Jean-Yves Chane-Ching

A general route to the synthesis of surfactant-free, solvent-dispersible ternary and quaternary chalcogenide nanocrystals

A general route to the synthesis of surfactant-free CuInS2 (CIS), Cu2CoSnS4 (CCTS) and Cu2ZnSnS4 (CZTS) nanocrystals dispersible in low boiling point solvents is proposed. These nanocrystal inks should be of great interest to the fabrication of thin film absorbers of chalcogenide solar cells.

Surfactant-free CZTS nanoparticles as building blocks for low-cost solar cell absorbers

A process route for the fabrication of solvent-redispersible, surfactant-free Cu₂ZnSnS₄ (CZTS) nanoparticles has been designed with the objective to have the benefit of a simple sulfide source which advantageously acts as (i) a complexing agent inhibiting crystallite growth, (ii) a surface additive providing redispersion in low ionic strength polar solvents and (iii) a transient ligand easily replaced by an carbon-free surface additive. This multifunctional use of the sulfide source has been achieved through a fine tuning of ((Cu²⁺)(a)(Zn²⁺)(b)(Sn⁴⁺)(c)(Tu)(d)(OH⁻)(e))(t⁺), Tu = thiourea) oligomers, leading after temperature polycondensation and S²⁻ exchange to highly concentrated (c > 100 g l⁻¹), stable, ethanolic CZTS dispersions. The good electronic properties and low-defect concentration of the sintered, crack-free CZTSe films resulting from these building blocks was shown by photoluminescence investigation, making these building blocks interesting for low-cost, high-performance CZTSe solar cells.

Synthesis and Optical Properties of Cu2CoSnS4 Colloidal Quantum Dots

Monodisperse quaternary chalcopyrite Cu2CoSnS4 colloidal quantum dots have been synthesized by acid peptization of a tailored Cu2CoSnS4 precursor displaying loosely packed, ultrafine primary crystallites. Well-defined peaks shifted to higher energy compared to the Cu2CoSnS4 bulk band gap value were observed on the UV-Vis absorption curve consistent with a quantum confinement behavior. First investigations by room temperature time resolved photoluminescence (TRPL) spectroscopy suggest that the photoluminescence emission does not arise from a donor–acceptor recombination.

Water-soluble, heterometallic chalcogenide oligomers as building blocks for functional films

Monometallic chalcogenide aqueous complexes such as (Sn2S6)4− and (Sn4S10)4− are widely used as functional ligands with applications in nano-electronics and solar cells. We propose a general process route to the formation of all-inorganic, heterometallic chalcogenide oligomers, thus expanding the range of these functional aqueous ligands. From electrospray ionization mass spectrometry, tetramers were shown to be the most predominant oligomers synthesized in Sn(IV)–Zn(II)–S(II), Sn(IV)–Zn(II)–Se(II) and Sn(IV)–Ga(III)–S(II) systems. While tetramers possessing exclusively one Zn cation were identified in the Sn(IV)–Zn(II)–S(II) system, the full range of solid solutions was achieved for (Sna–Gab–Sc)t− oligomers with 1 ≤ a ≤ 4. Using in situ characterization by 119Sn liquid NMR and Raman spectroscopy, supported by DFT calculations, we demonstrate that the various tetramers adopt a compact adamantane-like structure. The charge of the heterometallic oligomers was shown to be controlled by the doping cation valence and the chalcogenide anion deficiency in the tetramers. These water-soluble heterometallic chalcogenide oligomers can serve as ligands, residue-free dispersants or building blocks for functional film fabrication. Using these oligomers, we report here the fabrication of chalcogenide solar cells employing environmentally friendly, all-aqueous, (Sna–Znb–Sc)t−-capped CZTS nanocrystal inks.

Nanostructured materials with highly dispersed Au–Ce0.5Zr0.5O2 nanodomains: A route to temperature stable Au catalysts?

Our strategy to inhibit Au(0) growth with temperature involves the preparation of ultrafine Au clusters that are highly dispersed and strongly interacting with a thermally stable high-surface-area substrate. Temperature-stable Au-cluster-based catalysts were successfully prepared through the controlled synthesis of 3.5 nm Ce0.5Zr0.5O2 colloidal building blocks containing tailored strongly bound Au-cluster precursors. With the objective of stabilizing these Au clusters with temperature, grain growth of Ce0.5Zr0.5O2 nanodomains was inhibited by their dispersion through Al2O3 nanodomains. High surface area Au–Ce0.5Zr0.5O2–Al2O3 nanostructured composites were thus designed highlighting the drastic effect of Au cluster dispersion on Au(0) cluster growth. High thermal stability of our Au(0)-cluster-based catalysts was shown with the surprising catalytic activity for CO conversion observed on our nanostructured materials heated to temperatures as high as 800 °C for 6 h.