Synthesis of CdSe Nanoplatelets without Short-Chain Ligands: Implication for Their Growth Mechanisms

Jiang, Yidong; Ojo, Wilfried-Solo; Mahler, Benoît; Xu, Xiujuan; Abécassis, Benjamin; Dubertret, Benoît

doi:10.1021/acsomega.8b01006

Cited by 23 publications

(36 citation statements)

References 30 publications

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“…[47][48][49][50] This phenomenon is attributed to the shortened dimension of the exchanged ligand. [51] The X-ray diffraction (XRD) patterns show that the crystal structure is orthorhombic (ICSD 648451) before ligand exchange, see Figure 1d. [38] After ligand exchange, we observed peaks mainly associated with the α-phase of the perovskite crystal structure.…”

Section: Resultsmentioning

confidence: 99%

Preferred Growth Direction by PbS Nanoplatelets Preserves Perovskite Infrared Light Harvesting for Stable, Reproducible, and Efficient Solar Cells

Sánchez-Godoy

Erazo

Gualdrón‐Reyes

et al. 2020

Advanced Energy Materials

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Due to its impressive properties such as a high absorption coefficient, long diffusion length and low exciton dissociation energy, [2] the perovskite has been exploited in several applications, among them light amplifiers and lasers, [3-,5] light emitting diodes (LEDs), [6-8] and photovoltaic devices. [9,10] The halide perovskite structure, ABX 3 [11] allows multiple atom combinations, making it very versatile. In addition, it can be synthesized at a low temperature permitting a relatively easy synthesis by a broad range of methods. The monovalent cation A (formamidinium [FA], [12] methylammonium [MA], [13] or cesium [14]) is located in the cage of BX 6 4− octahedra, where B is the metal (commonly, lead or tin) and X a halide or combination of them. The most studied hybrid-perovskite materials are MAPbI 3 and FAPbI 3. Both compounds result in a perovskite structure, despite the difference in the tolerance factor (0.95 and 1.03, respectively, and the same octahedral factor. [15,16] MAPbI 3 is intrinsically phase stable at ambient Formamidinium-based perovskite solar cells (PSCs) present the maximum theoretical efficiency of the lead perovskite family. However, formamidinium perovskite exhibits significant degradation in air. The surface chemistry of PbS has been used to improve the formamidinium black phase stability. Here, the use of PbS nanoplatelets with (100) preferential crystal orientation is reported, to potentiate the repercussion on the crystal growth of perovskite grains and to improve the stability of the material and consequently of the solar cells. As a result, a vertical growth of perovskite grains, a stable current density of 23 mA cm −2 , and a stable incident photon to current efficiency in the infrared region of the spectrum for 4 months is obtained, one of the best stability achievements for planar PSCs. Moreover, a better reproducibility than the control device, by optimizing the PbS concentration in the perovskite matrix, is achieved. These outcomes validate the synergistic use of PbS nanoplatelets to improve formamidinium long-term stability and performance reproducibility, and pave the way for using metastable perovskite active phases preserving their light harvesting capability.

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Section: Resultsmentioning

confidence: 99%

Preferred Growth Direction by PbS Nanoplatelets Preserves Perovskite Infrared Light Harvesting for Stable, Reproducible, and Efficient Solar Cells

Sánchez-Godoy

Erazo

Gualdrón‐Reyes

et al. 2020

Advanced Energy Materials

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“…Recently, the possibility to synthesize NPLs without short chain carboxylate has been confirmed using cadmium octanoate. 23 However, no trace of insoluble material was visible with the naked eye at the onset of NPLs formation. To sum up the current understanding of NPLs formation, several different mechanisms have been proposed to date but direct experimental data are lacking to prove or disprove them.…”

Section: Introductionmentioning

confidence: 97%

Insights into the Formation Mechanism of CdSe Nanoplatelets Using in Situ X-ray Scattering

et al. 2019

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Two dimensional ultra thin CdSe nanoplatelets have attracted a large interest due to their optical properties but their formation mechanism is not well understood. Several 1 different mechanisms have been proposed: confined growth in a surfactant mesophase acting as a template, anisotropic ripening of small seeds into 2D nanoplatelets or continuous anisotropic growth of a limited number of nuclei. However, quantitative in situ data that could validate or disprove these formation scenarios are lacking. We use synchrotron-based small-angle and wide-angle X-ray scattering to probe the formation mechanism of CdSe nanoplatelets synthesized using a heating-up method. We prove the absence of a molecular mesophase in the reactive medium at the onset of nanoplatelet formation ruling out a templating effect. We also show that our data are inconsistent with the anisotropic ripening of small seeds whereas the evolution of the SAXS patterns during the reaction is consistent with the continuous lateral growth of nanoplatelets fed by reactive monomers. Finally, we show that when the final temperature of the synthesis is lowered, nanoplatelets with larger lateral dimensions form. We unravel that they bend in solution during their growth to yield nanoscrolls.

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Section: Introductionmentioning

confidence: 99%

“…In addition to the MSCs that display sharp optical absorption singlets, [3–15, 18–26] there is another type of nanospecies that exhibits sharp optical absorption doublets [16, 17, 27–44] . An example semiconductor is photoluminescent (PL) CdSe peaking at around 373/393 (Species‐393) or 433/460 nm (Species‐460) [16, 27–30] . Different assignments have been made, [35–39] with zero‐dimensional (0D) dMSC‐393 and/or 2D nanoplates NPL‐393 for Species‐393, and dMSC‐460 and/or NPL‐460 for Species‐460.…”

Section: Introductionmentioning

confidence: 99%

“…Various formation schemes have been proposed for these NPLs, including the self‐assembly of 0D dMSC‐460 to 2D NPL‐460 (Figure S1c) [38, 42–44] . For reaction mixtures of various Cd and Se precursors, the evolution of both Species‐393 and Species‐460 has been reported, with a decrease of the former and an increase of the latter at relatively late points in the reaction (Figure S1d) [16, 27–30] . Although there were indications that dMSC‐393 and dMSC‐460 formed from transformations of their respective counterpart PC‐393 and PC‐460, [16] the present study provides the first exposition of their growth relationship.…”

Section: Introductionmentioning

confidence: 99%

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Transformation Pathway from CdSe Magic‐Size Clusters with Absorption Doublets at 373/393 nm to Clusters at 434/460 nm

et al. 2021

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Divergent interpretations have appeared in the literature regarding the structural nature and evolutionary behavior for photoluminescent CdSe nanospecies with sharp doublets in optical absorption. We report ac omprehensive description of the transformation pathway from one CdSe nanospecies displaying an absorption doublet at 373/393 nm to another species with ad oublet at 433/460 nm. These two nanospecies are zero-dimensional (0D) magic-sizec lusters (MSCs) with 3D quantum confinement, and are labeled dMSC-393 and dMSC-460, respectively.S ynchrotron-based small-angle X-rays cattering (SAXS) returns ar adius of gyration of 0.92 nm for dMSC-393 and 1.14 nm for dMSC-460, and indicates that both types are disc shaped with the exponent of the SAXS form factor equal to 2.1. The MSCs develop from their unique counterpart precursor compounds (PCs), whichare labeled PC-393 and PC-460, respectively.For the dMSC-393 to dMSC-460 transformation, the proposed PCenabled pathwayiscomprised of three key steps,dMSC-393 to PC-393 (Step 1), PC-393 to PC-460 (Step 2i nvolving monomer addition), and PC-460 to dMSC-460 (Step 3). The present study provides af ramework for understanding the PC-based evolution of MSCs and howP Cs enable transformations between MSCs.

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Synthesis of CdSe Nanoplatelets without Short-Chain Ligands: Implication for Their Growth Mechanisms

Cited by 23 publications

References 30 publications

Preferred Growth Direction by PbS Nanoplatelets Preserves Perovskite Infrared Light Harvesting for Stable, Reproducible, and Efficient Solar Cells

Preferred Growth Direction by PbS Nanoplatelets Preserves Perovskite Infrared Light Harvesting for Stable, Reproducible, and Efficient Solar Cells

Insights into the Formation Mechanism of CdSe Nanoplatelets Using in Situ X-ray Scattering

Transformation Pathway from CdSe Magic‐Size Clusters with Absorption Doublets at 373/393 nm to Clusters at 434/460 nm

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