Method for producing core/shell nanoparticles and core/shell nanoparticles

Abstract

The present invention relates to a process for the continuous preparation of core-shell nanoparticles, comprising a core of a core material, preferably of a semiconductor material, and a shell of a shell material, preferably of a semiconductor material, wherein selected starling materials for the shell material are mixed with a dispersion of nanoparticles of the core material and are passed continuously through a reaction zone of a tubular reactor, and other starting materials for the shell material are fed to the reaction zone of the tubular reactor at two or more locations, preferably via a tubular membrane, and the starting materials for the shell material react in the reaction zone to form a shell around the nanoparticles of the core material. The invention also relates to the tubular reactor with the membrane and its use for the continuous synthesis of core-shell nanoparticles. The invention also relates to core-shell nanoparticles comprising a core of a core material, preferably of a first semiconductor material, and an outer shell of a shell material, characterized in that, between core and shell, there is only a layer of a transition zone, in which the proportion of the core material gradually decreases toward the shell, while the proportion of the shell material gradually increases.

1 .- 9 . (canceled) 
     
     
         10 . Core-shell nanoparticle comprising a core of a core material, preferably a first semiconductor material, and an outer shell of a shell material, preferably of a second semiconductor material, characterized in that, between the core and shell, there is only a layer of a transition zone, consisting only of the components of the core and the components of the shell material, and in which the proportion of the core material gradually deceases in the direction of the shell, while the proportion of the shell material increases gradually. 
     
     
         11 . The core-shell nanoparticles according to  claim 10 , wherein the core consists of a semiconductor material and the particle size distribution of the nanoparticles is such that the standard deviation (in nm) from the mean value of the diameter of the core-shell nanoparticles (in nm) is less than 20%, preferably less than 15%, more preferably less than 10%, even more preferably less than 7.5% of the mean. 
     
     
         12 . The core-shell nanoparticles according to  claim 10 , wherein the average diameter of the transition zone is 0.1 to 5 nm, preferably from 0.1 to 1 nm, and preferably the average diameter of the core-shell nanoparticles is 1 to 100 nm, preferably 3 to 15 nm, more preferably 4 to 8 nm. 
     
     
         13 . The core-shell nanoparticles according to  claim 10 , wherein the core material and the shell material are each a semiconductor material, preferably each being a II-VI, IV-VI or III-V semiconductor material. 
     
     
         14 . The core-shell nanoparticles according to  claims 10 , wherein the core-shell nanoparticles have a combination of the following core-shell materials: CdSe/ZnS, CdSe/CdZnS, or CdSe/CdZnS. 
     
     
         15 .- 24 . (canceled) 
     
     
         25 . A core-shell nanoparticle comprising:
 a core of a core material, and an outer shell of a shell material,   wherein, between the core and shell, there is only a layer of a transition zone, consisting essentially of the components of the core and the components of the shell material, and in which the proportion of the core material gradually deceases in the direction of the shell, while the proportion of the shell material increases gradually, and   wherein the core-shell nanoparticle is obtainable by a process of claim  2 .   
     
     
         26 . The core-shell nanoparticle of  claim 25  wherein the core material comprises a first semiconductor materials and the shell material comprises a second semiconductor material.