Process for preparing indium alkoxide compounds, the indium alkoxide compounds preparable by the process and the use thereof

Abstract

The present invention relates to indium alkoxide compounds preparable by reacting an indium trihalide InX.sub.3 where X=F, Cl, Br, I with a secondary amine of the formula R′.sub.2NH where R′=alkyl, in a molar ratio of 8:1 to 20:1 in relation to the indium trihalide, in the presence of an alcohol of the generic formula ROH where R=alkyl, to a process for preparation thereof and to the use thereof for production of indium oxide-containing or (semi)conductive layers.

Claims

1. An indium alkoxide compound of formula
[In.sub.6(O)(OR).sub.12X.sub.6].sup.2−A.sub.m.sup.z(ROH).sub.x, where R=alkyl; X=F, Cl, Br, and/or I; A=cation; z=valency of the cation; m.Math.z=2; and x=0 to 10.

2. The compound according to claim 1, wherein the compound has formula [In.sub.6(O)(OMe).sub.12Cl.sub.6].sup.2−[NH.sub.2R.sub.2].sup.+.sub.2(MeOH).sub.2.

3. A process for preparing an indium alkoxide compound, the process comprising: reacting an indium trihalide InX.sub.3 where X=F, Cl, Br, and/or I with a secondary amine of formula R′.sub.2NH where R′=alkyl, in a molar ratio of 8:1 to 20:1 in relation to the indium trihalide, in the presence of an alcohol of formula ROH where R=alkyl, wherein the indium alkoxide compound is the indium alkoxide compound according to claim 1.

4. The process according to claim 3, wherein the molar ratio of the secondary amine to the indium trihalide is from 8:1 to 15:1.

5. The process according to claim 4, wherein the indium trihalide is initially charged in the alcohol ROH and the secondary amine is added in a gaseous form, in a liquid form, or dissolved in a solvent.

6. The process according to claim 5, wherein the secondary amine is added at a rate of 0.5 to 5 mol per hour and mole of InX.sub.3.

7. The process according to claim 3, further comprising: separating and recrystallizing the indium alkoxide compound formed.

Description

(1) The examples which follow are intended to further illustrate the subject-matter of the present invention without having any limiting effect themselves.

INVENTIVE EXAMPLE

(2) Synthesis

(3) In a 30 l reactor freed of residual moisture, 1.30 kg of indium(III) chloride (InCl.sub.3, 5.9 mol) are suspended in 17.38 kg of dried methanol and a protective gas atmosphere by stirring. Dimethylamine (2.57 kg, 57 mol) is metered in at room temperature by means of a mass flow controller (0.86 kg/h, about 4 h), in the course of which a slightly exothermic reaction can be observed. Thereafter, the reaction mixture is kept at a temperature of 50° C. for 2 h, cooled down to room temperature and filtered. The filter residue is washed with 4×500 ml of dried methanol and dried under reduced pressure (0.1 mbar) for 8 h. The material is dissolved in boiling methanol and crystallized at −20° C.

(4) Production of a Formulation

(5) The material obtained is dissolved at a concentration of 50 mg/ml in 1-methoxy-2-propanol. The concentrate obtained is formulated as follows: 1 part concentrate to 2 parts 1-methoxy-2-propanol to 1 part ethanol. A further 3% by weight of tetrahydrofurfuryl alcohol (THFA) is added to this formulation. All the solvents used are anhydrous (<200 ppm H.sub.2O) and the mixing is effected under inert conditions (likewise anhydrous). The formulation obtained is finally filtered through a 200 nm PTFE filter.

(6) Coating

(7) A doped silicon substrate having an edge length of about 15 mm and having a silicon oxide coating thickness of about 200 nm and finger structures of ITO/gold was wetted with 100 μl of the abovementioned formulation. Then spin-coating is effected at 2000 rpm (30 seconds). Directly after this coating operation, the coated substrate is irradiated with UV radiation from a mercury vapour lamp within the wavelength range of 150-300 nm for 10 minutes. Subsequently, the substrate is heated on a hotplate at a temperature of 350° C. for one hour. After the conversion, it is possible to determine, in a glovebox, a value for field effect mobility (in the linear range) of μFET=14 cm.sup.2/Vs at 2 VDS.

COMPARATIVE EXAMPLE

(8) Synthesis

(9) In a 500 ml glass round-bottom flask freed of residual moisture, 5.0 g of indium(III) chloride (InCl.sub.3, 22.5 mmol) are dissolved under protective gas atmosphere in 250 ml of dried methanol by stirring, leaving a residue of InCl.sub.3 of <10% by weight (based on the starting weight). The metered addition of the dimethylamine base (5.0 g, corresponding to 111 mmol) is controlled by means of a mass flow controller, and it is added in the stoichiometric amount based on InCl.sub.3 at room temperature over a period of five hours, with observation of a slightly exothermic reaction at the start. Subsequently, the solution is evaporated completely, the remaining solid is taken up with 250 ml of dried methanol, filtered under protective gas (N.sub.2), washed repeatedly (10 washes) with dried methanol and dried under reduced pressure (<10 mbar) at room temperature for 12 h. The product yield was >80 mol % of indium(III) chlordimethoxide.

(10) Producing a Formulation

(11) The material obtained is dissolved at a concentration of 50 mg/ml in 1-methoxy-2-propanol. The concentrate obtained is formulated as follows: 1 part concentrate to 2 parts 1-methoxy-2-propanol to 1 part ethanol. A further 3% by weight of tetrahydrofurfuryl alcohol (THFA) is added to this formulation. All the solvents used are anhydrous (<200 ppm H.sub.2O) and the mixing is effected under inert conditions (likewise anhydrous). The formulation obtained is finally filtered through a 200 nm PTFE filter.

(12) A doped silicon substrate having an edge length of about 15 mm and having a silicon oxide coating thickness of about 200 nm and finger structures of ITO/gold was wetted with 100 μl of the abovementioned formulation. Then spin-coating is effected at 2000 rpm (30 seconds). Directly after this coating operation, the coated substrate is irradiated with UV radiation from a mercury vapour lamp within the wavelength range of 150-300 nm for 10 minutes. Subsequently, the substrate is heated on a hotplate at a temperature of 350° C. for one hour. After the conversion, it is possible to determine, in a glovebox, a value for field effect mobility (in the linear range) of μFET=8 cm.sup.2/Vs at 2 VDS.