Promising transparent and flexible thermoelectric modules based on p-type CuI thin films—A review

The state-of-the-art thermoelectric technology owns a unique capability of direct, noise-free, and efficient conversion of waste heat into valuable electricity. The conventional thermoelectric generators are complex and expensive in fabrication, which restricts their use in wearable and miniaturized electronics to fulfill the current and rapid growth in demands for sufficient self-powered energy harvesters. Herein, this comprehensive review paper highlights the promising and next-generation thermoelectric generators based on flexible, transparent, abundant, non-toxic, and lightweight p-type Copper Iodide (CuI) thin films. It introduces the principles of energy conversion within thin-film thermoelectric generators and the structure of p–n junction including the criteria in the selection of substrates, p-type and n-type materials, connecting electrodes, and modules designed to sustain its mechanical flexibility and optical transparency. This review underlines the morphology and properties of CuI thin-film thermoelectric generators to figure out the latest trends in advanced synthesis and characterization techniques. It draws attention to its promising applications in wearable biosensing, energy harvesting, and smart miniaturized electronics. It discusses also the challenges and prospects in boosting the thermoelectric performance of CuI thin-film generators. This targeting to exceed the unity in its Figure-of-Merit (ZT) values for excellent output power generation, large-scale production for commercialization, and long-term stability for reliable thermoelectric applications.This work was supported by Qatar University Grant no. GTRA-17722. The statements made herein are solely the responsibility of the authors. Open Access funding is provided by the Qatar National Library. All authors have read and agreed to the published version of the manuscript

Experimental and modeling analysis of p-type Bi0.4Sb1.6Te3 and graphene nanocomposites

The state-of-the-art Bismuth-Telluride (Bi2Te3) based systems are promising thermoelectric materials for efficient thermoelectric applications. In this study, the effect of graphene nanosheets (GNS) integrity on thermoelectric properties of a p-type Bi0.4Sb1.6Te3 alloy has been studied using high-energy ball milling and SPS sintering techniques. The synthesized pristine Bi0.4Sb1.6Te3 and 0.05wt% GNS/Bi0.4Sb1.6Te3 nanocomposites at different addition times of GNS have exhibited a single-phase and artifact-free bulk nanocrystalline Bi0.4Sb1.6Te3 with nanocrystals size of 17 nm. The TEM analysis confirmed the mechanical exfoliation of graphene filler in 5m nanocomposite into a single-layered nanostructure with an interplanar spacing of 0.343 nm. The prominent Raman features of the monolayered graphene sheet have appeared in the synthesized 5m-GNS/Bi0.4Sb1.6Te3 nanocomposite. This highlighted the crucial rule of graphene addition time on its structure and morphology of the synthesized nanocomposites. The ZT profile of 5m nanocomposite reached 0.801 at 348 K till 398 K. This resulted in 65% of improvements to the pristine Bi0.4Sb1.6Te3 pellet at 323 K. The obtained results were used to simulate a thermoelectric (TE) device module using ANSYS Workbench. The GNS nanocomposites have shown an ultrahigh output power of 95.57 W compared to 89.96 W for the pristine module at ΔT of 150 °C. The GNS addition has increased the output power of pristine Bi0.4Sb1.6Te3 by 7%, leading to comparable TE performance to other simulated Bi2Te3 systems

Mechanical properties of human hepatic tissues to develop liver-mimicking phantoms for medical applications

Using liver phantoms for mimicking human tissue in clinical training, disease diagnosis, and treatment planning is a common practice. The fabrication material of the liver phantom should exhibit mechanical properties similar to those of the real liver organ in the human body. This tissue-equivalent material is essential for qualitative and quantitative investigation of the liver mechanisms in producing nutrients, excretion of waste metabolites, and tissue deformity at mechanical stimulus. This paper reviews the mechanical properties of human hepatic tissues to develop liver-mimicking phantoms. These properties include viscosity, elasticity, acoustic impedance, sound speed, and attenuation. The advantages and disadvantages of the most common fabrication materials for developing liver tissue-mimicking phantoms are also highlighted. Such phantoms will give a better insight into the real tissue damage during the disease progression and preservation for transplantation. The liver tissue-mimicking phantom will raise the quality assurance of patient diagnostic and treatment precision and offer a definitive clinical trial data collection.This work was supported by Qatar University Grant no. GTRA-17722. The statements made herein are solely the responsibility of the authors. Open Access funding is provided by the Qatar National Library. This study was made possible by NPRP grants NPRP11S-1211-170083 from the Qatar National Research Fund (a member of Qatar Foundation). Open Access funding provided by the Qatar National Library

Effect of cold and hot compactions on corrosion behavior of p- and n-type bismuth telluride-based alloys developed through microwave sintering process

Bismuth Telluride (BiTe) based p-type and n-type alloys exhibit superior thermoelectric (TE) performance covering energy requirements for specialized and home utilization. The main challenge nowadays is the sustainability of their adequate TE performance in corrosive environments, which might activate the corrosion reactions, leading to the degradation of p/n semiconductors, and then failure of the TE device. This study investigates the electrochemical responses of cold and hot compacted, microwave-sintered p- and n-type BiTe alloys in a saline medium (3.5 wt% NaCl solution). XRD analysis of microwave-sintered cold- and hot-compacted BiTe pellets confirmed their phase purity and uniform crystal structure. Potentiodynamic polarization (PDP) and Electrochemical Impedance Spectroscopy (EIS) data showed enhancements in the corrosion behavior of hot-compacted p-type and cold-compacted n-type BiTe pellets. The study also proposes a corrosion resistance mechanism with an equivalent electrical circuit (EEC) to fit the experimental EIS data of both BiTe pellets. FE-SEM analysis showed visible microstructural evolutions of the BiTe pellets and their passive films. It revealed a remarkable improvement in the microstructure and blocking effect caused by the formed passive films coating the surfaces of the pellets and acting as a physical barrier preventing the passing of destructive Cl- ions. EDX spectra have proved the presence of p-type and n-type BiTe alloys, each with the corresponding dopant element of Antimony (Sb) or Selenium (Se), respectively, and in the same weight compositions for either hot or cold compacted pellets. AFM analysis examined the surface topography of developed pellets. It showed an increment in the surface roughness-mean-square (RMS) values with the development of passive films on p- and n-type BiTe alloys.This work was supported by Qatar University Grant no. GTRA-17722. The statements made herein are solely the responsibility of the authors. The authors would like to acknowledge the technical support from the Central Lab Unit (CLU) and the Center of Advanced Materials (CAM) at Qatar University. Open Access funding is provided by the Qatar National Library

Microstructure and mechanical properties of aluminum matrix composites with bimodal-sized hybrid NbC-B4C reinforcements

Aluminum (Al) is an earth-abundant metal recognized with superior properties for vital applications in the aerospace and transportation industries. Structural components of Al exhibit poor performance due to its inherent low mechanical strength. In this work, the mechanical properties of Al are enhanced by reinforcing with bimodal micron-sized Niobium Carbide (NbC) and nano-sized Boron Carbide (B4C) ceramic particles. Al-NbC-B4C hybrid composites have been synthesized via ball milling followed by cold compaction and microwave sintering. NbC micro-reinforcement composition has been kept fixed (5 wt%), while B4C nano-reinforcement composition varied from 0.5 wt%, 1.0 wt%, 1.5 wt%, and 2.0 wt%. XRD patterns revealed the high crystallinity with no detected new phases formed in the sintered composites. TEM micrographs presented the microstructure evolutions with uniform distribution of (micron + nano) hybrid bimodal-sized ceramic reinforcements in the Al matrix. FE-SEM micrographs and corresponding elemental mapping demonstrated the homogeneity in the elemental distribution of synthesized Al-NbC-B4C composites through the ball milling and microwave sintering processes. Roughness values and AFM images showed the formation of insoluble secondary phases dispersed in the Al matrix enhancing its surface resistance towards localized plastic deformations. Al-5 wt%NbC-2.0 wt%B4C composite has exhibited an ultrahigh improvement in the mechanical properties compared to pure Al. It showed enhancements in microhardness (46%), nanohardness (54%), and Young’s modulus (31%). It also showed high ultimate compression strength of 328 MPa and a low engineering failure strain of 0.64. FE-SEM compressive fractography confirmed the strengthened dispersion hardening effect from bimodal-sized ceramic particles obstacle multi-length cracks and resisting fracture failure.This work was supported by Qatar University Grant no. GTRA-17722. The statements made herein are solely the responsibility of the authors. The authors would like to acknowledge the technical support from the Central Laboratory Unit (CLU) at Qatar University. Open Access funding is provided by the Qatar National Library