Large-scale Techniques Developed to Produce Quantum Dots

A new method to mass produce semiconducting nano-particles for light-emitting displays, sensors, solar panels and biomedical applications has recently began picking up steam as a result of a demonstration by researchers at the Department of Energy's Oak Ridge National Laboratory. While there are countless potential applications for zinc sulfide nano-particles which is a type of quantum dot that is a semiconductor, the high cost and limited availability has been the primary obstacle to their widespread use.

This could change though due to a scalable ORNL technique that was outlined in a paper recently published in Applied Microbiology and Biotechnology. The ORNL bio-manufacturing technique is centered on a platform technology that can also produce nano-meter size semiconducting materials as well as magnetic, photo-voltaic, catalytic and phosphor materials and differs from  conventional inorganic approaches that uses expensive precursors, toxic chemicals, high temperatures and high pressures.

ORNL's Ji-Won Moon led a team and used bacteria fed by inexpensive sugar at a temperature of 150 degrees Fahrenheit in 25- and 250-gallon reactors  which ultimately produced about three-fourths of a pound of zinc sulfide nano-particles all without process optimization therefore leaving room for even higher yields. ORNL's bio-manufactured quantum dot synthesis occurs outside of the cells which is a stark contrast to most biological synthesis technologies that occur inside the cell and as a result the nano-materials are produced as loose particles that are easy to separate through simple washing and centrifuging.

The results were extraordinary as the ORNL approach reduced production costs by more than 90% compared to traditional methods. ORNL’s approach to control material synthesis at the nano-meter scale with sufficiently high reliability, reproducible and yield to be cost effective is the end game for all successful bio-manufacturing of light-emitting or semiconducting nano-particles.

Moon said,

Since bio-manufacturing can control the quantum dot diameter, it is possible to produce a wide range of specifically tuned semiconducting nano-materials, making them attractive for a variety of applications that include electronics, displays, solar cells, computer memory, energy storage, printed electronics and bio-imaging.

The researchers of ORNL envisions their quantum dots being used initially in buffer layers of photo-voltaic cells and other thin film-based devices which will benefit tremendously from their electro-optical properties as light-emitting materials.