Quantum dot led with spacer particles

Abstract

Embodiments of the present application relate to the use of quantum dots mixed with spacer particles. An illumination device includes a first conductive layer, a second conductive layer, and an active layer disposed between the first conductive layer and the second conductive layer. The active layer includes a plurality of quantum dots that emit light when an electric field is generated between the first and second conductive layers. The quantum dots are interspersed with spacer particles that do not emit light when the electric field is generated between the first and second conductive layers.

What is claimed is: 
     
         1 . A method of making an illumination device, comprising:
 depositing a first conductive layer on a substrate;   mixing a plurality of quantum dots with a plurality of spacer particles to form an active mixture,   wherein the plurality of spacer particles comprises a first group of spacer particles and a second group of spacer particles, and   wherein the first group of the spacer particles has a first spacer particle size substantially equal to a size of the quantum dots and the second group of the spacer particles has a second spacer particle size smaller than the size of the quantum dots;   depositing the active mixture as an active layer located above the first conductive layer, wherein the active layer comprises the quantum dots interspersed with the spacer particles; and   depositing a second conductive layer above the active layer,   wherein the quantum dots are configured to emit light when an electric field is generated between the first and second conductive layers, and the spacer particles are configured to not emit light when the electric field is generated between the first and second conductive layers.   
     
     
         2 . The method of  claim 1 , wherein the depositing the active mixture comprises spin-coating the active mixture to form the active layer. 
     
     
         3 . The method of  claim 1 , wherein the mixing comprises mixing the plurality of quantum dots with the plurality of spacer particles in a solvent. 
     
     
         4 . The method of  claim 3 , further comprising releasing the solvent from the active layer at room temperature. 
     
     
         5 . The method of  claim 1 , further comprising forming the quantum dots to each comprise a core structure and a shell structure surrounding the core structure. 
     
     
         6 . The method of  claim 5 , wherein the spacer particles comprise the same material as the shell structure. 
     
     
         7 . The method of  claim 5 , further comprising binding ligands to the shell structure of the quantum dots. 
     
     
         8 . The method of  claim 7 , further comprising binding ligands to the spacer particles. 
     
     
         9 . The method of  claim 7 , wherein the ligands on the quantum dots are the same as the ligands on the spacer particles. 
     
     
         10 . The method of  claim 1 , further comprising:
 depositing a first transport layer on the first conductive layer, the first transport layer being configured to facilitate the transport of holes from the first conductive layer to the active layer; and   depositing a second transport layer on the active layer, the second transport layer configured to facilitate the transport of electrons from the second conductive layer to the active layer.   
     
     
         11 . A method of fabricating a quantum dot light emitting diode (QLED), comprising:
 depositing a first electrode on a substrate;   forming a mixture of quantum dots and spacer particles,   wherein the spacer particles comprise a first group of spacer particles and a second group of spacer particles, and   wherein the first group of the spacer particles has a first spacer particle size substantially equal to a size of the quantum dots and the second group of the spacer particles has a second spacer particle size smaller than the size of the quantum dots;   depositing the mixture to form an active layer on the first electrode, wherein the active layer comprises the quantum dots interspersed with the spacer particles; and   depositing a second electrode on the active layer.   
     
     
         12 . The method of  claim 11 , wherein the depositing the mixture comprises spin-coating the mixture to form the active layer. 
     
     
         13 . The method of  claim 11 , wherein the mixing comprises mixing the quantum dots and the spacer particles in a non-polar solvent. 
     
     
         14 . The method of  claim 11 , wherein the mixing comprises mixing the quantum dots and the spacer particles in a 1:1 concentration ratio by weight, in a 1:2 concentration ratio by weight, or in a 2:1 concentration ratio by weight. 
     
     
         15 . The method of  claim 11 , further comprising forming the quantum dots to each comprise a core structure and a shell structure surrounding the core structure. 
     
     
         16 . The method of  claim 11 , wherein the spacer particles comprise a same material as the quantum dots. 
     
     
         17 . The method of  claim 11 , further comprising:
 forming the quantum dots to each comprise a core structure and a shell structure surrounding the core structure; and   binding ligands to the shell structure of the quantum dots.   
     
     
         18 . The method of  claim 11 , further comprising binding ligands to the spacer particles. 
     
     
         19 . The method of  claim 11 , further comprising depositing a semiconductor polymer layer between the first electrode and the active layer. 
     
     
         20 . The method of  claim 11 , further comprising:
 depositing a first transport layer on the first electrode, the first transport layer being configured to facilitate the transport of holes from the first electrode to the active layer; and
 depositing a second transport layer on the active layer, the second transport layer configured to facilitate the transport of electrons from the second electrode to the active layer.