Due to its electronic-grade quality and potential for scalability, two-dimensional (2D) MoS2 synthesized by chemical vapor deposition (CVD) has been widely explored for electronic/optoelectronic applications. As 2D MoS2 can be considered a 100% surface, its unique intrinsic properties are inevitably altered by the substrate upon which it is grown. However, systematic studies of substrate-layer interactions in CVD-grown MoS2 are lacking. In this study, we have analyzed built-in strain and charge doping using Raman and photoluminescence spectroscopy in 2D MoS2 grown by CVD on four unique substrates: SiO2/Si, sapphire, Muscovite mica, and hexagonal boron nitride. We observed decreasing strain and charge doping in grown MoS2 as the substrates become less rough and more chemically inert. The possible origin of strain was investigated through atomic force microscopy roughness measurements of the as-grown layer and substrate. Our results provide direction for device optimization through careful selection of the growth substrate and pave the way for further investigations to unravel the complex nature of the 2D monolayer-substrate interface.

Metal nanowire (MNW)‐based transparent electrode technologies have significantly matured over the last decade to become a prominent low‐cost alternative to indium tin oxide (ITO). Beyond reaching the same level of performance as ITO, MNW networks offer additional advantages including flexibility and low materials cost. To facilitate adoption of MNW networks as a replacement to ITO, they must overcome their inherent stability issues while maintaining their properties and cost‐effectiveness. Herein, the fundamental failure mechanisms of MNW networks are discussed in detail. Recent strategies to computationally model MNWs from the nano‐ to macroscale and suggest future work to capture dynamic failure to unravel mechanisms that account for convolution of the failure modes are highlighted. Strategies to characterize MNW network failure in situ and postmortem are also discussed. In addition, recent work about improving the stability of MNW networks via encapsulation is discussed. Lastly, a perspective is given on how to frame the requirements of MNW‐encapsulant hybrids with reference to their target applications, namely: solar cells, transparent film heaters, sensors, and displays. A cost analysis to comment on the feasibility of implementing MNW hybrids is provided, and critical areas to focus on for future work on MNW networks are suggested.

Owing to their high conductivity, transparency, flexibility, and compatibility with solution processes, silver nanowire (AgNW) networks have been widely explored as a promising alternative to indium tin oxide (ITO). However, their susceptibility to corrosion and thermal instability still remain limiting factors for widespread adoption in a range of devices including solar cells, transparent heaters, and light-emitting diodes. In this study, we report a scalable and economically viable process involving electrophoretic deposition (EPD) to fabricate a highly stable hybrid transparent electrode with a sandwich-like structure, where a AgNW network is covered by graphene oxide (GO) films on both sides. The newly developed all solution process allows the conductive transparent film to be transferred to an arbitrary surface after deposition and demonstrates excellent sheet resistance (15 Ω/sq) and tunable transmittance (70–87% at 550 nm). Unlike bare AgNW networks, the hybrid electrode retains its original conductivity under long-term storage at up to 80% relative humidity. This chemical resilience is explained by the absence of silver corrosion products for the AgNW encapsulated by GO as indicated by X-ray photoelectron spectroscopy. In situ voltage ramping and resistance measurements up to 20 V indicate a novel stabilization mechanism enabled by the presence of GO which delays the failure onset and prevents abrupt divergence of the resistance to the megaohm range experienced by bare AgNW networks. The double-sided nature of the GO coating offers combined stability and performance to the AgNW network, which adds unique versatility of our electrodes to be used toward applications that require a wide range of thermal and chemical stabilities.

Controlled design and patterning of layered transition metal dichalcogenides (TMDs) into specific dimensions and geometries hold great potential for next-generation micro/nanoscale electronic applications. Herein we report the large-scale fabrication of MoS 2 ribbons with widths ranging from micro-to nanoscale. We also demonstrate their unique electric and thermal properties introduced by the shape change and defect creation, with particular focus on the performance associated with light-matter interactions. Our theoretical calculation indicates significantly increased absorption and scattering efficiency of the MoS 2 ribbons with decreasing width. As a result, enhanced photocarrier generation ability was detected on their phototransistors with defectmodulated light-response behavior. We further studied the light-induced thermal transport This article is protected by copyright. All rights reserved. 2properties of the MoS 2 ribbons. We observed a decreased thermal conductivity on narrower ribbons, attributed to the defects created during fabrication. We also found that the effect of phonon scattering at ribbon edges on their thermal conductivity is insignificant, and the thermal transport has no obvious dependence on the ribbon direction at such width scale. This study evaluated the prospects for designing and fabricating TMD semiconductors with specific geometries for future optoelectronic applications.

Semitransparent organic solar cells (ST-OSCs) have garnered strong interest for building integrated photovoltaics (PV) and wearable electronics. Although seen as an appealing low-cost PV technology, OSCs suffer from high instability against moisture and gas, which limits their widespread commercialization. A method is proposed to increase significantly the lifetime of inverted ST-OSCs by encapsulating a silver nanowire (AgNW)-based anode with graphene oxide (GO). AgNWs are covered with a GO layer on both sides leading to a sandwich-like structure using only scalable and solution-compatible processes. On one side of the AgNW network, an ultrathin GO layer allows for protecting the AgNWs from the acidic poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) hole transport layer (HTL) underneath without jeopardizing the device energy level alignment and the Ohmic contact between the HTL and the AgNWs. On the other side, a thicker GO layer at the top aims to prevent the AgNWs from degradation because of atmospheric sulfidation. Such double-sided GO encapsulation offers efficient protection to both the AgNW network and the entire device stack. A fivefold increase in the overall device lifetime without additional encapsulation is demonstrated. Cross-linking the PEDOT:PSS layer with (3-glycidyloxypropyl)trimethoxysilane is also found to be essential to preserve the PEDOT:PSS integrity during device fabrication and achieve high fill factors.

Solution-processed silver nanowire (AgNW) networks are promising as next-generation transparent conductive electrodes due to their excellent optoelectronic properties, mechanical flexibility, as well as low material and processing costs. However, AgNWs are prone to thermally induced fragmentation and chemical degradation, necessitating a conformal protective coating typically achieved by low-throughput methods such as sputtering or atomic layer deposition. Herein, we report a facile all-solution-based approach to synthesize a conformally coated AgNW network by nanosized reduced graphene oxide R­(nGO). In this method, probe ultrasonication is used to obtain nanosized GO, which is coated on AgNWs by a layer-by-layer approach and then chemically treated to form R­(nGO)/AgNW. We show that our transparent electrode has excellent transmittance (85–92%) and sheet resistance (17.5 Ω/sq), combined with outstanding thermal and electrothermal stability, thanks to the conformal nature of the R­(nGO) film, and demonstrate its use as a transparent heater with a high maximum temperature. This, in conjunction with improved long-term chemical and mechanical bending stability of R­(nGO)/AgNW, indicates that our newly developed process represents an effective and low-cost strategy to improve the overall operational resilience of metal nanowire-based transparent conductive electrodes.

The application of machine learning to predict materials properties measured by experiments are valuable yet difficult due to the limited amount of experimental data. In this work, we use a multifidelity random forest model to learn the experimental formation enthalpy of materials with prediction accuracy higher than the Perdew−Burke−Ernzerhof (PBE) functional with linear correction, PBEsol, and metageneralized gradient approximation (meta-GGA) functionals (SCAN and r 2 SCAN), and it outperforms the hotly studied deep neural network-based representation learning and transfer learning. We then use the model to calibrate the DFT formation enthalpy in the Materials Project database and discover materials with underestimated stability. The multifidelity model is also used as a data-mining approach to find how DFT deviates from experiments by explaining the model output.

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