Scientists have synthesized a molecular ink that cures under ambient air below 150 °C and transforms into a highly conductive, corrosion-resistant form of copper. By enlisting smart organic molecules that weave a self-protecting armor during the curing process, this groundbreaking ink may redefine how next-generation flexible electronics and energy systems are made (Science 2026, DOI: 10.1126/science.aed4488).
After sitting submerged in seawater for 6 months, a chemically treated strip of copper remains unchanged (left). That exposure causes an untreated strip of copper to corrode (right). Credit:
Daniela Benites
“Copper is highly conductive, abundant, and far less expensive than silver, but it oxidizes and corrodes easily, which limits its practical use in printable electronics,” says Shenqiang Ren, a materials scientist at the University of Maryland, College Park, and a coauthor of the study. Conventional protective methods such as applying chemically inert coatings, forming surface electron-rich layers, and sintering copper nanoparticles involve processing at high temperatures that render them unsuitable for low-temperature fabrication of modern electronics. They also force a bitter compromise between high electrical conductivity and enduring stability.
To circumvent this problem, Ren and his team developed a specialized molecular ink they call copper-organic matrix. It is composed of copper formate, activating solvents such as 2-amino-2-methylpropanol or diethylene glycol butyl ether, and reductive organic molecules such as dopamine, ascorbic acid, and citric acid. After the ink is formulated and deposited onto a substrate—for example, paper or flexible electronics—it is heated in ambient air at low temperatures, just 100–150 °C. “This allows the copper ink to be printed onto flexible or conventional substrates and processed under relatively mild conditions while still achieving high conductivity and long-term environmental stability,” Ren says.
The organic acids reduce copper formate to metallic copper and then form a protective carbon-based shell around the copper particles. The activating solvents in the ink are responsible for making this reaction possible at such low temperatures—a clear improvement over the alternative of sintering coupled with chemical vapor deposition, which requires a temperature around 600 ºC and an atmosphere of hydrogen and nitrogen.
The ink exhibits shear-thinning behavior, which leads to easy printing, good wettability on diverse substrates, and a long shelf life; it retains over 97% of its initial conductivity after 6 months of ambient storage. The printed copper conductors retain more than 95% of their initial conductivity for more than 1,000 hours at pH 3, more than 200 hours in 10 mM Na2S, and more than 240 hours at 140 °C. In contrast, commercial copper films fail within hours. The printed metal also boasts a notably low electrical resistivity of 8.95 μΩ · cm.
Unyong Jeong, a materials scientist at Pohang University of Science and Technology who was not involved in the study, says in an email that he finds the work “impressive” and the stability under strongly acidic conditions “particularly notable.” He thinks once the mechanism that explains how a thin amorphous carbon layer that imparts thermal and chemical stability is elucidated, “this strategy can be extended to a variety of other corrodible inexpensive metals.”
“The resistivity achieved at low temperatures under ambient conditions is certainly compelling,” says DuPont’s Ajay Virkar, who was not involved in the study. He says he finds the results “both interesting and impressive.” The combination of low-temperature and ambient processing is “particularly attractive,” he says, as it is difficult to achieve both features in copper inks compared with alternatives such as silver inks.
