Colloidal CsX (X = Cl, Br, I) Nanocrystals and Their Transformation to CsPbX<sub>3</sub> Nanocrystals by Cation Exchange

Shamsi, Javad; Dang, Zhiya; Ijaz, Palvasha; Abdelhady, Ahmed L.; Bertoni, Giovanni; Moreels, Iwan; Manna, Liberato

doi:10.1021/acs.chemmater.7b04827

Cited by 76 publications

(121 citation statements)

References 19 publications

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“…(b) As explained in the main text, and to aid the discussion of aging, the NC is further (arbitrarily) divided into core, inner, and outer shell. For a realistic NC requiring colloidal stability, the outermost layer 61 is commonly replaced either by ligand pairs {AX′}, where A = cationic ligand (e.g., oleylammonium) and X′ = anionic ligand (e.g., bromide, oleate), respectively, or more recently also with zwitterionic ligands {AX′}, e.g., sulfobetaines. In either case, the anion/lead ratio (now [X + X′]/Pb) still falls within the yellow shaded area depicted in (a), and green circles correspond to full capping by the {AX′} ligand shell.…”

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confidence: 99%

Rationalizing and Controlling the Surface Structure and Electronic Passivation of Cesium Lead Halide Nanocrystals

et al. 2018

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Colloidal lead halide perovskite nanocrystals (NCs) have recently emerged as versatile photonic sources. Their processing and luminescent properties are challenged by the lability of their surfaces, i.e., the interface of the NC core and the ligand shell. On the example of CsPbBr3 NCs, we model the nanocrystal surface structure and its effect on the emergence of trap states using density functional theory. We rationalize the typical observation of a degraded luminescence upon aging or the luminescence recovery upon postsynthesis surface treatments. The conclusions are corroborated by the elemental analysis. We then propose a strategy for healing the surface trap states and for improving the colloidal stability by the combined treatment with didodecyldimethylammonium bromide and lead bromide and validate this approach experimentally. This simple procedure results in robust colloids, which are highly pure and exhibit high photoluminescence quantum yields of up to 95–98%, retained even after three to four rounds of washing.

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Rationalizing and Controlling the Surface Structure and Electronic Passivation of Cesium Lead Halide Nanocrystals

et al. 2018

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“…113 Novel synthesis approaches for pure CsX NCs have recently been reported and could aid in designing synthesis routes toward CsBr|CsPbBr 3 composites. 114 Furthermore, devices have so far been limited to Cs 4 PbBr 6 |CsPbBr 3 , and it remains to be seen whether or not other halide-based composites, like Cs 4 PbI 6 |CsPbI 3 , are stable enough to use in devices.…”

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Zero-Dimensional Cesium Lead Halides: History, Properties, and Challenges

Akkerman

Abdelhady

Manna

2018

J. Phys. Chem. Lett.

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Over the past decade, lead halide perovskites (LHPs) have emerged as new promising materials in the fields of photovoltaics and light emission due to their facile syntheses and exciting optical properties. The enthusiasm generated by LHPs has inspired research in perovskite-related materials, including the so-called “zero-dimensional cesium lead halides”, which will be the focus of this Perspective. The structure of these materials is formed of disconnected lead halide octahedra that are stabilized by cesium ions. Their optical properties are dominated by optical transitions that are localized within the individual octahedra, hence the title “‘zero-dimensional perovskites”. Controversial results on their physical properties have recently been reported, and the true nature of their photoluminescence is still unclear. In this Perspective, we will take a close look at these materials, both as nanocrystals and as bulk crystals/thin films, discuss the contrasting opinions on their properties, propose potential applications, and provide an outlook on future experiments.

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“…4 Yet, to date, the optical properties of Cs2ZnCl4 on the nanoscale have not been investigated, nor has any doping been attempted. 5 This work aims to fill this gap, and is also motivated by the quest for non-toxic metal halide nanocrystals (NCs) with optical properties comparable to those of Pb-based perovskite NCs. 6 We developed a colloidal synthesis of undoped and Cu-doped Cs2ZnCl4 NCs, and examined their optical properties.…”

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Bright Blue Emitting Cu-Doped Cs₂ZnCl₄ Colloidal Nanocrystals

et al. 2020

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We report here the synthesis of undoped and Cu-doped Cs2ZnCl4 nanocrystals (NCs), in which we could tune the concentration of Cu from 0.7% to 7.5%. According to electron paramagnetic resonance analysis, in 0.7% and 2.1% Cu-doped NCs the Cu ions were present in the +1 oxidation state only, while in NCs at higher Cu concentrations we could detect Cu(II) ions. The undoped Cs2ZnCl4 NCs were non emissive, while the Cu-doped samples had a bright intra-gap photoluminescence (PL) at 2.6eV mediated by band-edge absorption. The PL quantum yield was maximum (~55%) for the samples with low Cu concentration (≤ 2.1%) and it systematically decreased when further increasing the concentration of Cu, reaching 15% for the NCs with the highest doping level (7.5%). Density functional theory calculations indicated that the PL emission could be ascribed only to Cu(I) ions: these ions introduce intra-gap states that promote the formation of selftrapped excitons, through which an efficient emission takes place.

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Colloidal CsX (X = Cl, Br, I) Nanocrystals and Their Transformation to CsPbX₃ Nanocrystals by Cation Exchange

Cited by 76 publications

References 19 publications

Rationalizing and Controlling the Surface Structure and Electronic Passivation of Cesium Lead Halide Nanocrystals

Rationalizing and Controlling the Surface Structure and Electronic Passivation of Cesium Lead Halide Nanocrystals

Zero-Dimensional Cesium Lead Halides: History, Properties, and Challenges

Bright Blue Emitting Cu-Doped Cs₂ZnCl₄ Colloidal Nanocrystals

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Colloidal CsX (X = Cl, Br, I) Nanocrystals and Their Transformation to CsPbX3 Nanocrystals by Cation Exchange

Cited by 76 publications

References 19 publications

Rationalizing and Controlling the Surface Structure and Electronic Passivation of Cesium Lead Halide Nanocrystals

Rationalizing and Controlling the Surface Structure and Electronic Passivation of Cesium Lead Halide Nanocrystals

Zero-Dimensional Cesium Lead Halides: History, Properties, and Challenges

Bright Blue Emitting Cu-Doped Cs2ZnCl4 Colloidal Nanocrystals

Contact Info

Product

Resources

About

Colloidal CsX (X = Cl, Br, I) Nanocrystals and Their Transformation to CsPbX₃ Nanocrystals by Cation Exchange

Bright Blue Emitting Cu-Doped Cs₂ZnCl₄ Colloidal Nanocrystals