Heavy Cyanate Analogues as Precursors to Group III-V Semiconductor Nanoparticles

Lead Research Organisation: University of Oxford
Department Name: OxICFM CDT

Abstract

Materials capable of emitting light with a specific colour (or energy) have a variety of uses, predominantly in displays. Developing bespoke materials allows us to improve current applications, such as improving image resolution in displays, and access brand new technologies, such as biological imaging agents.
Semiconductor nanoparticles, known as quantum dots, are some of the smallest materials known that are capable of emitting light over a wide range of energies. Quantum dots are highly tuneable, emitting different energy light depending on their composition, size and surface character. Their miniscule size and customisable emissive properties has resulted in their extensive exploration and development.
Materials composed of cadmium, selenium and tellurium are most exploited in quantum dots, due in part to well-developed protocols for their preparation. Their reliable preparation, combined with attractive optical properties, lead to their commercialization in early quantum dot television displays. Yet despite significant progress, the highly toxic elements of which they are composed (cadmium and selenium) has proven a prohibitive factor in their wider adoption. The inherent toxicity of these elements largely precludes their use within biological applications. Moreover, growing legislative limitations on cadmium concentration in consumer goods has further reduced commercial interest.
Quantum dots composed of less toxic, more environmentally benign elements, such as gallium, indium, and phosphorus, are prominent alternatives to cadmium and selenium containing materials. Their contrastingly lower toxicity makes these materials enticing for use in consumer
and bioimaging applications.
A key challenge with this class of material is the highly reactive and dangerous chemicals required to make them. These chemicals ignite spontaneously in air, making them difficult to handle on a large scale. Furthermore, their high reactivity results in quantum dots of poorer optical quality, compared to cadmium and selenium materials. Our research looks to overcome these challenges by exploring a less reactive, more easily handled family of precursors.
Our research will investigate a family of emerging chemicals, known as heavy cyanate analogues, which may offer a more accessible and safer route to generate less toxic quantum dots. These chemicals have proven effective sources of elements such as phosphorus in
molecular research, but as of yet are unexplored in the preparation of quantum dots. We envision that these chemicals, some of which are considerably air and moisture tolerant, could be beneficial alternatives to current, more hazardous, precursors.
This work aims to investigate whether this new family of chemicals can be used to prepare quantum dots. This project falls within the EPSRC Manufacturing the Future research area. If successful, this work would represent an unprecedented application for this family of chemicals - taking fundamental research and applying it to larger, more valuable materials. With the easily scalable preparation known for these chemicals, they are attractive alternatives from both
a scientific and manufacturing perspective.
In summary, this research will explore heavy cyanate analogues as alternative precursors for low-toxicity quantum dots, with the goal of developing safer, industrially attractive preparations.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/S023828/1 01/04/2019 30/09/2027
2329381 Studentship EP/S023828/1 01/10/2019 30/09/2023 Jack Howley