Electroluminescent device with integrated sensor and method for controlling the emission of the device

Patent metadata

Field	Value
Publication number	US-9847446-B2
Application number	US-201414778017-A
Country	US
Kind code	B2
Filing date	Mar 25, 2014
Priority date	Mar 28, 2013
Publication date	Dec 19, 2017
Grant date	Dec 19, 2017

Abstract

An electroluminescent device comprises a structure comprising a set of nanowires on the surface of a substrate, comprising: a first series of primary so-called emission nanowires (NTi e ) comprising nanowires connected to first electrical contacts and capable of emitting light under the action of a forward first voltage from a forward voltage or current source; a second series of secondary detection nanowires (NTi d ) adjacent to the primary nanowires, connected to second electrical contacts and capable of generating a photocurrent under the action of an ambient light and/or of a portion of the light emitted by some of the primary nanowires, under the control of a second reverse voltage, from a voltage or current source; means for controlling the forward voltage as a function of the photocurrent. A method for controlling the luminance of an electroluminescent device is provided.

First claim

The invention claimed is:

1. An electroluminescent device comprising a structure comprising a set of nanowires on a surface of a substrate, further comprising:
a first series of primary emission nanowires (NTi e ) comprising nanowires connected to first electrical contacts and capable of emitting light under the action of a forward first voltage from a forward voltage or current source; and
a second series of secondary detection nanowires (NTi d ) adjacent to said primary nanowires, connected to second electrical contacts and capable of generating a photocurrent under the action of at least one of an ambient light and a portion of the light emitted by some of said primary nanowires, under the control of a second reverse voltage;
wherein the photocurrent is used to regulate a control voltage of the electroluminescent device.

2. The electroluminescent device as claimed in claim 1 , comprising means for injecting said photocurrent into the forward voltage or current source so as to regulate said forward voltage, said means for injecting comprising a circuit external to said structure and comprising a current comparator comparing the photocurrent generated (I ph ) by the secondary nanowires to a given reference current (I ref ) and acting on a power supply regulator of said forward voltage or current source to control the voltage of the primary nanowires.

3. The electroluminescent device as claimed in claim 1 , wherein:
said second series of secondary detection nanowires (NTi d ) comprises at least one subset of detection nanowires capable of generating a photocurrent (I ph ) under the control of a zero or reverse voltage, in the presence of ambient light; and
said device comprising a circuit external to said structure and comprising a current comparator comparing the photocurrent generated by the secondary nanowires to a threshold current (I ph·s ), so as to activate, via a power supply equipped with a switch, said electroluminescent device if said photocurrent value (I ph ) is less than said threshold current value (I ph·s ).

4. The electroluminescent device as claimed in claim 1 , wherein said nanowires are covered by a transparent conductive layer, discontinuous between said primary nanowires and said secondary nanowires, so as to electrically disassociate one of said first electrical contacts from one of said second electrical contacts.

5. The electroluminescent device as claimed in claim 1 , wherein the substrate comprises, on a rear face defined as being opposite the face comprising said nanowires, a contact layer common to one of said first electrical contacts and to one of said second electrical contacts.

6. The electroluminescent device as claimed in claim 1 , comprising subsets of secondary nanowires distributed over said substrate.

7. The electroluminescent device as claimed in claim 1 , comprising a plurality of subsets of primary nanowires likely to emit photons at different wavelengths λi c , said device emitting a composite light resulting from the sum of the emissions at the different wavelengths λi c .

8. The electroluminescent device as claimed in claim 7 , comprising a plurality of subsets of secondary nanowires, each subset of secondary nanowires being adjacent to a subset of primary nanowires emitting photons at a wavelength λi c , so as to be able to pick up said photons at said wavelength λi c .

9. The electroluminescent device as claimed in claim 1 , wherein said nanowires have structures based on heterojunction of III-V materials.

10. A method for controlling an electroluminescent device comprising a structure comprising a set of nanowires on a surface of a substrate, further comprising: a first series of primary emission nanowires (NTi e ) comprising nanowires connected to first electrical contacts and capable of emitting light under the action of a forward first voltage from a forward voltage or current source; and a second series of secondary detection nanowires (NTi d ) adjacent to said primary nanowires, connected to second electrical contacts and capable of generating a photocurrent under the action of at least one of an ambient light and a portion of the light emitted by some of said primary nanowires, under the control of a second reverse voltage; wherein the photocurrent is used to regulate a control voltage of the electroluminescent device, the method comprising:
a step of detection of at least one photocurrent from at least one subset of secondary nanowires under the action of an ambient light and of a portion of a light emitted by some of said primary nanowires, under the control of a second reverse voltage; and
a step of controlling at least one subset of primary nanowires under the action of a forward voltage as a function of said photocurrent.

11. The method for controlling the electroluminescent device as claimed in claim 10 , comprising a step of controlling, prior to said detection step, at least one subset of primary so-called emission nanowires (NTi e ), the emission of which is partly picked up by said secondary nanowires.

12. The method for controlling the electroluminescent device as claimed in claim 11 , further comprising controlling the luminance of the electroluminescent device wherein controlling the luminance comprises the following steps:
the application of a first initial voltage to at least one subset of primary nanowires;
the application of a reverse voltage to at least one subset of the secondary nanowires so as to detect a photocurrent; and
the integration of said photocurrent in the determination of a control voltage to be applied to said primary nanowires so as to regulate the luminance of said device.

13. The method for controlling the electroluminescent device as claimed in claim 11 , further comprising controlling the distribution of the surface luminance of the electroluminescent device, wherein controlling the distribution comprises:
the application of a first initial voltage to a plurality of subsets of primary nanowires;
the application of a reverse voltage to a plurality of subsets of secondary nanowires, each subset of secondary nanowires being adjacent to a subset of primary nanowires emitting photons at a wavelength, said secondary nanowires being distributed over all of said substrate so as to detect a photocurrent per subset of secondary nanowires; and
the integration of said photocurrents in the determination of a control voltage to be applied to said subsets of primary nanowires respectively associated with said subsets of secondary nanowires so as to regulate the surface distribution of the luminance of said device.

14. A method for controlling the color of an electroluminescent device comprising a structure comprising a set of nanowires on a surface of a substrate, further comprising: a first series of primary emission nanowires (NTi e ) comprising nanowires connected to first electrical contacts and capable of emitting light under the action of a forward first voltage from a forward voltage or current source; and a second series of secondary detection nanowires (NTi d ) adjacent to said primary nanowires, connected to second electrical contacts and capable of generating a photocurrent under the action of at least one of an ambient light and a portion of the light emitted by some of said primary nanowires, under the control of a second reverse voltage; wherein the photocurrent is used to regulate a control voltage of the electroluminescent device; and a plurality of subsets of primary nanowires likely to emit photons at different wavelengths λi c , said device emitting a composite light resulting from the emission of a plurality of subsets of nanowires emitting at

Assignees

• Aledia

Inventors

• Cagli Carlo
• Anania Giorgio

Classifications

• H01L33/24

  Electricity · mapped topic

• H01L33/06 Primary

  Electricity · mapped topic

• H01L27/15

  Electricity · mapped topic

• H01L33/32

  Electricity · mapped topic

• H01L33/16

  Electricity · mapped topic