METHOD AND APPARATUS FOR SENSING INFRARED RADIATION

• US 20120286296A1
• Filed: 11/24/2010
• Published: 11/15/2012
• Est. Priority Date: 11/24/2009
• Status: Active Grant

• Current Assignee: University of Florida Research Foundation, Incorporated (State University System of Florida)
• Original Assignee: University of Florida Research Foundation, Incorporated (State University System of Florida)
• Inventors: So, Franky, Kim, Do Young
• Granted Patent: US 8,796,699 B2
• Time in Patent Office: Days
• US Class Current: 257/82
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: G01J 5/20 using resistors, thermistors or semiconductors sensitive to radiation, e.g. photoconductive devices
• CPC Class Codes: H01L 31/101 Devices sensitive to infrared, visible or ultraviolet radiation
• CPC Class Codes: H01L 31/14 the light source or sources being controlled by the semiconductor device sensitive to radiation, e.g. image converters, image amplifiers or image storage devices
• CPC Class Codes: H01L 33/0045 the devices being superluminescent diodes
• CPC Class Codes: H10K 2102/103 comprising indium oxides, e.g. ITO
• CPC Class Codes: H10K 50/00 Organic light-emitting devices integrated devices or assemblies of multiple devices H10K59/00, H10K65/00; organic semiconductor lasers H01S5/36
• CPC Class Codes: H10K 50/19 Tandem OLEDs
• CPC Class Codes: H10K 50/80 Constructional details
• CPC Class Codes: H10K 59/00 Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
• CPC Class Codes: H10K 65/00 Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element and at least one organic radiation-sensitive element, e.g. organic opto-couplers organic image sensors integrated with organic light-emitting devices H10K39/34; OLED displays integrated with photosensors H10K59/13
• CPC Class Codes: H10K 85/211 Fullerenes, e.g. C60
• CPC Class Codes: H10K 85/311 Phthalocyanine
• CPC Class Codes: H10K 85/322 comprising boron
• CPC Class Codes: H10K 85/324 comprising aluminium, e.g. Alq3
• CPC Class Codes: H10K 85/342 comprising iridium
• CPC Class Codes: H10K 85/631 Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine
• CPC Class Codes: Y10S 977/954 Of radiant energy

Abstract

Embodiments of the invention pertain to a method and apparatus for sensing infrared (IR) radiation. In a specific embodiment, a night vision device can be fabricated by depositing a few layers of organic thin films. Embodiments of the subject device can operate at voltages in the range of 10-15 Volts and have lower manufacturing costs compared to conventional night vision devices. Embodiments of the device can incorporate an organic phototransistor in series with an organic light emitting device. In a specific embodiment, all electrodes are transparent to infrared light. An IR sensing layer can be incorporated with an OLED to provide IR-to-visible color up-conversion. Improved dark current characteristics can be achieved by incorporating a poor hole transport layer material as part of the IR sensing layer.

Claims

1. A device for sensing infrared (IR) radiation, comprising:

a first electrode;

an infrared (IR) sensing layer, wherein a first end of the IR sensing layer is in contact with the first electrode;

a first light emitting device (LED), wherein a first end of the first LED is in contact with a second end of the infrared sensing layer;

a first charge separation layer, wherein a first end of the first charge separation layer is in contact with a second end of the first LED;

a second LED, wherein a first end of the second LED is in contact with the second end of the charge separation layer;

a second electrode, wherein the second electrode is in contact with the second end of the second electrode;

wherein when a potential is applied between the first and second electrodes and the IR sensing layer is exposed to IR radiation a sensing electron and a sensing hole are generated in the IR sensing layer and a first hole and a first electron are generated in the first charge separation layer, wherein one of the first hole and the first electron is passed to the first LED, wherein one of the sensing electron and the sensing hole generated in the IR sensing layer is passed into the first LED and combines with the one of the first hole and the first electron, respectively, in the first LED to produce a first emitted photon, wherein the other of the first hole and the first electron generated in the first charge separation layer is passed to the second LED and combines with a corresponding electron or hole passed into the second LED to produce a second emitted photon.

2. The device according to claim 1, wherein the sensing electron is passed into the first LED and combines with the first hole, wherein the first electron is passed into the second LED and combines with the corresponding hole passed into the second LED.

3. The device according to claim 1, wherein the sensing hole is passed into the first LED and combines with the first electron, wherein the first hole is passed into the second LED and combines with the corresponding electron passed into the second LED.

4. The device according to claim 1:

wherein the corresponding electron or hole passed into the second LED is passed into the second LED from the second electrode.

5. The device according to claim 1, wherein the first electrode is at least partially transparent.

6. The device according to claim 1, wherein the first electrode is transparent.

7. The device according to claim 1, wherein the second electrode is at least partially transparent.

8. The device according to claim 1, wherein the second electrode is transparent.

9. The device according to claim 8, wherein the second electrode is a film of MgAg.

10. The device according to claim 9, wherein the film of MgAg has a thickness of 20 μ

m or less.

11. The device according to claim 1, further comprising at least one additional LED and a corresponding at least one additional charge separation layer, wherein a first end of each of the at least one additional LED is in contact with a second end of the corresponding at least one additional charge separation layers, wherein the at least one additional LED and the corresponding at least one additional charge separation layer are interposed between the second end of the second LED and the second electrode such that the first end of the first additional charge separation layer is in contact with the second end of the second LED and the second electrode is in contact with the second end of the last of the at least one additional LED, wherein the other of the first hole and the first electron generated in the first charge separation layer is passed to the second LED and combines with a corresponding electron or hole passed into the second LED from the second charge separation layer, wherein the corresponding electron or hole passed into the second LED is one of a second electron or second hole generated in the first additional charge separation layer, wherein the other of the second electron or second hole is passed to the first additional LED and combines with a corresponding electron or hole passed into the first additional LED from either the second electrode or a second additional charge separation layer.

12. The device according to claim 1, wherein the infrared sensing layer comprises a poor hole transporting material having a current density less than 1 mA/cm².

13. The device according to claim 1, wherein the first electrode comprises ITO.

14. The device according to claim 1, wherein the first LED and the second LED are light emitting diodes.

15. The device according to claim 1, wherein the first LED and the second LED are organic light emitting devices.

16. The device according to claim 14, wherein the first LED and the second LED are organic light emitting diodes.

17. The device according to claim 15, wherein the IR sensing layer is an organic IR sensing layer.

18. The device according to claim 1, wherein the first LED and the second LED are thin film light emitting devices.

19. The device according to claim 11, wherein the at least one additional LED comprises one to six additional LED and the corresponding at least one additional charge separation layer comprises a corresponding one to six additional charge separation layers.

20. The device according to claim 1, wherein the first emitted photon and the second emitted photon are visible photons.

21. The device according to claim 1, wherein the IR sensing layer is sensitive for wavelengths in the range of 0.8 μ

m to 2 μ

m.

22. The device according to claim 1, wherein the first emitted photon and the second emitted photon have different wavelengths.

23. The device according to claim 15, wherein at least one of the first organic LED and the second organic LED comprises an organic emissive layer having a first dye molecule that emits blue light, a second dye molecule that emits green light, and a third dye molecule that emits red light.

24. A device for sensing infrared (IR) radiation, comprising:

an IR sensing layer, wherein the IR sensing layer exhibits has a current density less than 1 mA/cm²; and

an organic light emitting diode (OLED) on the IR sensing layer, the OLED arranged to receive electrons generated in the IR sensing layer.

25. A device for sensing infrared (IR) radiation, comprising:

an IR sensing layer, wherein the IR sensing layer exhibits has a current density less than 1 mA/cm²; and

an organic light emitting diode (OLED) on the IR sensing layer, the OLED arranged to receive holes generated in the IR sensing layer.

26. The device according to claim 25, wherein the IR sensing layer is in contact with the OLED, further comprising a first electrode, and a poor hole transporting layer positioned between the IR sensing layer and the first electrode, wherein the poor hole transporting layer has a current density of less than 1 mA/cm².

27. The device according to claim 25, wherein the hole blocking layer comprises SnPc:

C₆₀.

28. The device according to claim 25, wherein the OLED comprises a phosphorescent emitter.

29. The device according to claim 25, wherein the IR sensing layer comprises:

an organic infrared absorbing material, and

an acceptor material, wherein the organic IR absorbing material and the acceptor material are mixed in the IR sensing layer.

30. The device according to claim 25, wherein the IR sensing layer comprises a fullerene.

31. The device according to claim 25, wherein the IR sensing layer comprises quantum dots.