Emerging Chalcohalide Materials for Energy Applications

Abstract

Semiconductors with multiple anions currently provide a new materials platform from which improved functionality emerges, posing new challenges and opportunities in material science. This review has endeavored to emphasize the versatility of the emerging family of semiconductors consisting of mixed chalcogen and halogen anions, known as “chalcohalides”. As they are multifunctional, these materials are of general interest to the wider research community, ranging from theoretical/computational scientists to experimental materials scientists. This review provides a comprehensive overview of the development of emerging Bi- and Sb-based as well as a new Cu, Sn, Pb, Ag, and hybrid organic–inorganic perovskite-based chalcohalides. We first highlight the high-throughput computational techniques to design and develop these chalcohalide materials. We then proceed to discuss their optoelectronic properties, band structures, stability, and structural chemistry employing theoretical and experimental underpinning toward high-performance devices. Next, we present an overview of recent advancements in the synthesis and their wide range of applications in energy conversion and storage devices. Finally, we conclude the review by outlining the impediments and important aspects in this field as well as offering perspectives on future research directions to further promote the development of chalcohalide materials in practical applications in the future.

Advances in Chalcogenide Crystal Growth: Flux and Solution Syntheses, and Approaches for Postsynthetic Modifications

“…For example, the flux, often a salt, can integrate into the structure and form salt-inclusion materials or mixed-anion compositions. , When the flux is not reactive with the reagents, it can still affect the final phase. For instance, different flux compositions, NaCl, NaCl/NaI, and NaBr/NaI, in the Na–Ga–Se system can facilitate the crystallization of NaGa 3 Se 5 , [Na 2 Cl]­GaSe 2 , Na 2 GaSe 3 , and Na 4 Ga 2 Se 5 phases, respectively. , Moreover, the flux can mediate the formation of specific polymorphs, as is demonstrated in the crystallization of orthorhombic-[Na 2 Cl]­GaS 2 (Na 2 S n /NaCl flux) versus tetragonal-[Na 2 Cl]­GaS 2 (Na 2 S n /NaCl/NaI flux) , and monoclinic (no flux) versus cubic (KI flux) polymorphs of Ga 2 S 3 …”

“…Chalcogenide compounds containing Q n 2– anions ( Q = S, Se, and Te; n = 1–8) stand out in materials chemistry due to the presence of soft (covalent) metal chalcogenide bonding, which creates a rich and diverse crystal chemistry that is responsible for the many observed properties of chalcogenide materials. , In fact, the electronic structures and distinctive bonding features of chalcogenides have paved the way for their use in applications in the semiconductor, superconductor, and thermoelectric industries, as well as in nanomaterials, batteries, and catalysis. − Future advances in functional chalcogenide material chemistry are expected to arise from developing new or improved synthetic routes that can lead to the discovery of novel compositions and structures. One such approach, materials discovery via crystal growth, is considered a cornerstone of solid-state and materials chemistry; , it both allows the precise determination of crystal structures via single-crystal X-ray diffraction (SC-XRD) and creates the ability to use single crystals for intrinsic property measurements, and it can also advance fundamental physical science and help develop material-specific applications.…”

“…Chalcogenide compounds containing Q n 2− anions (Q = S, Se, and Te; n = 1−8) stand out in materials chemistry due to the presence of soft (covalent) metal chalcogenide bonding, which creates a rich and diverse crystal chemistry that is responsible for the many observed properties of chalcogenide materials. 1,2 In fact, the electronic structures and distinctive bonding features of chalcogenides have paved the way for their use in applications in the semiconductor, superconductor, and thermoelectric industries, as well as in nanomaterials, batteries, and catalysis. 2−16 Future advances in functional chalcogenide material chemistry are expected to arise from developing new or improved synthetic routes that can lead to the discovery of novel compositions and structures.…”

Improving Long‐Term Stability of Kesterite Thin‐Film Solar Cells with Oxide/Metal/Oxide Multilayered Transparent Conducting Electrodes

“…The earth-abundant kesterite, Cu 2 ZnSn(S,Se) 4 (CZTSSe), has been considered a promising absorber material for thin-film solar cells (TFSCs) due to their outstanding optoelectronic properties. [1,2] Recently, kesterite-based devices have achieved a certified power conversion efficiency (PCE) of >13% (with the active area). [3,4] However, the reported PCE is still lower than that of its counterparts, such as Cu(In,Ga)Se 2 (CIGS) and CdTe, which have PCEs of >22%.…”

Multifunctional Electrochromic Devices for Energy Applications

“…A lot of research work has been done on energy conversion and storage which is available in comprehensive reviews published recently. − Thus, the current review focuses on the work integrating electrochromism with energy storage applications. Electrochromic materials , are a set of materials that change their optical appearance when an electric bias is applied.…”