Two-phase anion exchange synthesis: multiple passivation for highly efficient and stable CsPbCl₃ nanocrystals

Abstract

In recent year, substantial progress has been made in the synthesis of colloidal CsPbX3 (X = Cl, Br, I) nanocrystals (NCs). However, the anion exchange reaction always synthesize the CsPbCl3...

Anion Exchange in Cesium Lead Halide Perovskite Nanocrystals via Radiation Chemistry of Halohydrocarbons

“…A maximum in PLQYs vs the anion exchange degree was often reported in the literature, indicative of a fluorescence enhancement induced by anion exchange such as substituting I of CsPbI 3 with Br or substituting Br of CsPbBr 3 with Cl. This kind of fluorescence enhancement was usually attributed to the excessive halide sources introduced in halide anion exchange that will fill halide vacancies and result in a reduction in surface defects. , …”

“…Cesium lead halide (CsPbX 3 , X = Cl, Br, and I) perovskite nanocrystals (NCs) have attracted great attention due to their outstanding photoelectric properties and promising applications in illumination, photo­(electro)­catalysis, and solar cells. − Interestingly, CsPbX 3 NCs’ band gaps and thus optical and electrical properties can be modulated by adjusting the proportion of halide atoms (Cl, Br, and I), − which can be easily achieved by anion exchange in the postsynthesis process via mixing CsPbCl 3 , CsPbBr 3 , and CsPbI 3 NCs in appropriate ratios or mixing the solutions of NCs with halide anion precursors. − Many halide precursors have been utilized and investigated, including hydrohalic acids or halide gas precursors, , halide ammonium salts, ,,, trimethylsilyl halide reagents, , tetrafluoroborate halide salts, and inorganic metal halides. ,, Unfortunately, perovskite NCs are unstable in polar solvents. , These precursors for anion exchange and polar solvents needed for dissolving them, usually aliphatic alcohols or N , N -dimethylformamide (DMF), often cause decomposition or undesired deformation of perovskite NCs. Therefore, using inert halide precursors, for example, haloalkanes, is of high interest.…”

Recent Advances in Enhancing and Enriching the Optical Properties of Cl‐Based CsPbX3 Nanocrystals

“…[53] The femtosecond transient absorption showed few deep-level defects in the final products that could capture carriers. [54] Adv. Optical Mater.…”

“…This method benefits from the good solubility of CdCl 2 in water, guaranteeing adequate Cl-to-Br exchange at high concentrations of the original substrate. [54] In the direct V Cl passivation methods, abundant Cl − ions from various compounds were directly dropped into the CsPbCl 3 NCs solution. The Cl − ions diffuse from the solution to the surface and then to the interior of the CsPbCl 3 NCs, where they directly occupy the V Cl sites, coordinating with uncoordinated Pb or Cs and repairing the corresponding defects.…”

“…Ligands bind to the surfaces of various motifs, based on the covalent bond classification, ligands are well described as L-, X-, and Z-type (Figure 4c), based on the number of electrons (2, 1, and 0, respectively) provided by neutral ligands to metals when a bond to the surface of NCs is formed. [36,54] Although treatment with Z-type metal halide ligands can increase the PLQYs of CdSe, CdS, and InP QDs and the efficiency of sintered CdTe solar cells, related investigations on the CsPbX 3 system have rarely been reported. Consequently, in the following section, we mainly discuss X-type and L-type ligands.…”