Synergistically Coordinated Ni Complex Ink for Low‐Temperature and Highly Reliable Printed Electronics

Abstract Metal complex inks offer a promising route for particle‐free metal patterning in printed electronics fabrication. However, the development of reliable metal complex inks with low sintering temperatures remains challenging. In this study, a Ni‐based complex ink is developed by coordinating Ni 2+ with both σ‐donor and π‐donor amine ligands. The dual‐ligand strategy effectively lifts the orbital degeneracy of Ni 2+ center, enhances electron transfer, and lowers the pyrolysis temperature from 250 to 180 °C. The formulated Ni–amine complex ink demonstrates excellent printability, long‐term stability, and tunable rheological properties, enabling the formation of high‐performance Ni circuits with fine resolution of 100 µm and high conductivity of 5.8 × 10 6 S m −1 . Furthermore, the low‐temperature‐processable Ni complex ink enables the integration of different functional metals through additive printing, resulting in fully printed thin‐film thermocouple arrays with a broad temperature sensing capability beyond 200 °C and a reliable sensitivity of 27.2 µV K −1 . This study establishes a new methodology for modulating orbital energy level through ligand field engineering, thereby providing a general strategy for the design of transition metal complexes suitable for low‐temperature, additive electronic manufacturing.