N-fluoroalkyl-substituted dibromonaphthalene diimides and their use as semiconductor

Abstract

The present invention relates to compounds of the formula (I) where R.sup.1 and R.sup.2 independently of each other, are selected from 1H,1HC.sub.2-C.sub.10-perfluoroalkyl and 1H,1H,2H,2HC.sub.3-C.sub.10-perfluoroalkyl, except for the compound of formula (I), where R.sup.1 and R.sup.2 are both 1H,1H-perfluorobutyl, and to their use, especially as an n-type semiconductor. ##STR00001##

Claims

1. A compound of formula I ##STR00005## where R.sup.1 and R.sup.2, independently of each other, are 2,2,2-trifluoroethyl or 2,2,3,3,3-pentafluoropropyl.

2. The compound according to claim 1, wherein R.sup.1 and R.sup.2 are the same.

3. The compound according to claim 1, is 2,6-dibromo-N,N-bis(2,2,2-trifluoroethyl)-naphthalene[1,8:4,5]bis(dicarboximide); or 2,6-dibromo-N,N-bis(1H,1H-pentafluoropropyl)-naphthalene-[1,8:4,5]bis(dicarboximide).

4. A semiconductor, comprising the compound according to claim 1.

5. A thin film semiconductor, comprising the compound according to claim 1.

6. An organic field effect transistor, comprising a substrate comprising at least one gate structure, a source electrode and a drain electrode, and at least one compound according to claim 1 as a semiconductor material.

7. The organic field effect transistor according to claim 6, having a top-gate bottom-contact configuration.

8. The organic field effect transistor according to claim 6, having a bottom-gate bottom-contact configuration.

9. A substrate, comprising a plurality of organic field-effect transistors, wherein at least some of the field-effect transistors comprising at least one compound according to claim 1.

10. A semiconductor unit, comprising at least one substrate according to claim 9.

11. An organic solar cell, comprising at least one compound according to claim 1.

12. A semiconductor, comprising the compound according to claim 3.

13. A thin film semiconductor, comprising the compound according to claim 3.

14. An organic field effect transistor, comprising a substrate comprising at least one gate structure, a source electrode and a drain electrode, and at least one compound according to claim 3 as a semiconductor material.

15. A substrate, comprising a plurality of organic field-effect transistors, wherein at least some of the field-effect transistors comprising at least one compound according to claim 3.

16. An organic solar cell, comprising at least one compound according to claim 3.

Description

EXAMPLES

Example 1 (Comparison, Compound (21) of WO 2007/074137)

2,6-Dibromo-N,N-bis(1H,1H-perfluorobutyl)-naphthalene[1,8:4,5]bis(dicarboximide) (compound of the formula I, where R1 and R2 are 2,2,3,3,3,4,4,4-heptafluorobutyl)

(1) 1.17 g (3.96 mmol) of 97% strength N,N-dibromoisocyanuric acid were added to a solution of 2.00 g (3.17 mmol) of N,N-bis(1H,1H-perfluorobutyl)-naphthalene[1,8:4,5]bis(dicarboximide) [described in H. E. Katz et al., Materials Research Society Symposium Proceedings (2001), 665 (Electronics, Optical and Optoelectronic Polymers and Oligomers), 271-280] in 240 mL of 95 to 97% strength sulfuric acid at room temperature. The reaction flask was darkened with aluminium foil. The solution was stirred for 28 hours at room temperature. Subsequently, the solution was poured on 1.5 kg of ice and neutralized with NaOH. The aqueous phase was extracted twice with 750 mL of dichloromethane. The combined organic extracts were dried over magnesium sulfate, filtered and concentrated to dryness. The residue was suspended in n-heptane and filtered. The filter cake obtained was dried to yield 2.29 g of a yellow solid. Recrystallization from 80 mL of isobutanol yielded 2.06 g (83% yield) of a yellow solid showing only one spot in thin-layer chromatography. A sample was sublimed at 175? C. (1.2?10.sup.?6 mbar). The melting point of the sublimed sample was 323? C.

(2) .sup.1H-NMR (400 MHz, D.sub.8-THF): ?=9.00 (s, 2H), 5.08 (t, 4H) ppm.

Example 2

2,6-Dibromo-N,N-bis(2,2,2-trifluoroethyl)-naphthalene[1,8:4,5]bis(dicarboximide) (compound of formula I, where R1 and R2 are 2,2,2-trifluoroethyl)

2.1 N,N-Bis(2,2,2-trifluoroethyl)-naphthalene[1,8:4,5]bis(dicarboximide)

(3) The title compound was prepared as described in H. E. Katz et al., Materials Research Society Symposium Proceedings (2002), 665 (Electronics, Optical and Optoelectronic Polymers and Oligomers), 271-280.

(4) .sup.1H-NMR (400 MHz, CDCl.sub.3): ?=8.86 (s, 4H), 4.96 (q, J.sub.HF=8.44 Hz, 4H) ppm

2.2 2,6-Dibromo-N,N-bis(2,2,2-trifluoroethyl)-naphthalene[1,8:4,5]bis(dicarboximide)

(5) 0.587 g (2.05 mmol) of N,N-dibromoisocyanuric acid were added to a solution of 0.80 g (1.9 mmol) of N,N-bis(2,2,2-trifluoroethyl)-naphthalene-[1,8:4,5]bis(dicarboximide) in 160 mL of 95 to 97% strength sulfuric acid at room temperature. The solution was stirred for 40 hours at room temperature. Subsequently, the reaction mixture was poured on 1 L of icewater. The precipitate was filtered off and purified by column chromatography (dichloromethane/pentane 1:1) several times, and then by recrystallization in o-xylene. 0.060 g (5% yield) of a light yellow solid were obtained.

(6) .sup.1H-NMR (400 MHz, CDCl.sub.3): ?=9.08 (s, 2H), 4.97 (q, 4H, J=8.56 Hz) ppm.

Example 3

2,6-Dibromo-N,N-bis(1H,1H-perfluoropropyl)-naphthalene[1,8:4,5]bis(dicarboximide) (compound of the formula I, where R1 and R2 are 2,2,3,3,3-pentafluoropropyl)

3.1 N,N-Bis(1H,1H-perfluoropropyl)-naphthalene[1,8:4,5]bis(dicarboximide)

(7) The title compound was prepared as described in H. E. Katz et al., Materials Research Society Symposium Proceedings (2002), 665 (Electronics, Optical and Optoelectronic Polymers and Oligomers), 271-280.

(8) .sup.1H-NMR (400 MHz, CDCl.sub.3): ?=8.87 (s, 4H), 4.99 (q, J.sub.HF=14.4 Hz, 4H) ppm

3.2 2,6-Dibromo-N,N-bis(1H,1H-perfluoropropyl)-naphthalene[1,8:4,5]bis(dicarboximide)

(9) 0.655 g (2.28 mmol) of N,N-dibromoisocyanuric acid were added to a solution of 1.10 g of (2.07 mmol) N,N-bis(1H,1H-perfluoropropyl)-naphthalene-[1,8:4,5]bis-(dicarboximide) in 160 mL of 95 to 97% strength sulfuric acid at room temperature. The solution was stirred for 40 hours at room temperature. Subsequently, the reaction mixture was poured on 1 L of icewater. The precipitate was filtered off and purified by column chromatography (dichloromethane/pentane 1:1) several times. 0.205 g (14% yield) of a light yellow solid were obtained.

(10) .sup.1H-NMR (400 MHz, CDCl.sub.3): ?=9.08 (s, 2H), 4.99 (q, 4H, J=14.7 Hz) ppm.

Example 4

2,6-Dibromo-N,N-bis(1H,1H-perfluoropentyl)-naphthalene[1,8:4,5]bis(dicarboximide) (compound of formula I, where R1 and R2 are 2,2,3,3,4,4,5,5,5-nonafluoropentyl)

(11) 4.1 N,N-Bis(1H,1H-perfluoropentyl)-naphthalene[1,8:4,5]bis(dicarboximide) The title compound was prepared as described in J. H. Oh et al., Adv. Funct. Mater. 2010, 20, 2148-2156.

(12) .sup.1H-NMR (400 MHz, CDCl.sub.3): ?=8.87 (s, 4H), 5.04 (t, JHF=15.2 Hz, 4H) ppm.

4.2 2,6-Dibromo-N,N-bis(1H,1H-perfluoropentyl)-naphthalene[1,8:4,5]bis(dicarboximide)

(13) 0.560 g (1.76 mmol) of N,N-dibromoisocyanuric acid were added to a solution of 1.00 g (1.34 mmol) of N,N-bis(1H,1H-perfluoropropyl)-naphthalene-[1,8:4,5]bis-(dicarboximide) in 140 mL of 95 to 97% strength sulfuric acid at room temperature. The solution was stirred for 40 hours at room temperature. Subsequently, the reaction mixture was poured on 1 I icewater. The precipitate was filtered off and purified by column chromatography (dichloromethane/pentane 1:1) several times, and then by recrystallization in ethyl acetate. 0.344 g (29% yield) of a light yellow solid were obtained.

(14) 1H-NMR (400 MHz, CDCl.sub.3): ?=9.08 (s, 2H), 5.05 (q, 4H, J=15.6 Hz) ppm.

Example 5

General Procedure for the Fabrication of Vapor-Deposited OFETs in the Bottom-Gate Top-Contact Configuration

(15) Highly doped p-type silicon (100) wafers (0.01-0.02 ?.Math.cm) were used as substrates A. Highly doped p-type silicon (100) wafers (0.005-0.02 ?.Math.cm) with a 100 nm thick thermally grown SiO.sub.2 layer (capacitance 34 nF/cm2) were used as substrates B.

(16) Onto substrates A, a 30 nm thick layer of aluminum is deposited by thermal evaporation in a Leybold UNIVEX 300 vacuum evaporator from a tungsten wire, at a pressure of 2?10.sup.?6 mbar and with an evaporation rate of 1 nm/s. The surface of the aluminum layer is oxidized by a brief exposure to an oxygen plasma in an Oxford reactive ion etcher (RIE, oxygen flow rate: 30 sccm, pressure: 10 mTorr, plasma pow-power: 200 W, plasma duration 30 sec) and the substrate is then immersed into a 2-propanol solution of a phosphonic acid (1 mMol solution of C.sub.14H.sub.29PO(OH).sub.2 [TDPA] or 1 mMol solution of C.sub.7F.sub.15C.sub.11H.sub.22PO(OH).sub.2 [FODPA]) and left in the solution for 1 hour, which results in the formation of a self-assembled monolayer (SAM) of phosphonic acid molecules on the aluminum oxide surface. The substrate is taken out of the solution and rinsed with pure 2-propanol, dried in a stream of nitrogen and left for 10 min on a hotplate at a temperature of 100? C. The total capacitance of the AlO.sub.x/SAM gate dielectric on substrate A is 810 nF/cm.sup.2 in case of C.sub.14H.sub.29PO(OH).sub.2 and 710 nF/cm.sup.2 in case of C.sub.7F.sub.15C.sub.11H.sub.22PO(OH).sub.2.

(17) On substrates B, an about 8 nm thick layer of Al.sub.2O.sub.3 is deposited by atomic layer deposition in a Cambridge NanoTech Savannah (80 cycles at a substrate temperature of 250? C.). The surface of the aluminum oxide layer is activated by a brief exposure to an oxygen plasma in an Oxford reactive ion etcher (RIE, oxygen flow rate: 30 sccm, pressure: 10 mTorr, plasma power: 200 W, plasma duration 30 sec) and the substrate is then immersed into a 2-propanol solution of a phosphonic acid (1 mMol solution of C.sub.14H.sub.29PO(OH).sub.2 [TDPA] or 1 mMol solution of C.sub.7F.sub.15C.sub.11H.sub.22PO(OH).sub.2 [FODPA]) and left in the solution for 1 hour, which results in the formation of a self-assembled monolayer (SAM) of phosphonic acid molecules on the aluminum oxide surface. The substrate is taken out of the solution and rinsed with pure 2-propanol, dried in a stream of nitrogen and left for 10 min on a hotplate at a temperature of 100? C. The total capacitance of the SiO.sub.2/AlO.sub.x/SAM gate dielectric on substrate B is 32 nF/cm.sup.2 (independent on the choice of the phosphonic acid).

(18) The contact angle of water on the TDPA-treated substrates is 108?, and on the FODPA-treated substrates 118?.

(19) A 30 nm thick film of the organic semiconductor is deposited by thermal sublimation in a Leybold UN IVEX 300 vacuum evaporator from a molybdenum boat, at a pressure of 2?10.sup.?6 mbar and with an evaporation rate of 0.3 nm/s.

(20) For the source and drain contacts 30 nm of gold is evaporated through a shadow mask in a Leybold UNIVEX 300 vacuum evaporator from tungsten boat, at a pressure of 2?10.sup.?6 mbar and with an evaporation rate of 0.3 nm/s. The transistors have a channel length (L) ranging from 10 to 100 ?m and a channel width (W) ranging from 50 to 1000 ?m.

(21) To be able to contact the back side of the silicon wafer, the wafer (which also serves as the gate electrode of the transistors) is scratched on the back side and coated with silver ink.

(22) The electrical characteristics of the transistors are measured on a Micromanipulator 6200 probe station using an Agilent 4156C semiconductor parameter analyzer. All measurements are performed in air at room temperature. The probe needles are brought into contact with the source and drain contacts of the transistors by putting them down carefully on top of the gold contacts. The gate electrode is contacted through the metal substrate holder onto which the wafer is placed during the measurements.

(23) To obtain the transfer curve the drain-source voltage (V.sub.DS) is held to 3 V (in case of substrate A) or 40 V (in case of substrate B). The gate-source voltage V.sub.GS is swept at medium speed from 0 to 3 V in steps of 0.03 V (substrate A) or from 0 to 40 V in steps of 0.4 V (substrate B) and back. The charge-carrier mobility is extracted in the saturation regime from the slope of (I.sub.D).sup.1/2 versus V.sub.GS.

(24) To obtain the output characteristics the drain-source voltage (V.sub.DS) is swept at medium speed from 0 to 3 V in steps of 0.03 V (substrate A) and from 0 to 40 V in steps of 0.4 V (substrate B), while the gate-source voltage V.sub.GS is held at up to 8 different voltages (e.g. 0, 0.5, 1, 1.5, 2, 2.5, 3 V in case of substrate A or 0, 10, 20, 30, 40 V in case of substrate B).

(25) Table 1 gives the field-effect mobilities (?) and on/off ratios (I.sub.on/I.sub.off) for semi-conductors with a thick (substrate B) gate dielectric with a certain SAM layer at a certain substrate temperature (T.sub.sub) measured in ambient air.

(26) TABLE-US-00001 TABLE 1 Field- Semi- Substrate effect conductor tempe- mobility On/Off from Sub- rature ? [cm.sup.2/ ratio example strate SAM T.sub.sub [? C.] Vs] I.sub.on/I.sub.off 1* B C.sub.14H.sub.29PO(OH).sub.2 50 0.90 5 ? 10.sup.6 1* B F.sub.15C.sub.7H.sub.22C.sub.11PO(OH).sub.2 50 1.02 10.sup.7 2 B C.sub.14H.sub.29PO(OH).sub.2 50 1 2 ? 10.sup.8 3 B C.sub.14H.sub.29PO(OH).sub.2 50 0.85 2 ? 10.sup.8 4 B F.sub.15C.sub.7H.sub.22C.sub.11PO(OH).sub.2 70 0.7 2 ? 10.sup.7 *comparison

Example 6

Procedure for a Solution-Processed OFET on a Standard Substrate in the Top-Gate Bottom-Contact Configuration

(27) A 0.5% solution of the semiconductor in ethyl acetate warmed to 50? C. was spincoated (Spin Coater: Primus STT15) on a standard PET substrate at 1000 rpm. The standard PET substrate consisted of a PET foil (Mitsubishi DN4600) with shadow-mask patterned, 50 nm thick gold Source and Drain contacts. After deposition of the semiconductor, Cytop CTL-809 (9%) was spincoated at 3500 rpm as a dielectric layer (thickness 660 nm, ?.sub.r=2,1). Immediately after spincoating, the substrate was placed on a hot-plate an annealed for 10 min at 100? C. Finally, 50 nm thick gate electrodes has been patterned by thermal evaporation of gold through a shadow-mask.

(28) The electrical characteristics of the transistor was measured with an Agilent 4155C Semiconductor Parameter Analyzer. The transistor had a channel width (W) of 500 ?m and a channel length (L) of 50 ?m. All measurements were performed in air at room temperature.

(29) To obtain the transfer curve the drain-source voltage (U.sub.DS) is held to 40 V. The gate-source voltage U.sub.GS is swept at medium speed from ?20 to 60 V in steps of 2 V and back. The charge-carrier mobility is extracted in the saturation regime from the slope m of (I.sub.D).sup.1/2 versus V.sub.GS using the following equations:

(30) $?=\frac{m^2*2L}{C_G*W}{C}_G={\mathrm{.Math.}}_0*{\mathrm{.Math.}}_r\frac{1}{d}$

(31) where ?.sub.0 is the vacuum permittivity of 8.85?10.sup.?12 As/Vm.

(32) To obtain the output characteristics the drain-source voltage (V.sub.DS) is swept at medium speed from 0 to 60 V in steps of 2 V, while the gate-source voltage V.sub.GS is held at up to 5 different voltages (e.g. 0, 15, 30, 45, 60 V).

(33) Table 2 gives the threshold voltage U.sub.th, the field-effect mobilities (?) and on/off ratios (I.sub.on/I.sub.off) for a solution-processed OFET on a silicon wafer in the top-gate bottom-contact configuration measured in ambient air.

(34) TABLE-US-00002 TABLE 2 Semiconductor Threshold voltage Field-effect mobility On/Off ratio from example U.sub.th [V] ? [cm.sup.2/Vs] I.sub.on/I.sub.off 1* 16.9 0.061 1.7 ? 10.sup.2 4 11.0 0.17 2.5 ? 10.sup.2 *comparison

Example 7

Procedure for a Solution-Processed OFET on a Silicon Wafer in the Bottom-Gate Bottom-Contact Configuration

(35) A 0.5% solution of the semiconductor in ethyl acetate warmed to 50? C. was spincoated (Spin Coater: Primus STT15) on an untreated standard silicon substrate at 1000 rpm. The standard silicon substrate consisted of a silicon wafer with a 230 nm thick silicon dioxide layer (?.sub.r=3.9) and lithographically patterned S/D contacts consisting of 30 nm thick gold and ITO adhesive.

(36) The electrical characteristics of the transistors were measured with an Agilent 4155C Semiconductor Parameter Analyzer. The transistors had a channel width (W) of 10000 ?m and a channel length (L) of 10 ?m. All measurements were performed in air at room temperature.

(37) To obtain the transfer curve the drain-source voltage (U.sub.DS) is held to 40 V. The gate-source voltage U.sub.GS is swept at medium speed from ?20 to 40 V in steps of 2 V and back. The charge-carrier mobility is extracted in the saturation regime from the slope of (I.sub.D).sup.1/2 versus V.sub.GS.

(38) To obtain the output characteristics the drain-source voltage (V.sub.DS) is swept at medium speed from 0 to 40 V in steps of 2 V, while the gate-source voltage V.sub.GS is held at up to 5 different voltages (e.g. 0, 10, 20, 30, 40 V).

(39) Table 3 gives the field-effect mobilities (?) and on/off ratios (I.sub.on/I.sub.off) for a solution-processed OFET on a silicon wafer in the bottom-gate bottom-contact configuration measured in ambient air.

(40) TABLE-US-00003 TABLE 3 Semiconductor Threshold voltage Mobility On/Off ratio from example U.sub.th [V] ? [cm.sup.2/Vs] I.sub.on/I.sub.off 1* 3.2 0.00024 5.3 ? 10.sup.4 4 7.5 0.0011 1.4 ? 10.sup.5 *comparison