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Bi₂Te₃ is a promising thermoelectric material that is often touted as one of the best-performing low-temperature thermoelectric materials. As a result, it has been widely used commercially, both for clean energy generation and in cooling devices. Like many other thermoelectric materials, defects play a key role in the performance of Bi₂Te₃. As a result, numerous studies have attempted to experimentally and computationally map out the dominant defects in the phase, these include efforts to determine the dominant defect, estimate defect energies, and predict their concentration. The computer coupling of phase diagrams and thermochemistry (CALPHAD) is one of many tools under the auspices of the materials genome initiative (MGI) that enables the rapid design of new functional materials with improved properties. The Defect energy formalism (DEF) with a charged sublattice, an offshoot of the Compound energy formalism (CEF), provides a way to directly include first-principle defect energy calculations into CALPHAD descriptions of solid phases. The introduction of the charge sublattice enables the estimation of the free carrier concentrations in the phase. Here we apply the DEF to the Bi₂Te₃ system, emphasizing the robustness of the DEF in describing meaningful endmembers and the elimination of fitting parameters. Unlike previous assessments using the Wagner–Schottky defect model, we include the description of the charged defects in our assessment. The DEF with a charged sublattice provides a good prediction of the non-stoichiometry of the phase when compared with experimental data and also predicts a thermodynamic defect concentration at low temperature that is physically reasonable.

Interdigitated back-contact (IBC) electrode configuration is a novel approach toward highly efficient Photovoltaic (PV) cells. Unlike conventional planar or sandwiched configurations, the IBC architecture positions the cathode and anode contact electrodes on the rear side of the solar cell. This review provides a comprehensive overview of back-contact (BC) solar cells, commencing with the historical context of the inception of the back-contact silicon (BC-Si) solar cells and its progression into various designs such as metallization wrap through, emitter wrap through, and interdigitated configurations. This review emphasizes back-contact perovskite solar cells (BC-PSCs), due to their potential for achieving higher efficiencies and better stability compared to traditional PSC architectures. Herein, we discuss the classification of BC-PSCs based on the position of rear electrodes, including interdigitated and quasi-interdigitated structures. These structures are further analyzed by investigating their implementation via various electrode patterning techniques, such as photolithography, microsphere lithography, cracked film lithography, network-like porous titanium (Ti) electrodes, v-shaped grooves, and lateral-structure perovskite single crystal/shadow masks, used in the development of various types of BC-PSCs. Finally, this review concludes by suggesting potential solutions to the current challenges associated with BC-PSCs to tap into the full potential of this technology. This review aims to provide readers with an in-depth understanding of the latest advancements in BC PV technology, particularly BC-PSCs, and the potential directions for future research and innovation.

The development of the Internet of Things (IoT) not only facilitates our lives but also dramatically grows data. Artificial synaptic devices appear to represent an emerging physical solution compared to the existing computational architectures. Memristive devices are of great interest with their high integration and low power consumption in the field of synaptic devices. In this work, we demonstrate short-term plasticity (STP) and long-term plasticity (LTP) by regulating synaptic weights with different stimulus pulses. Moreover, the application in neuromorphic computing is further exhibited by image recognition with an accuracy of 95.2 % under the modified National Institute of Standards and Technology database. Therefore, Nd-doped Bi₄Ti₃O₁₂ memristors, as emerging artificial synaptic devices, are expected to achieve breakthroughs in artificial intelligence and promote the development of neuromorphic computing and intelligent systems.

Nowadays, the growing threat of environmental pollution and the energy crisis have accelerated the advancement of sustainable energy sources and highly efficient energy storage technologies. Supercapacitors' outstanding efficiency and accessibility have attracted much interest in portable electronics. However, compared to other energy storage devices, commercially available supercapacitors offer minimal advantages, and it is also very difficult to balance their electrochemical performance, such as cyclability, energy density, and capacitance. Fabricating high-performance supercapacitors with attractive electrical parameters and flexibility depends on the composition of the electrodes.

Nanocellulose, which is derived from waste biomass because of its high mechanical strength, strong chemical reactivity, and biodegradability, has been used to integrate 2D, 1D, and zero-dimensional inorganic additive materials to develop a promising material for supercapacitor electrodes. The present review summarises recent advancements in the progress of nanocellulose/2D-, 1D-, and zero-dimensional inorganic material-based composite electrodes for their application in supercapacitors. Different strategies for developing nanocellulose/inorganic additive-based composite electrodes are reviewed, and subsequently, the potential of nanocellulose/multidimensional inorganic additive-based electrodes in supercapacitors is fully elaborated. In the end, current challenges and future directions for the development finally, current challenges and future directions for developing nano cellulose-based nanocomposite electrodes in supercapacitors were also discussed.

This review presents recent breakthroughs in the realm of nonlinear Hall effects, emphasizing central theoretical foundations and recent experimental progress. We elucidate the quantum origin of the second-order Hall response, focusing on the Berry curvature dipole, which may arise in inversion symmetry broken systems. The theoretical framework also reveals the impact of disorder scattering effects on the nonlinear response. We further discuss the possibility of obtaining nonlinear Hall responses beyond the second order. We examine symmetry-based indicators essential for the manifestation of nonlinear Hall effects in time-reversal symmetric crystals, setting the stage for a detailed exploration of theoretical models and candidate materials predicted to exhibit sizable and tunable Berry curvature dipole. We summarize groundbreaking experimental reports on measuring both intrinsic and extrinsic nonlinear Hall effects across diverse material classes. Finally, we highlight some of the other intriguing nonlinear effects, including nonlinear planar Hall, nonlinear anomalous Hall, and nonlinear spin and valley Hall effects. We conclude with an outlook on pivotal open questions and challenges, marking the trajectory of this rapidly evolving field.

Highly transparent and flexible amorphous Sn-doped In₂O₃ (a-ITO) films deposited on flexible and bio-compatible cyclic olefin polymer (COP) substrate using a direct-current magnetron sputtering at room temperature were used as flexible and transparent electrodes for transparent wearable sensors. The figure of merits (FoM) value was calculated to determine the optimal sputtering process for the a-ITO electrodes by varying the direct current power, working pressure, oxygen flow rate, and a-ITO thickness. The optimized a-ITO/COP with a high FoM value of 8.9 exhibited a low sheet resistance of 36 Ohm/square, average transmittances of 89.5 % in the visible wavelength region, and a small critical bending radius of 7 mm, which are acceptable transparent electrodes for fabrication of wearable and transparent wearable sensors. To demonstrate the feasibility of the a-ITO/COP substrate as a promising wearable sensor, we examined the performance of wearable temperature sensors, wearable heaters, and wearable glucose sensors. The successful operation of a-ITO/COP-based temperature sensors with high sensitivity, transparent heaters with a saturation temperature of 87.8 °C at 6 V, and glucose sensors with high sensitivity indicates that a-ITO/COP is a promising bio-compatible electrode for next-generation wearable bionic electronics.

ZnO nanotetrapods (ZnO NTs) with a non-centrosymmetric crystal structure consisting of four 1-D arms interconnected together through a central crystalline core, introduce interesting piezoelectric semiconducting responses in nanorods in the bent state. Considering the widespread applications of nanotetrapods in semiconductor devices, it becomes very crucial to establish a coupled model based on piezoelectric and piezotronic effects to investigate the carrier transport mechanism, which is being reported here in detail for the first time. In this work, we established a multiphysics coupled model of stress-regulated charge carrier transport by the finite element method (FEM), which considers the full account of the wurtzite (WZ) and zinc blende (ZB) regions as well as the spontaneous polarization dependence and the dependence of the material properties on the arm orientation. It is discovered that the forward gain of ZnO NT in the lateral force working mode is almost 50 % higher than that in the nanorod or in the normal force working mode while the reverse current is reduced to negligible. Through the simulation calculations and corresponding analysis, it is confirmed that the developed piezoelectric polarization charges are able to regulate the transport and distribution of carriers in ZnO crystal, which lays a theoretical foundation for the application of piezo-semiconductive ZnO NT devices in advanced technologies.

Perovskites have emerged as a promising new generation of photovoltaic conversion materials, gradually surpassing traditional silicon-based materials in solar cell research. This development is primarily due to their superior power-conversion efficiency (PCE), simple fabrication process, and cost-effective production. However, the low stability of perovskite ionic crystals poses a significant challenge to their stability, hindering the progress of perovskite materials and devices. Although two-dimensional (2D) perovskites offer improved stability, adding organic amine ions results in a quantum confinement effect that reduces the optoelectronic performance of devices. To counter this issue, the strategic design of suitable spacer cations offers a potential solution. Aromatic amine ions possess greater polarity and structural adjustability compared to aliphatic amine ions, making them advantageous in mitigating the quantum confinement effect. This review focuses on phenylethylammonium (PEA) as a representative aromatic spacer cation. It categorizes the evolution of these cations into four trajectories: alkyl chain modification, substitution of hydrogen atoms on the aromatic ring with specific substituents, replacement of benzene rings with aromatic heterocycles, and utilization of multiple aromatic rings instead of a monoaromatic ring. The structure, properties, and corresponding device performance of aromatic spacer cations utilized in reported 2D perovskites are discussed, followed by the presentation of a series of factors for selecting and designing aromatic amine ions for future development.

Neuromorphic electronics has received increased attention for their application in brain-inspired computing and artificial sensorimotor nerves. Metal halide perovskite (MHP) has been proved to be a candidate material for use in optoelectronic neuromorphic devices. Herein, we review on the recent research progress of MHP materials, with the focus on their applications in neuromorphic optoelectronics. First, we review on the MHP materials that are used for optoelectronic devices especially for neuromorphic applications, in the sequence of all-inorganic, organic-inorganic hybrid and lead-free MHP materials. Then, we summarize the design and fabrication of two-terminal (2-T) and three-terminal (3-T) synaptic devices, including working mechanisms as operated by electrical and light inputs, and the relationship between electrical properties with material composition and structure of functional layers. Finally, we review on the applications of these devices on pattern recognition, bionic vision, neuromorphic sensing and modulation, experience and associative learning, logic computing and high-pass filtering. This review aims could potentially inspire future research in the field of neuromorphic optoelectronic electronics.

The integration of rectifying effects with resistance switching in a self-rectifying memristor offers the opportunity to suppress the sneak current in high-density crossbar arrays for energy-efficient neuromorphic computing. Here, we report a new type of two-terminal self-rectifying memristor that gets rid of asymmetric complex structures by using CsPbBr₃ perovskite nanocrystals (NCs). The simple metal-insulator-metal (Au/CsPbBr₃ NCs/Au) configuration that eases integration exhibits multiple resistance states that can be precisely controlled by the stimulus properties and dynamical rectifying characteristics dependent on both the bias voltage and bias time. We have extended an earlier proposed theory that predicts electric-potential-distribution-controlled rectification to rationalize all the observed rectifying behavior that are regulated by mobile-ion-induced interfacial electrochemical reactions and found excellent agreement between theory and experiments. Our study thus demonstrates the possibility of constructing controllable self-rectifying memristors without involving asymmetric complex structures, paving a new way for resolving the sneak current issue in crossbar arrays of memristors.