Quantum dots finally take a giant leap forward
Quantum dot technology has taken another leap forward, as researchers have discovered a way to make near-perfect superstructures out of these infinitesimal crystals.
Scientists have long harbored high hopes for these tiny crystalline structures that can precisely convert and tune incoming light, but an apparently insurmountable hurdle has been the inability to fuse them together directly. Until now.
This latest research, published Monday in the journal Nature Materials, has , arranging quantum dots together in an order almost without blemish.
鈥淧reviously, they were just thrown together, and you hoped for the best,鈥� says lead researcher Tobias Hanrath, of Cornell University鈥檚 School of Chemical and Biomolecular Engineering, in a telephone interview with 海角大神.
鈥淚t was like throwing a couple thousand batteries into a bathtub and hoping you get charge flowing from one end to the other.鈥�
Each crystal 鈥� each quantum dot 鈥� consists of about 5,000 atoms. Because of the distinct properties these crystals exhibit, not least their emission or absorption of different wavelengths of light according to how they are manipulated, they offer much promise in various fields of technology.
But the challenge has always been finding a way to connect the dots with one another, and to their surroundings, directly, without introducing another substance that would impact both purity and structure.
The breakthrough achieved by Dr. Hanrath and his team represents the culmination of several years鈥� work, which the professor likens to 鈥減laying lego but with atomic-sized building blocks.鈥�
鈥淚f you take several quantum dots, all perfectly the same size, and you throw them together, they鈥檒l automatically align into a bigger crystal,鈥� Hanrath tells the Monitor. 鈥淚t鈥檚 the same idea as a bucket of tennis balls automatically assuming an ordered pattern, or stacking cannonballs on top of each other.鈥�
The difference here is that Hanrath鈥檚 team has enabled those quantum dots not just to arrange themselves in a random, if ordered, manner, but the crystals can now actually stick to one another.
Previous work had shown that if you placed the quantum dots on a fluid surface, similar to placing oil on water, the crystals could be fused together. But this latest work sought to take that to a new level of perfection.
They have, essentially, created crystal superstructures that are defect-free.
鈥淭ake silicon,鈥� says Hanrath. 鈥淓very silicon atom is the same size. In our case, the building blocks are almost the same size, but there is 5 percent variability in diameter, so you can鈥檛 make a perfect crystal superstructure, but as far as you can, we鈥檝e pushed it to the point of perfection.鈥�
There is scope for this research to have direct technological applications, or to improve existing technologies, particularly in areas such as display screens and solar cells, or even in flexible electronics.
Yet the direct applications are not what excites the professor most of all.
He uses the example of graphene, talking of the predictions surrounding its possibilities, the uses to which it could be put, but saying that, until we have better, more stable, samples, it is hard to carry out the necessary research.
鈥淭his is what we鈥檝e done with quantum dot solids, taking them to an unprecedented level of perfection,鈥� says Hanrath, 鈥渟o what excites us most is the scientific advance in itself and where this could take us next.鈥澛�
