scholarly journals Strong Bidentate Coordination for Surface Passivation and Ligand-Shell Engineering of Lead Halide Perovskite Nanocrystals in the Strongly Quantum-Confined Regime

2021 ◽  
Author(s):  
Aaron Malinoski ◽  
Guoxiang Hu ◽  
Chen Wang
Keyword(s):  
Surface Passivation ◽  
Bidentate Coordination ◽  
Perovskite Nanocrystals ◽  
Ligand Shell ◽  
Halide Perovskite ◽  
Quantum Confined ◽  
Lead Halide

scholarly journals : Strong bidentate coordination for surface passivation and ligand-shell engineering of lead halide perovskite nanocrystals in the strongly quantum confined regime

2021 ◽  
Author(s):  
Aaron Malinoski ◽  
Guoxiang Hu ◽  
Chen Wang
Keyword(s):  
Surface Engineering ◽  
Molecular Structures ◽  
Quantum Yields ◽  
Ionic Character ◽  
Purification Procedure ◽  
Bidentate Coordination ◽  
Perovskite Nanocrystals ◽  
Halide Perovskite ◽  
Quantum Confined ◽  
Lead Halide

The surface of lead halide perovskite nanocrystals (PNCs) is unique compared to conventional metal chalcogenide or pnictogenide semiconductor nanoparticles for its ionic character and the dynamic ligand layer, which makes them unstable in stock solutions and hinders the development of surface engineering strategies. This work employs a chelating strategy to form stable coordination on the PNC surface. Through screening a series of heterocyclic aromatic carboxylates, we found the best ligand, picolinate (PIC), with exceptional passivation effect to the surface traps of CsPbBr3 PNCs in the strongly quantum confined regime, resulting in > 0.8 photoluminescence quantum yields. The exciton lifetime in the passivated PNC approaches the radiative decay limit in various solvents. From an NMR titration experiment, the binding affinity of PIC is estimated to be at least 15 to 30 folds stronger than the original ligand from synthesis. The NMR and FTIR spectroscopic data and first-principles calculations elucidate the bidentate nature of the PIC coordination at the surface Pb site and the coadsorption of the ammonium-PIC ion pair. In apolar solvents, such as cyclohexane, the binding of PIC is stoichiometric to the available surface sites, suggesting the structure as a potent candidate for anchoring functional molecular structures to the PNC surface. In polar solvents, the strong affinity of PIC on the PNC surface provides protection for carrying out the precipitation-redissolution purification procedure that removes synthetic residual from the as-synthetic PNC samples. By modifying the purification procedure, we also develop a cation exchange procedure to replace the original oleylammonium cation with desired structures that consist of an ammonium anchoring group. Our results provide a direction for constructing strong interactions to protect the vulnerable surface of PNCs and pave the road for developing surface engineering strategies to functionalize these nanoparticles.

scholarly journals Strong bidentate coordination for surface passivation and ligand-shell engineering of lead halide perovskite nanocrystals in the strongly quantum confined regime

2021 ◽  
Author(s):  
Aaron Malinoski ◽  
Guoxiang Hu ◽  
Chen Wang
Keyword(s):  
Surface Engineering ◽  
Molecular Structures ◽  
Quantum Yields ◽  
Ionic Character ◽  
Purification Procedure ◽  
Bidentate Coordination ◽  
Perovskite Nanocrystals ◽  
Halide Perovskite ◽  
Quantum Confined ◽  
Lead Halide

The surface of lead halide perovskite nanocrystals (PNCs) is unique compared to conventional metal chalcogenide or pnictogenide semiconductor nanoparticles for its ionic character and the dynamic ligand layer, which makes them unstable in stock solutions and hinders the development of surface engineering strategies. This work employs a chelating strategy to form stable coordination on the PNC surface. Through screening a series of heterocyclic aromatic carboxylates, we found the best ligand, picolinate (PIC), with exceptional passivation effect to the surface traps of CsPbBr3 PNCs in the strongly quantum confined regime, resulting in > 0.8 photoluminescence quantum yields. The exciton lifetime in the passivated PNC approaches the radiative decay limit in various solvents. From an NMR titration experiment, the binding affinity of PIC is estimated to be at least 15 to 30 folds stronger than the original ligand from synthesis. The NMR and FTIR spectroscopic data and first-principles calculations elucidate the bidentate nature of the PIC coordination at the surface Pb site and the coadsorption of the ammonium-PIC ion pair. In apolar solvents, such as cyclohexane, the binding of PIC is stoichiometric to the available surface sites, suggesting the structure as a potent candidate for anchoring functional molecular structures to the PNC surface. In polar solvents, the strong affinity of PIC on the PNC surface provides protection for carrying out the precipitation-redissolution purification procedure that removes synthetic residual from the as-synthetic PNC samples. By modifying the purification procedure, we also develop a cation exchange procedure to replace the original oleylammonium cation with desired structures that consist of an ammonium anchoring group. Our results provide a direction for constructing strong interactions to protect the vulnerable surface of PNCs and pave the road for developing surface engineering strategies to functionalize these nanoparticles.

Exploring the surface chemistry of cesium lead halide perovskite nanocrystals

Nanoscale ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 986-999 ◽  
Author(s):  
Roberto Grisorio ◽  
Milvia Elena Di Clemente ◽  
Elisabetta Fanizza ◽  
Ignazio Allegretta ◽  
Davide Altamura ◽  
...  
Keyword(s):  
Surface Chemistry ◽  
Surface Passivation ◽  
Organic Ligands ◽  
Perovskite Nanocrystals ◽  
Halide Perovskite ◽  
Lead Halide

The surface passivation by organic ligands of differently composed cesium lead halide perovskite nanocrystals was explored.

scholarly journals Transforming Colloidal Cs4PbBr6 Nanocrystals by Poly(maleic anhydride-alt-1-octadecene) into Stable CsPbBr3 Perovskite Emitters Through Intermediate Heterostructures

2020 ◽  
Author(s):  
Dmitry Baranov ◽  
Gianvito Caputo ◽  
Luca Goldoni ◽  
Zhiya Dang ◽  
Riccardo Scarfiello ◽  
...  
Keyword(s):  
Maleic Anhydride ◽  
Cryogenic Temperature ◽  
Colloidal Stability ◽  
Surface Passivation ◽  
High Resolution Electron Microscopy ◽  
Dual Emission ◽  
Perovskite Nanocrystals ◽  
Resolution Electron ◽  
Halide Perovskite ◽  
Lead Halide

The preparation of strongly emissive CsPbBr<sub>3</sub> perovskite nanocrystals with a robust surface passivation is a challenge in the field of lead halide perovskite nanomaterials. We report an approach to prepare polymer-capped CsPbBr<sub>3</sub> perovskite nanocrystals by reacting oleylammonium/oleate-capped Cs<sub>4</sub>PbBr<sub>6</sub> nanocrystals with poly(maleic anhydride-alt-1-octadecene) (PMAO). PMAO contains succinic anhydride units that are reactive towards the oleylamine species present on Cs<sub>4</sub>PbBr<sub>6 </sub>nanocrystals’ surface and produces polysuccinamic acid, which, in turn, triggers the Cs<sub>4</sub>PbBr<sub>6</sub> to CsPbBr<sub>3 </sub>conversion. The transformation occurs through the formation of Cs<sub>4</sub>PbBr<sub>6</sub>-CsPbBr<sub>3</sub> heterostructures as intermediates, which were captured because of the mild reactivity of PMAO and were investigated by high-resolution electron microscopy. The Cs<sub>4</sub>PbBr<sub>6</sub>-CsPbBr<sub>3</sub> heterostructures demonstrate a dual emission at cryogenic temperature with an indication of the energy transfer from Cs<sub>4</sub>PbBr<sub>6</sub> to CsPbBr<sub>3</sub>. The fully-transformed CsPbBr<sub>3</sub> NCs have high photoluminescence quantum yield and enhanced colloidal stability, which we attribute to the adhesion of polysuccinamic acid to the NC surface through its multiple functional groups in place of oleate and alkylammonium ligands. The PMAO-induced transformation of Cs<sub>4</sub>PbBr<sub>6</sub> NCs opens up a strategy for the chemical modification of metal halide NCs initially passivated with nucleophilic amines.

Rapid sampling during synthesis of lead halide perovskite nanocrystals for spectroscopic measurement

MRS Advances ◽  
2019 ◽  
Vol 4 (36) ◽  
pp. 1957-1964 ◽  
Author(s):  
James C. Sadighian ◽  
Michael L. Crawford ◽  
Cathy Y. Wong
Keyword(s):  
Surface Passivation ◽  
Photophysical Properties ◽  
Spectroscopic Measurement ◽  
Ex Situ ◽  
Spectroscopic Measurements ◽  
Perovskite Nanocrystals ◽  
Rapid Sampling ◽  
Fluorescence Measurements ◽  
Halide Perovskite ◽  
Lead Halide

ABSTRACTThe photophysical properties of lead halide perovskite nanocrystals (NCs) are critical to their potential application in light emitting devices and other optoelectronics, and are typically characterized using optical spectroscopies. Measurements of nuclei and nascent NC photophysics during synthesis provide insight into how the reaction can be changed to control the properties of the resulting NCs. However, these measurements are typically only performed ex situ after growth is halted by centrifuging the reaction mixture for several minutes. Here, a method is reported to rapidly sample the reaction mixture during a solvation-limited synthesis to enable multiple spectroscopic measurements during nucleation and NC growth. Absorbance and fluorescence measurements of a reaction mixture during the formation of methylammonium lead triiodide perovskite NCs are reported. The changing positions of spectral features as a function of reaction time show the expected weakening of exciton confinement during NC growth. The evolving fluorescence spectra demonstrate that the capping and surface passivation of nascent NCs changes during the reaction. The species in the reaction mixture, particularly during the early stages of the synthesis, are shown to be unstable. This indicates that, even for a relatively slow solvation-limited reaction, the photophysics of the reaction mixture can only be accurately captured if spectroscopic measurements are completed within seconds of sampling. The common use of centrifugation to quench NC syntheses prior to spectroscopic measurement biases the NC population towards more stable, well-capped NCs and does not accurately report on the full NC population in a reaction mixture.

Lead Halide Perovskite Nanocrystals: Stability, Surface Passivation, and Structural Control

ChemNanoMat ◽  
2017 ◽  
Vol 3 (7) ◽  
pp. 456-465 ◽  
Author(s):  
Binbin Luo ◽  
Sara Bonabi Naghadeh ◽  
Jin Z. Zhang
Keyword(s):  
Structural Control ◽  
Surface Passivation ◽  
Perovskite Nanocrystals ◽  
Halide Perovskite ◽  
Lead Halide

scholarly journals Transforming Colloidal Cs4PbBr6 Nanocrystals by Poly(maleic anhydride-alt-1-octadecene) into Stable CsPbBr3 Perovskite Emitters Through Intermediate Heterostructures

2020 ◽  
Author(s):  
Dmitry Baranov ◽  
Gianvito Caputo ◽  
Luca Goldoni ◽  
Zhiya Dang ◽  
Riccardo Scarfiello ◽  
...  
Keyword(s):  
Maleic Anhydride ◽  
Cryogenic Temperature ◽  
Colloidal Stability ◽  
Surface Passivation ◽  
High Resolution Electron Microscopy ◽  
Dual Emission ◽  
Perovskite Nanocrystals ◽  
Resolution Electron ◽  
Halide Perovskite ◽  
Lead Halide

The preparation of strongly emissive CsPbBr<sub>3</sub> perovskite nanocrystals with a robust surface passivation is a challenge in the field of lead halide perovskite nanomaterials. We report an approach to prepare polymer-capped CsPbBr<sub>3</sub> perovskite nanocrystals by reacting oleylammonium/oleate-capped Cs<sub>4</sub>PbBr<sub>6</sub> nanocrystals with poly(maleic anhydride-alt-1-octadecene) (PMAO). PMAO contains succinic anhydride units that are reactive towards the oleylamine species present on Cs<sub>4</sub>PbBr<sub>6 </sub>nanocrystals’ surface and produces polysuccinamic acid, which, in turn, triggers the Cs<sub>4</sub>PbBr<sub>6</sub> to CsPbBr<sub>3 </sub>conversion. The transformation occurs through the formation of Cs<sub>4</sub>PbBr<sub>6</sub>-CsPbBr<sub>3</sub> heterostructures as intermediates, which were captured because of the mild reactivity of PMAO and were investigated by high-resolution electron microscopy. The Cs<sub>4</sub>PbBr<sub>6</sub>-CsPbBr<sub>3</sub> heterostructures demonstrate a dual emission at cryogenic temperature with an indication of the energy transfer from Cs<sub>4</sub>PbBr<sub>6</sub> to CsPbBr<sub>3</sub>. The fully-transformed CsPbBr<sub>3</sub> NCs have high photoluminescence quantum yield and enhanced colloidal stability, which we attribute to the adhesion of polysuccinamic acid to the NC surface through its multiple functional groups in place of oleate and alkylammonium ligands. The PMAO-induced transformation of Cs<sub>4</sub>PbBr<sub>6</sub> NCs opens up a strategy for the chemical modification of metal halide NCs initially passivated with nucleophilic amines.

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