Disparity of the Nature of the Band Gap between Halide and Chalcogenide Single Perovskites for Solar Cell Absorbers.

Chalcogenide perovskites ABX (A = Ca, Sr, or Ba; B = Ti, Zr, or Hf; and X = O, S, or Se) have been considered as promising candidates for overcoming the stability and toxic issues of halide perovskites. In this work, we unveil the disparity of the nature of the band gap between halide and chalcogenide perovskites. First-principles calculations show that the prototype cubic phase of chalcogenide perovskites exhibits indirect band gaps with the valence band maximum and the conduction band minimum located at R and Γ points, respectively, in the Brillion zone.

Materials Design of Solar Cell Absorbers Beyond Perovskites and Conventional Semiconductors via Combining Tetrahedral and Octahedral Coordination.

Tetrahedral coordination structures, e.g. crystalline Si, GaAs, CdTe, and octahedral coordination structures, e.

Zwitterion functionalized carbon nanotube/polyamide nanocomposite membranes for water desalination.

We have shown from both simulations and experiments that zwitterion functionalized carbon nanotubes (CNTs) can be used to construct highly efficient desalination membranes. Our simulations predicted that zwitterion functional groups at the ends of CNTs allow a high flux of water, while rejecting essentially all ions. We have synthesized zwitterion functionalized CNT/polyamide nanocomposite membranes with varying loadings of CNTs and assessed these membranes for water desalination.