The Preparation of Other Chalcogenides and Pnictide Nanomaterials - Semiconductor Quantum Dots: Organometallic and Inorganic Synthesis - page 92

CHAPTER 4

d n 1 y 4 n g | 2

The Preparation of Other
Chalcogenides and Pnictide
Nanomaterials

4.1 Copper-Based Chalcogenides
It could be argued that the organometallic route to quantum dots (QDs) has
found the most success with chalcogen-containing semiconducting particles,
as the II VI families of materials are easily prepared yielding

exceptionally high-quality QDs. Other families of technically important
semiconductors incorporating chalcogens have also been prepared, notably
I

- VI and IV -

.

VI materials, which have potential applications in solar energy, espe-
cially CuInSe 2 , which has a bandgap between 1.04 eV ( ca. 1190 nm) and 1.10
eV ( ca. 1125 nm), and an exciton radius of 21.2 nm. 1 The related material
CuInS 2 , with a bandgap of ca. 1.53 eV (810 nm) and an excitonic diameter of
8.2 nm, 2,3 has also been prepared. Most of the synthetic pathways described
are similar in their approach, apart from the preparation of I

- III -

- III - VI QDs

using single-source precursors, which is covered in Chapter 7.
The ternary compound CuInSe 2 has been synthesised in the form of
spherical QDs, ca. 4 nm in diameter, by the injection of InCl 3 and CuCl,
dissolved in trioctylphosphine (TOP), in trioctylphosphine oxide (TOPO) at
100 C, followed by the injection of trioctylphosphine selenide (TOPSe) an
hour later at 250 C and growth for 1 day. 4,5 The particles, isolated by the
usual solvent/non-solvent interaction, exhibited a band edge at ca. 420 nm
and broad emission with a maximum at 440 nm. This emission pro  le is in

- -

stark contrast to other reports of Cu Se materials, which have optical

properties predominantly in the red/infrared region, and may have some

In