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Tuning the Optical Properties of Cesium Lead Halide Perovskite Nanocrystals by Anion Exchange Reactions.

Akkerman QA, D'Innocenzo V, Accornero S, Scarpellini A, Petrozza A, Prato M, Manna L - J. Am. Chem. Soc. (2015)

Bottom Line: This approach gives access to perovskite semiconductor NCs with both structural and optical qualities comparable to those of directly synthesized NCs.We also show that anion exchange is a dynamic process that takes place in solution between NCs.Therefore, by mixing solutions containing perovskite NCs emitting in different spectral ranges (due to different halide compositions) their mutual fast exchange dynamics leads to homogenization in their composition, resulting in NCs emitting in a narrow spectral region that is intermediate between those of the parent nanoparticles.

View Article: PubMed Central - PubMed

Affiliation: †Nanochemistry Department, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy.

ABSTRACT
We demonstrate that, via controlled anion exchange reactions using a range of different halide precursors, we can finely tune the chemical composition and the optical properties of presynthesized colloidal cesium lead halide perovskite nanocrystals (NCs), from green emitting CsPbBr3 to bright emitters in any other region of the visible spectrum, and back, by displacement of Cl(-) or I(-) ions and reinsertion of Br(-) ions. This approach gives access to perovskite semiconductor NCs with both structural and optical qualities comparable to those of directly synthesized NCs. We also show that anion exchange is a dynamic process that takes place in solution between NCs. Therefore, by mixing solutions containing perovskite NCs emitting in different spectral ranges (due to different halide compositions) their mutual fast exchange dynamics leads to homogenization in their composition, resulting in NCs emitting in a narrow spectral region that is intermediate between those of the parent nanoparticles.

No MeSH data available.


(A) Sketch of interparticle anion exchange.(B) XRD patterns ofthe pristine CsPbCl3, CsPbBr3 and CsPbCl3 NCs and of the samples after mixing. (C) Optical absorptionand PL spectra of various CsPb(Br:Cl)3 and CsPb(Br:I)3 NCs prepared via interparticle exchange. (D) and (E) TEMimages of CsPbBr3:CsPbCl3 1:1 (8.5 ± 1.2nm) and CsPbBr3:CsPbCl3 1:1 (8.9 ± 1.4nm), respectively. Scale bars correspond to 50 nm.
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fig4: (A) Sketch of interparticle anion exchange.(B) XRD patterns ofthe pristine CsPbCl3, CsPbBr3 and CsPbCl3 NCs and of the samples after mixing. (C) Optical absorptionand PL spectra of various CsPb(Br:Cl)3 and CsPb(Br:I)3 NCs prepared via interparticle exchange. (D) and (E) TEMimages of CsPbBr3:CsPbCl3 1:1 (8.5 ± 1.2nm) and CsPbBr3:CsPbCl3 1:1 (8.9 ± 1.4nm), respectively. Scale bars correspond to 50 nm.

Mentions: Anextreme case of halide precursor is represented by the NCs themselves:anion exchange could be achieved even by mixing solutions containingperovskite NCs of different halide compositions and therefore emittingin different spectral ranges (Figure 4A). The resulting NCs emitted in a narrow spectralregion that was intermediate between those of the parent particles.This suggests a fast partition dynamics of halide ions between theNCs and the solution phase, likely meditated by the residual excessorganic stabilizers present in solution. A few examples are reportedin Figure 4C and Figure S12. Pure CsPbI3 NCs from adirect synthesis, mixed with CsPbBr3 NCs, yielded differentemitting samples, with PL energies depending on the ratios of theCsPbX3 NCs that were mixed, and PLQYs in line with thoseobserved when performing exchanges with the other halide precursors,as shown in Table 2. Furthermore, interparticle exchange did not affect size and shapeof the NCs: all NC samples, before mixing, had comparable averagesizes and shapes. These remained practically the same after mixing(see TEM images of Figure 4D,E).


Tuning the Optical Properties of Cesium Lead Halide Perovskite Nanocrystals by Anion Exchange Reactions.

Akkerman QA, D'Innocenzo V, Accornero S, Scarpellini A, Petrozza A, Prato M, Manna L - J. Am. Chem. Soc. (2015)

(A) Sketch of interparticle anion exchange.(B) XRD patterns ofthe pristine CsPbCl3, CsPbBr3 and CsPbCl3 NCs and of the samples after mixing. (C) Optical absorptionand PL spectra of various CsPb(Br:Cl)3 and CsPb(Br:I)3 NCs prepared via interparticle exchange. (D) and (E) TEMimages of CsPbBr3:CsPbCl3 1:1 (8.5 ± 1.2nm) and CsPbBr3:CsPbCl3 1:1 (8.9 ± 1.4nm), respectively. Scale bars correspond to 50 nm.
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Related In: Results  -  Collection

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fig4: (A) Sketch of interparticle anion exchange.(B) XRD patterns ofthe pristine CsPbCl3, CsPbBr3 and CsPbCl3 NCs and of the samples after mixing. (C) Optical absorptionand PL spectra of various CsPb(Br:Cl)3 and CsPb(Br:I)3 NCs prepared via interparticle exchange. (D) and (E) TEMimages of CsPbBr3:CsPbCl3 1:1 (8.5 ± 1.2nm) and CsPbBr3:CsPbCl3 1:1 (8.9 ± 1.4nm), respectively. Scale bars correspond to 50 nm.
Mentions: Anextreme case of halide precursor is represented by the NCs themselves:anion exchange could be achieved even by mixing solutions containingperovskite NCs of different halide compositions and therefore emittingin different spectral ranges (Figure 4A). The resulting NCs emitted in a narrow spectralregion that was intermediate between those of the parent particles.This suggests a fast partition dynamics of halide ions between theNCs and the solution phase, likely meditated by the residual excessorganic stabilizers present in solution. A few examples are reportedin Figure 4C and Figure S12. Pure CsPbI3 NCs from adirect synthesis, mixed with CsPbBr3 NCs, yielded differentemitting samples, with PL energies depending on the ratios of theCsPbX3 NCs that were mixed, and PLQYs in line with thoseobserved when performing exchanges with the other halide precursors,as shown in Table 2. Furthermore, interparticle exchange did not affect size and shapeof the NCs: all NC samples, before mixing, had comparable averagesizes and shapes. These remained practically the same after mixing(see TEM images of Figure 4D,E).

Bottom Line: This approach gives access to perovskite semiconductor NCs with both structural and optical qualities comparable to those of directly synthesized NCs.We also show that anion exchange is a dynamic process that takes place in solution between NCs.Therefore, by mixing solutions containing perovskite NCs emitting in different spectral ranges (due to different halide compositions) their mutual fast exchange dynamics leads to homogenization in their composition, resulting in NCs emitting in a narrow spectral region that is intermediate between those of the parent nanoparticles.

View Article: PubMed Central - PubMed

Affiliation: †Nanochemistry Department, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy.

ABSTRACT
We demonstrate that, via controlled anion exchange reactions using a range of different halide precursors, we can finely tune the chemical composition and the optical properties of presynthesized colloidal cesium lead halide perovskite nanocrystals (NCs), from green emitting CsPbBr3 to bright emitters in any other region of the visible spectrum, and back, by displacement of Cl(-) or I(-) ions and reinsertion of Br(-) ions. This approach gives access to perovskite semiconductor NCs with both structural and optical qualities comparable to those of directly synthesized NCs. We also show that anion exchange is a dynamic process that takes place in solution between NCs. Therefore, by mixing solutions containing perovskite NCs emitting in different spectral ranges (due to different halide compositions) their mutual fast exchange dynamics leads to homogenization in their composition, resulting in NCs emitting in a narrow spectral region that is intermediate between those of the parent nanoparticles.

No MeSH data available.