Vickers Evan T, Chen Ziyi, Cherrette Vivien, Smart Tyler, Zhang Peng, Ping Yuan, Zhang Jin Z
Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA.
Department of Chemistry, Dalhousie University, Halifax, NS, Canada B3H 4R2.
Research (Wash D C). 2021 Jan 7;2021:6047971. doi: 10.34133/2021/6047971. eCollection 2021.
Recent progress has been made on the synthesis and characterization of metal halide perovskite magic-sized clusters (PMSCs) with composition ( = CHNH or Cs, = Pb, and = Cl, Br, or I). However, their mechanism of growth and structure is still not well understood. In our effort to understand their structure and growth, we discovered that a new species can be formed without the CHNH component, which we name as molecular clusters (MCs). Specifically, CHNHPbBr PMSCs, with a characteristic absorption peak at 424 nm, are synthesized using PbBr and CHNHBr as precursors and butylamine (BTYA) and valeric acid (VA) as ligands, while MCs, with an absorption peak at 402 nm, are synthesized using solely PbBr and BTYA, without CHNHBr. Interestingly, PMSCs are converted spontaneously overtime into MCs. An isosbestic point in their electronic absorption spectra indicates a direct interplay between the PMSCs and MCs. Therefore, we suggest that the MCs are precursors to the PMSCs. From spectroscopic and extended X-ray absorption fine structure (EXAFS) results, we propose some tentative structural models for the MCs. The discovery of the MCs is critical to understanding the growth of PMSCs as well as larger perovskite quantum dots (PQDs) or nanocrystals (PNCs).
在具有特定组成（ = CHNH 或 Cs， = Pb，且 = Cl、Br 或 I）的金属卤化物钙钛矿魔法尺寸簇（PMSCs）的合成与表征方面已取得了最新进展。然而，它们的生长机制和结构仍未得到很好的理解。在我们试图了解其结构和生长的过程中，我们发现可以在没有 CHNH 成分的情况下形成一种新物质，我们将其命名为分子簇（MCs）。具体而言，以 PbBr 和 CHNHBr 作为前驱体，丁胺（BTYA）和戊酸（VA）作为配体，合成出了在 424 nm 处有特征吸收峰的 CHNHPbBr PMSCs，而仅使用 PbBr 和 BTYA，不使用 CHNHBr，合成出了在 402 nm 处有吸收峰的 MCs。有趣的是，PMSCs 会随着时间自发地转化为 MCs。它们电子吸收光谱中的等吸收点表明 PMSCs 和 MCs 之间存在直接的相互作用。因此，我们认为 MCs 是 PMSCs 的前驱体。根据光谱和扩展 X 射线吸收精细结构（EXAFS）结果，我们提出了一些关于 MCs 的初步结构模型。MCs 的发现对于理解 PMSCs 以及更大的钙钛矿量子点（PQDs）或纳米晶体（PNCs）的生长至关重要。
