Rapid low-temperature, vacuum-free metallization via melted metal spray for electronic and photovoltaic devices

• Introduces a vacuum-free molten-alloy spray strategy for rapid ambient metallization. • Metallic electrode deposition achieved in <10 s with substrate heating below 3 °C. • Specific contact resistivity of 0.43 mΩ·cm 2 to fluorine-doped tin oxide, comparable to evaporated silver. • ≈40× lower energy consumption than vacuum-based silver deposition. This work introduces the Melted Metal Spray (MMS) process, a simple and highly accessible rapid prototyping metallization technique that enables metal deposition under ambient conditions without the need for vacuum systems or elevated temperatures. The MMS method achieves uniform metallic layers in less than 10 s with a minimal thermal load on the substrate (temperature rise < 3 °C) making it highly suitable for thermally sensitive materials . Compared with conventional metallization approaches that rely on high-vacuum or high-temperature environments, MMS offers an environmentally benign, cost-effective and scalable alternative using simple equipment and air operation. The resulting metallic films exhibit electrical performance comparable to thermally evaporated silver , achieving a specific contact resistivity of 0.43 ± 0.11 mΩ·cm 2 at the metal/ fluorine-doped tin oxide (FTO) interface for a ∼100 µm thick layer deposited electrodes. The method’s compatibility with a wide range of substrates , including polymeric supports, enables the fabrication of conductive circuits that maintain functionality under mechanical deformation highlighting its potential for flexible and wearable electronics . Moreover, the successful integration of MMS contacts into perovskite photovoltaic devices demonstrates its feasibility for emerging optoelectronic applications. Overall, MMS represents a promising low power requirements, low-cost, low-temperature, and vacuum-free metallization strategy for next-generation electronic and photovoltaic systems.