Apparatus and method for modulating photon output of a quantum dot light emitting device
View Patent ↗An apparatus is provided for modulating the photon output of a plurality of free standing quantum dots. The apparatus comprises a first electron injection layer ( 210, 310, 410 ) disposed between a first electrode ( 212, 312, 412 ) and a layer ( 208, 308, 408 ) of the plurality of free standing quantum dots. A hole transport layer ( 206, 306, 406 ) is disposed between the layer ( 208, 308, 408 ) of the plurality of quantum dots and a second electrode ( 204, 304, 404 ). A light source ( 224, 324, 424 ) is disposed so as to apply light to the layer ( 208, 308, 408 ) of the plurality of free standing quantum dots. The photon output of the layer ( 208, 308, 408 ) of the plurality of free standing quantum dots is modulated by applying a voltage to the first and second electrodes ( 212, 312, 412, 204, 304, 404 ). Electrons excited to a higher energy state within layer ( 208, 308, 408 ) of the free standing quantum dots by the light source ( 224, 324, 424 ) are prevented from returning to a lower state by electrons from the electric field of the applied voltage, and therefore the free standing quantum dots are prevented from emitting a photon. The voltage source ( 216, 316, 416 ) may be modulated to vary the photon output.
1. A light emitting device disposed comprising:
a first electrode;
a first electron injection layer disposed over the first electrode;
a first layer of a plurality of free standing quantum dots having a size selected for emitting light having a first predetermined wavelength disposed over the electron injection layer;
a first hole transport layer disposed adjacent the first layer of the plurality of quantum dots;
a second electrode disposed over the first hole transport layer;
a light source disposed and configured to apply radiation emitted by the light source to the first layer of the plurality of free standing quantum dots to create a first photon output including the first predetermined wavelength, wherein the radiation emitted by the light source includes a wavelength shorter than the first predetermined wavelength, the application of radiation to the first layer of the plurality of free standing quantum dots being controlled by a switch connected to a first voltage source for selectively activating the light source; and
a switching device coupled between the first and second electrodes and configured to be coupled to a second voltage source for modulating intensity of the first photon output created by the application of radiation to the first layer of the plurality of free standing quantum dots by adjusting the magnitude of a first plurality of electrons injected into the free standing quantum dots to provide a desired first photon output intensity,
wherein the application of radiation to the first plurality of free standing quantum dots and the injection of the first plurality of electronics into the first plurality of free standing quantum dots are separately controlled.
2. The light emitting device of claim 1 wherein the switching device may be adjusted to provide different voltages to the first and second electrodes.
3. The light emitting device of claim 1 further comprising:
a third electrode spatially disposed from the second electrode;
a second electron injection layer disposed over the second electrode;
a second layer of a plurality of free standing quantum dots disposed over the second electron injection layer, the second layer of a plurality of free standing quantum dots being disposed contiguous to the first layer of a plurality of free standing quantum dots;
a second hole transport layer disposed over the second layer of a plurality of quantum dots; and
a fourth electrode disposed over the second hole transport layer;
the light source disposed and configured to apply radiation to the second layer of a plurality of free standing quantum dots;
a second switching device coupled between the third and fourth electrodes and configured to be coupled to the second voltage source.
4. The light emitting device of claim 3 wherein the first and second layers are disposed adjacent to one another.
5. The light emitting device of claim 3 further comprising:
a fifth electrode spatially disposed from the fourth electrode;
a third electron injection layer disposed over the fifth electrode;
a third layer of a plurality of free standing quantum dots disposed over the third electron injection layer, the third layer of a plurality of free standing quantum dots being disposed contiguous to the second layer of a plurality of free standing quantum dots;
a third hole transport layer disposed over the third layer of a plurality of quantum dots;
a sixth electrode disposed over the third hole transport layer;
the light source disposed and configured to apply radiation to the third layer of a plurality of free standing quantum dots; and
a third switching device coupled between the fifth and sixth electrodes and configured to be coupled to the second voltage source.