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Metal mesh transparent electrodes present a promising alternative to Indium-Tin Oxide (ITO) due to their adjustable period and favourable trade-off between transmittance and conductivity. In this work, a template-free, non-high temperature hybrid additive manufacturing approach of the polyacrylonitrile (PAN)/Cu core--shell structure high-resolution metal mesh flexible transparent electrode (FTE) is proposed. The electric field-driven (EFD) 3D printing method was employed to print ultra-fine lines with widths as low as 1 μm. The composite-plating process combining electroless plating and electroplating has solved the structural defects of single deposition process. The prepared FTE has an excellent conductivity down to 1 Ω/sq and 89% light transmission (at 550 nm). Its exceptional mechanical properties and environmental stability make it suitable for diverse working environments. Even after undergoing 2000 bends at a radius of 3 mm, the resistance change rate remains as low as 1.4%. The resistance exhibits an approximately 8% change rate in the acid--base environment experiments conducted over 72 h. The flexible touch screen prepared with this FTE exhibits excellent writing performance in both flat and curved working scenarios. Furthermore, the significant potential of this FTE in the field of optoelectronics is effectively demonstrated through its exceptional luminescent performance in electroluminescent devices. [ABSTRACT FROM AUTHOR]

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 (Rs) 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. [ABSTRACT FROM AUTHOR]

Flexible transparent electrodes are widely used in flexible displays, optoelectronic devices, flexible heating/electromagnetic shielding devices, and flexible sensors. However, significant challenges remain to obtain stable service under harsh environments, owing to the limitations of flexible transparent substrates and conductive materials. Herein, a simple and cost‐effective fabrication approach for harsh‐environment flexible transparent electrodes (HFTEs) is demonstrated via the electric field‐driven microscale 3D printing of a silver mesh on a colorless polyimide (CPI) substrate. Vertical jet orientation on the CPI substrate is realized by controlling the printing parameters, which effectively reduce the instability of the cone jet and is conducive to the preparation of the high‐precision silver mesh on the CPI substrate. The HFTE exhibits good optoelectronic properties (resistance of 4.82 Ω sq−1 and transmittance of 92.26%), and excellent extreme environmental stability with a negligible increase in sheet resistance under various cyclic tests (200 000 bending cycles, 100 adhesion tests, high temperature heating capacity of 360 °C, 80 h of chemical attack, and 120 days of atmospheric environment attack). Baking of quail eggs and deicing experiments are also conducted, which successfully demonstrate the practical viability of the HFTE. Thus, the proposed technique offers a simple and efficient solution for the manufacturing of HFTEs. [ABSTRACT FROM AUTHOR]

• Presented a process for 3D printing of high quality, and pure Copper interconnects. • Investigated the thermal stability of the printed metal microstructures. • An upper bound limit of 300 °C was identified using SEM/FIB and in situ SEM micro-compression experiment. Micro/nanoscale 3D printing of metals is promising for printed electronics and sensors. It is important to evaluate how material properties of the microscale 3D-printed metals change at high temperature, though such studies are currently very limited. Here, we investigate morphological and mechanical property changes in copper interconnects 3D-printed by pulsed electrodeposition process. The results revealed significant surface damage and void formation in printed Cu after annealing at 450 °C. No significant surface damages or voids were observed for printed Cu annealed at 300 °C, however, their strength dropped ~40% from the strength of the as-deposited material (~868 MPa). Such results are important to determine the operation temperature range for interconnects fabricated by microscale 3D printing. [ABSTRACT FROM AUTHOR]