Exposure of high index facets in KDP crystals

Zhou

et al. 2019

J. Phys. Chem. C

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The existence of the organic component (MA) in MAPbBr 3 guarantees its cubic crystal lattice stabilities to satisfy the tolerance factor but increases the chemical instability risk when encountering moisture, oxidation, and heat. Mixed cations, particularly when using cesium cation (Cs + ), prove to be an effective way of improving both stability and optoelectronic performances of hybrid perovskite films applied in solar cells. However, the intrinsic effect of Cs + on the crystal structure, lattice defects, and optoelectronic properties of MAPbBr 3 is still unclear till now because grain boundary numbers and interface defect densities in films increase complexity; so, it is not easy to explore the intrinsic nature of how Cs + affects the optoelectronic properties of MAPbBr 3 . Single crystals (SCs) of MAPbBr 3 provide an ideal medium to investigate the influence of Cs + on the crystal structure and optoelectronic performances. Herein, we grew a series of MA 1−x Cs x PbBr 3 SCs. This reveals that Cs + inhibits the growth of MAPbBr 3 SCs, causes crystal lattice shrinkage, decreases crystal defects, and therefore reduces the dark currents, decreases the trap densities, and optimizes the optoelectronic properties. Our work provides a reference for the relationship between the composition of the mixed lead halide perovskites and the optoelectronic properties.

Section: Resultsmentioning

confidence: 99%

Cesium Decreases Defect Density and Enhances Optoelectronic Properties of Mixed MA_1–xCs_xPbBr₃ Single Crystal

Zhou

et al. 2019

J. Phys. Chem. C

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“…As we know that, high index facets are considered to show high reaction activities and large surface energies in the fields of crystal growth and catalytic. For example, the presence of WO 4 2− in KDP growth solutions, the high index facets of (512) were appeared. Su provided a novel idea to interpret the high index surfaces for nanocrystals on the basis of a hypothesis of atoms or molecular migrations to equilibrium positions.…”

Section: Introductionmentioning

confidence: 99%

From smooth to stepped, coarse and derivative high index facets on (111) facets of cubic bismuth phosphate crystal

Zhao

Crystal Research and Technology

et al. 2016

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The bcc like structure of cubic bismuth phosphate (Bi 13.1 PO δ ) crystal, makes (111) facets hardly be exposed according to the Bravais rule. In this paper, we are focusing on the exposure of smooth (111) facets on cubic bismuth phosphate crystal, and particularly on the process of the smooth (111) facets transforming to stepped and coarse (111) facets by varying the growth conditions, such as the Bi: P ratio of the raw materials, pH values, EDTA concentrations, etc. The results revealed that lower Bi: P ratio was beneficial to smooth (111) facets and with a rise of Bi: P ratio, the (111) facets transformed from smooth surface to stepped and coarse surfaces. With a moderate Bi: P ratio and EDTA concentrations, novel facets with high index were derived on the (111) facets, which were deduced as (611) facets. Additionally, the growth mechanism of the process was summarized in terms of the growth units affected by the Bi: P ratio, pH values and the presence of EDTA.

Improvement of growth habit and optical properties of rapidly grown KDP crystal by adding diethylene triamine pentacetate acid in growth solution

Zhu

Wang

Crystal Research and Technology

et al. 2013

By altering the concentration of a new additive ‐ diethylene triamine pentacetate acid (DTPA) in the growth solution, a series of KDP crystals were obtained by the “point seed” rapid growth method. The growth rates up to about 20 mm/day. Effects of DTPA on the growth habit and optical properties of these as‐grown KDP crystals were investigated. The results reveal that, with the increase of DTPA concentration in growth solution, the contents of impurity metal ions incorporated into crystal and aspect ratio of crystal morphology were both decreased gradually, while the UV transmittance of crystal was enhanced continually. In the presence of moderate concentration of DTPA (100–200 ppm), the solution stability was increased and optical properties of crystal (including optical homogeneity, light scattering and laser damage threshold) were all improved. However excessive doping (>500 ppm) has opposite effects. The impact mechanism was also analyzed combining with the structure of KDP crystal and chemical characteristics of DTPA molecular.