Optically-Regulated Optical Emission Using Colloidal Quantum Dot Nanocrystals

Abstract

The present invention relates to the emission of light which occurs in proportion with an electrical signal, an optical signal, or the combination of both. The emission of light may occur due to the passage of current through a light-emitting polymer, or due to energy transfer of excitons from this polymer to light-emitting quantum dots. Optical sensitivity is achieved through the inclusion of another species of quantum dots whose absorption is generally at longer wavelengths relative to the light-emitting material. Light incident upon the device results in an enhanced current flow in the presence of an applied bias, and thus enhanced excitation of the light-emitting moity is achieved in proportion with the optical power absorbed by the light-absorbing moity. Two device architectures are presented, one based on a mutilayer structure in which the functions of light absorption and light emission are separated, and the other in which these functions are integrated within a single active region.

1 . A device for detecting light in a pre-selected wavelength range and converting the detected light into light of at least one pre-selected wavelength and emitting the light at said at least one pre-selected wavelength, comprising: 
 a substrate and a first electrically conducting electrode layer on the substrate;    a first layer of first nanocrystals located on the first electrically conducting electrode layer which absorb light in said pre-selected wavelength range;    at least second layer of at least second nanocrystals which emit light at said at least one pre-selected wavelength located on the first layer of first nanocrystals; and    a second electrically conducting electrode layer on the at least second layer of the second nanocrystals,    wherein at least one of said substrate and first electrically conducting electrode layer and said second electrically conducting electrode layer is substantially transparent to the light in the pre-selected wavelength range and light at the at least one pre-selected wavelength, and    wherein when the light in said pre-selected wavelength range is incident on said first layer of first nanocrystals a photocurrent is responsively produced when a voltage is applied between the first and second electrically conducting electrode layers, and 
 wherein said photocurrent acts to pump the at least second layer of the at least second nanocrystals which responsively emit light at the at least one pre-selected wavelength.  
   
     
     
         2 - 71 . (canceled)