Perovskite interfaces with protective zinc compounds – DFT computation and related experiments

Perovskite nanocrystals exhibit excellent PLQY close to unity. However, they degrade rapidly upon environmental exposure without a protective coating. Many studies have focused on core-shell structural strategies to enhance their stability, but the interfacial interactions between soft perovskite core-shell materials remain poorly understood. This thesis systematically studies the interfaces between perovskite nanocrystals and protective shells made of zinc compounds such as zinc sulfide and zinc phosphate. The results indicate that pure ZnS is unlikely to form stable bonds with the Pb-I terminated perovskite (100) surface at any orientation or termination. Therefore, the existence of the experimentally reported CsPbBr3/ZnS core-shell quantum dots may originate from unavoidable interfacial impurities or surface defects that are conductive to bonding. As an alternative, Zn₃(PO₄)₂ was prosed as a new shell material for FAPbI3. Different from ZnS, Zn₃(PO₄)₂ interacts more strongly with the perovskite surface, especially at the Pb-I termination. However, the interaction induces significant interface distortion, leading to a narrowing of the band gap from 2.19 eV to 0.90 eV. Importantly, the introduction of iodine impurities can alleviate these distortions and restore the band gap to a value close to that of pure FAPbI3, highlighting the potential of the FAPbI3/Zn₃(PO₄)₂ core-shell structure for optoelectronic applications. Ab initio molecular dynamics (AIMD) simulations at room temperature were also performed, revealing significant differences in the structural and electronic properties compared to static 0 K relaxation. This demonstrates that to obtain a realistic model of the perovskite/shell interface, it is crucial to introduce finite temperature effects, which have often been neglected in previous studies. In summary, this study demonstrates that successful core-shell interface engineering is crucial to protecting perovskite nanocrystals and maintaining their exceptional optical properties. These advances are expected to enable efficient luminescent solar concentrators (LSCs), paving the way for scalable solar energy harvesting in urban environments.

Grantor dc:publisher

UNSW, Sydney

Year dc:date

2026

Author dc:creator

• Zhang, Weiyi

• Perovskite
• Quantum Dots
• DFT
• Luminescent Solar Concentrator
• Core/Shell
• anzsrc-for: 40 ENGINEERING

Statement dc:rights

• open access
• CC BY 4.0
• free_to_read

Licence

• https://purl.org/coar/access_right/c_abf2
• https://creativecommons.org/licenses/by/4.0/

Language dc:language

en

Identifier

https://doi.org/10.26190/unsworks/32283

OAI identifier oai:identifier

oai:unsworks.library.unsw.edu.au:1959.4/107788