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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.

Two-dimensional (2D) perovskite nanosheets have attracted great attention in recent years due to their unique morphological advantages and high qualifications in constructing miniature optoelectronic devices. However, there remains unexplored aspects regarding the structural evolution during spacer decoupling in nanosheet formation and the recoupling process in heterostructure assembly, which limits the understanding of the nanosheet structure-property relationship. Here, based on the advances and limitations of nanosheet preparations, we recommend further optimization of the synthesis method to achieve quality and prosperity for the whole family (including quasi-2D and Dion-Jacobson phases). Due to structural relaxation stem from extreme reduction of thickness, we propose to explore the microstructural evolution of 2D perovskite nanosheets, e.g. through high-resolution microscopy and spring-mass modeling to understand the different lattice arrangements and vibrational modes of nanosheets compared to bulk materials. Finally, we discuss the preparation and application of heterostructures based on 2D perovskite nanosheets and emphasize the structural rearrangement during van der Waals interface assembly in heterostructures. We hope this work will improve researcher's understanding of structure-property relationship of 2D perovskite nanosheets and accelerate research progress in this field.

Two-dimensional (2D) transition metal dichalcogenides (TMDs) with native high-$\kappa$ oxides have presented a new avenue towards the development of next-generation ultra-scaled field-effect transistors (FETs). These materials have been experimentally shown to form a natively compatible oxide layer with a high dielectric constant, which can help scale down both the transistor size and the supply voltage. We present a material and device performance study into the use of several of these materials – namely HfS${}_2$, HfSe${}_2$, ZrS${}_2$, ZrSe${}_2$ – as channels in sub-10 nm FETs. All four materials exhibit isotropic transport at 10 nm channel length with ON currents over 1000 $\mu$A/$\mu$m but show anisotropic transport and degraded ON currents at 5 nm channel length. In general, the sulfide family excels in terms of subthreshold characteristics at sub-10 nm channel lengths. HfS${}_2$, in particular, surpasses all the other materials in terms of ON currents and subthreshold swing (SS), allowing it to also achieve excellent intrinsic performance. We have identified HfS${}_2$ as a superior material within this TMD family for sub-10 nm FETs.

In modern technology, optoelectronics plays a pivotal role, finding applications in diverse areas like solar cells, light-emitting diodes (LEDs), and photodetectors. Perovskite materials, known for their exceptional optical properties, are gaining attraction due to their light weight, flexibility, and ease of production. The expanding markets of wearable electronics and flexible displays have underscored the importance of developing flexible perovskite optoelectronic devices. However, the prevalent use of lead in high-performance perovskite devices poses significant environmental and health risks, casting doubt on their commercial future. This review commences with examining lead hazards, followed by a discussion on how first-principles calculations aid in designing lead-free perovskites. We survey the synthesized lead-free perovskites and explore their properties. The focus then shifts to the latest advancements in flexible optoelectronic devices utilizing lead-free perovskites, including solar cells, LEDs, and near-infrared photodetectors. Additionally, we explore the role of TCAD (Technology Computer-Aided Design) in simulating and optimizing these devices, highlighting its impact on device design and efficiency.

The heterojunction channel architecture has emerged as a viable solution to enhance the performance of metal-oxide thin-film transistors (TFTs), addressing the performance limitations of single-channel counterparts. However, carrier mobility enhancement through a channel thickness design often encounters significant challenges such as the negative threshold voltage (V_th) shift. In this study, we present a cation doping strategy, designed to regulate V_th shift while simultaneously boosting carrier mobility in zinc-tin-oxide (ZTO)-based heterojunction TFTs. A comprehensive investigation of ZTO-based semiconductors was conducted to explore the impact of cation doping on the energy band structure and to find an optimal heterojunction channel structure for high carrier mobility and stability. The resulting ZTO/Ti-doped ZTO (Ti:ZTO) heterojunction TFTs demonstrated a field-effect mobility of 39.7 cm²/Vs, surpassing the performance of ZTO TFTs (16.1 cm²/Vs), with a minimal change in the V_th. Furthermore, the ZTO/Ti:ZTO TFTs exhibited enhanced bias-stress stability compared to the ZTO TFTs. We attribute the improved mobility and stability to the electron accumulation near the oxide channel heterointerface facilitated by band bending and defect passivation effect arising from the Ti:ZTO back-channel layer, respectively.

Heterogenous integration of complex epitaxial oxides onto Si and other target substrates is recently gaining traction. One of the popular methods involves growing a water-soluble and highly reactive sacrificial buffer layer, such as Sr₃Al₂O₆ (SAO), at the interface and a functional oxide on top of this. To improve the versatility of layer transfer techniques, it is desired to utilize stable (less reactive) sacrificial layers without compromising on the transfer rates. In this study, we utilized a combination of chemical vapor deposited (CVD) graphene as a 2D material at the interface and pulsed laser deposited (PLD) water-soluble SrVO₃ (SVO) as a sacrificial buffer layer. We then exploit the well-known enhancement of liquid diffusivities by monolayer graphene to enhance the dissolution rate of SVO over ten times without compromising its atmospheric stability. We demonstrate the versatility of our hybrid- graphene-SVO- template by growing ferroelectric BaTiO₃ (BTO) via PLD and Pb(Zr, Ti)O₃ (PZT) via Chemical Solution Deposition (CSD) technique and transferring them onto the target substrates and establishing their ferroelectric properties. Our hybrid templates allow for the realization of the potential of complex oxides in a plethora of device applications for MEMS, electro-optics, and flexible electronics.

The immediate compelling demand of eco-friendly and portable energy sources for various applications is increasing day by day as the world is moving towards faster technological advancements and industrial revolution. We are surrounded by many gadgets of daily usage which are either needed energy to run them continuously or something to store the energy to make it portable for later use. The invention of battery and continuous research in this field to enhance the electrochemical performance of the existing battery chemistries are hot topics for researchers. Li-ion batteries stood out as the most reliable and suitable device for storing energy. These have applications from small scale such as mobile phone to bigger applications like electric vehicles. Highest theoretical capacity, lightweight, high energy density and many other parameters of Li metal anodes make them attractive choice for the applications which shows lowest electrochemical potential of $-3.04V$ versus standard hydrogen electrode. Storage of more energy, occupying less space and able to deliver better cyclic and rate capability are some prerequisites for the advanced batteries before their usage in bigger applications. Researchers are now trying to find the alternate materials for cathode and anode. The different structural cathode materials are being tested and various anode chemistries have been tried. Silicon additive anodes have the potential to replace the regular graphite anode material because of 10 times larger specific capacity. This paper reviews the anode materials which are currently under research to enhance the performance of Li-ion battery in comparison with the currently commercialized graphite anode. The anode materials reviewed in this paper are categorized based on Li-insertion mechanism as intercalation, alloys, conversion and MOF. The synthesis methods and electrochemical performance are reported and discussed. A comparative study with other metal-ions and metal-air battery is also put forward to make an idea about the efficiency of the material along with the various challenges and future perspective in the development of the anode materials in Li-ion batteries.