Dong-Youn Shin

With the rapid expansion of flexible electronics, there is an urgent need for sustainable production methods that enhance device performance while minimizing environmental impact. This work presents an innovative, green approach for fabricating flexible, patterned electrodes via electric field-driven self-organization of conductive fibers onto flexible substrates. By applying high voltage to both the dispensing nozzle and an underlying printed circuit board substrate, the system leverages controlled electric fields to direct fiber jets with precision, eliminating the need for conventional masking techniques. The fiber composition-polyethylene oxide integrated with silver nanoparticles-provides both conductivity and environmental compatibility. This streamlined technique notably reduces material usage, processing time, and chemical waste. Practical demonstrations involve the construction of flexible conductive electrodes for humidity and temperature sensors, achieving a low sheet resistance near 10 Ω sq⁻¹, attesting to the method’s functional viability. The process ensures precise fiber alignment and consistent deposition, paving the way for its integration into flexible sensor and device applications. This study underscores the potential of electric field manipulation to revolutionize coating processes for sustainable and scalable production in flexible electronics.

This study introduces the approach for precisely controlling the trajectory of fluid jets by employing electric field manipulation to confine fiber deposition to specific areas on flexible substrates, particularly within various electronic device applications. Applying similar polar high voltage to both the nozzle tip and printed circuit board generates complementary electric fields, directing the fluid jet to the desired locations on the flexible substrate. This innovative technique eliminates the necessity for traditional masking methods, resulting in reduced ink consumption, streamlined production processes, and minimized chemical waste. To illustrate practical applications, we fabricate flexible conductive electrodes for media façade applications and real-time sensor monitoring, showcasing the effectiveness of integrating Ag nanoparticles into functional electronic components. With an approximate sheet resistance of 10 Ω/sq2, our system adeptly controls Ag nanoparticle deposition within defined areas. This approach not only aligns fibers precisely but also ensures uniform deposition, making it ideal for various flexible applications. Overall, this study underscores the potential of electric field manipulation to revolutionize surface and coating technology, offering a promising avenue for sustainable and efficient manufacturing processes, particularly in flexible applications. The resulting patterned electrodes can be employed in a wide range of flexible electronic devices, contributing to more sustainable and efficient manufacturing processes in the industry.

Low-cost flexible transparent conductive films (TCFs) with direct writing of metal grids have been explored as a promising alternative to conventional indium-tin-oxide-based TCFs for future flexible electronics. However, flexible TCFs have raised technical concerns because of their disadvantages, such as low resolution, low productivity, poor optoelectrical performance, poor thermal stability, and adverse moiré fringes, which primarily arise from the superposition of periodic patterns. Herein, a facile and highly productive method to fabricate moiré-fringeless TCFs with good optoelectrical characteristics and excellent thermal stability is presented using a single-pass printed random serpentine network of medium-field electrospun silver microfibres (AgMFs) with a line width of 2.32 ± 0.97 μm by exploiting the random serpentine motion of medium-field electrospinning, enabling moiré-fringeless TCFs. The electrical in-plane anisotropy of the TCFs can be kept well below 110.44 ± 1.26% with the in situ junction formation of the AgMFs in the transverse direction. Combined thermal and chemical annealing of the AgMFs enables high productivity by reducing the thermal annealing time by 40%. The good optoelectrical performance, fair electrical in-plane anisotropy, high productivity, and superior thermal stability of the TCFs with the single-pass printed random serpentine network of medium-field electrospun AgMFs are suitable properties for flexible electronics such as ultra-large digital signage with LEDs.

The epoch of flexible electronics demands new measures to interconnect electronic components and circuits under mechanical deformations such as bending, rolling, folding, and even stretching. Although liquid metal has been proposed as an alternative to solid‐state solder alloys and conductive adhesives, its corrosive nature rapidly deteriorates the electrical and structural integrity of metallic interconnects and has remained an arduous challenge. A facile solution‐processable method to construct a flexible and electrically conductive diffusion barrier on aluminum electrodes, which are vulnerable to liquid metal, is presented. The stacked layers of graphene oxide (GO) in conjunction with poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) effectively block the diffusion of liquid metal, where PEDOT:PSS serves as an electrically conducting medium to complement the non‐conductive trait of GO, and as an impeding factor together with GO against the diffusion of liquid metal. A fluidic interconnect using liquid metal and aluminum electrodes with the solution‐processed diffusion barrier of the PEDOT:PSS/GO composite exhibits a better electrical contact property than a conventional interconnect. Finally, a novel proof of concept of sliding interconnection is demonstrated by rolling a carbon nanofiber‐coated liquid metal ball on aluminum electrodes coated with the PEDOT:PSS/GO composite, offering a new opportunity beyond flexibility and stretchability.

A shingled silicon photovoltaic (PV) module without busbars on the front side of a solar cell can increase the light-receiving area and provide more power than a conventional PV module. However,...