초록 ▼

The present invention intends to provide a light-emitting transistor (LEFET), a light-emitting device with a switching function, which can produce an adequately strong emission of light with higher emission efficiency. The drain electrode 25 is made of aluminum and the source electrode 24 is made of

The present invention intends to provide a light-emitting transistor (LEFET), a light-emitting device with a switching function, which can produce an adequately strong emission of light with higher emission efficiency. The drain electrode 25 is made of aluminum and the source electrode 24 is made of gold. When a voltage is applied between the source electrode 24 and the drain electrode 25, the source electrodes 24 and the drain electrodes 25 inject positive holes and electrons into the light-emitter layer 26, respectively. The positive holes and the electrons recombine, whereby the light-emitter layer 26 generates light. The on/off state of the emission can be controlled by switching the gate voltage on and off. In contrast to conventional LEFETs in which the drain electrode is also made of gold, the present invention uses aluminum, whose work function is lower than that of gold, whereby a larger number of electrons is injected into the light-emitter layer 26 at a lower voltage. Therefore, both the emission strength and the emission efficiency are improved.

대표청구항 ▼

The invention claimed is: 1. A light-emitting transistor, comprising: a) a gate electrode covered with an insulating film; b) a first source/drain electrode provided on the insulating film and made of an electron-injecting material whose work function is equal to or lower than 4.26 electron-volts;

The invention claimed is: 1. A light-emitting transistor, comprising: a) a gate electrode covered with an insulating film; b) a first source/drain electrode provided on the insulating film and made of an electron-injecting material whose work function is equal to or lower than 4.26 electron-volts; c) a second source/drain electrode provided separately from the first source/drain electrode on the insulating film and made of a hole-injecting material whose work function is higher than 4.26 electron-volts, the second source/drain electrode including an adhesive base layer made of the electron-injecting material and entirely covered with the hole-injecting material; and d) a light-emitter layer provided on the insulating film between the first source/drain electrode and the second source/drain electrode and made of an organic semiconductor. 2. The light-emitting transistor according to claim 1, wherein the electron-injecting material is aluminum, magnesium, calcium, magnesium-silver alloy, or a combination of two or more of these materials. 3. The light-emitting transistor according to claim 1, wherein the hole-injecting material is gold, platinum, indium tin oxide, chromium, nickel or a combination of two or more of these materials. 4. The light-emitting transistor according to claim 1, wherein the light-emitter layer includes a light emitter in which a material of an area that is in contact with the first source/drain electrode is different from that of another area that is in contact with the second source/drain electrode, and the area on the side of the first source/drain electrode is made of an electron transport material and the area on the side of the first source/drain electrode is made of a hole transport material. 5. The light-emitting transistor according to claim 1, wherein the thickness of the insulating film satisfies an interference condition for an emission wavelength of the light emitter layer. 6. A laser light source, comprising; a) a gate electrode covered with an insulating film; b) first source/drain electrode provided on the insulating film and made of an electron-injecting material whose work function is equal to or lower than 4.26 electron-volts; c) a second source/drain electrode provided separately from the first source/drain electrode on the insulating film and made of a hole-injecting material whose work function is higher than 4.26 electron-volts, the second source/drain electrode including an adhesive base layer made of the electron-injecting material and entirely covered with the hole-injecting material; d) a light-emitter layer provided between the first source/drain electrode and the second source/drain electrode and made of an organic semiconductor; and e) a diffraction grating provided between the first source/drain electrode and the second source/drain electrode in order to diffract light emitted from the light-emitter layer. 7. The laser light source according to claim 6, wherein the diffraction grating is formed on the gate electrode between the first source/drain electrode and the second source/drain electrode. 8. A laser light source, comprising: a) a gate electrode covered with an insulating film; b) a comb-shaped first source/drain electrode provided on the insulating film and made of an electron-injecting material whose work function is equal to or lower than 4.26 electron-volts; c) a second source/drain electrode, consisting of a comb-shaped electrode made of a hole-injecting material whose work function is higher than 4.26 electron-volts, which is provided on the insulating film and arranged so that its comb-teeth engage into the comb-teeth of the aforementioned first source/drain electrode to form a diffraction grating consisting of said two sets of comb-teeth; and d) a light-emitter layer provided between the first source/drain electrode and the second source/drain electrode and made of an organic semiconductor. 9. A light-emitting transistor, comprising: a) a gate electrode covered with an insulating film; b) first source/drain electrode provided on the insulating film and made by stacking a layer of an electron-injecting material whose work function is equal to or lower than 4.26 electron volts and a layer of a hole-injecting material whose work function is higher than 4.26 electron-volts; c) a second source/drain electrode provided separately from the first source/drain electrode on the insulating film and made by stacking a layer of the same electron-injecting material and a layer of the same hole-injecting material as the first source/drain electrodes in the same order as the first source/drain electrodes; and d) a light-emitter layer provided on the insulating film between the first source/drain electrode and the second source/drain electrode and made of an organic semiconductor. 10. The light-emitting transistor according to claim 9, wherein the electron-injecting material is aluminum, magnesium, calcium, magnesium-silver alloy, or a combination of two or more of these materials. 11. The light-emitting transistor according to claim 9, wherein the hole-injecting material is gold, platinum, indium tin oxide, chromium, nickel or a combination of two or more of these materials. 12. The light-emitting transistor according to claim 9, wherein the light-emitting layer includes a light emitter in which a material of an area that is in contact with the first source/drain electrode is different from that of another area that is in contact with the second source/drain electrode, and the area on the side of the first source/drain electrode is made of an electron transport material and the area on the side of the first source/drain electrode is made of a hole transport material. 13. The light-emitting transistor according to claim 9, wherein the thickness of the insulating film satisfies a condition for an interference condition for an emission wavelength of the light emitter layer. 14. A laser light source, comprising: a) a gate electrode covered with an insulating film; b) a first source/drain electrode provided on the insulating film and made of an electron-injecting material whose work function is equal to or lower than 4.26 electron-volts; c) a second source/drain electrode provided separately from the first source/drain electrode on the insulating film and made of a hole-injecting material whose work function is higher than 4.26 electron-volts; the first source/drain electrode including an adhesive base layer made of the hole-injecting material and entirely covered with the electron-injecting material; d) a light-emitter layer provided between the first source/drain electrode and the second source/drain electrode and made of an organic semiconductor; and e) a diffraction grating provided between the first source/drain electrode and the second source/drain electrode in order to diffract light emitted from the light-emitter layer. 15. The laser light source according to claim 14, wherein the diffraction grating is formed on the gate electrode between the first source/drain electrode and the second source/drain electrode. 16. A light-emitting transistor, comprising: a) a gate electrode covered with an insulating film; b) a first source/drain electrode provided on the insulating film and made of an electron-injecting material whose work function is equal to or lower than 4.26 electron-volts; c) a second source/drain electrode provided separately from the first source/drain electrode on the insulating film and made of a hole-injecting material whose work function is higher than 4.26 electron-volts, the first source/drain electrode including an adhesive base layer made of the hole-injecting material and entirely covered with the electron-injecting material; and d) a light-emitter layer provided on the insulating film between the first source/drain electrode and the second source/drain electrode and made of an organic semiconductor. 17. The light-emitting transistor according to claim 16, wherein the electron-injecting material is aluminum, magnesium, calcium, magnesium-silver alloy, or a combination of two or more of these materials. 18. The light-emitting transistor according to claim 16, wherein the hole-injecting material is gold, platinum, indium tin oxide, chromium, nickel or a combination of two or more of these materials. 19. The light-emitting transistor according to claim 16, wherein the light-emitter layer includes a light emitter in which a material of an area that is in contact with the first source/drain electrode is different from that of another area that is in contact with the second source/drain electrode, and the area on the side of the first source/drain electrode is made of an electron transport material and the area on the side of the first source/drain electrode is made of a hole transport material. 20. The light-emitting transistor according to claim 16, wherein the thickness of the insulating film satisfies an interference condition for an emission wavelength of the light-emitter layer.