David Mitzi | Searcharxiv

arXiv2017

First-Principles Understanding of the Electronic Band Structure of Copper-Antimony Halide Perovskite: The Effect of Magnetic Ordering

We report the understanding of the electronic band structure of $Cs_4CuSb_2Cl_{12}$ perovskite through first-principles density-functional theory calculations. We find that the most stable state has the antiferromagnetic configuration where each $[CuCl_6]$ octahedral chain along the [010] direction is antiferromagnetic. The reasonable band structure of the compound can be obtained only if both the correct magnetic order and the improved exchange interaction of the Cu $\it{d}$ electrons are taken into account.

cond-mat.mtrl-sci↗

arXiv2017

Parity-Forbidden Transitions and Their Impacts on the Optical Absorption Properties of Lead-Free Metal Halide Perovskites and Double Perovskites

Using density-functional theory calculations, we analyze the optical absorption properties of lead (Pb)-free metal halide perovskites (AB$^{2+}$X$_3$) and double perovskites (AB$^+$B$^{3+}$X$_6$) (A = Cs or monovalent organic ion, B$^{2+}$ = non-Pb divalent metal, B$^+$ = monovalent metal, B$^{3+}$ = trivalent metal, X = halogen). We show that, if B$^{2+}$ is not Sn or Ge, Pb-free metal halide perovskites exhibit poor optical absorptions because of their indirect bandgap nature. Among the nine possible types of Pb-free metal halide double perovskites, six have direct bandgaps. Of these six types, four show inversion symmetry-induced parity-forbidden or weak transitions between band edges, making them not ideal for thin-film solar cell application. Only one type of Pb-free double perovskite shows optical absorption and electronic properties suitable for solar cell applications, namely those with B$^+$ = In, Tl and B$^{3+}$ = Sb, Bi. Our results provide important insights for designing new metal halide perovskites and double perovskites for optoelectronic applications.

cond-mat.mtrl-sci↗