Defects in Lead Halide Perovskite Nanocrystals: Analogies and (Many) Differences with the Bulk

Brinck, Stephanie ten; Zaccaria, F.; Infante, Ivan

doi:10.1021/acsenergylett.9b01945

Cited by 98 publications

(125 citation statements)

References 39 publications

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“…Careful computational analysis can help here, as demonstrated for example, for the case of small CdSe clusters [15]. The dominant role of surface defects is also of huge interest in lead halide perovskites, since their optical properties appear to be very defect-tolerant but nevertheless show large differences between defects in the bulk and the surface [16].…”

Section: Semiconductor Compositesmentioning

confidence: 99%

Tuning the Optical Band Gap of Semiconductor Nanocomposites—A Case Study with ZnS/Carbon

2020

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The linear photochemical response of materials depends on two critical parameters: the size of the optical band gap determines the onset of optical excitation, whereas the absolute energetic positions of the band edges define the reductive or oxidative character of photo-generated electrons and holes. Tuning these characteristics is necessary for many potential applications and can be achieved through changes in the bulk composition or particle size, adjustment of the surface chemistry or the application of electrostatic fields. In this contribution the influence of surface chemistry and fields is investigated systematically with the help of standard DFT calculations for a typical case, namely composites prepared from ZnS quantum dots and functionalized carbon nanotubes. After comparing results with existing qualitative and quantitative experimental data, it is shown conclusively, that the details of the surface chemistry (especially defects) in combination with electrostatic fields have the largest influence. In conclusion, the development of novel or improved photoresponsive materials therefore will have to integrate a careful analysis of the interplay between surface chemistry, surface charges and interaction with the material environment or substrate.

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Section: Semiconductor Compositesmentioning

confidence: 99%

Tuning the Optical Band Gap of Semiconductor Nanocomposites—A Case Study with ZnS/Carbon

2020

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“… 1 − 8 The efficient photoluminescence (PL) emission of LHP NCs stems from their intrinsic defect tolerant nature. 3 , 9 , 10 In these systems, various works have shown that their surface passivation, via a proper choice of surfactants, plays a fundamental role in achieving both colloidally stable and strongly emissive LHP NCs. 9 , 11 Aliphatic amines and carboxylic acids (most often oleylamine and oleic acid) are the standard ligands employed in the synthesis of these NCs, eventually passivating their surface as charged species (as ammonium and carboxylate ions, respectively).…”

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confidence: 99%

Stable and Size Tunable CsPbBr₃ Nanocrystals Synthesized with Oleylphosphonic Acid

Goldoni²,

et al. 2020

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We employed oleylphosphonic acid (OLPA) for the synthesis of CsPbBr 3 nanocrystals (NCs). Compared to phosphonic acids with linear alkyl chains, OLPA features a higher solubility in apolar solvents, allowing us to work at lower synthesis temperatures (100 °C), which in turn offer a good control over the NCs size. This can be reduced down to 5.0 nm, giving access to the strong quantum confinement regime. OLPA-based NCs form stable colloidal solutions at very low concentrations (∼1 nM), even when exposed to air. Such stability stems from the high solubility of OLPA in apolar solvents, which enables these molecules to reversibly bind/unbind to/from the NCs, preventing the NCs aggregation/precipitation. Small NCs feature efficient, blue-shifted emission and an ultraslow emission kinetics at cryogenic temperature, in striking difference to the fast decay of larger particles, suggesting that size-related exciton structure and/or trapping-detrapping dynamics determine the thermal equilibrium between coexisting radiative processes.

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“…Deep trap states can indeed emerge from an incomplete surface passivation after the synthesis, which leads to the formation of undercoordinated (dangling) ions at the surface. 35 , 39 − 41 To probe this effect, we performed DFT calculations by preparing cubic DP NCs model systems with a Cs 324 (Ag+Na) 108 Bi 108 Cl 756 stoichiometry. This corresponds to a cube with a side of about 3.0 nm, which is both affordable computationally and relevant from an experimental standpoint (see also Computational Methodology in the Supporting Information for further details).…”

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confidence: 99%

Compositional Tuning of Carrier Dynamics in Cs₂Na_1–xAg_xBiCl₆ Double-Perovskite Nanocrystals

et al. 2020

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We devised a hot-injection synthesis to prepare colloidal double-perovskite Cs 2 NaBiCl 6 nanocrystals (NCs). We also examined the effects of replacing Na + with Ag + cations by preparing and characterizing Cs 2 Na 1– x Ag x BiCl 6 alloy NCs with x ranging from 0 to 1. Whereas Cs 2 NaBiCl 6 NCs were not emissive, Cs 2 Na 1– x Ag x BiCl 6 NCs featured a broad photoluminescence band at ∼690 nm, Stokes-shifted from the respective absorption by ≥1.5 eV. The emission efficiency was maximized for low Ag + amounts, reaching ∼3% for the Cs 2 Na 0.95 Ag 0.05 BiCl 6 composition. Density functional theory calculations coupled with spectroscopic investigations revealed that Cs 2 Na 1– x Ag x BiCl 6 NCs are characterized by a complex photophysics stemming from the interplay of (i) radiative recombination via trapped excitons localized in spatially connected AgCl 6 –BiCl 6 octahedra; (ii) surface traps, located on undercoordinated surface Bi centers, behaving as phonon-assisted nonradiative decay channels; and (iii) a thermal equilibrium between trapping and detrapping processes. These results offer insights into developing double-perovskite NCs with enhanced optoelectronic efficiency.

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Defects in Lead Halide Perovskite Nanocrystals: Analogies and (Many) Differences with the Bulk

Cited by 98 publications

References 39 publications

Tuning the Optical Band Gap of Semiconductor Nanocomposites—A Case Study with ZnS/Carbon

Tuning the Optical Band Gap of Semiconductor Nanocomposites—A Case Study with ZnS/Carbon

Stable and Size Tunable CsPbBr₃ Nanocrystals Synthesized with Oleylphosphonic Acid

Compositional Tuning of Carrier Dynamics in Cs₂Na_1–xAg_xBiCl₆ Double-Perovskite Nanocrystals

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Defects in Lead Halide Perovskite Nanocrystals: Analogies and (Many) Differences with the Bulk

Cited by 98 publications

References 39 publications

Tuning the Optical Band Gap of Semiconductor Nanocomposites—A Case Study with ZnS/Carbon

Tuning the Optical Band Gap of Semiconductor Nanocomposites—A Case Study with ZnS/Carbon

Stable and Size Tunable CsPbBr3 Nanocrystals Synthesized with Oleylphosphonic Acid

Compositional Tuning of Carrier Dynamics in Cs2Na1–xAgxBiCl6 Double-Perovskite Nanocrystals

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Product

Resources

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Stable and Size Tunable CsPbBr₃ Nanocrystals Synthesized with Oleylphosphonic Acid

Compositional Tuning of Carrier Dynamics in Cs₂Na_1–xAg_xBiCl₆ Double-Perovskite Nanocrystals