Flexible Transparent Conductors Research Articles

Molybdenum doped indium oxide thin films grown on mica substrates with high near-infrared transparency and electron mobility for flexible optoelectronic and spintronic applications

In the era of the artificial intelligence, flexible multifunctional films that combine optical transparency, electrical conductivity, and ferromagnetism are highly beneficial for many advanced applications. Herein, we fabricated a flexible magnetic transparent conductor molybdenum doped indium oxide (IMoO) thin film on a mica substrate using a pulsed laser deposition (PLD) technique. The valence states of Mo dopants were determined to be Mo4+ and Mo6+ by X-ray photoelectron spectroscopy (XPS) analysis. From the measured optical transmittance spectrum, average visible (Vis) and near-infrared (NIR) transmittance (Tave_Vis and Tave_NIR) values in IMoO film are calculated to be 85.9 % and 85.4 %, respectively. The IMoO film shows an electron mobility (μe) of around 113 cm2 V−1 s−1 and a sheet resistance (Rs) of 69 Ω. We illustrate the benefits of Mo doping, which leads to increased NIR transparency and μe compared to commercially available tin-doped indium oxide (ITO). On the other hand, the IMoO film shows clear magnetic hysteretic behaviors at room temperature, indicating the presence of ferromagnetism. The main origin of the ferromagnetism is presumably attributed to the Mo4+ ions with an electronic configuration of 4 d2. Bending cyclic tests reveal favourable mechanical durability and bending stability in the IMoO/mica films. Our systematic investigation demonstrates that IMoO film possesses a superior optoelectronic performance beyond ITO, Mn-doped indium oxide (IMnO), and Sn-Mn-codoped indium oxide (ITMnO), substantiating the potential of the IMoO/mica film as a high-performance transparent conductive magnetic material for flexible optoelectronic and spintronic applications.

Flexible, transparent and conductive wearable electronic skin based on 2D titanium carbide (MXene) ink

Flexible and transparent conductors are essentially required in epidermal wearable devices such as electronic-skins (E-skins) that facilitate human interaction and biofeedback. However, due to the “trade-off” effect between high electrical conductivity and optical transparency, it is difficult to obtain transparent E-skins with high electrical conductivity. Furthermore, traditional transparent conductor is bulky and brittle which is not suitable for flexible and wearable applications. Herein, ultrathin two-dimensional (2D) titanium carbide (MXene) nanosheets with metallic conductivity, hydrophilic surface and excellent mechanical flexibility was proposed as a novel high-performance transparent conductor, which was further developed as wearable E-skins. Solution-processable MXene conductive ink was obtained by facilely etching Al from MAX phase for large-scale spray coating to obtain flexible transparent conductors. The flexible, transparent, and conductive MXene-based electrodes own a sheet resistance as low as 200 Ω/sq, while with high optical transparency of 60% @550 nm, which is sufficient for the applications of E-skins. Moreover, the transparent MXene-based soft E-skins also exhibits outstanding mechanical flexibility which could maintain its high opto-electrical performance even after 1000 cyclic bending tests. In addition, the robust flexible transparent MXene-based E-skins also could accurately identify the movements of human body including approaching, touching and pressing, which is essentially required in various application scenarios such as human-machine interactions, touch panels and healthcare sensors. The solution-processable flexible, transparent and conductive MXene-based E-skins holds tremendous potential in emerging wearable applications.

All-inorganic flexible epitaxial SrNbO3/mica thin films with ultrahigh figure of merit as indium-free transparent conductors

Nowadays, flexible transparent conductors (TCs) have been widely applied for solar cells, stretchable integrated circuits, sensor networks, and human-machine interaction devices. Recently, nondoped correlated metallic oxides (CMOs) have aroused great interest as indium-free TCs. In this work, an all-inorganic flexible CMO thin film with an ultrahigh figure of merit (FOM) value was fabricated using a simple preparation technology: the direct deposition of epitaxial SrNbO3 thin films on a stratiform mica substrate via a pulsed laser deposition (PLD) process. From the measured optical transmittance (Tr) spectra in conjunction with the ellipsometic data, it is found that SrNbO3 film possesses a superior visible light transparency compared with commonly investigated SrVO3 due to its larger bandgap. The charge transport measurements indicate that the dc electrical conductivity (σ) of SrNbO3 is higher than that of SrVO3, attributed presumably to a weaker electron correlation and therefore a smaller effective electron mass (m*) in SrNbO3. Bending cyclic tests reveals high mechanical durability and bending stability in SrNbO3 films. This detailed investigation demonstrates a great potential of the all-inorganic flexible epitaxial SrNbO3/mica film as an indium-free TC with high performance for future optoelectronic applications.

Ag-Doped Free-Standing 2D TiO2 Sheets: Electronic, Optical, Magnetic, and Self-Healing Behaviour.

Beyond a critical doping level, Ag - 2D TiO2 sheets (ATO) are deemed to be a flexible transparent conductor, useful for visible-range functional photonic/optoelectronic devices/sensors, sunlight-sensitive catalysis, and light-activated resistive switching. Due to the lack of control of surface energy which often leads to the formation of structural defects and even dimensionality crossover (2D to 0D) of materials during doping reaction, it is challenging to obtain ATO with a controlled doping level. Gauging the urgency, therefore we report the surface energy-controlled synthesis of ATO employing liquid phase exfoliation of TiO2 and subsequent hydrothermal Ag-doping in the presence of Hexamethylenetetramine (HMTA). Electron microscopy and atomic force microscopy reveal ATO sheets with large lateral dimensions. 6-fold, 4-fold, and strain-mediated crystallographic phases of 2D ATO have been revealed by high-resolution electron imaging. Successful tuning of the band gap down to ~ 2 eV with Ag doping up to ~ 10% is obtained. Synthesized 2D ATO have been investigated for their electrical, optical, optoelectronic, photoluminescence, and ferromagnetic behaviour. Visible light-sensitive thermally/structurally robust semiconductor/conductor via tuneable doping will pave the way for their flexible as well as wearable device applications. Self-healing effect of AFM tip-generated mechanical stress has also been demonstrated.

Bio‐Inspired Differential Capillary Migration of Aqueous Liquid Metal Ink for Rapid Fabrication of High‐Precision Monolayer and Multilayer Circuits

AbstractManipulating liquid metal inks to create conductive microstructures has attracted widespread interest as liquid metal microstructures are turning into influential components in flexible electronics. However, it is challenging to prevent the issues with low precision, low efficiency, and residue caused by sedimentation, free diffusion, and the Marangoni effect. Inspired by the water transport in plants, the wetting‐induced assembly method based on the differential capillary effect for liquid metal ink is created to realize the facile and rapid manufacture of liquid metal conductive microstructures. The single‐micron accuracy circuits with a minimum of ≈4 µm straight lines are fabricated to a centimeter scale. This method can also be extended to the preparation of multilayer circuits (minimum 5 µm through hole). The resulting entirely flexible stretchable circuits make it possible to construct highly stretchable devices, such as flexible transparent conductors and stretching sensors. Transparent conductors exhibit excellent mechanical (maximum ≈750% tensile rupture limit) and optoelectronic properties (the transmittance reaches ≈87% and the sheet resistance is ≈0.5 Ω/□)|making them suitable for optically‐clear electromagnetic shielding. This study offers a fresh and plain approach to solving the assembly problem of liquid metal inks, paving the way for the creation of flexible electronic devices

Optimized optical/electrical/mechanical properties of ultrathin metal films for flexible transparent conductor applications: review [Invited

Transparent conductors are essential for high-performance optoelectronic devices. Recently, ultrathin metal films have received great attention as emerging transparent conductors to replace status quo indium tin oxide (ITO) due to their excellent optoelectrical properties with mechanical flexibility. Understanding an ultrathin metal film's optoelectrical properties with respect to thickness scaling is the prerequisite for the design of high-performance metal film-based transparent conductors. This review paper aims to focus on the evolution of ultrathin metal film’s optical properties as thickness scales. Such evolution of optical properties will be associated with electrical properties by exploring various resistivity scattering models aiming to better understand a film’s intrinsic physical property at an extremely thin scale and provide a guideline for enhancing the film’s intrinsic optoelectrical properties for transparent conductor application. Next, optical design considerations to enhance transparency at visible and near-infrared range are discussed including recent reinforcement learning methods as a potential strategy for transparent conductor design. Then, mechanical flexibility of various ITO-replacement electrodes is discussed as well as the mechanism for the metal film-based transparent conductor's excellent endurance against mechanical stress. Lastly, some of the unique benefits of using a metal film transparent conductor for optoelectronic device application are discussed.

선택적 레이저 소결을 이용한 유연인쇄전자소자 제작

It is necessary to develop a low temperature process that can deposit and pattern metal on a heat sensitive substrate because most flexible printed electronics use high temperature sensitive materials such as plastic. The most commonly used photolithography process is not suitable for flexible printed electronics because the high temperature thermal treatment process and chemicals are not compatible with plastic. Recently research has been actively conducted on a method of minimizing thermal damage to plastic and high-resolution metal patterning by using selective laser sintering after forming a liquid metal nanoparticle thin film without using existing photolithography and vacuum deposition. In this review paper, we explore flexible printed electronics such as flexible thin film transistors and flexible transparent conductors using selective laser sintering of nanomaterials and discuss future development directions.

Biodegradable, Flexible Transparent Ordered Ag NWs Micromesh Conductor for Electrical Heater and Electromagnetic Interference Shielding Applications

Flexible transparent and biodegradable conductors with excellent performance are quite desirable for the development of portable electrical heaters and electromagnetic interference (EMI) shielding. As a promising candidate, electrical homogeneity and stability are required for a silver nanowire (Ag NW) network conductor to increase its reliability and robustness. Herein, an optimally well organized silver nanowire micromesh (Ag NMs) electrode embedded in biodegradable poly(l-lactic acid) (Ag NMs/ePLLA) is prepared without a template by virtue of the coffee-ring effect. The Ag NMs/ePLLA electrode possesses a low sheet resistance variation (<5%), leading to a highly homogeneous temperature distribution and a rapid response time of 6 s with a saturation temperature of 111.8 °C at a low driving voltage of 3 V. Moreover, the Ag NMs/ePLLA film also shows an outstanding EMI shielding efficiency of ∼27.6 dB in X-band with a sheet resistance of ∼10 Ω/sq to prevent electromagnetic radiation pollution and excellent biodegradable properties to avoid pollution by electronic waste. Therefore, the multifunctional portable Ag NMs/ePLLA electrode provides great opportunities in the application fields of thermal management and EMI shielding.

Weathering and Material Characterization of ZTO/Ag/ZTO Coatings on Polyethylene Terephthalate Substrates for the Application of Flexible Transparent Conductors

Flexible transparent conducting coatings have been adopted in many novel optoelectrical devices for energy-related applications. Laminated coatings composed of oxide/metal/oxide (abbreviated as OMO) layers are promising alternative materials to indium tin oxide (ITO). However, the durability and weatherability of free-standing OMO samples—including laminated OMO coatings and polymeric substrates—affects the performance of the related optoelectrical components and devices. It is necessary to study the degradation mechanisms in terms of optoelectrical and mechanical properties through the weathering tests. In this study, we performed indoor accelerated and outdoor weathering tests on commercial OMO samples composed of ZTO/Ag/ZTO coatings on polyethylene terephthalate (PET) substrates. The effects of environmental stressors such as ultraviolet (UV) radiation, elevated temperature, and mechanical bending on the degradation behaviors of OMO samples were investigated. Comprehensive material characterizations including UV–Vis spectroscopy, four-point probing, tensile tests, and Raman spectroscopy were carried out. The OMO coating was robust against the weathering tests, while the PET substrates underwent embrittlement upon long-term weathering. The embrittled PET substrates consequently impaired the mechanical flexibility and bendability of the OMO coatings. The results of this study provide an in-depth understanding of the durability and weatherability of silver-based OMO flexible transparent conductive materials.

Toward flexible X-tronics: Transparent conductors with enhanced room-temperature ferromagnetism using Sn–Mn-codoped In2O3/mica thin films

Herein, flexible transparent conductors (TCs) with enhanced room-temperature ferromagnetism were fabricated via growing an Sn–Mn-codoped In2O3 (ITMO) film on a flexible mica substrate. The ITMO/mica film shows an average transmittance (Ta) of 81.9% in the visible region and a sheet resistance (Rs) of 58 Ω, which are comparable to those of the flexible Sn-doped In2O3 (ITO) and Mn-doped In2O3 (IMO) films in the previous reports. Moreover, the ITMO/mica film exhibits a room-temperature ferromagnetism with a saturation magnetization (Ms) of 29.1 emu/cc and a coercive field (Hc) of 430 Oe. The ferromagnetism in ITMO/mica film is much stronger than that in the previously reported IMO/mica films. The charge transport measurements in conjunction with bending tests indicate that the ITMO/mica film possesses large critical bending strains (ϵcr) and thus a robust mechanical durability. The optical and magnetic properties of the ITMO/mica film are also well maintained during the bending cyclic tests. The demonstration of the flexible multifunctional ITMO/mica films with remarkable performance in various aspects paves a route toward future flexible X-tronics.

Microflow Manipulation by Velocity Field Gradient: Spontaneous Patterning of Silver Nanowires for Tailored Flexible Transparent Conductors (Adv. Mater. Technol. 8/2022)

Microflow Manipulation by Velocity Field Gradient: Spontaneous Patterning of Silver Nanowires for Tailored Flexible Transparent Conductors (Adv. Mater. Technol. 8/2022)

High-Performance Flexible Transparent Electrical Heater Based on a Robust Ordered Ag Nanowire Micromesh Conductor

High-performance electrical heaters with a rapid thermal response, homogeneous temperature distribution, and chemical and mechanical robustness are desirable for inevitable use in various areas such as defrosting windows and wearable thermotherapy. Herein, optimally engineered ordered Ag nanowire micromeshes are partially embedded in poly(ethylene terephthalate) matrix (Ag NMs/ePET) via a facile spray coating and transfer approach for flexible transparent conductor and electrical heater applications, which exhibit a slight sheet resistance variation of less than 5%. The resultant Ag NMs/ePET heater exhibits uniform heat distribution over the entire film and can achieve a saturation temperature of 134 °C with a rapid response time of 5 s under an input voltage of 6 V. In addition, owing to the large-diameter nanowire micromesh structure and the protective effect of PET encapsulation, the flexible transparent Ag NMs/ePET heater presents excellent mechanical and chemical robustness in extreme environments and still maintains a stable heating performance after 5000 repeated bending cycles (r = 5 mm) and exposure to a corrosive solution. This work lays the foundation for improving the electrical heater performance and provides a facile methodology to fabricate a high-performance flexible transparent conducting film for other innovative applications.

Microflow Manipulation by Velocity Field Gradient: Spontaneous Patterning of Silver Nanowires for Tailored Flexible Transparent Conductors

AbstractFlexible transparent conductors (TCs) are the fundamental components for emerging soft optoelectronics because of their excellent optical, electrical, and mechanical properties. These properties are attributed to reasonable alignment of conductive functional nanomaterials, especially 1D inorganic nanowires. Although various patterning technologies are proposed, patterning highly transparent conductors with satisfactory conductivity and flexibility in a facile, scalable, and versatile manner remains an open issue. Here, a directed self‐assembly strategy is presented for patterning silver nanowires (AgNWs) into flexible TCs with a cross‐linked network structure using microflow velocity‐field‐induced alignment at a liquid–solid interface. Under dual‐surface architectonics, the periodically varying internal microflow in the overcoated AgNW suspension facilitates the spontaneous alignment of the AgNWs on the designated regions in a layer‐by‐layer manner, yielding highly ordered AgNW TCs with an ultrahigh transmittance (98.2%), low sheet resistance (29.7 Ω sq−1), and prominent mechanical deformability. The proposed strategy is further applied to fabricate high‐accuracy arbitrary AgNW circuits to realize flexible transparent heaters with adjustable localized heat sources. This is a universal and customizable method for producing functional nanomaterials with hardly any scale or shape limitations in a streamlined fashion and provides great freedom for prototyping and manufacturing high‐performance soft optoelectronics.

Super Flexible Transparent Conducting Oxide‐Free Organic–Inorganic Hybrid Perovskite Solar Cells with 19.01% Efficiency (Active Area = 1 cm2)

Flexible Photovoltaic Devices In article number 2100733, Sang Hyuk Im and co-workers developed super flexible transparent conducting oxide (TCO)-free perovskite solar cells with a single-layered graphene electrode on polydimethylsiloxane substrates with excellent bending stability. By co-doping the graphene/PTAA layers with varying concentrations of Li-TFSI additives, the optoelectronic properties of the TCO-free electrode could be manipulated to optimize charge collection for highly efficient and flexible photovoltaic devices.

Super Flexible Transparent Conducting Oxide‐Free Organic–Inorganic Hybrid Perovskite Solar Cells with 19.01% Efficiency (Active Area = 1 cm2)

Highly efficient organic–inorganic hybrid perovskite solar cells (OIHP‐SCs) are often fabricated on a transparent conducting oxide (TCO) substrate such as indium tin oxide (ITO). However, the presence of TCOs is disadvantageous to the development of flexible OIHP‐SCs due to the brittle nature of ITO which is easily breakable during bending. Herein, a flexible TCO‐free OIHP‐SC is demonstrated by using lithium bis(trifluoromethane)sulfonimide (Li‐TFSI) as a codopant for the single‐layer graphene transparent conducting electrode and poly(triarylamine) hole‐transporting material (HTM) on a flexible polydimethylsiloxane substrate. The optical and electrical properties of the Li‐TFSI‐doped graphene substrate are measured by controlling the doping amount and the best conditions for charge extraction are established at a doping concentration of 20 mm Li‐TFSI, thus optimizing the device photovoltaic performance. As a result, a highest power conversion efficiency of 19.01% is demonstrated by the flexible TCO‐free OIHP‐SC devices with an active area of 1 cm2. In addition, the flexible TCO‐free OIHP‐SCs exhibit good bending stability after 5000 bending cycles at radii of 6, 4, and 2 mm and excellent light soaking stability under 1 Sun light intensity over 1000 h as opposed to the poor stability when using poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate as the HTM.

Highly reliable flexible transparent conductors prepared with Cu/Ni grid by vacuum-free solution process

In this work, Highly reliable and high-performance metal-mesh network transparent conductive film (TCF) is fabricated on flexible substrate by lithography and electroplating without high temperature which combines the advantages of both approaches, exhibiting enhanced adhesion, improved thermostability and reduced resistivity. The Cu/Ni/PEDOT:PSS (CNP) TCF with a sheet resistance of ~0.13 Ω/sq at transmittance of ~86% has a high figure of merit ( FoM ) up to 17,000. The fabricated CNP shows enhanced adhesion to polyethylene terephthalate (PET) substrates, and the sheet resistance does not show great change after the bending test and folding cycle tests, which attributes to the protection of the PEDOT:PSS. Moreover, the CNP film displays excellent stability that the sheet resistance does not show great increase after several months at room temperature and maintain original resistance at high temperature (150 °C). According to Joule heating, a visible transparent heater is fabricated to evaluate the thermal performance of our CNP film, which shows rapid heating at very low voltage. • A simple, low cost and fast preparation method is reported to prepare transparent electrode with excellent performance. • The CNP transparent film has excellent optical electrical properties and a high F value (~17,000). • The sheet resistance almost unchanged at the room temperature for 12 months showing long-term stability.

Assemblies and composites of gold nanostructures for functional devices

AbstractGold has been one of the most vastly used noble metals due to its unique properties. In modern manufacturing, gold is extensively used in electronics industry as electrical connectors due to the high conductivity and corrosion resistance. With advancements in gold chemistry and nanofabrication technologies, gold materials can be tailored down to the dimension of nanoscale, which enables various novel properties. However, it is still a huge challenge to realize practical functional devices by rational utilizing these gold nanostructures‐based materials. Herein, the recent developments in the design and fabrication of various functional devices based on assemblies and composites of gold nanostructures are summarized. Starting from the plasmonic effect, optical colorimetric sensors, optoelectronics and surface‐enhanced Raman spectroscopy sensors are introduced. Followed by conductive devices with novel properties, flexible transparent conductors, stretchable electronics, wearable and implantable devices are discussed. Both bottom‐up and top‐down approaches to prepare assemblies and composites are covered. In addition, the challenges and future developments in the field are also addressed. It is believed that further developments in gold nanostructures‐based materials will greatly contribute to the next‐generation biosensors, optoelectronics, wearable and implantable electronics.

Computational Study of the Curviness Percolation Threshold in Nanotube/Nanowire Networks for Flexible and Transparent Conductors

Two-dimensional (2D) or quasi-2D networks of one-dimensional (1D) nanoelements, such as carbon nanotubes, metal nanowires, and graphene nanoribbons, have attracted significant research interest recently for next-generation flexible and transparent conductors, as a replacement for indium tin oxide (ITO), which suffers from brittleness, scarcity, high cost, and slow deposition. These nanotube/nanowire networks can be used in many device applications, such as touch screens, flat panel displays, solar cells, light-emitting diodes (LEDs), and wearable flexible electronics. They also have applications in thin film transistors and resistive switching memory.At the high optical transmittance values required for flexible and transparent conductors, the electrical properties of nanotube/nanowire networks are governed by percolation transport, which deals with the formation of long-range connectivity in random networks. As a result, Monte Carlo simulations need to be employed to theoretically calculate, predict, and optimize the electrical properties of 1D nanoelement networks [1,2]. In most computational work, nanotubes/nanowires in such networks have been modeled as straight sticks. However, experimentally deposited nanotubes/nanowires exhibit some degree of curviness.There has been some computational work on the density percolation threshold of carbon nanotube/nanofiber networks and nanocomposites at fixed curviness, where the network undergoes an insulator-to-conductor phase transition [3-7]. These studies have shown that curviness increases the density percolation threshold of random networks. However, the curviness percolation threshold at fixed density has not been investigated.In this work, we employ Monte Carlo simulations to compute the curviness percolation threshold in 2D networks consisting of curvy nanotubes or nanowires. We generate curvy nanotubes/nanowires using third order Bezier curves, which are parametric functions specified by the values of four control points. We introduce the concept of the curviness angle, which puts a geometrical constraint on the locations of the two intermediate control points of the Bezier curve, and hence on the statistical distribution of nanotube/nanowire curviness in the network. For a more universal definition of the degree of curviness, we define the curl ratio as the ratio of the actual length of the nanotube/nanowire to the effective straight length between its two ends. Using simulation data, we establish an empirical relationship between curviness angle and curl ratio.We first study the percolation probability as a function of curviness angle at fixed density for randomly distributed nanotube/nanowire networks. We extract the curviness percolation threshold at fixed density characterized by the critical curviness angle and the critical curl ratio using finite size scaling analysis. We find that the critical curviness angle and curl ratio increase with increasing density. We also find that there is a minimum (maximum) density below (above) which the percolation probability is 0 (1) regardless of the curviness angle. Second, we find that nanotube/nanowire alignment significantly changes the curviness percolation threshold, resulting in a reversal of the percolation probability versus curviness angle curve.These results show that nanotube/nanowire curviness plays a significant role in determining the percolation threshold in 2D or quasi-2D networks, films, or nanocomposites consisting of 1D nanoelements. These results further show that computational studies are an essential tool for providing insights into the insulator-to-conductor transition in nanotube/nanowire networks, which are promising candidates for a wide range of applications such as flexible transparent conductors, thin film transistors, and resistive switching memory.[1] N. Fata, S. Mishra, Y. Xue, Y. Wang, J. Hicks, and A. Ural, J. Appl. Phys. 128, 124301 (2020).[2] J. Hicks, J. Li, C. Ying, and A. Ural, J. Appl. Phys. 123, 204309 (2018).[3] Y. B. Yi, L. Berhan, and A. M. Sastry, J. Appl. Phys. 96, 1318 (2004).[4] L. Berhan and A. M. Sastry, Phys. Rev. E 75, 041121 (2007).[5] C. Li and T.-W. Chou, Appl. Phys. Lett. 90, 174108 (2007).[6] Y. Yu, S. Song, Z. Bu, X. Gu, G. Song, and L. Sun, J. Mater. Sci. 48, 5727 (2013).[7] H. M. Ma, X.-L. Gao, and T. B. Tolle, Appl. Phys. Lett. 96, 061910 (2010). Figure 1

All-Solution-Processed Molybdenum Oxide-Encapsulated Silver Nanowire Flexible Transparent Conductors with Improved Conductivity and Adhesion.

A novel transparent conductive conductor composed of a silver nanowire (AgNW) network and MoOx on a flexible polyethylene terephthalate (PET) substrate, with contemporaneously improved adhesion and reduced resistivity, is prepared using the full-solution process without high-temperature annealing. Under the optimized conditions, a MoOx/AgNW/MoOx multilayer is achieved, which shows much superior optoelectronic performance to that obtained from ITO with a high optical transmittance of 89.2% and a low sheet resistance of ∼12.5 Ω/sq. Unlike pure AgNW films, the sheet resistance is little changed after the tape and ultrasonication tests, illustrating a very strong adhesion to the PET substrate after the encapsulation of MoOx. Moreover, the multilayer film exhibits excellent stability to resist mechanical bending and acid damage. In addition, the successful implementation of the flexible transparent heater demonstrates the practical application value of the electrode.

Plasma-treated room temperature synthesized CuCrO2/Au/CuCrO2 on Polyethylene terephthalate: Towards a high-performance flexible p-type transparent conductor

TCO/metal/TCO multilayer structures have been long used to improve the properties of transparent conducting oxides (TCOs). Herein, we investigated the influence of direct current-sputtered gold (Au) sandwiched between two CuCrO2 (CCO) layers deposited by radio frequency-sputtering at room temperature on quartz substrates. We show that this structure has the capability to increase the electrical conductivity significantly while maintaining suitable transparency. The resistivity of our optimized structure was ~28 Ω/sq, and its average transparency in the visible region was around 42%. We also showed that this structure has the capability to be deposited on polyethylene terephthalate (PET) flexible substrates with comparable properties, and plasma-treatment can further improve its features due to surface modification. The results indicate that plasma-treated CCO/Au/CCO multilayer deposited on PET substrates has a promising potential to be used as a flexible and transparent conducting electrode in solar cells and other applications.