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Advances in Lead-Free Double Perovskite Nanocrystals, Engineering Band-gaps and Enhancing Stability Through Composition Tunabilty

Abstract

In this topical review we focus on recent advances in studies of lead-free perovskite in bulk form and as nanocrystals. Substituting lead in halide perovskites is essential to overcome toxicity concerns and improve the relative low stability of these materials. Lead free double perovskites in which the unit cell is doubled, and two divalent lead cations are replaced by mono and trivalent cations, expand material possibilities beyond a limited divalent cationic substitution. The current main challenge with the double perovskite metal halides lies in overcoming their inherently indirect and disallowed optical transitions. In this review, we discuss recent discoveries of the synthesis of these materials and highlight how nanocrystals can serve as model systems to explore schemes of cationic exchange, doping and alloying for engineering the electronic structure of double perovskites. In nanocrystals, quantum confinement effects can modify the electronic structure and resulting optical transition, increasing the absorption cross section and emission, properties important for optoelectronic devices. Lastly, the enlarged surface to volume ratio in nanocrystals adds a surface energy term that may enhance stability of metastable crystallographic phases. We review how nanocrystal can inform on phases that are inherently stable and study how facile exchange reactions can help make material compositions that are impossible to make in any other way. Finally, based on our recent synthetic experience we emphasize analogs and similarities between lead based and lead-free perovskite nanocrystals. We aim that our insight along with a summary of recent progress of this fast-growing field will help expand interest in lead free perovskites, towards a greener and brighter future.

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Publication details

The article was received on 31 Jan 2019, accepted on 25 Mar 2019 and first published on 27 Mar 2019


Article type: Review Article
DOI: 10.1039/C9NR01031A
Citation: Nanoscale, 2019, Accepted Manuscript

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    Advances in Lead-Free Double Perovskite Nanocrystals, Engineering Band-gaps and Enhancing Stability Through Composition Tunabilty

    S. Khalfin and Y. Bekenstein, Nanoscale, 2019, Accepted Manuscript , DOI: 10.1039/C9NR01031A

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