Formula 1
AB.sub.x(1), wherein A is a structural moiety that consists of at least two atoms and comprises a conjugated system of delocalized electrons, each B is independently selected from an imine functional group (Ia) ##STR00022## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4 are independently selected from C.sub.1-C.sub.30 alkyl, C.sub.2-C.sub.30 alkenyl, C.sub.2-C.sub.30 alkenyl, C.sub.3-C.sub.30 cycloalkyl, C.sub.6-C.sub.30 aryl, C.sub.2-C.sub.30 heteroaryl, C.sub.7-C.sub.30 arylalkyl, C.sub.3-C.sub.30 heteroarylalkyl, the wave line represents a covalent bond to the imine nitrogen atom, G is in each group (Ia) independently selected from a quarternary carbon atom and from a cyclopropenylidene structural moiety, x is an integer equal to one or higher, and the lone electron pair of the imine nitrogen atom and/or the pi-electrons of the imine double bond of at least one group B is conjugated with the conjugated system of delocalized electrons comprised in the structural moiety A, with the proviso that two or more of the substituents R.sup.1, R.sup.2, R.sup.3, R.sup.4 may be connected to form a ring that may contain also unsaturation and, if any of the substituents R.sup.1, R.sup.2, R.sup.3, R.sup.4 comprises two or more carbon atoms, up to one third of the overall count of the carbon atoms in the substituent or in any ring formed by two connected substituents can be replaced with heteroatoms independently selected from O, S, N and B, and wherein the device is a solar cell.

2. Organic electronic device according to claim 1, wherein x is an integer selected from 2, 3 and 4 and the lone electron pairs of the imine nitrogen atoms and/or the pi-electrons of the imine double bonds of at least two groups B are conjugated with the conjugated system of delocalized electrons comprised in the structural moiety A.

3. Organic electronic device according to claim 1, wherein A is a C.sub.3-C.sub.40 arene or C.sub.2-C.sub.40 heteroarene structural moiety that contains one conjugated system of delocalized electrons.

4. Organic electronic device according to claim 1, wherein A is a C.sub.6-C.sub.18 arene or C.sub.4-C.sub.18 heteroarene structural moiety and the lone electron pairs of the imine nitrogen atoms and/or the pi-electrons of the imine double bonds of all groups B are conjugated with the conjugated system of delocalized electrons comprised in the structural moiety A.

5. Organic electronic device according to claim 1, having a layered structure comprising several layers.

6. Organic electronic device according to claim 5, wherein the layer comprising the compound of Formula 1 is an electron transport layer or an electron injection layer.

7. Organic electronic device according to claim 5, wherein the layer comprising the compound of Formula 1 is an electron transport layer comprising an electron transport matrix and having a thickness of more than 50 nm, or a neat layer having a thickness less than 5 nm.

8. Organic electronic device according to claim 5, wherein the layer comprising the compound of Formula 1 is in direct contact to an electrode.

9. Organic electronic device according to claim 5, wherein a layer comprising the compound of Formula 1 is in direct contact to an electron transport layer.

10. Organic electronic device according to claim 5, wherein the layer comprising the compound of Formula 1 is part of a pn-junction connecting a light absorbing unit to an additional light absorbing unit in a tandem device or in a multiple stacked device and/or a pn-junction connecting a cathode or an anode to a light absorbing unit.

11. Organic electronic device according to claim 6, wherein the layer comprising the compound of Formula 1 is an electron transport layer comprising an electron transport matrix and having a thickness of more than 50 nm, or a neat layer having a thickness less than 5 nm.

12. Organic electronic device comprising: a layered structure, wherein the layered structure comprises (i) an anode, (ii) a cathode, and (iii) a layer comprising an n-dopant arranged between the anode and the cathode; wherein the n-dopant comprises a compound having Formula 1
AB.sub.x(1), wherein A is a structural moiety that consists of at least two atoms and comprises a conjugated system of delocalized electrons, each B is independently selected from an imine functional group (Ia) ##STR00023## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4 are independently selected from C.sub.1-C.sub.30 alkyl, C.sub.2-C.sub.30 alkenyl, C.sub.2-C.sub.30 alkenyl, C.sub.3-C.sub.30 cycloalkyl, C.sub.6-C.sub.30 aryl, C.sub.2-C.sub.30 heteroaryl, C.sub.7-C.sub.30 arylalkyl, C.sub.3-C.sub.30 heteroarylalkyl, the wave line represents a covalent bond to the imine nitrogen atom, G is in each group (Ia) independently selected from a quarternary carbon atom and from a cyclopropenylidene structural moiety, x is an integer equal to one or higher, and the lone electron pair of the imine nitrogen atom and/or the pi-electrons of the imine double bond of at least one group B is conjugated with the conjugated system of delocalized electrons comprised in the structural moiety A, with the proviso that two or more of the substituents R.sup.1, R.sup.2, R.sup.3, R.sup.4 may be connected to form a ring that may contain also unsaturation and, if any of the substituents R.sup.1, R.sup.2, R.sup.3, R.sup.4 comprises two or more carbon atoms, up to one third of the overall count of the carbon atoms in the substituent or in any ring formed by two connected substituents can be replaced with heteroatoms independently selected from O, S, N and B.

13. Organic electronic device according to claim 12, wherein x is an integer selected from 2, 3 and 4 and the lone electron pairs of the imine nitrogen atoms and/or the pi-electrons of the imine double bonds of at least two groups B are conjugated with the conjugated system of delocalized electrons comprised in the structural moiety A.

14. Organic electronic device according to claim 12, wherein A is a C.sub.3-C.sub.40 arene or C.sub.2-C.sub.40 heteroarene structural moiety that contains one conjugated system of delocalized electrons.

15. Organic electronic device according to claim 12, wherein A is a C.sub.6-C.sub.18 arene or C.sub.4-C.sub.18 heteroarene structural moiety and the lone electron pairs of the imine nitrogen atoms and/or the pi-electrons of the imine double bonds of all groups B are conjugated with the conjugated system of delocalized electrons comprised in the structural moiety A.

16. Organic electronic device according to claim 12, wherein the layer comprising the n-dopant is an electron transport layer or an electron injection layer.

17. Organic electronic device according to claim 12, wherein the layer comprising the n-dopant is an electron transport layer comprising an electron transport matrix and having a thickness of more than 50 nm, or a neat layer having a thickness less than 5 nm.

18. Organic electronic device according to claim 12, wherein the layer comprising the n-dopant is in direct contact to the anode or the cathode.

19. Organic electronic device according to claim 12, further comprising an electron transport layer, wherein the layer comprising the n-dopant is in direct contact to the electron transport layer.

20. Organic electronic device according to claim 12, further comprising a light absorbing unit, wherein the layer comprising the n-dopant is part of a pn-junction connecting the light absorbing unit to an additional light absorbing unit in a tandem device or in a multiple stacked device and/or a pn-junction connecting the cathode or the anode to the light absorbing unit.

Description

DESCRIPTION OF EXEMPLARY EMBODIMENTS

(1) In the following, exemplary embodiments are disclosed with reference to figures of a drawing.

(2) The figures show:

(3) FIG. 1 is a schematic diagram representing a stack of layers which forms a solar cell.

(4) FIG. 2 is a schematic diagram representing a stack of layers of a solar cell comprising an electron transport layer (ETL).

(5) FIG. 3 is a schematic diagram of a solar cell used in the Device example 2

(6) FIG. 4 is a currentvoltage characteristics of an OSC according to Device example 2, comprising compound C13 as the n-dopant in the ETL

(7) According to FIG. 1, an organic solar cell comprises at least a substrate 10, an anode 11, a light absorbing unit 12, and a cathode 13. The stack of layers can also be inverted, wherein layer 11 would be the cathode, and layer 13 would be the anode. Additional light absorbing units can be provided in the organic solar cell.

(8) In one embodiment, the substrate 10 can be a transparent substrate, such as a glass, or polymeric plate or web. The anode 11 can be a transparent conducting oxide, such as ITO, FTO, AlZO. The cathode 13 can comprise aluminum or an aluminum alloy. Alternatively, the light absorbing unit 12 can comprise a blend of a donor polymer, preferentially a thiophene containing polymer, and an acceptor, preferentially a fullerene or a soluble fullerene derivative. In this embodiment, an additional layer comprising the compound according to Formula 1 (such as a doped electron transport layer) or consisting of it (such as an electron extracting layer) is formed between the light absorbing unit 12 and the cathode 13. Optionally, the layer structure can be inverted.

(9) In an alternative embodiment, the anode 11 is not transparent and mainly comprises aluminum or an aluminum alloy. The substrate 10 is not necessarily transparent. The cathode 13 comprises a transparent conducting oxide layer or a thin transparent metal layer having a thickness of less than 30 nm.

(10) Still in connection to FIG. 1, in another embodiment, the substrate 10, the anode 11, and the cathode 13 are transparent. In this embodiment, the overall device is semi-transparent, because it does not have 100% absorption of the incident light for any wavelength in the visible range of wavelengths.

(11) Multiple stacked devices (e.g. tandem devices) can also be provided. In such devices, at least one additional light absorbing unit is formed between the light absorbing unit 12 and the cathode 13. Additional organic or inorganic layers may be formed to provide a suitable electronic connection and optical optimization of the layer position. Preferentially, at least parts of these functions are provided by layers comprising a compound according to the Formula 1.

(12) FIG. 2 shows a stack of layers representing an organic solar cell comprising a substrate 20, an anode 21, a light absorbing unit 22 comprising an absorption layer, an organic electron transport layer (ETL) 23, and a cathode 24. The stack of layers can also be inverted. The ETL can be formed between the cathode 24 and the absorption layer 22. Additional light absorbing units can be provided in the solar cell.

(13) In one embodiment, the organic electron transport layer 23 can comprise as its main component an electron transport matrix (ETM) compound and the compound according to the Formula 1 as a dopant. The doped ETL 23 can have any thickness. Its thickness is preferably smaller than 50 nm in the case that there is no additional absorption layer between the light absorbing layer 22 and the cathode 24.

(14) All embodiments as described in connection to FIG. 1 can also be applied for the solar cell according to FIG. 2.

(15) All figures are schematic representations of the layered structure of a solar cell. Some device features are not shown such as electrical connections, encapsulation, optical structures which are external to the electrodes, etc. The layer thicknesses are not drawn to scale. At least one of the electrodes (anode and/or cathode) is transparent in the wavelength range in which the device is active.

(16) In another embodiment, the light absorbing unit 22 is a donor-acceptor bulk heterojunction, e.g. a blend of donor-acceptor materials. The donor is preferentially formed by a strong absorbing compound comprising a pyrrole or a thiophene group. The acceptor is preferentially a C.sub.58, C.sub.60, or C.sub.70 fullerene or a soluble fullerene derivative. The ETL 23 can comprise a compound according to the Formula 1 as a dopant.

(17) In Table 1, preferred exemplary compounds according to Formula 1 are listed together with conductivities achieved if 10 wt. % of an inventive compound has been doped into one of ETMs E1, E2, E3. HOMO values were measured by cyclic voltammetry in dichloromethane (DCM), the values with asterisk in tetrahydrofuran (THF), n.s. means no signal.

(18) E1 stands for the fullerene C.sub.60 (CAS 99685-96-8, LUMO 1.0 V vs Fc.sup.+/Fc, see Chem. Rev. 2000, vol. 100, p. 1075, Table 1),

(19) TABLE-US-00001 TABLE 1 Conductivity in given HOMO matrix (CV) 10.sup.5 S .Math. cm.sup.1 dopant Dopant formula V E1 E2 E3 C1 0.79 C2 0.40 0.37* C3 0.39 C4 0 0.76 8750 142** C5 0.34 C6 0.21 36 170** 0.0004 0.007 C7 0.64 2430 157** 4 132 0.4 115 C8 0.46 157 136** 0.04 147** C9 0.39 26 >170** C10 0.37 6.5 >170** C11 0.60 C12 0.13* 40 170** C13 n.s.* 7 122** C14 0 0.17* 0.3 163** C15 n.s.* 1.5 >170**

(20) The second value listed below certain conductivity values and highlighted with double asterisk gives the temperature of maximum conductivity in C. If the temperature rises above this value, gradual conductivity decrease is observed. In OPV, it is advantageous if the maximum conductivity temperature is higher than 100 C. Preferably, it is higher than 110 C., more preferably higher than 120 C., even more preferably higher than 130 C., most preferably higher than 140 C. The obtained results showed that the provided compounds allow an efficient n-doping in typical ETMs used in OPV, with very good temperature stability of conductivity.

EXAMPLES

(21) Auxiliary Procedures

(22) The syntheses were done with commercially available starting compounds and anhydrous solvents that were not additionally purified. .sup.13C NMR spectra were measured at 125 MHz in deuterochloroform as solvent.

(23) Cyclic Voltammetry

(24) The redox potentials given at particular compounds were measured in an argon deaerated, dry 0.1M THF solution of the tested substance, under argon atmosphere, with 0.1M tetrabutylammonium hexafluorophosphate supporting electrolyte, between platinum working electrodes and with an Ag/AgCl pseudo-standard electrode, consisting of a silver wire covered by silver chloride and immersed directly in the measured solution, with the scan rate 100 mV/s. The first run was done in the broadest range of the potential set on the working electrodes, and the range was then adjusted within subsequent runs appropriately. The final three runs were done with the addition of ferrocene (in 0.1M concentration) as the standard. The average of potentials corresponding to cathodic and anodic peak of the studied compound, after subtraction of the average of cathodic and anodic potentials observed for the standard Fc.sup.+/Fc redox couple, afforded finally the values reported above.

Synthesis Example 1

N-(chloro(dimethylamino) methylene)-N-methylmethanaminium chloride (I2)

(25) 37.8 mL (440 mmol) oxalyl dichloride were added slowly to a solution of 10.5 mL (88 mmol) 1,1,3,3-tetramethylurea in 60 mL chloroform under argon atmosphere. After stirring for 16 hours at 85 C. (under reflux), the solvent was distilled off and the residue washed with diethyl ether. After drying in vacuo, 14.9 g (87.6 mmol; 99.5%) N-(chloro(dimethylamino) methylene)-N-methylmethanaminium chloride were obtained.

Synthesis Example 2

2-chloro-1,3-dimethyl-1H-benzo[d]imidazol-3-ium hexafluoro phosphate (I3)

(26) To 12.5 g (81.9 mmol) 2-chloro-1H-benzo[d]imidazole in 175 ml water, 20.6 g (245.7 mmol) sodium hydrogen carbonate and 46.6 mL (491.5 mmol) dimethyl sulphate were added. The mixture was stirred 10 hours at 80 C. After cooling to 0 C., 30 mL hydrogen hexafluoro phosphate(V) were added. Filtration of the precipitate, washing with water and drying in vacuo gave 14.84 g (45.44 mmol; 55%) 2-chloro-1,3-dimethyl-1H-benzo[d]imidazol-3-ium hexafluoro phosphate.

Synthesis Example 3

1-(chloro(piperidin-1-yl)methylene)piperidin-1-ium chloride (I4)

(27) 33 mL (38.4 mmol) oxalyl dichloride were added slowly to 15.3 g (7.8 mmol) di(piperidin-1-yl)methanone in 150 mL chloroform under argon atmosphere. The mixture was stirred for 20 hours at 80 C. After distillation of the solvent and drying in vacuo, the 1-(chloro(piperidin-1-yl)methylene)piperidin-1-ium chloride was used for the next synthesis step without further purification.

Synthesis Example 4

1,4-phenylene diimidophosgene intermediate (I6)

(28) Into a stirred solution of 50.00 g 1,4-phenylene diisocyanate in 250 mL chloroform kept by means of an ice cooling bath at the temperature between 0 and 25 C., dry gaseous chlorine has been introduced during approximately 1 hour, until the gas absorption ceased. After additional 3 hours stirring at RT, the solution was rotary evaporated to afford 71 g light grey crystalline solid which was crystallized from 700 mL EE. Obtained 61.3 g white crystalline solid. LC/MS 270 (M).

Synthesis Example 5

N1,N2,N4,N5-tetrakis(1,3-dimethylimidazolidin-2-ylidene)benzene-1,2,4,5-tetraamine (C1)

(29) 1.49 g (8.8 mmol) 2-chloro-1,3-dimethyl-4,5-dihydro-1H-imidazol-3-ium chloride (commercially available intermediate II) in 24 mL acetonitrile were added to a suspension of 0.5 g (1.76 mmol) benzene-1,2,4,5-tetraamine tetrahydrochloride in 10 mL acetonitrile and 3.2 mL triethylamine at 0 C. under argon atmosphere. The mixture was stirred for 1.5 hours at 0 C. After filtration of the formed precipitate and distillation of the solvent, the residue was dissolved in aqueous hydrochloric acid (having 10 wt. % concentration) and alkalized with aqueous sodium hydroxide (20 wt. %). The precipitate was filtered, washed with water and dried in vacuo to give 0.92 g (1.76 mmol; 100% of theoretical yield) white solid. The product was purified by gradient sublimation for analytical characterisation.

(30) Melting point: 290 C.

Synthesis Example 6

N3,N3,N4,N4-tetrakis(1,3-dimethylimidazolidin-2-ylidene)-[1,1-biphenyl]-3,3,4,4-tetraamine (C2)

(31) 2.00 g (11.83 mmol) 2-chloro-1,3-dimethyl-4,5-dihydro-1H-imidazol-3-ium chloride (I1) in 10 mL acetonitrile were added to a suspension of 0.61 g (2.85 mmol) biphenyl-3,3,4,4-tetraamine in 20 mL acetonitrile and 4.6 mL triethylamine under argon atmosphere. The mixture was stirred for 2 days at room temperature. After filtration of the precipitate and distillation of the solvent, the residue was suspended in 2 M sodium hydroxide solution and stirred for 5 minutes at 45 C. 1.17 g (1.95 mmol; 68%) off-white solid were obtained after filtration, washing with water and drying in vacuo. The product was purified by gradient sublimation for analytical characterisation.

(32) Melting point: 231 C.

Synthesis Example 7

N1-(1,3-dimethylimidazolidin-2-ylidene)-N4,N4-bis(4-((1,3-dimethylimidazolidin-2-ylidene)amino)phenyl)benzene-1,4-diamine (C3)

(33) 2.00 g (11.9 mmol) 2-chloro-1,3-dimethyl-4,5-dihydro-1H-imidazol-3-ium chloride (I1) in 20 mL acetonitrile were added to a suspension of 1.00 g (3.4 mmol) N1,N1-bis(4-aminophenyl)benzene-1,4-diamine in 30 mL acetonitrile and 3.8 mL triethylamine under argon atmosphere. The mixture was stirred for 24 hours at room temperature. After distillation of the solvent, the residue was suspended in 2 M sodium hydroxide solution and stirred for 5 minutes at 45 C. 1.4 g (2.42 mmol; 71%) rose solid were obtained after filtration, washing with water and acetone and drying in vacuo. The product was purified by gradient sublimation for analytical characterisation.

(34) Melting point: 226 C.

Synthesis Example 8

2,2,2,2-(benzene-1,2,4,5-tetrayl)tetrakis(1,1,3,3-tetramethylguanidine) (C4)

(35) 14.9 g (87.6 mmol) N-(chloro(dimethylamino)methylene)-N-methylmethanaminium chloride (I2) in 250 mL acetonitrile were added to a suspension of 5 g (17.6 mmol) benzene-1,2,4,5-tetraamine tetrahydrochloride in 100 mL acetonitrile and 51 mL triethylamine at 0 C. under argon atmosphere. The mixture was stirred for 2 hours at 0 C. After distillation of the solvent, the residue was dissolved in aqueous hydrochloric acid (10 wt. %) and alkalized with 20 wt. % aqueous sodium hydroxide. Extraction with toluene, washing with acetonitrile and drying in vacuo gave 3.16 g (5.96 mmol; 34%) white solid. The product was purified by gradient sublimation for analytical characterisation.

(36) Melting point: 206 C.

Synthesis Example 9

N1,N4-bis(1,3-dimethylimidazolidin-2-ylidene)-2-methoxybenzene-1,4-diamine (C5)

(37) 1.sup.st Step

(38) 3.0 g (17.8 mmol) 2-methoxy-4-nitroaniline and 0.8 g palladium on charcoal (10 wt. %) were added to 100 ml tetrahydrofuran (THF). 8.66 mL (114 mmol) hydrazine monohydrate in 40 ml THF were cautiously added and the reaction mixture was stirred at 90 C. for 3 hours. After cooling, the suspension was filtered and the collected solid washed with THF. The filtrate was reduced to a gray residue under reduced pressure. 2.44 g (17.66 mmol, 99%) 2-methoxybenzene-1,4-diamine were stored under argon and used without further purification.

(39) 2.sup.nd Step

(40) 2.00 g (11.9 mmol) 2-chloro-1,3-dimethyl-4,5-dihydro-1H-imidazol-3-ium chloride (II) in 20 mL acetonitrile were added to a suspension of 0.66 g (4.7 mmol) 2-methoxybenzene-1,4-diamine in 20 mL acetonitrile and 2.4 mL triethylamine under argon atmosphere. The mixture was stirred for 50 hours at room temperature. After filtration of the precipitate and distillation of the solvent, the residue was suspended in 2 M aqueous sodium hydroxide solution and stirred for 5 minutes at 45 C. The precipitate was filtered, the solvent distilled off, the residue suspended in acetonitrile/methanol mixture and filtered through an alumina pad (Polygram Alox N/UV.sub.254). 1.2 g (3.63 mmol; 77%) orange solid were obtained after drying in vacuo. The product was purified by gradient sublimation for analytical characterisation.

(41) Melting point: 149 C.

Synthesis Example 10

N1,N4-bis(1,3-dimethyl-1H-benzo[d]imidazol-2(3H)-ylidene)benzene-1,4-diamine (C6)

(42) 14.84 g (45.44 mmol) 2-chloro-1,3-dimethyl-1H-benzo[d]imidazol-3-ium hexafluoro phosphate (I3) in 50 mL acetonitrile were added to a suspension of 1.97 g (18.18 mmol) benzene-1,4-diamine in 250 mL acetonitrile and 15.7 mL triethylamine under argon atmosphere at 0 C. The mixture was stirred for 20 hours at room temperature. The precipitate was filtered, washed with acetonitrile, suspended in 2 M sodium hydroxide solution and stirred for 5 minutes at 45 C. 6.42 g (11.65 mmol; 64%) white solid was obtained after filtration, washing with water and drying in vacuo. The product was purified by gradient sublimation for analytical characterisation.

(43) Melting point: 290 C.

Synthesis Example 11

N1,N2,N4,N5-tetrakis(1,3-dimethyl-1H-benzo[d]imidazol-2(3H)-ylidene)benzene-1,2,4,5-tetraamine (C7)

(44) 15.3 g (46.84 mmol) 2-chloro-1,3-dimethyl-1H-benzo[d]imidazol-3-ium hexafluoro phosphate (I3) in 50 mL acetonitrile were added to a suspension of 2.66 g (9.37 mmol) benzene-1,2,4,5-tetraamine tetrahydrochloride in 250 mL acetonitrile and 16 mL triethylamine under argon atmosphere. The mixture was stirred for 20 hours at room temperature. The precipitate was filtered, washed with acetonitrile, suspended in 2 M sodium hydroxide solution and stirred for 5 minutes at 45 C. 5.7 g (7.97 mmol; 85%) white solid was obtained after filtration, washing with water and drying in vacuo. The product was purified by gradient sublimation for analytical characterisation.

(45) Melting point: 374 C.

Synthesis Example 12

N1,N2,N4-tris(di(piperidin-1-yl)methylene)benzene-1,2,4-triamine (C8)

(46) 19.6 g (78 mmol) 1-(chloro(piperidin-1-yl)methylene)piperidin-1-ium chloride (I4) in 150 mL acetonitrile and 65 mL triethylamine were added to a suspension of 5.1 g (26 mmol) benzene-1,2,4-triamine dihydrochloride in 160 mL acetonitrile and 22 mL triethylamine under argon atmosphere. The mixture was stirred for 72 hours at room temperature. The precipitate was filtrated and the solvent distilled off. The residue was purified by column chromatography in chloroform/methanol and by precipitation in hexane from a dichloromethane solution, to give 2 g (3.04 mmol; 12%) foamy solid. The product was purified by gradient sublimation for analytical characterisation.

Synthesis Example 13

N1,N2,N4-tris(1,3-dimethyl-1H-benzo[d]imidazol-2(3H)-ylidene)benzene-1,2,4-triamine (C9)

(47) 11.7 g (35.83 mmol) 2-chloro-1,3-dimethyl-1H-benzo[d]imidazol-3-ium hexafluoro phosphate (I3) in 25 mL acetonitrile were added to a suspension of 1.79 g (9.13 mmol) benzene-1,2,4-triamine dihydrochloride in 40 mL acetonitrile and 12.7 mL triethylamine under argon atmosphere at 0 C. The mixture was stirred for 72 hours at room temperature. The precipitate was filtered, washed with acetonitrile, suspended in 2 M sodium hydroxide solution and stirred for 5 minutes at 45 C. 2.5 g (4.5 mmol; 49%) grey solid were obtained after filtration, washing with water and acetonitrile and drying in vacuo. The product was purified by gradient sublimation for analytical characterisation.

Synthesis Example 14

N1-(1,3-dimethyl-1H-benzo[d]imidazol-2(3H)-ylidene)-N4,N4-bis(4-((1,3-dimethyl-1H-benzo[d]imidazol-2(3H)-ylidene)amino)phenyl)benzene-1,4-diamine (C10)

(48) 3.15 g (9.65 mmol) 2-chloro-1,3-dimethyl-1H-benzo[d]imidazol-3-ium hexafluorophosphate (I3) in 25 mL acetonitrile were added to a suspension of 0.75 g (2.57 mmol) N1,N1-bis(4-aminophenyl)benzene-1,4-diamine in 75 mL acetonitrile and 3.2 mL triethylamine under argon atmosphere at 0 C. The mixture was stirred for 48 hours at room temperature. The precipitate was filtered, washed with acetonitrile, suspended in 2 M aqueous sodium hydroxide solution and stirred for 5 minutes at 45 C. 0.9 g (1.25 mmol; 49%) foamy solid was obtained after filtration, washing with water and drying in vacuo. The product was purified by gradient sublimation for analytical characterisation.

Synthesis Example 15

3,3-(1,4-phenylenebis(azanylylidene))bis(N1,N1,N2,N2-tetramethylcycloprop-1-ene-1,2-diamine) (C11)

(49) A 25 ml flask was charged with 10 mL of acetonitrile, 1 g (2 mmol) of chloro bis(dimethylamino) cyclopropylium hexachloroantimonate (commercially available intermediate I5) and 0.6 mL 1.8 diazabicyclo[5.4.0]undec-7-ene. Diamino benzene (86 mg, 0.8 mmol) was added and the resulting mixture was kept at 90 C. overnight. After cooling, the suspension was filtered and the dark filter cake was washed with acetonitrile. The filtrate was concentrated in vacuo to afford red oil that was dissolved in dichloromethane. The organic layer was washed with diluted sodium hydroxide solution and two times with water. After drying with magnesium sulphate, the solvent was removed in vacuum. 54 mg (19%) yellowish solid were isolated.

Synthesis Example 16

N,N-Bis-(di-morpholin-4-yl-methylene)-benzene-1,4-diamine (C12)

(50) 8.10 g (30 mmol, 1 eq) 1,4-phenylene diimidophosgene intermediate (I6) was dissolved under nitrogen in 150 mL dry THF, 42 mL (480 mmol, 16 eq) morpholine added under cooling in an ice bath (exothermic), 16 h stirred at RT, white suspension evaporated under vacuum on rotary evaporator, 75 mL morpholine added, heated for 5 h in a 110 C. hot oil bath, the suspension turned brown-yellow, stirred at RT for additional 16 h. The reaction mixture has been dissolved in 750 mL chloroform, extracted with 375 mL 2M aqueous NaOH, the aqueous phase extracted twice with 375 mL chloroform, combined organic phase extracted with 188 mL 2M NaOH and 375 mL brine, dried with sodium sulphate and rotary evaporated, affording 15.5 g of light brown solid. The crude product was purified by boiling with 150 mL absolute ethanol, the suspension cooled to RT, filtered, washed with absolute ethanol and dried in vacuum. Obtained 13.69 g white solid comprising according to NMR probe 96% purity with 4% solvent, further purified by crystallization from isopropyl alcohol.

(51) Elemental analysis: C, 60.79% (theor. 61.00), H, 7.55% (theor. 7.68), N, 17.64% (theor. 17.78). LC/MS-ESI 473 (M+H), .sup.13C-NMR: 48.80, 66.75, 122.31, 144.46 and 157.09 ppm.

Synthesis Example 17

N-[4-(N,N-Dimethyl-N,N-diphenyl-guanidino)-phenyl]-N,N-dimethyl-N,N-diphenyl-guanidine (C13)

(52) 5.40 g (20 mmol, 1 eq) 1,4-phenylene diimidophosgene intermediate (I6) was mixed under nitrogen with 34.6 mL neat N-methylaniline (320 mmol, 16 eq) to form a greenish suspension without an exothermic effect. Under heating, an exothermic reaction starts at 60 C., the mixture solidified during cca 30 min at 90 C. Cooled down, suspended with an ultrasound bath in 150 mL diethyl ether, light grey solid filtered, dissolved in 300 mL chloroform, extracted with 160 mL 1M aqueous NaOH, the aqueous phase extracted twice with 50 mL chloroform, combined organic extracts washed with 100 mL 1 M NaOH and 100 mL brine, dried over sodium sulphate, filtered and the filtrate rotary evaporated under vacuum. Obtained 18.2 g light pink solid, purified by boiling with toluene and, subsequently, with ethanol and chloroform, to afford a white solid finally purified by crystallization from isopropyl alcohol.

(53) Elemental analysis: C, 77.79% (theor. 78.23), H, 6.53% (theor. 6.57), N, 15.11% (theor. 15.20). LC/MS-APCI 552 (M), .sup.13C-NMR: 39.63, 117.41, 120.15, 122.10, 123.81, 128.51 and 153.79 ppm.

Synthesis Example 18

N,N,N,N-Tetraphenyl-N-[4-(N,N,N,N-tetraphenyl-guanidino)-phenyl]-guanidine (C14)

(54) 5.00 g (18.5 mmol, 1 eq) 1,4-phenylene diimidophosgene intermediate (I6) was mixed under nitrogen with 50.143 g neat diphenyl amine (296 mmol, 16 eq) molten by heating the reaction flask in a 70 C. warm oil bath. After one hour at 100 C., the originally yellow-green homogeneous mixture turned brown. Cooled down to RT, mixed with 50 mL diethyl ether, treated with ultrasound, until the oily viscous mixture turned into a yellow suspension. 100 mL saturated aqueous NaHCO.sub.3 added, the orange-brown organic phase separated, the aqueous phase extracted twice with 50 mL EE, combined organic phases extracted with 50 mL saturated aqueous NaHCO.sub.3 and rotary evaporated to form 47 g yellow oil that after addition 300 mL EE formed in the ultrasound bath a fine suspension, which after filtration and drying afforded 6.26 g of a yellow solid. The crude product has been further purified by subsequent crystallizations from toluene and isopropyl alcohol.

(55) Elemental analysis: C, 83.80% (theor. 83.97), H, 5.63% (theor. 5.54), N, 10.40% (theor. 10.49). LC/MS-ESI 801 (M+H), .sup.13C-NMR: 121.28, 123.88, 124.10, 124.33, 125.00, 128.54, 128.69, 143.22, 144.30, 144.86, 150.50 ppm.

Synthesis Example 19

N-[4-(N,N,N,N-Tetra-p-tolyl-guanidino)-phenyl]-N,N,N,N-tetra-p-tolyl-guanidine (C15)

(56) 5.24 g (20.0 mmol, 1 eq) 1,4-phenylene diimidophosgene intermediate (I6) was mixed under nitrogen with 63.13 g neat p,p-ditolyl amine (320 mmol, 16 eq) molten by heating the reaction flask a 85 C. warm oil bath. After three hours at 100 C. the brown solution has been cooled down, diluted with 500 mL chloroform and agitated with 250 mL 2M aqueous NaOH. The organic phase was separated, the aqueous phase was extracted twice with 250 mL chloroform, the combined organic phases were extracted subsequently with 250 mL 2M NaOH, 250 mL brine, dried over sodium sulphate and rotary evaporated to afford 70 g viscous substance that was dissolved in 300 mL EE, concentrated, dissolved in 200 mL boiling ethanol, and crystallized by cooling to RT. Obtained crude product has been chromatographed on a silica column with EE:petrolether as eluent, to afford 6.97 g yellow crystalline solid. .sup.13C-NMR: 20.84, 20.92, 121.17, 122.53, 123.85, 124.70, 128.35, 128.93, 129.14, 132.29, 132.96, 133.52, 139.73, 142.08, 142.60, 143.15, 143.30, 146.02, 150.79 ppm.

(57) In device examples, following auxiliary compounds were used:

(58) N4,N4,N4,N4-tetra([1,1-biphenyl]-4-yl)-[1,1:4,1-terphenyl]-4,4-diamine (HT1, CAS 925431-34-4) as a hole transport matrix, 1,2,3-triylidenetris(cyanomethanylylidene))tris-(2,3,5,6-tetrafluorobenzonitrile)-cyclopropane (PD2, CAS 1224447-88-4), tetrakis (1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidinato) ditungsten (II) (W.sub.2(hpp).sub.4, CAS 463931-34-2)

Device Example 1

(59) A pn junction device was used to benchmark the new dopants according to Formula 1 with the strong donor W.sub.2(hpp).sub.4. The pn-junction device was made on a glass substrate using ITO as anode, a 50 nm p-doped HTL (hole transport layer) consisting of the hole transport matrix HT1 and p-dopant PD2 in weight ratio 9:1, a 50 nm electron transport layer consisting of fullerene C.sub.60 as matrix, doped with one of the new dopants according to Formula 1 in weight ratio 7:3, and an Al cathode. The voltage necessary for a current density of 5 mA/cm.sup.2 was 0.02 V for compound C7, 0.64 V for compound C12, 0.65 V for compound C13, 0.30 V for compound C14 and 0.78 V for compound C15. The value for compound C7 is surprisingly good, given the much lower donating strength in comparison with W.sub.2(hpp).sub.4 (HOMO<<1.0 V vs Fc.sup.+/Fc), which in the same arrangement allowed to operate the pn junction at the voltage of 0.01 V for the current density of 5 mA/cm.sup.2. Compounds C12-C15, having even lower reduction strength in terms of their redox potentials listed in the Table 1, still allowed the operation of the pn junction at voltages below 1 V.

Device Example 2

(60) The layer structure of the experimental photovoltaic device designed for assessment of the applicability of the imine compounds of the present invention in semiconducting materials is schematically shown as FIG. 3. The device was prepared on the glass substrate 30 bearing a 90 nm ITO cathode 31, by vacuum deposition of the following layers: 10 nm thick ETL 32 made of fullerene C.sub.60 doped with a compound of Formula 1 in a weight ratio 9:1, 20 nm thick absorption layer 33 made of C.sub.60, 30 nm thick absorption layer 34 made of C.sub.60 and zinc phtalocyanine in weight ratio 1:1, 2 nm thick hole extraction layer 35 made of HT1, 40 nm thick HTL 36 made of HT1 doped with PD2 in weight ratio 19:1, 2 nm thick hole injection layer 37 made of neat PD2 and 100 nm thick aluminium anode 38. Comparison of performance of the device for several inventive electron transport materials gives the Table 2.

(61) TABLE-US-00002 TABLE 2 Voc Jsc fill factor efectivity dopant (V) (mA/cm.sup.2) (%) saturation (%) C7 0.53 9.1 56 1.12 2.7 C12 0.53 8.9 56 1.13 2.6 C13 0.53 9.0 56 1.12 2.7

(62) The obtained results surprisingly show that even the compounds of Formula 1 that have less negative redox potentials than 0.3 V vs Fc.sup.+/Fc can be successfully used in semiconducting materials for OSCs.

(63) The features of the invention disclosed in the above specification, the claims and the drawing may be important individually as well as in any combination for the implementation of the invention in its various embodiments.

(64) Abbreviations Used Throughout the Application

(65) AlZO aluminium zinc oxide

(66) APCI atmospheric pressure chemical ionization

(67) CAS Chemical Abstract Service reference number

(68) CV cyclic voltammetry

(69) DCM dichloromethane

(70) EE diethyl ether

(71) EIL electron injection/extraction layer

(72) ESI electrospray ionization

(73) ETL electron transport layer

(74) ETM electron transport matrix

(75) Fc ferrocene

(76) Fc.sup.+ ferrocenium

(77) FTO fluorine-doped tin oxide

(78) HBL hole blocking layer

(79) HIL hole injecting layer

(80) HOMO highest occupied molecular orbital

(81) HPLC high performance liquid chromatography

(82) HTL hole transport layer

(83) HTM hole transport matrix

(84) ITO indium tin oxide

(85) LC liquid chromatography

(86) LUMO lowest unoccupied molecular orbital

(87) mol. % molar percent

(88) MS mass spectrometry

(89) NMR nuclear magnetic resonance

(90) OLED organic light emitting diode

(91) OPV organic photovoltaics

(92) OSC organic solar cell

(93) OVPD organic vapor phase deposition

(94) QE quantum efficiency

(95) PCBM phenyl C61 Butyric Acid Methyl Ester

(96) R.sub.f retardation factor in TLC

(97) TCNQ tetracyanoquinodimethane

(98) T.sub.g glass transition temperature

(99) TLC thin layer chromatography

(100) vs versus

(101) VTE vacuum thermal evaporation

(102) wt. % weight percent