The path towards a high-performance solution-processed kesterite solar cell ☆

The structural and electronic properties of Cu2ZnSnS4 and Cu2ZnSnSe4 are studied using first-principles calculations. We find that the low energy crystal structure obeys the octet rule and is the kesterite (KS) structure. However, the stannite or partially disordered KS structures can also exist in synthesized samples due to the small energy cost. We find that the dependence of the band structure on the (Cu,Zn) cation ordering is weak and predict that the band gap of Cu2ZnSnSe4 should be on the order of 1.0 eV and not 1.5 eV as was reported in previous absorption measurements.

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Crystal and electronic band structure of Cu2ZnSnX4 (X=S and Se) photovoltaic absorbers: First-principles insights

This review captures the synthesis, assembly, properties, and applications of copper chalcogenide NCs, which have achieved significant research interest in the last decade due to their compositional and structural versatility. The outstanding functional properties of these materials stems from the relationship between their band structure and defect concentration, including charge carrier concentration and electronic conductivity character, which consequently affects their optoelectronic, optical, and plasmonic properties. This, combined with several metastable crystal phases and stoichiometries and the low energy of formation of defects, makes the reproducible synthesis of these materials, with tunable parameters, remarkable. Further to this, the review captures the progress of the hierarchical assembly of these NCs, which bridges the link between their discrete and collective properties. Their ubiquitous application set has cross-cut energy conversion (photovoltaics, photocatalysis, thermoelectrics), en...

Compound Copper Chalcogenide Nanocrystals

Several mechanisms can extend the equilibrium domain of a liquid phase into the solid region of the normal phase diagram. The causes of premelting, which include surface melting, interface curvature and substrate disorder, occur in all types of substances, including H2O. In the case of H2O, premelting can have important environmental consequences, among which are the heaving of frozen ground, breakdown of rock and concrete, sintering of snow, flow of glaciers, scavenging of atmospheric trace gases by snow and ice, and the electrification of thunderclouds. The article reviews the basic mechanisms of premelting and discusses their roles in the environmental phenomena. The principal results of numerous studies are reviewed, and trends in current research are outlined.

http://iopscience.iop.org/article/10.1088/0034-4885/58/1/003/pdf

The premelting of ice and its environmental consequences

The electronic structure as well as the optical response of kesterite and stannite structures of Cu2ZnSnS4 and Cu2ZnSnSe4 are analyzed by a relativistic full-potential linearized augmented plane wa ...

Electronic and optical properties of Cu2ZnSnS4 and Cu2ZnSnSe4

Thermal analysis and synthesis from the melts of Cu-based quaternary compounds Cu–III–IV–VI4 and Cu2–II–IV–VI4 (II=Zn, Cd; III=Ga, In; IV=Ge, Sn; VI=Se)

The Cu2-II-IV-VI4 compounds (II = Zn, Cd; IV = Si, Ge, Sn; VI = S, Se, Te) with a tetrahedral coordinated structure have been investigated, as compared with the results of the products synthesized from respective elemental mixtures. These crystal structures and melting points are determined, using differential thermal analysis and powder X-ray diffraction, respectively. The optical band gaps of these balk crystals grown by the horizontal gradient freezing or Iodine transport method are also measured by optical absorption. These melting points, lattice constants and band gaps are found to vary linearly with increasing of mean atomic weight, and can be established from the empirical equations.

Structural, thermodynamical and optical properties of Cu2-II-IV-VI4 quaternary compounds

The upper critical magnetic field Hc2 was measured on single crystals of the recently-discovered superconducting YBa2Cu3O7+y oxide. The Hc2 along the basal plane is estimated to be larger than that along the c-axis by a factor of 5. A small anisotropy of Hc2 in the basal plane is also found. It is not clear at present whether this small anisotropy is intrinsic or due to crystal imperfectness such as micro-twinnings.

https://iopscience.iop.org/article/10.1143/JJAP.26.L726/pdf

Anisotropy of the Upper Critical Magnetic Field in Single Crystal YBa2Cu3O7+y

A flux method using KCl as a solvent is proposed for single-crystal growth of Bi-Sr-Ca-Cu-O compounds. Bi-Sr-Ca-Cu-O thin plates are grown by slowly cooling a KCl solution maintained at 850~950°C. Four-probe electrical resistance measurement indicates that the as-grown crystals act as a superconductor with a transition temperature of about 80 K.

https://iopscience.iop.org/article/10.1143/JJAP.27.L844/pdf

Akinori Katsui

Papers

Thermal analysis and synthesis from the melts of Cu-based quaternary compounds Cu–III–IV–VI4 and Cu2–II–IV–VI4 (II=Zn, Cd; III=Ga, In; IV=Ge, Sn; VI=Se)

Structural, thermodynamical and optical properties of Cu2-II-IV-VI4 quaternary compounds

Anisotropy of the Upper Critical Magnetic Field in Single Crystal YBa2Cu3O7+y

Crystal Growth of Superconducting Bi–Sr–Ca–Cu–O Compounds from KCl Solution

Crystal Growth of Superconducting Bi-Sr-Ca-Cu-O Compounds from KCl Solution : Electrical Properties of Condensed Matter