High-performance Flexible Transparent Electrodes Research Articles

Overcoming the Tradeoff of Visible Transparency and Electrical Conductance via Dual Smoothing of Dielectric/Metal Interfaces in Cu-Thin-Layer-Based Transparent Electrodes.

The rapid advancement of flexible optoelectronic devices, such as light-emitting diodes, solar cells, and electrochromic devices, necessitates the development of high-performance flexible transparent electrodes (TEs). Dielectric/metal/dielectric (DMD)-type TEs are promising alternatives to conventional indium tin oxide (ITO) due to the high electrical conductance, excellent visible transparency, and sufficient mechanical flexibility. However, the tradeoff between electrical conductance and visible transparency poses a challenge to performance enhancement. This study introduces an Ar-ion-mediated interface modification method to address this tradeoff by dual smoothing of dielectric/metal interfaces in TiOx/Cu/ZnO TEs. Implementing this dual smoothing methodology significantly enhances both electrical conductance and visible light transmittance, achieving a Haacke figure of merit 200% higher than that of an unmodified otherwise identical structure. The highest figure of merit is 0.113 Ω-1, a record high for Cu-thin-layer-based DMD TEs, far surpassing ITO electrode values. Further, the enhanced optoelectronic performance remains highly durable under severe and simultaneous electrical, thermal, and mechanical stresses, showcasing the potential for significant advances in flexible optoelectronics.

Conductive Nanofiber Web Film with Polydimethylsiloxane Sidewalls Selectively Coated through a Plasma Process for High Performance Flexible Transparent Electrodes.

Transparent electrodes are commonly used in various applications, such as solar cells, touch screens, smart windows, wearable electronic devices, and rollable flexible displays. Currently, indium tin oxide (ITO) is widely used as a transparent electrode material. However, ITO is not suitable for next-generation transparent electrodes that require flexibility; therefore, alternative nanomaterials, such as carbon nanotubes, conductive polymers, and metal nanowires, are being studied. However, these nanomaterials have poor mechanical strength and limited substrate availability. In this study, we developed a high-performance transparent electrode web film fabrication process based on conductive nanofibers, in which metal nanofibers are semiembedded in polydimethylsiloxane (PDMS). The mechanical strength of the conductive nanofibers was improved through the PDMS coating on the entire surface of the film, and the semiembedded structure of the nanofibers was realized using the reactive ion etching (RIE) process. In this study, we confirmed through transparency/conductivity analysis and bending, cycle, and taping tests that the transparent electrode fabricated using our approach has excellent mechanical strength and conductivity. Finally, the transparent electrode fabricated using our method can be widely applied as a next-generation transparent electrode because the process is easy and simple and requires inexpensive equipment and materials.

Free-standing ultra-thin film with semi-embedded metal nanofiber web for high-performance flexible transparent electrodes

We develop a novel manufacturing process for freestanding conductive nanofiber web films in which metal nanofibers are semi-embedded in polydimethylsiloxane (PDMS) to realize high-performance flexible transparent electrode films. This concept utilizes a sacrificial layer to induce a very thin, free-standing film, and the semi-embedded structure maintains the nanofiber web structure. The excellent adhesion properties of PDMS as well as improved mechanical strength mean that it can be applied to large area devices. In this study, we demonstrate that our approach has improved mechanical strength and excellent conductivity through transparency/conductivity analysis and bending, cycle, and taping tests.

Fabrication of submicron linewidth silver grid/ionogel hybrid films for highly stable flexible transparent electrodes via asymmetric wettability template-assisted self-assembly

High-performance flexible transparent electrodes are the basis for the continuous upgrading of optoelectronic devices. Silver grids are attractive for replacing traditional indium tin oxide (ITO) as the premier transparent electrode materials, due to their high transmittance, excellent conductivity, and low cost. However, large linewidth and oxidation of silver grids are limiting the practical application of the resulting optoelectronic devices. Here, we report an effective and scalable solution-based method to prepare highly stable flexible transparent silver grid electrodes with submicron linewidth by the asymmetric wettability template-assisted self-assembly of silver nanoparticles (AgNPs), which is then encapsulated by a thin transparent conductive ionogel as protective layer. It is demonstrated that the linewidth of silver grids can be precisely controlled by the concentration of the AgNP dispersion. Wrapping with the ionogel nanolayer have no deterioration for conductivity and transmittance of the grid electrodes. The optimized hybrid grid electrodes exhibit low sheet resistance of 24.6 Ω sq−1 and high transparency of 99%. More importantly, the introduction of the iongel nanolayer endows the hybrid grid electrodes with excellent mechanical flexibility and thermal, electrical, and chemical stability. As a proof of concept demonstration, the submicron linewidth silver grid/ionogel hybrid films are successfully used to fabricate flexible smart windows and transparent touch panel. We envision that this work will shed new light on the development of next-generation optoelectronic applications which need ultrahigh resolution displays.

Ultra-Highly Cross-Aligned AgNWs Network by a Facile Liquid-Bridge Assisted Couette-Flow Solution Process: Toward Mass-Producing High-Performance Flexible Transparent Electrodes

Open AccessCCS ChemistryRESEARCH ARTICLES18 Jan 2023Ultra-Highly Cross-Aligned AgNWs Network by a Facile Liquid-Bridge Assisted Couette-Flow Solution Process: toward Mass-Producing High-Performance Flexible Transparent Electrodes Xiaoxun Li, Lili Meng, Min Zhang, Kejie Zhang, Lei Jiang and Huan Liu Xiaoxun Li Google Scholar More articles by this author , Lili Meng Google Scholar More articles by this author , Min Zhang Google Scholar More articles by this author , Kejie Zhang Google Scholar More articles by this author , Lei Jiang Google Scholar More articles by this author and Huan Liu Google Scholar More articles by this author https://doi.org/10.31635/ccschem.023.202302694 SectionsSupplemental MaterialAboutPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareFacebookTwitterLinked InEmail Cross-aligned silver nanowires (CA-AgNWs), a unique network widely used in flexible transparent electrodes (FTEs), have been well developed using various solution processes. However, these approaches suffered from limitations of both the large alignment deviation and the solution waste, especially in large-area fabrication, which deteriorates the performance of FTEs. Here, we developed a facile liquid-bridge assisted Couette-flow solution shearing approach, which enables aligning AgNWs into a highly ordered horizontal array in a large area (120 cm2). Particularly, the alignment deviation, evaluated by the statistic full width at half-maximum (FWHM), is rather small with a value of ca. 12.6, by several times lower than those made by other solution processes. The fibrous liquid-bridge is responsible for transferring liquid steadily onto the substrate, during which process AgNWs are aligned roughly by the solution shearing. Worthnoting is the following further aligning process under the enhanced shearing force by the Couette-flow. Consequently, the ultra-highly CA-AgNWs network was prepared, leading to a high-performance FTE with high conductivity (7 Ω sq-1), high transparency (93 %), long lifetime (over 180 days), good adhesion-stability (200 times tape test) and good flexibility. Moreover, the strategy is applicable for the mass-production, benefiting for the practical application of high-performance optoelectronic devices. Download figure Download PowerPoint Previous articleNext article FiguresReferencesRelatedDetails Issue AssignmentVolume 0Issue jaPage: 1-32Supporting Information Copyright & Permissions© 2023 Chinese Chemical Society Downloaded 0 times PDF downloadLoading ...

Micro–nano dual-scale embedded graphene/Ag architectures for flexible low-voltage-driven transparent electrothermal films

Micro–nano dual-scale embedded graphene/Ag architectures are designed for fabricating high-performance flexible transparent electrodes, thus realizing low-voltage-driven transparent electrothermal films.

Recent progress in the flexible organic solar cells based on Ag micro/nano-structured transparent electrodes

<p indent="0mm">High-performance flexible transparent electrodes play a decisive role in achieving high-efficiency flexible organic solar cells. Silver micro/nano-structured transparent electrodes, such as Ag-grid and AgNWs, hold great promise as an effective flexible transparent electrode for flexible organic solar cells due to their advantages of high electrical conductivity, high light transmittance, excellent mechanical bending resistance and low cost. In the past ten years, flexible organic solar cells based on silver micro/nano-structured transparent electrodes have achieved significant breakthrough in power conversion efficiency. In this review, we first introduced several different preparation methods of silver micro/nano structures. Next, we summarized the optimization methods for the conductivity of AgNWs films. Then, we summarized the progress of flexible organic solar cells based on silver micro/nano-structured transparent electrodes. Finally, we provided a brief challenge analysis for the developments of flexible organic solar cells based on silver micro/nano-structured transparent electrodes.

PDMS micro-dewy spider-web-like metal nanofiber films for fabrication of high-performance transparent flexible electrode with improved mechanical strength

Research to develop next-generation flexible transparent electrode materials using various nanomaterials is being actively pursued, and nanomaterials with sufficient conductivity and transparency for replacing ITO have been realized. However, because numerous nanomaterials are in contact physically and overlap with each other to form a wide conductive two-dimensional space, the mechanical strength of an electrode film composed of nanomaterials and the adhesion to the substrate are limited significantly. In this study, we develop a new fabrication process for microsized polydimethylsiloxane (PDMS) droplet-coated conductive nanofiber web films to achieve high-performance flexible transparent electrode films. This concept is inspired by the structure of a spider web with dew, and PDMS microdroplets with transparency and elasticity mimicking the dew of a spider web are introduced into the film. These PDMS microdroplets can improve the mechanical strength to maintain the nanofiber web structure, as well as improve adhesion with various substrates and films owing to the excellent adhesive properties of PDMS. In this study, we confirm the superiority of our approach via transparency/conductivity analysis as well as bending, cycle, wind resistance, and immersion tests. Because this approach involves an extremely short process time of less than 5 min as well as inexpensive equipment and materials, it is expected to be widely applied to various next-generation optoelectronic devices such as flexible displays and wearable devices.

Directly Printed Embedded Metal Mesh for Flexible Transparent Electrode via Liquid Substrate Electric-Field-Driven Jet.

Flexible transparent electrodes (FTEs) with embedded metal meshes play an indispensable role in many optoelectronic devices due to their excellent mechanical stability and environmental adaptability. However, low‐cost, simple, efficient, and environmental friendly integrated manufacturing of high‐performance embedded metal meshes remains a huge challenge. Here, a facile and novel fabrication method is proposed for FTEs with an embedded metal mesh via liquid substrateelectric‐field‐driven microscale 3D printing process. This direct printing strategy avoids tedious processes and offers low‐cost and high‐volume production, enabling the fabrication of high‐resolution, high‐aspect ratio embedded metal meshes without sacrificing transparency. The final manufactured FTEs with 80 mm × 80 mm embedded metal mesh offers excellent optoelectronic performance with a sheet resistance (R s) of 6 Ω sq−1 and a transmittance (T) of 85.79%. The embedded metal structure still has excellent mechanical stability and good environmental suitability under different harsh working conditions. The practical feasibility of the FTEs is successfully demonstrated with a thermally driven 4D printing structure and a resistive transparent strain sensor. This method can be used to manufacture large areas with facile, high‐efficiency, low‐cost, and high‐performance FTEs.

Rapid nanowelding of silver nanowires by focused-light-scanning for high-performance flexible transparent electrodes

Silver nanowires (AgNWs) have been considered as one of the most promising flexible transparent electrodes (FTEs) material for next-generation optoelectronic devices. However, the large contact resistance between AgNWs could deteriorate the conductivity of FTEs. In the present work, high-performance AgNWs FTEs were obtained by means of focused-light-scanning (FLS), which could lead to the large-area, rapid and high-quality welding between AgNWs within a short time, forming the reliable and stable AgNWs network. The results of the optoelectronic tests show that after FLS, the sheet resistance of the AgNWs FTEs sharply decreased from 5113 Ω/sq to 7.7 Ω/sq, with maintaining a high transmittance (∼94%). Finally, a high-performance flexible transparent heater was fabricated by using FLS, showing reach a relatively high temperature in a short response time and rapid response at low input voltage. The findings offer an effective pathway to greatly improve the conductivity of AgNWs FTEs.

Transparent Electrodes: Templateless, Plating‐Free Fabrication of Flexible Transparent Electrodes with Embedded Silver Mesh by Electric‐Field‐Driven Microscale 3D Printing and Hybrid Hot Embossing (Adv. Mater. 21/2021)

In article number 2007772, Xiaoyang Zhu, Hongbo Lan, and co-workers develop a maskless, templateless, and plating-free fabrication approach for high-performance flexible transparent electrodes with an embedded silver mesh by combining electric-field-driven microscale 3D printing and hybrid hot-embossing. The fabricated flexible, transparent electrode exhibits excellent photoelectric properties, remarkable mechanical stability, and environmental adaptability.

Wetting-Induced Fabrication of Graphene Hybrid with Conducting Polymers for High-Performance Flexible Transparent Electrodes.

Graphene has attracted extensive attention for the supply of electrically conductive, optically transparent, and mechanical robust electrodes for flexible optoelectrical devices, as an alternative to commercial indium tin oxide, due to its superior mechanical, electrical, and optical properties. However, conventional chemical vapor deposition is impeded by harsh conditions and complicated processes, and it is still a challenge to fabricate high-performance graphene transparent electrode in a facile and scalable solution-processable route. Herein, a wetting-induced scalable solution-processable approach to fabricate graphene hybrid with conductive ionogel and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), i.e., graphene/ionogel@PEDOT:PSS (G/Ionogel@PEDOT:PSS), for high-performance flexible transparent electrode (FTE) is reported, achieving a low sheet resistance of 30 Ω sq-1 and a high transmittance of 88% at 550 nm. The as-fabricated trinary hybrid FTE as both transparent electrode and electrochromic layer is applied to a compact indium tin oxide (ITO)-free three-layered flexible electrochromic device, showing fast switching response, good electrochromic contrast, and reliable stability. Our work enables a scalable solution-processable approach for the generation of graphene-based FTE and functional devices.

High Performance Flexible Transparent Electrode via One‐Step Multifunctional Treatment for Ag Nanonetwork Composites Semi‐Embedded in Low‐Temperature‐Processed Substrate for Highly Performed Organic Photovoltaics

AbstractFor ideal flexible transparent electrodes, the features of good electrical/optical properties, low surface roughness, efficient charge transportation, robust electrical stability under simultaneously continuous operation bias, and mechanical bending are critical. Herein, a flexible transparent electrode fulfilling all these features is demonstrated by silver (Ag) nanonetwork composites semi‐embedded in low‐temperature‐processed colorless polyimide (cPI), which shows a figure of merit over 1000 (5.4 Ω sq−1 sheet resistance and &gt;94% diffused transmission at 550 nm wavelength), extremely smooth topography (&lt;1 nm root‐mean‐square roughness and &lt;3 nm peak‐to‐valley roughness), remarkable bending stability under continuous operation bias, and increased work function favoring the band alignment with typical charge transport layers for efficient devices. These characteristics are attributed to one‐step multifunctional chemical treatment on the composite of Ag nanowires and an example polymer of poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). The strategic one‐step process simultaneously offers selective welding at nanowires cross junctions to form an Ag nanonetwork, and removing polyvinylpyrrolidone surfactant from Ag nanowires and PSS from PEDOT:PSS. The flexible electrode also favors the residue‐free cPI transfer for applications. Flexible organic solar cells (OSCs) made from the electrode achieve an averaged power conversion efficiency of 14.46% (best, 15.12%), which is the best flexible OSCs reported so far.

Realizing Ultrahigh Mechanical Flexibility and >15% Efficiency of Flexible Organic Solar Cells via a "Welding" Flexible Transparent Electrode.

The power conversion efficiencies (PCEs) of flexible organic solar cells (OSCs) still lag behind those of rigid devices and their mechanical stability is unable to meet the needs of flexible electronics at present due to the lack of a high-performance flexible transparent electrode (FTE). Here, a so-called "welding" concept is proposed to design an FTE with tight binding of the upper electrode and the underlying substrate. The upper electrode consisting of solution-processed Al-doped ZnO (AZO) and silver nanowire (AgNW) network is well welded by utilizing the capillary force effect and secondary growth of AZO, leading to a reduction of the AgNWs junction site resistance. Meanwhile, the poly(ethylene terephthalate) is modified by embedding the AgNWs, which are then used to link with the AgNWs in the upper hybrid electrode, thus enhancing the adhesion of the electrode to the substrate. By this welding strategy, critical bottleneck issues relating to the FTEs in terms of optoelectronic and mechanical properties are comprehensively addressed. The single-junction flexible OSCs based on this welded FTE show a high performance, achieving a record high PCE of 15.21%. In addition, the PCEs of the flexible OSCs are less influenced by the device area and display robust bending durability even under extreme test conditions.

A scalable polymer-free method for transferring graphene onto arbitrary surfaces

An efficient and reliable transfer for graphene onto the substrates of interests acts as the crucial bridge between the graphene synthesis and applications. The main reason that this issue has not been fully addressed is the use of a polymer medium to protect the one-atom-thick material during the transfer process. Here we demonstrate a general and scalable method to transfer chemical-vapor-deposited graphene onto arbitrary surfaces without any polymers, which yields the transfer of macroscopically and microscopically clean, continuous and uniform graphene samples onto a wide variety of substrates, as well as the scalable layer-by-layer graphene epitaxial structures. Moreover, the transferred graphene exhibits an overall 100% enhancement in the electrical conductivity compared with the conventional method, so that various high-performance flexible transparent electrodes can be demonstrated. We believe that this new transfer technique will offer the opportunities to the industrialization of next generations of flexible electronics and other graphene-based disruptive technologies.

Breaking 12% efficiency in flexible organic solar cells by using a composite electrode

The performance of flexible organic solar cells (OSCs) significantly relies on the quality of transparent flexible electrode. Here, we used silver nanowires (AgNWs) with various weight ratios to dope high-conductive poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PH1000) to optimize the optical and electronic properties of PH1000 film. A high-quality flexible composite electrode PET/Ag-mesh/PH1000:AgNWs-20 with smooth surface, a low sheet resistance of 6 Ω/sq and a high transmittance of 86% at 550-nm wavelength was obtained by doping 20 wt% AgNWs to PH1000 (PH1000:AgNWs-20). The flexible OSCs based on the PET/Ag-mesh/PH1000:AgNWs-20 electrode delivered a power conversion efficiency (PCE) of 12.07% with an open circuit voltage ( V oc) of 0.826 V, a short-circuit current density ( J sc) of 20.90 mA/cm2 and a fill factor (FF) of 69.87%, which is the highest reported PCE for the flexible indium-tin oxide (ITO)-free OSCs. This work demonstrated that the flexible composite electrodes of PET/Ag-mesh/PH1000:AgNWs are promising alternatives for the conventional PET/ITO electrode, and open a new avenue for developing high-performance flexible transparent electrode for optoelectronic devices.

Entirely solution-processed and template-assisted fabrication of metal grids for flexible transparent electrodes

Photopatterned seamless polymer meshes coated chemically with aluminum are successfully demonstrated as metal grids for high-performance flexible transparent electrodes.

Ultraflexible and High-Performance Multilayer Transparent Electrode Based on ZnO/Ag/CuSCN.

Driven by huge demand for flexible optoelectronic devices, high-performance flexible transparent electrodes are continuously sought. In this work, a flexible multilayer transparent electrode with the structure of ZnO/Ag/CuSCN (ZAC) is engineered, featuring inorganic solution-processed cuprous thiocyanate (CuSCN) as a hole-transport antireflection coating. The ZAC electrode exhibits an average transmittance of 94% (discounting the substrate) in the visible range, a sheet resistance ( Rsh) of 9.7 Ω/sq, a high mechanical flexibility without Rsh variation after bending 10 000 times, a long-term stability of 400 days in ambient environment, and a scalable fabrication process. Moreover, spontaneously formed nanobulges are integrated into ZAC electrode, and light outcoupling is significantly improved. As a result, when applied into super yellow-based flexible organic light-emitting diode, the ZAC electrode provides a high-current efficiency of 23.4 cd/A and excellent device flexibility. These results suggest that multilayer thin films with ingenious material design and engineering can serve as a promising flexible transparent electrode for optoelectronic applications.

Unraveling the solvent induced welding of silver nanowires for high performance flexible transparent electrodes.

A solution processed metal nanowire network is a promising flexible transparent electrode to replace brittle metal oxides for printable optoelectronics applications, but suffers from the issue of pseudo contact between nanowires. Herein, using volatile solvent mists as a powerful "zipper", we demonstrate a simple and rapid method to effectively weld silver nanowires, which dramatically improves the conductivity and robustness of the silver nanowire network based flexible transparent electrodes. We reveal that for a stacked network structure, the unique wedge-shaped nanogaps between the long nanowires and substrate provide a strong capillary force during solvent evaporation, which is much larger than that between zero-dimensional nanoparticles and gives a decisive contribution for nanowire junction welding, and this nanowire-substrate interplay force is positively related to the wettability of the substrate. At the same time, the dissolution-reprecipitation of the capping agent on the silver nanowire surface as the natural adhesive can fix the network on the substrate tightly, which enhances the robustness of the network. Our approach solves two key issues in solution-processed transparent electrodes in one simple step, and is compatible with various mild solution-processed optoelectronic devices, especially those containing heat-sensitive or chemical-sensitive materials. Moreover, a new type of invisible infrared encryption display is demonstrated based on this approach.

New approach for fabricating hybrid-structured metal mesh films for flexible transparent electrodes by the combination of electrospinning and metal deposition

In this study, hybrid-structured metal mesh (HMM) films as potential flexible transparent electrodes, composed of aligned micro-sized metal fibers integrated into random network of metal nanofibers, were fabricated by the combination of electrospinning and metal deposition. These naturally fiber-bridged HMMs, with a gold layer thickness of 85 nm, exhibited a high transmittance of around 90% and a sheet resistance of approximately 10 Ω sq−1, as well as favorable mechanical stability under bending stress. These results demonstrate that the approach employed herein is a simple, highly efficient, and facile process for fabricating, uniform, interconnected fiber networks with potential for producing high-performance flexible transparent electrodes.