Production method for carbon-based light-emitting material

Abstract

Provided is a production method for a carbon-based light-emitting material that generates light having a wavelength of 500 to 700 nm when exposed to excitation light having a wavelength of 300 to 600 nm. The production method comprises a step for mixing and heating a starting material containing ascorbic acid, an acid catalyst containing an inorganic acid, and a solvent.

Claims

1. A method for producing a carbonaceous luminescent material that, when exposed to excitation light having a wavelength of 300 to 600 nm, emits light having a wavelength of 550 to 700 nm, which method comprises the step of mixing together and heating an ascorbic acid-containing starting material, an inorganic acid-containing acid catalyst and a solvent, wherein the solvent consists of water.

2. The method for producing a carbonaceous luminescent material of claim 1, wherein the starting material further includes a polycarboxylic acid.

3. The method for producing a carbonaceous luminescent material of claim 2, wherein the polycarboxylic acid is citric acid.

4. The method for producing a carbonaceous luminescent material of any one of claims 1 to 3, wherein the starting material further includes an amino group-containing compound.

5. The method for producing a carbonaceous luminescent material of claim 4, wherein the amino group-containing compound is an amino group-containing polyalkylene glycol.

6. The method for producing a carbonaceous luminescent material of claim 5, wherein the amino group-containing compound is an amino group-containing polyethylene glycol.

7. The method for producing a carbonaceous luminescent material of claim 1, wherein the carbonaceous luminescent material has a graphene structure.

Description

EXAMPLES

(1) Working Examples are given below to more concretely illustrate the invention, although the invention is not limited by these Examples. The equipment used was as follows. (1) Fluorescence Spectrum: FP-6500, from JASCO Corporation (2) Measurement of Quantum Yield: UV-3600 from Shimadzu Corporation, and

(2) FP-6500 from JASCO Corporation.

Working Example 1

Synthesis of Carbonaceous Luminescent Material 1

(3) A 10 mL sample bottle was charged with 0.2 g of ascorbic acid (03420-65, from Nacalai Tesque Inc.) and 4 mL of phosphoric acid (27618-55, from Nacalai Tesque Inc.; 85 wt % aqueous solution), following which the bottle was tightly stoppered and the contents were reacted for 4 hours at 90° C. on an oil bath. Although the system became black and tarry, Carbonaceous Luminescent Material 1 was obtained as the portion that dissolves in a 85 wt % aqueous phosphoric acid solution.

Working Example 2

Synthesis of Carbonaceous Luminescent Material 2

(4) A 10 mL sample bottle was charged with 0.2 g of ascorbic acid (03420-65, from Nacalai Tesque Inc.), 0.2 g of citric acid (09109-85, from Nacalai Tesque Inc.) and 4 mL of phosphoric acid (27618-55, from Nacalai Tesque Inc.; 85 wt % aqueous solution), following which the bottle was tightly stoppered and the contents were reacted for 12 hours at 90° C. on an oil bath. Although the system became black and tarry, Carbonaceous Luminescent Material 2 was obtained as the portion that dissolves in a 85 wt % aqueous phosphoric acid solution.

Working Example 3

Synthesis of Carbonaceous Luminescent Material 3

(5) A 10 mL sample bottle was charged with 0.2 g of ascorbic acid (03420-65, from Nacalai Tesque Inc.), 1 mL of PEG-NH.sub.2 (466627, from Aldrich Co.) and 4 mL of phosphoric acid (27618-55, from Nacalai Tesque Inc.; 85 wt % aqueous solution), following which the bottle was tightly stoppered and the contents were reacted for 4 hours at 90° C. on an oil bath. Although the system became black and tarry, Carbonaceous Luminescent Material 3 was obtained as the portion that dissolves in a 85 wt % aqueous phosphoric acid solution.

Working Example 4

Synthesis of Carbonaceous Luminescent Material 4

(6) A 10 mL sample bottle was charged with 0.2 g of ascorbic acid (03420-65, from Nacalai Tesque Inc.), 0.2 g of citric acid (09109-85, from Nacalai Tesque Inc.), PEG-NH.sub.2 (466627, from Aldrich Co.) and 4 mL of phosphoric acid (27618-55, from Nacalai Tesque Inc.; 85 wt % aqueous solution), following which the bottle was tightly stoppered and the contents were reacted for 3 hours at 90° C. on an oil bath. Although the system became black and tarry, Carbonaceous Luminescent Material 4 was obtained as the portion that dissolves in a 85 wt % aqueous phosphoric acid solution.

Comparative Example 1

(7) A 10 mL sample bottle was charged with 0.2 g of citric acid (09109-85, from Nacalai Tesque Inc.) and 4 mL of phosphoric acid (27618-55, from Nacalai Tesque Inc.; 85 wt % aqueous solution), following which the bottle was tightly stoppered and the contents were reacted for 12 hours at 90° C. on an oil bath. However, a material that emits light at a long wavelength was not obtained.

(8) [Measurement of Fluorescence Spectra]

(9) The fluorescence spectra and quantum yields of the carbonaceous luminescent materials obtained in Working Examples 1 to 4 were measured. The results are shown in Table 1.

(10) TABLE-US-00001 TABLE 1 Major fluorescence characteristics Carbonaceous Excitation Fluorescence luminescent wavelength wavelength Half-width material (nm) (nm) (nm) Working 1 373, 385 572, 629 10, 20 Example 1 Working 2 373 573, 629 11, 26 Example 2 Working 3 386, 397 596, 651 19, 48 Example 3 Working 4 386 595, 655 18, 56 Example 4

(11) As shown in Table 1, the carbonaceous luminescent materials obtained by the method of the invention emit red fluorescence.