Synthesis, Crystal Structure, and Transport Properties of the Hexagonal Mo9 Cluster Compound Ag3RbMo9Se11

2.11 - Accurate characterization of indoor photovoltaic performance

Ambient energy harvesting has great potential to contribute to sustainable development and address growing environmental challenges. Converting waste energy from energy-intensive processes and systems (e.g. combustion engines and furnaces) is crucial to reducing their environmental impact and achieving net-zero emissions. Compact energy harvesters will also be key to powering the exponentially growing smart devices ecosystem that is part of the Internet of Things, thus enabling futuristic applications that can improve our quality of life (e.g. smart homes, smart cities, smart manufacturing, and smart healthcare). To achieve these goals, innovative materials are needed to efficiently convert ambient energy into electricity through various physical mechanisms, such as the photovoltaic effect, thermoelectricity, piezoelectricity, triboelectricity, and radiofrequency wireless power transfer. By bringing together the perspectives of experts in various types of energy harvesting materials, this Roadmap provides extensive insights into recent advances and present challenges in the field. Additionally, the Roadmap analyses the key performance metrics of these technologies in relation to their ultimate energy conversion limits. Building on these insights, the Roadmap outlines promising directions for future research to fully harness the potential of energy harvesting materials for green energy anytime, anywhere.

Electronic Band Structure and Transport Properties of the Cluster Compound Ag3Tl2Mo15Se19

Mo-based cluster compounds are a large class of materials with complex crystal structures that give rise to very low lattice thermal conductivity. Here, we report on the crystal structure and transport property measurements (5-800 K) of the novel Tl-filled compound Ag₃Tl₂Mo₁₅Se₁₉. This compound adopts a crystal structure described in the rhombohedral R3 c space group [ a = 9.9601(1) Å, c = 57.3025(8) Å, and Z = 6] built by the covalent arrangement of octahedral Mo₆ and bioctahedral Mo₉ clusters in a 1:1 ratio, with the Ag and Tl atoms filling the large cavities between them. Transport property measurements performed on polycrystalline samples indicate that this compound behaves as a heavily doped semiconductor with mixed electrical conduction. Electronic band structure calculations combined with a semiclassical approach using the Boltzmann transport equation are in good agreement with these measurements. This compound exhibits a lattice thermal conductivity as low as 0.4 W m^-1 K^-1 because of highly disordered Ag and Tl atoms. Because of the low thermopower values induced by the mixed electrical conduction, the dimensionless thermoelectric figure of merit ZT remains moderate with a peak value of 0.18 at 750 K.