A sustainable future for photonic colloidal nanocr

A sustainable future for photonic colloidal nanocrystals

First published on the web 18th June 2015


Colloidal nanocrystals – produced in a growing variety of shapes, sizes and compositions – are rapidly developing into a new generation of photonic materials, spanning light emitting as well as energy harvesting applications. Precise tailoring of their optoelectronic properties enables them to satisfy disparate application-specific requirements. However, the presence of toxic heavy metals such as cadmium and lead in some of the most mature nanocrystals is a serious drawback which may ultimately preclude their use in consumer applications. Although the pursuit of non-toxic alternatives has occurred in parallel to the well-developed Cd- and Pb-based nanocrystals, synthetic challenges have, until recently, curbed progress. In this review, we highlight recent advances in the development of heavy-metal-free nanocrystals within the context of specific photonic applications. We also describe strategies to transfer some of the advantageous nanocrystal features such as shape control to non-toxic materials. Finally, we present recent developments that have the potential to make substantial impacts on the quest to attain a balance between performance and sustainability in photonics.


With regard to III–V NCs, notable progress in direct synthesis has been accompanied with the use of cation exchange, a method that has been generalized to other material classes. First, the synthesis of high-PL InP QDs62 with a spectral coverage that rivals CdSe, and converging performance indicates that these materials are accessible via traditional means. Cation exchange,21,23,58,83 on the other hand, is an emerging route used to obtain III–V NCs,21,22 Zn-based II–VI89 and even ternary chalcogenides.58 A prominent advantage of this approach is that it preserves the narrow size distributions as well as the shape of initial NCs, providing the possibility to obtain shape-controlled NCs that are difficult to grow via direct routes. Although the presence of toxic metals during synthesis might still form an issue, they do not remain in discernible quantities in the end-applications, and are contained in a controlled environment at the fabrication stage with appropriate waste disposal, satisfying the requirements for sustainable development of colloidal NCs.

http://pubs.rsc.org/en/content/articlehtml/20...age=search

.....good overview.....still reading