Substituting Copper with Silver in the BiMOCh Layered Compounds (M = Cu or Ag; Ch = S, Se, or Te): Crystal, Electronic Structure, and Optoelectronic Properties

Abstract

The synthesis of BiAgOCh (Ch = S or Se) compounds has been successfully achieved via the ion exchange of copper with silver in aqueous solutions, starting from the copper parent phase. Optical and electrical measurements of BiAgOCh powders confirm an increase in both the bandgap and the electrical resistivity, as compared to those of the copper compounds. The structure of the BiAgOS phase has been clearly examined. X-ray diffraction synchrotron measurements coupled with advanced high-resolution transmission electron microscopy analysis evidenced a Ag-deficient structure, as well as Bi-rich defects, both types of defects being oppositively charged. Silver atoms are also found in interstial sites, which explains the two-dimensional ionic conductivity. This structural study combined with theoretical calculations explains the intrinsic conductivity behavior of these semiconductors linked to the mutual compensation of both defect types in the structure and to the increase in the hole effective mass. This study shows the feasibility of modifying the optoelectronic properties of the BiMOCh compounds, with the goal of integrating them in heterojunction solar cells. Moreover, it provides very precise insight into the complexity of the relationship between structural defects and optoelectronic properties.

Anharmonicity and ultralow thermal conductivity in layered oxychalcogenides BiAgOCh (Ch = S, Se, and Te)

“…This method above with the simulation package Phono3py code [23] has been successfully applied to predicting the thermal conductivities of many other materials, such as ZrNiPb [25] , BiTeBr [26] , and TaCoSn [27] et al respectively, which are close to the experimentally measured values [8] . These smallish differences are mainly due to the fact that GGA often overestimates the lattice constants of solids [28] .…”

“…Recently, BiCuOSe oxyselenides have acquired ever-increasing attention as very promising thermoelectric materials due to their high value of ZT (1.5 at 900 K) [7][8][9][10][11][12] . The outstanding TE properties could be mainly ascribed to their intrinsically low thermal conductivity of BiCuOSe and its alloys [13][14][15][16][17][18] .…”

Enhanced Photophysical Properties of Bi2S3/AgBiS2 Nanoheterostructures Synthesized via Ag(I) Cation Exchange-Mediated Transformation of Binary Bi2S3

“…The Bi 2 S 3 / AgBiS 2 NHSs show a nearly 17 times higher photocurrent gain value than that of the pure Bi 2 S 3 . Photocurrent gain for pure AgBiS 2 NRs is superior to that of a BiAgOS (∼50) compound possibly due to one-dimensional morphology …”

“…In this regard, the CE process opens up a new window to synthesize ternary materials staring from a binary parent material. In earlier studies, it was reported that bismuth silver oxysulfide (BiAgOS) can be synthesized from the parent copper compound (BiCuOS), employing the cation exchange of Cu + by Ag + ion. , The favorable semiconducting properties of BiAgOS having a bandgap of ∼1.5 eV give rise to interesting photoconversion applications. The compound BiAgS 2 is isoelectronic to BiAgOS, and its comparable bandgap value may be attractive to design a photodetector.…”

Aqueous‐Based Low‐Temperature Synthesis and Thin‐Film Properties of Oxysulfide BiCuOS Nanoparticles

“…This photoconductivity effect represents a substantial increase compared to that of BiCuOS measured separately, previously reported, for which I ph /I dark = 0.5. [41] The junction is therefore strongly photosensitive and could be used as a photodetection device for instance. The most common inorganic phases reported as p-type absorber layers in photodiode or photovoltaic pn junctions are Si, GaAs, CdTe, InP, CuInSe 2 , Zn 3 P 2 , CIGS (CuIn x Ga y Se), CZTS (Cu 2 ZnSnS 4 ), WSe 2 .…”