Cubic Crystal Structure Formation and Optical Properties within the Ag-BII -MIV -X (BII = Sr, Pb; MIV = Si, Ge, Sn; X = S, Se) Family of Semiconductors.

Journal Article (Journal Article)

Quaternary chalcogenide semiconductors are promising materials for energy conversion and nonlinear optical applications, with properties tunable primarily by varying the elemental composition and crystal structure. Here, we first analyze the connections among several cubic crystal structure types, as well as the orthorhombic Ag2 PbGeS4 -type structure, reported for select members within the Ag-BII -MIV -X (BII = Sr, Pb; MIV = Si, Ge, Sn; X = S, Se) compositional space. Focusing on the Ag-Pb-Si-S and Ag-Sr-Sn-S systems, we show that one structure type, with the formulas Ag2 Pb3 Si2 S8 and Ag2 Sr3 Sn2 S8 , is favored. We have prepared powder and single-crystal samples of Ag2 Pb3 Si2 S8 and Ag2 Sr3 Sn2 S8 , showing that each takes on the noncentrosymmetric cubic space group I 4̅3d and is isostructural to the previously reported compound Ag2 Sr3 Ge2 Se8 . Through hybrid density functional theory calculations, these cubic compounds are demonstrated to be (quasi-)direct band gap semiconductors with high densities of states at the band maxima. The band-gap energies are measured by reflectance spectroscopy as 1.95(3) and 2.66(4) eV for Ag2 Pb3 Si2 S8 and Ag2 Sr3 Sn2 S8 , respectively. We further measure the optical properties and show the electronic band structures of three other isostructural AI -BII -MIV -X-type materials, i.e., Ag2 Sr3 Si2 S8 , Ag2 Sr3 Ge2 S8 , and Ag2 Sr3 Ge2 Se8 , showing that the band gaps can be predictably tuned by element substitution. Detailed visual analyses of the different structures and of their relationships with other members of the Ag-BII -MIV -X compositional family provide a basis for a broader understanding of the structure formation and optoelectronic properties within the quaternary chalcogenide semiconductor family.

Full Text

Duke Authors

Cited Authors

  • McKeown Wessler, GC; Wang, T; Blum, V; Mitzi, DB

Published Date

  • February 2, 2022

Published In

Volume / Issue

  • 61 / 6

Start / End Page

  • 2929 - 2944

PubMed ID

  • 35107292

Electronic International Standard Serial Number (EISSN)

  • 1520-510X

International Standard Serial Number (ISSN)

  • 0020-1669

Digital Object Identifier (DOI)

  • 10.1021/acs.inorgchem.1c03805

Language

  • eng