Quantum dot materials from work being carried out at CRANN. Figures A and B show suspended CdTe quantum dots. The optical properties and colours of emitted radiation are controlled by size.

Nanoscience is defined as the study of objects at length scales where materials show different physical and mechanical properties than that of equivalent bulk objects, says Michael Morris.

The size dimensions needed are less than 100 nm or around one billionth of a metre. Nanotechnology is the application of “nanoengineered materials” towards specific applications where enhanced material
properties can lead to increased material performance.

While nanotechnology and nanoscience have become ingrained in the public consciousness, exciting interest and academic momentum, many observers have a perception that nanotechnology is a triumph of “style over substance” and the transfer of nanotechnology to the market place remains a distant goal. In reality, the nano-revolution in technology is already underway and products which contain nanoscale materials are increasing exponentially.

Figure B

The most obvious examples are computer processors where individual transistors are approaching sub-50 nm size.

Another area where nanoscience is having an impact and expected to lead to dramatic changes in technology is in the area of solid state lighting (SSL).

SSL is an emerging technological area expected to have a significant impact in the area of domestic/industrial design and construction and result in lowering energy use while improving light quality.

Figure C shows red and green quantum dots deposited over latex spheres (courtesy of John Donegan CRANN).

Advances in the application of SSL have been catalysed by development of the light emitting diode (LED) and the organic light emitting diode (OLED) which have allowed the development of relatively inexpensively produced, bright sources that operate at lower power than conventional sources.

An LED is essentially a very small semiconductor chip which has been doped with impurities to create an N-P junction.

The active components are normally based around gallium nitride with indium doping rather than conventional silicon which has very low efficiency for this process. The junction created by the doping process consists of separated regions of negative (electrons) and positive charge (holes).

M A Morris is Director of Nanoscale Electronics at the Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin and a Professor of Inorganic Materials Chemistry at University College Cork

This is an extract from an article featured in the Feburary edition of Construction Engineer - Click HERE to Subscribe Today!