Synthesis and Characterization of Ternary SnxGe1–xSe Nanocrystals

Buckley, Jannise J.; Rabuffetti, Federico A.; Hinton, Hannah L.; Brutchey, Richard L.

doi:10.1021/cm3023665

Cited by 22 publications

(21 citation statements)

References 31 publications

(16 reference statements)

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“…3, the direct bandgaps of Ge-and Sb-doped SnS films are in the range of 1.25-1.35 and 1.30-1.39 eV, respectively, which are obtained from their reflectance spectra by performing the Kubelka-Munk transformation [17,18], showing that the direct bandgaps increase with the Ge and Sb concentrations, respectively. The similar trend was also observed in the Sn 1 − x Sb x Se [15] and Sn x Ge 1 − x Se alloys [19]. The direct bandgaps of SnS, GeS, and Sb 2 S 3 are about 1.3, 1.6, and 1.5-1.6 eV, respectively [1,10,20].…”

Section: Tunable Bandgaps Of Ge-and Sb-doped Sns Filmssupporting

confidence: 79%

Effects of Ge- and Sb-doping and annealing on the tunable bandgaps of SnS films

et al. 2015

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Section: Tunable Bandgaps Of Ge-and Sb-doped Sns Filmssupporting

confidence: 79%

Effects of Ge- and Sb-doping and annealing on the tunable bandgaps of SnS films

et al. 2015

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“…5 tBuÀSeÀSeÀtBu serves as precursor to SnSe, 6 hexagonal BiSe, 7 and Sn x Ge 1Àx Se nanocrystals. 8 Photolysis of tBuÀTeÀTeÀtBu in aqueous micellar conditions yields Te 0 nanorods. 9 Aqueous reaction of MeÀSeÀSeÀMe with SnCl 2 in an autoclave yields SnSe nanosheets.…”

Section: Ialkyl Dichalcogenides (Ràeàeàr;mentioning

confidence: 99%

Shape-Programmed Nanofabrication: Understanding the Reactivity of Dichalcogenide Precursors

et al. 2013

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Dialkyl and diaryl dichalcogenides are highly versatile and modular precursors for the synthesis of colloidal chalcogenide nanocrystals. We have used a series of commercially available dichalcogenide precursors to unveil the molecular basis for the outcome of nanocrystal preparations, more specifically, how precursor molecular structure and reactivity affect the final shape and size of II-VI semiconductor nanocrystals. Dichalcogenide precursors used were diallyl, dibenzyl, di-tert-butyl, diisopropyl, diethyl, dimethyl, and diphenyl disulfides and diethyl, dimethyl, and diphenyl diselenides. We find that the presence of two distinctively reactive C-E and E-E bonds makes the chemistry of these precursors much richer and interesting than that of other conventional precursors such as the more common phosphine chalcogenides. Computational studies (DFT) reveal that the dissociation energy of carbon-chalcogen (C-E) bonds in dichalcogenide precursors (R-E-E-R, E = S or Se) increases in the order (R): diallyl < dibenzyl < di-tert-butyl < diisopropyl < diethyl < dimethyl < diphenyl. The dissociation energy of chalcogen-chalcogen (E-E) bonds remains relatively constant across the series. The only exceptions are diphenyl dichalcogenides, which have a much lower E-E bond dissociation energy. An increase in C-E bond dissociation energy results in a decrease in R-E-E-R precursor reactivity, leading to progressively slower nucleation and higher selectivity for anisotropic growth, all the way from dots to pods to tetrapods. Under identical experimental conditions, we obtain CdS and CdSe nanocrystals with spherical, elongated, or tetrapodal morphology by simply varying the identity and reactivity of the dichalcogenide precursor. Interestingly, we find that precursors with strong C-E and weak E-E bond dissociation energies such as Ph-S-S-Ph serve as a ready source of thiol radicals that appear to stabilize small CdE nuclei, facilitating anisotropic growth. These CdS and CdSe nanocrystals have been characterized using structural and spectroscopic methods. An intimate understanding of how molecular structure affects the chemical reactivity of molecular precursors enables highly predictable and reproducible synthesis of colloidal nanocrystals with specific sizes, shapes, and optoelectronic properties for customized applications. D ialkyl dichalcogenides (RÀEÀEÀR;where R = alkyl or aryl, E = S, Se, or Te) recently re-emerged as highly versatile molecular precursors for the solution-phase synthesis of colloidal nanocrystals. Intriguingly, these dichalcogenides enable the isolation of metastable nanocrystalline phases with unusual composition and morphology. tBuÀEÀEÀtBu (E = S or Se) precursors allow the isolation of CuInE 2 and Cu 2 SnE 3 nanocrystals with metastable wurtzite phases. 1,2 A change in reaction solvent from oleylamine to squalene leads to CuInE 2 nanocrystals with the more stable chalcopyrite phase. 2,3 tBuÀSÀSÀtBu serves as precursor to In 2 S 3 nanorods 4 and Cu 2Àx S nanocrystals with a wide range of morpholog...

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“…Note that if we count in the entropy contributed by lattice vibration, the solubility may be underestimated. In fact, the Sn x Ge 1-x Se alloys have been successfully fabricated by Buckley et al, who heated precursor solutions to 500 K and held for 4.75 h with stirring [38]. …”

Section: Resultsmentioning

confidence: 99%

“…On the other hand, the growth of Ge x Sn 1-x Se alloys is believed as a cation exchange mechanism [38], which means that nucleation begins as SnSe (or a tin-rich selenide) and gradually incorporates Ge over the growth period. Thermodynamic driving force for the exchange can be evaluated from the calculations of substitution energy, which is defined as

E_{s} = E (d o p e d) - E (p u r e) - n μ_{G e} + n μ_{S n}

where E ( doped ) and E ( pure ) are the total energies of the Ge-doped and pure SnSe supercells, μ Ge and μ Sn represent the chemical potentials of the Ge and Sn atoms, respectively.…”

Section: Resultsmentioning

confidence: 99%

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First-Principles Study on the Stabilities, Electronic and Optical Properties of GexSn1-xSe Alloys

et al. 2018

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We systematically study, by using first-principles calculations, stabilities, electronic properties, and optical properties of GexSn1-xSe alloy made of SnSe and GeSe monolayers with different Ge concentrations x = 0.0, 0.25, 0.5, 0.75, and 1.0. Our results show that the critical solubility temperature of the alloy is around 580 K. With the increase of Ge concentration, band gap of the alloy increases nonlinearly and ranges from 0.92 to 1.13 eV at the PBE level and 1.39 to 1.59 eV at the HSE06 level. When the Ge concentration x is more than 0.5, the alloy changes into a direct bandgap semiconductor; the band gap ranges from 1.06 to 1.13 eV at the PBE level and 1.50 to 1.59 eV at the HSE06 level, which falls within the range of the optimum band gap for solar cells. Further optical calculations verify that, through alloying, the optical properties can be improved by subtle controlling the compositions. Since GexSn1-xSe alloys with different compositions have been successfully fabricated in experiments, we hope these insights will contribute to the future application in optoelectronics.

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Synthesis and Characterization of Ternary Sn_xGe_1–xSe Nanocrystals

Cited by 22 publications

References 31 publications

Effects of Ge- and Sb-doping and annealing on the tunable bandgaps of SnS films

Effects of Ge- and Sb-doping and annealing on the tunable bandgaps of SnS films

Shape-Programmed Nanofabrication: Understanding the Reactivity of Dichalcogenide Precursors

First-Principles Study on the Stabilities, Electronic and Optical Properties of GexSn1-xSe Alloys

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