Chemistry of Doped Colloidal Nanocrystals

Abstract

Synthetic control over inorganic nanocrystals has made dramatic strides so that a great number of binary and a few ternary or more complex compounds can now be prepared with good control over size and physical properties. Recently, chemists have tackled the long-standing challenge of introducing dopant atoms into nanocrystals, and strategies that apply across diverse compositions are beginning to emerge. In this review, we first briefly summarize the array of characterization methods used to assess doping efficacy for reference throughout the discussion. We then enumerate chemical strategies for doping with illustrative examples from the literature. A key concept is that the reactions leading to growth of the host crystal and to deposition of dopant ions must be balanced to succeed in incorporating dopants during crystal growth. This challenge has been met through various chemical strategies, and new methods, such as postsynthetic diffusion of dopant ions, continue to be developed. The opportunity to deliver new functionality by doping nanocrystals is great, particularly as characterization methods and synthetic control over introduction of multiple dopants advance.

Generation of white light from co-doped (Cu and Mn) ZnSe QDs

“…But in case of Cu incorporation in ZnSe, the increase in the band gap (by virtue of increase in size) is observed ( Figure 3). The change in the band gap is attributed to change in the reaction kinematics [15,33,34]; PLE measurements on such QDs will give a band edge at different positions (since the sizes are different). But if both the ions are present in the same QD, then the band-edge position should be the same.…”

Functionalisation of Colloidal Transition Metal Sulphides Nanocrystals: A Fascinating and Challenging Playground for the Chemist

“…Focusing instead on nanocrystals, a very exciting class of systems [36,41,50,139,150, in which the relevance of surface becomes important and the properties transition with respect to the bulk is particularly noticeable [208,241,248,249], their surface chemistry has been the topic of extensive research and contributions, mostly on oxide NCs [36,41,50,202,209,210,215,219,221,222,240,246,[250][251][252][253][254][255][256][257][258][259][260]. Little attention has been instead paid to sulphide NCs, though some contribution focus on both their synthesis [261][262][263][264][265][266][267] as well as on their surface chemistry [152,262,[268][269][270][271][272]…”

“…This wide and diversified class of inorganic materials has been the topic of several contributions, addressing their synthesis and characterisation , functionalisation [37][38][39][40], surface chemistry and eventually applications [1,[6][7][8][9][10][11]15,27,30,33,35,[41][42][43][44][45][46][47][48][49]. Nanocrystals present features which are different from those of bulk materials, particularly at the surface.…”

The Nanoscience Paradigm: “Size Matters!”

“…CdSe, or insulators, e.g. SiO 2 ) [1,5], alloys (e.g., FePt, Cd 1-x Zn x S) [1], doped materials (e.g., ZnSe:Mn, NaYF 4 :Yb,Er) [21][22][23][24], or combinations of two (or more) different materials joined by one or more interfaces in the same nanoparticle (i.e., heteronanocrystals, e.g., a CdSe core surrounded by a ZnS shell) [1] (see Chap. 6 for details).…”