The Use of Single-Source Precursors in Nanoparticle Synthesis - Semiconductor Quantum Dots: Organometallic and Inorganic Synthesis - page 224

CHAPTER 7

d n 1 y 4 n g | 4

The Use of Single-Source
Precursors in Nanoparticle
Synthesis

7.1 VI-Based Materials

The preparation of nanomaterials described in preceding chapters mainly
relied on a binary approach, i.e. the cationic and anionic constituents (o

II

-

en
termed monomers) were supplied by separate precursors in the form of
organometallic or inorganic compounds. These organometallic-based routes
to nanoparticles initially drew inspiration from precursors designed for use
in chemical vapour deposition (CVD) 1 processes and were o



.

en pyrophoric



and highly toxic. 2
Green chemical routes to nanomaterials utilising precursors such as
carboxylic acid salts and solutions of elemental chalcogens provide a safer
alternative, as discussed in Chapter 1, but cadmium salts, selenium and
tellurium still present an exposure hazard. An elegant alternative is the use of
a single-source precursor, where the constituent moieties of the target
semiconductor are present in an inorganic complex with the M - X bond

already in place (M anion, such as a chalcogen or

pnictide). Decomposition, usually thermally induced, causes the elimination
of side groups on the complex leaving the semiconductor phase, either
deposited on a substrate or free in solution. A key advantage of this method
of synthesis is that the majority of single-source precursors are stable solids
at room temperature, which allows rigorous puri

¼ metal cation, X ¼

-
nite storage. The use of single-source precursors in CVD is well established,
with numerous groups worldwide developing precursor chemistry. Precursor

 cation and almost inde