On the grain boundary charge transport in p-type polycrystalline nanoribbon transistors.

Grain boundaries (GB) profoundly influence charge transport, and their localized potential barrier with a high density of defect states plays a crucial role in polycrystalline materials. There are a couple of models to estimate the density of states (DoS) of nanostructured materials in field-effect transistors (FETs) that probe interface traps between the semiconductor and dielectric but not at the grain boundaries. Here, we report on utilizing Levinson's and Seto's models of grain boundary transport and correlate them with the temperature-dependent hopping transport in copper iodide (CuI) polycrystalline nanoribbon (PNR) FETs. Experimentally, PNRs are obtained by e-beam lithography and thermal evaporation of CuI. To investigate the impact of GB, the devices are fabricated with different channel aspect ratios by varying widths (80, 260, and 570 nm) and lengths (20 to 90 µm). Owing to the high hole concentration, PNR FETs operate in depletion mode at 300 K. At various low temperatures (80-300 K), the figures-of-merits of FETs are estimated to understand device performance. We determine GB barrier heights, activation energy, and density of GB trap states and find equivalence between the two models. Furthermore, we calculate temperature-dependent hopping and trap-limited transport parameters to obtain DoS at the Fermi energy, trapped and free charge carrier density, localization length, hopping distance, hopping energy, etc. at various channel lengths. Based on this quantitative analysis, we propose a channel length-dependent GB barrier height variation due to the in-plane electric field and elucidate CuI energy band levels.

Self-Sanitization in a Silk Nanofibrous Network for Biodegradable PM0.3 Filters with In Situ Joule Heating.

In the contemporary way of life, face masks are crucial in managing disease transmission and battling air pollution. However, two key challenges, self-sanitization and biodegradation of face masks, need immediate attention, prompting the development of innovative solutions for the future. In this study, we present a novel approach that combines controlled acid hydrolysis and mechanical chopping to synthesize a silk nanofibrous network (SNN) seamlessly integrated with a wearable stainless steel mesh, resulting in the fabrication of self-sanitizable face masks. The distinct architecture of face masks showcases remarkable filtration efficiencies of 91.4, 95.4, and 98.3% for PM0.3, PM0.5, and PM1.0, respectively, while maintaining a comfortable level of breathability (ΔP = 92 Pa). Additionally, the face mask shows that a remarkable thermal resistance of 472 °C cm2 W-1 generates heat spontaneously at low voltage, deactivating Escherichia coli bacteria on the SNN, enabling self-sanitization. The SNN exhibited complete disintegration within the environment in just 10 days, highlighting the remarkable biodegradability of the face mask. The unique advantage of self-sanitization and biodegradation in a face mask filter is simultaneously achieved for the first time, which will open avenues to accomplish environmentally benign next-generation face masks.

Layer-by-Layer Assembly-Based Heterointerfaces for Modulating the Electronic Properties of Ti3C2Tx MXene.

Two-dimensional (2D) transition-metal carbides (MXenes) are emerging as promising materials for a wide range of applications owing to their intriguing electrical, optical, and optoelectronic properties. However, the modulation of metallic Ti3C2Tx MXene electronic properties is the key challenge to fabricate functional nanoelectronic devices. Here, we demonstrate a solution-processable route to fabricate Ti3C2Tx MXene/CuI nanoparticle heterointerfaces by employing a layer-by-layer assembly process. The charge transfer at the heterointerfacial assembly is monitored qualitatively from the quenched photoluminescence emission of CuI. The stable electrical conductivity and consistent Raman spectra of the 3-LBL assembly (three sequential stacks of CuI/MXene) signify the oxidation stability of Ti3C2Tx thin films even after exposure to the ambient environment for 2 months. Furthermore, the 3-LBL assembly exhibited a three-dimensional (3D) variable-range hopping-based electrical conduction in the temperature range 2 ≤ T < 100 K, contrary to the weak localized transport phenomenon in Ti3C2Tx MXene. The difference in charge transport mechanism is supported by distinct magnetoresistance (MR) of the Ti3C2Tx MXene (negative MR, -0.4%) and 3-LBL assembly (positive MR, 1.6%). Therefore, the modulated electrical transport and superior oxidation stability of the Ti3C2Tx MXene in the 3-LBL assembly have the potential to develop next-generation optoelectronic and memory devices.