A self-driving laboratory advances the Pareto front for material properties

Useful materials must satisfy multiple objectives, where the optimization of one objective is often at the expense of another. The Pareto front reports the optimal trade-offs between these conflicting objectives. Here we use a self-driving laboratory, Ada, to define the Pareto front of conductivities and processing temperatures for palladium films formed by combustion synthesis. Ada discovers new synthesis conditions that yield metallic films at lower processing temperatures (below 200 °C) relative to the prior art for this technique (250 °C). This temperature difference makes possible the coating of different commodity plastic materials (e.g., Nafion, polyethersulfone). These combustion synthesis conditions enable us to to spray coat uniform palladium films with moderate conductivity (1.1 × 10⁵ S m^-1) at 191 °C. Spray coating at 226 °C yields films with conductivities (2.0 × 10⁶ S m^-1) comparable to those of sputtered films (2.0 to 5.8 × 10⁶ S m^-1). This work shows how a self-driving laboratoy can discover materials that provide optimal trade-offs between conflicting objectives.