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Phase-Selective Synthesis of CIGS Nanoparticles with Metastable Phases Through Tuning Solvent Composition
摘要： I-III-VI2 compounds have shown great interests in the application of functional semiconductors. Among them, Cu(In,Ga)S2 has been a promising candidate due to its excellent optoelectronic properties. Although the polymorphs of Cu(In,Ga)S2 have been attracted extensive attentions, the efforts to developing the methodologies for phase-controlled synthesis of them are rare. In this paper, we reported a phase-selective synthesis of CIGS nanoparticles with metastable phases via simply changing the composition of solvents. For the wet chemistry synthesis, the microstructure of the initial nuclei is decisive to the crystal structure of final products. In the formation of Cu(In,Ga)S2, the solvent environment is the key factor, which could affect the coordination of monomers and influence the thermodynamic conditions of Cu-S nucleation. Moreover, wurtzite and zincblende Cu(In,Ga)S2 nanoparticles are selectively prepared by choosing pure en or its mixture with deionized water as reaction solvent. The as-synthesized wurtzite Cu(In,Ga)S2 possess a band gap of 1.6 eV and a carrier mobility of 4.85 cm2/Vs, which indicates its potential to construct a heterojunction with hexagonal-structured CdS for solar cells.
关键词： Nanoparticles,Wurtzite,Phase-selective,Zincblende,Metastable,CIGS
更新于2025-09-23 15:21:01
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Atomistic theory of electronic and optical properties of InAsP/InP nanowire quantum dots
摘要： We present here an atomistic theory of the electronic and optical properties of hexagonal InAsP quantum dots in InP nanowires in the wurtzite phase. These self-assembled quantum dots are unique in that their heights, shapes, and diameters are well known. Using a combined valence-force-field, tight-binding, and configuration-interaction approach we perform atomistic calculations of single-particle states and excitonic, biexcitonic, and trion complexes as well as emission spectra as a function of the quantum dot height, diameter, and As versus P concentration. The atomistic tight-binding parameters for InAs and InP in the wurtzite crystal phase were obtained by ab initio methods corrected by empirical band gaps. The low energy electron and hole states form electronic shells similar to parabolic or cylindrical quantum confinement, only weakly affected by hexagonal symmetry and As fluctuations. The relative alignment of the emission lines from excitons, trions, and biexcitons agrees with that for InAs/InP dots in the zincblende phase in that biexcitons and positive trions are only weakly bound. The random distribution of As atoms leads to dot-to-dot fluctuations of a few meV for the single-particle states and the spectral lines. Due to the high symmetry of hexagonal InAsP nanowire quantum dots the exciton fine structure splitting is found to be small, of the order a few μeV with significant random fluctuations in accordance with experiments.
关键词： fine structure splitting,electronic properties,optical properties,emission spectra,tight-binding,single-particle states,excitonic complexes,InAsP quantum dots,InP nanowires,wurtzite phase,configuration-interaction,valence-force-field,atomistic theory
更新于2025-09-23 15:19:57
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Synthesis of Curved CuIn1-xGax(S1-ySey)2 Nanocrystals and Complete Characterization of their Diffraction Contrast Effects
摘要： Herein, we report the synthesis and complete structural characterization of curved CuIn1-xGax(S1-ySey)2 (x = y = 0.5) nanocrystals, which adopt a 2D nanoplate morphology and crystallize in the hexagonal wurtzite phase. A detailed transmission electron microscopy (TEM) analysis reveals that the 2D nanoplates are predominately [001]-oriented and exhibit a unique bend contour pattern, due to curvature on the (001) basal plane. The contrast behavior of bend contours in this system is further supported through specimen tilting experiments inside the TEM, in combination with dark-field (DF) imaging in both TEM and scanning TEM (STEM) modes. This bending is believed to originate from the proximity effect of the top and bottom (001) surfaces.
关键词： bend contours,CuIn1-xGax(S1-ySey)2,hexagonal wurtzite phase,TEM,nanocrystals
更新于2025-09-09 09:28:46