Ligand-mediated synthesis of compositionally related cesium lead halide CsPb<sub>2</sub>X<sub>5</sub> nanowires with improved stability

Ruan, Longfei; Lin, Jin-Tai; Shen, Wei; Deng, Zhengtao

doi:10.1039/c8nr00883c

Cited by 34 publications

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“…In addition to nanoplates, CsPb 2 X 5 nanowire and nanocubes (Figure 4b,c) could be successfully synthesized by reprecipitation and hot-injection method, respectively. [63,64] Figure 4d,e illustrate a typical HRTEM image and selected area electron diffraction (SAED) pattern of CsPb 2 Br 5 NCs. The interfinger distance of 0.30 and 0.42 nm in the HRTEM image can be indexed to (220) and (200) planes of tetragonal CsPb 2 Br 5 , respectively.…”

Section: D-networked Cspb 2 Xmentioning

confidence: 99%

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Low‐Dimensional‐Networked Cesium Lead Halide Perovskites: Properties, Fabrication, and Applications

et al. 2020

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resistance against thermal-treatment compared to organic-inorganic hybrid lead halide perovskites (MAPbX 3 and FAPbX 3), due to the high thermal decomposition temperature of inorganic cations, thus drawing much attention. Owing to their impressive features, all-inorganic lead halide perovskites have been greatly useful in photovoltaic and optoelectronic applications, including solar cells, light-emitting diodes (LEDs), lasers, photodetectors and photocatalysis. [5-17] The conspicuous achievements in CsPbX 3 provoke the rapid development of its derivatives, Cs 4 PbX 6 and CsPb 2 X 5. These Cs x Pb y X z materials are composed of the same element compositions and [PbX 6 ] 4− unit cells. However, they possess completely different connectivity characters of [PbX 6 ] 4− octahedrons. CsPbX 3 is classified as a type of 3D perovskite, because [PbX 6 ] 4− octahedra are corner-shared along all three axes, while CsPb 2 X 5 has a sandwich-like arrangement with Cs + cations in between PbX 2 crystallographic planes, which can be regarded as a 2D phase. In Cs 4 PbX 6 , disconnected [PbBr 6 ] 4− octahedra are completely decoupled by Cs + cations. Among these three structures, CsPb 2 X 5 and Cs 4 PbX 6 , with dimensional-network less than 3 are referred to as lowdimensional-networked cesium lead halide perovskites. Besides the connectivity, these structures can be understood from a confinement perspective. CsPbX 3 is not confined in any dimension such that it can be considered as a 3D networked semiconductor. CsPb 2 X 5 and Cs 4 PbX 6 are confined in one dimension and all three dimensions, hence the name 2D and 0D structures, respectively. [18,19] In CsPb 2 X 5 and Cs 4 PbX 6 , the excitons cannot dissociate easily within all dimensions; instead, they are confined in the PbX 2 planes and individual [PbX 6 ] 4− units, respectively, resulting in larger bandgaps compared to the traditional ABX 3 phase. Figure 1 illustrates these three structures with different dimensions. Until now, comprehensive accounts of these Cs x Pb y X z materials have been made. However, most recent research focuses on CsPbX 3 , which has excellent optical properties and promising potential in various applications. Its derivatives, CsPb 2 X 5 and Cs 4 PbX 6 have achieved tremendous progress but are still far behind that of CsPbX 3. Many problems still seriously limit the rapid development of these low-dimensional-networked perovskites, a typical one being the debate on the origin of their luminescence. In this Review article, we focus on Cs 4 PbX 6 and CsPb 2 X 5 , and attempt to unveil their features, potential in All-inorganic cesium lead halide perovskites have emerged as promising optoelectronic materials with excellent photophysical properties and great potential in a variety of applications. In parallel with the most investigated CsPbX 3 , its derivates, Cs 4 PbX 6 and CsPb 2 X 5 , with low-dimensional-networked structures have also attracted great attention. In this review, recent advancements on the low-dimensional-networked cesium lead halide perovs...

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Section: D-networked Cspb 2 Xmentioning

confidence: 99%

Section: Properties and Emission Originsmentioning

confidence: 99%

Low‐Dimensional‐Networked Cesium Lead Halide Perovskites: Properties, Fabrication, and Applications

et al. 2020

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“…The root cause for the dispute is the lack of one-to-one correlation between luminescence and structure, and an experimental technique that can distinguish luminescence from point defects versus nanoinclusions. For example, the structure of a single Cs4PbBr6 nanocrystal was confirmed by high resolution TEM, but the PL of the same exact nanoparticle was not reported or confirmed, even though this nanocrystal was selected from an ensemble of emissive nanocrystals 7,14,37,38 , so one-to-one relationship was not solidly established 15 . On the other hand, it is well known that lead halide perovskites are very sensitive to electron beams and can easily get damaged 39 , thus the TEM evidence from both sides could be questionable.…”

Section: Introductionmentioning

confidence: 99%

Revealing the Origin of Luminescence Center in 0D Cs₄PbBr₆ Perovskite

et al. 2019

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Zero dimensional perovskite Cs4PbBr6 has attracted considerable attention recently not only because of its highly efficient green photoluminescence (PL), but also its two highly debated opposing mechanisms of the luminescence: embedded CsPbBr3 nanocrystals versus intrinsic Br vacancy states. After a brief discussion on the root cause of the controversy, we provide sensitive but noninvasive methods that can not only directly correlate luminescence with the underlying structure, but also distinguish point defects from embedded nanostructures. We first synthesized both emissive and non-emissive Cs4PbBr6 crystals, obtained the complete Raman spectrum of Cs4PbBr6 and assigned all Raman bands based on density functional theory simulations. We then used correlated Raman-PL as a passive structure-property method to identify the difference between emissive and non-emissive Cs4PbBr6 crystals and revealed the existence of CsPbBr3 nanocrystals in emissive Cs4PbBr6. We finally employed a diamond anvil cell to probe the response of luminescence centers to hydrostatic pressure. The observations of fast red-shifting, diminishing and eventual disappearance of both green emission and Raman below Cs4PbBr6 phase transition pressure of ~3 GPa is compatible with CsPbBr3 nanocrystal inclusions as green PL emitters and cannot be explained by Br vacancies. The resolution of this long-lasting controversy paves the way for further device applications of low dimensional perovskites, and our comprehensive optical technique integrating structure-property with dynamic pressure response is generic and can be applied to other emerging optical materials to understand the nature of their luminescent centers.

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“…These experiments clearly indicate that the newly formed CsPb 2 Br 5 nanosheets are nonemissive in nature. It is already known in the literature that CsPb 2 Br 5 is an indirect bandgap semiconductor and thus it is nonemissive …”

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“…It is already known in the literature that CsPb 2 Br 5 is an indirect bandgap semiconductor and thus it is nonemissive. [55][56][57] Moisture-induced structural changes of CsPbBr 3 nanocrystals were further investigated using TEM analysis. Interestingly, in the presence of moisture, 3D CsPbBr 3 cubic nanocrystals transformed to 2D CsPb 2 Br 5 nanosheets (Figure 2A,B).…”

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Role of Capped Oleyl Amine in the Moisture‐Induced Structural Transformation of CsPbBr₃ Perovskite Nanocrystals

Sandeep

Gopika

Revathi

2019

Physica Rapid Research Ltrs

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The moisture‐induced structural decomposition of lead halide perovskites is the major challenge in solar cells and light‐emitting diodes based on perovskites as the active material. The presence of moisture results in the structural conversion of cubic 3D CsPbBr3 nanocrystals to 2D CsPb2Br5 nanosheets before its decomposition to PbBr2. The capping agent used, oleyl amine, plays a crucial role in this structural transformation. The presence of moisture converts the capping agent, oleyl amine, to its salt, which transforms the 3D CsPbBr3 perovskite nanocrystals to 2D CsPb2Br5 nanosheets. Further, these CsPb2Br5 nanosheets decompose to trigonal PbBr2, in the presence of higher amounts of water. Also, the amount of capping agent, oleyl amine, plays an important role in the rate of moisture‐induced structural transformations. The rate of decomposition increases with the amount of oleyl amine used as a result of the reaction of water with the excess ligands. By revealing the exact mechanism of the structural alterations in the presence of water, new design strategies can be used to prevent the decomposition of perovskites.

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Ligand-mediated synthesis of compositionally related cesium lead halide CsPb₂X₅ nanowires with improved stability

Cited by 34 publications

References 44 publications

Low‐Dimensional‐Networked Cesium Lead Halide Perovskites: Properties, Fabrication, and Applications

Low‐Dimensional‐Networked Cesium Lead Halide Perovskites: Properties, Fabrication, and Applications

Revealing the Origin of Luminescence Center in 0D Cs₄PbBr₆ Perovskite

Role of Capped Oleyl Amine in the Moisture‐Induced Structural Transformation of CsPbBr₃ Perovskite Nanocrystals

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Ligand-mediated synthesis of compositionally related cesium lead halide CsPb2X5 nanowires with improved stability

Cited by 34 publications

References 44 publications

Low‐Dimensional‐Networked Cesium Lead Halide Perovskites: Properties, Fabrication, and Applications

Low‐Dimensional‐Networked Cesium Lead Halide Perovskites: Properties, Fabrication, and Applications

Revealing the Origin of Luminescence Center in 0D Cs4PbBr6 Perovskite

Role of Capped Oleyl Amine in the Moisture‐Induced Structural Transformation of CsPbBr3 Perovskite Nanocrystals

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Ligand-mediated synthesis of compositionally related cesium lead halide CsPb₂X₅ nanowires with improved stability

Revealing the Origin of Luminescence Center in 0D Cs₄PbBr₆ Perovskite

Role of Capped Oleyl Amine in the Moisture‐Induced Structural Transformation of CsPbBr₃ Perovskite Nanocrystals