Ag₂Q‐Based (Q = S, Se, Te) Silver Chalcogenide Thermoelectric Materials

Abstract

should have a high electrical conductivity (σ), a high Seebeck coefficient (S), and a low thermal conductivity (κ). [6][7][8][9] Cu 2 Q-and Ag 2 Q-based (Q = S, Se, Te) chalcogenides are exemplified with partially decoupled electrical and thermal transports. Over the past decade, Cu 2 Q materials have been widely investigated, showcasing remarkable zT values (around 2.0) at high temperatures. [10][11][12][13][14] As the homologous compounds sharing some common features, Ag 2 Q-based silver chalcogenides have arisen as a new spotlight in thermoelectrics (Figure 1) in recent years. Notably, the high zT values near unity of Ag 2 Se [15][16][17] make it a potential candidate for room-temperature thermoelectric application. In fact, Ag 2 Q compounds are "old" materials whose discovery can be traced back to the 19th century. [18][19][20] Their thermoelectric properties were first reported in the 1940s-1960s during which decent performance of Ag 2 Se and Ag 2 Te was unveiled. [21][22][23][24][25][26] After that, the study on Ag 2 Q had faded out over decades accompanying the low ebb of thermoelectric research. [27,28] Upon the turn of the century, especially over the last 10 years, the revival has come for thermoelectrics, bringing about great progress in transport theories, [29][30][31][32][33] advanced synthesis, [34][35][36][37] and characterization techniques, [38][39][40] and even the research paradigm. [41][42][43] All these progresses have boosted zT from 1 to 2 in not a few new or old thermoelectric materials. [44][45][46][47][48] In the same period, the booming of flexible/wearable electronics necessitates thermoelectric materials having both high performance and deformability at room temperature. [49][50][51][52] All these factors inspire people to revisit Ag 2 Q-based materials.Ag 2 Q-based materials exhibit a low lattice thermal conductivity originating from the large disorder or even liquid-like behavior of Ag ions. [53][54][55][56] They tend to show n-type conduction with a high electron mobility. [15,57,58] Apart from the thermoelectric properties, an exceptional room-temperature plasticity has been found in Ag 2 S-based materials (Figure 1), [59] which is quite rare and valuable for inorganic semiconductors. [60] Beyond the binary compounds, several ternary and even quaternary Ag 2 (S, Se, Te) alloys have been developed, exhibiting both high zT values and excellent plastic deformability. [54,[61][62][63] In addition, CuAgQ materials, the intermediate compounds between Ag 2 Q and Cu 2 Q, have also received wide attention as promising thermoelectric materials. [64][65][66][67] Considering the new, intriguing scientific issues and great application prospects of Ag 2 Q-based silver chalcogenide thermoelectric materials, here in this review, we try to provide the Thermoelectric technology provides a promising solution to sustainable energy utilization and scalable power supply. Recently, Ag 2 Q-based (Q = S, Se, Te) silver chalcogenides have come forth as potential thermoelectric materials that are endowed wi...

Advances in Ag2Se-based thermoelectrics from materials to applications

“…212 The improved ionic character induces a less sharp band edge and an enlarged E g . 212 Fig. 6(b) plots the S-alloying content ( x )-dependent n and μ at room temperature, 117 in which n and μ show complex changing trends with increasing alloying contents.…”

“…143 Ag 2 Se-based films exhibit excellent thermoelectric performance and considerable flexibility, making them good candidates for FTEDs. 212,231…”

Proton Irradiation Effects on the Pyroelectric Properties of P‐Type Bismuth Antimonide/Poly(vinylidene fluoride–trifluoroethylene) Composite Films

“…Commonly, the thermal conductivity of thermoelectric material is larger than that of P(VDF-TrFE). [28][29][30] It means that doping a P(VDF-TrFE) film with thermoelectric fillers should increase its thermal conductivity, thereby producing a rapid thermal-release electrical response that shortens the pyroelectric response time. Therefore, the thermoelectric fillers are chosen in this work.…”

From Brittle to Ductile: A Scalable and Tailorable All-Inorganic Semiconductor Foil through a Rolling Process toward Flexible Thermoelectric Modules

“…Among these inorganic TE materials, Ag 2 Se is an n-type degenerate semiconductor with a narrow band gap in the range of 0.04–0.18 eV and exhibits superior TE performance near room temperature. − However, Ag 2 Se is also rigid and brittle, so a huge effort was made to fabricate flexible Ag 2 Se materials. Flexibility can be achieved in rigid materials as long as their thickness is small enough. , For instance, flexibility can be realized by depositing the Ag 2 Se thin film on flexible polymer substrates or fabricating Ag 2 Se/polymer composites. − Another approach to improve the flexibility of Ag 2 Se has been raised with the discovery of the metal-like ductility in Ag 2 S. , The combination of ductility in Ag 2 S and superior TE performance in Ag 2 Se may engender a promising method to fabricate ductile all-inorganic TE materials with simultaneous high ZT and flexibility. , Recently, silver chalcogenides, that is, Ag 2 (S/Se/Te)-based materials have become one of the hot topics in the TE community because of their superior TE properties and exceptional ductility, which is promising to fabricate full-inorganic flexible TE modules . For example, Wu et al developed a method composed of vacuum-assisted filtration and hot pressing to fabricate sulfur-doped Ag 2 Se films on a flexible nylon substrate.…”