Abstract
Cesium lead halide perovskite nanocrystals (NCs) have emerged as promising luminescent materials for a range of applications. However, the creation of highly luminescent violet-emitting CsPbCl3 NCs mostly relies on doping of a limited number of small-sized metal ions or post-synthetic surface treatment of NCs. Alkaline-earth (AE) metals (e.g., Ca2+, Sr2+, and Ba2+) have been proposed to be able to substitute Pb2+ in halide perovskites, yet it remains incompletely understood whether AE metal ions can be incorporated into the perovskite lattice or can be merely situated at the surface. Here, we explore the possibility of using AE metal ions for the suppression of the formation of trap centers, which leads us to develop a one-pot synthetic passivation strategy to boost the violet-emitting efficiency of CsPbCl3 NCs through the creation of a Ca2+/Sr2+ involved passivation layer. The photoluminescence quantum yield of violet emission reaches 77.1% by incorporating an optimal amount of Ca2+. A wide range of optical and structural characterizations, coupled with first-principles calculations, aid in clarifying the underlying mechanism for the AE-metal-dependent passivation of CsPbCl3 NCs. Specifically, based on the experimental and theoretical results, a model is proposed for the observed abnormal incorporation phenomenon of AE2+ ions in NCs (i.e., Ba2+ can be incorporated into the core of NCs, Ca2+/Sr2+ can only be at/near the surface, while Mg2+ can neither be in the core nor at the surface). We believe that the knowledge gained here may not only offer a new perspective to obtain high-efficiency violet-emitting perovskite NCs through a one-pot synthetic passivation but can also help elucidate the functions that AE2+ ions play in the optimization of perovskite optoelectronic devices.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 3974-3983 |
| Number of pages | 10 |
| Journal | Chemistry of Materials |
| Volume | 31 |
| Issue number | 11 |
| DOIs | |
| State | Published - May 8 2019 |
Bibliographical note
KAUST Repository Item: Exported on 2020-10-01Acknowledgements: This work was supported by the National Natural Science Foundation of China (grant nos. 11874275, 11574225, and 51672106), a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD), and a project supported by State Key Laboratory of Luminescence and Applications. The SPring-8 experiment was carried out with the approval of the Japan Synchrotron Radiation Research Institute (JASRI; Proposal No. 2018B0074 and 2019A0068). We thank the staff at the BL14W1 beamline at the Shanghai Synchrotron Radiation Facility for XAFS measurements. First-principles calculations were performed on TianHe-1(A) at National Supercomputer Center in Tianjin.