Atomic Layer Deposition coating of quantum dots in beads

点击翻译按钮获取中文摘要

Nanoco is the sole UK manufacturer and supplier of state of the art quantum dots (QDs), tiny semiconductor crystals only a few nanometers in size. QDs exhibit unusual and interesting energy efficient properties that are exciting commercially in many fast growing markets including electroluminescent displays, solid state lighting, solar cells, biotechnology and biomedicine. The QDs’ many advantages over conventional devices include higher performance, increased efficiency and significantly lower environmental impact. New markets to exploit their unique properties are close to commercial exploitation. The majority of QDs currently in commercial applications contain cadmium (Cd), a toxic heavy metal which is damaging to the environment. New legislation is preventing/minimising the use of Cd worldwide and Japanese companies will not exploit any Cd-based technology. Of necessity biomedical applications require heavy metal free dots. Nanoco has developed proprietary synthetic routes to produce heavy metal free dots of equivalent performance and stability to Cd-based systems in large quantities. However the QDs currently need to undergo intricate and expensive surface modification to improve their stability in air. For commercial exploitation it is essential that the dots can be easily handled by customers (typically giant electronic companies). An alternative process ensuring stability is to coat beads containing the dots with an oxide using Atomic Layer Deposition (ALD).Nanoco has carried out proof of principle ALD trials with Liverpool University but now needs to develop a process in-house with a modified reactor, prior to industrial scale-up. The ALD coating of Cd-free QDs requires detailed investigation and development. The end result of this project would be the late stage prototype of an industrial scalable process based on ALD of oxides.