Advancing the Pareto front using a self-driving laboratory

Self-driving laboratories present the opportunity to accelerate the discovery and optimization of materials. A major challenge associated with this optimization process is that useful materials must satisfy multiple objectives, where the optimization of one objective is often at the expense of another. The Pareto front reports the optimized trade-offs between competing objectives. Here we report a self-driving laboratory, "Ada", that defines the Pareto front of conductivities and processing temperatures for palladium films formed by combustion synthesis using various oxidants and fuels. Ada successfully identified previously untested synthesis conditions that resulted in the discovery of lower processing temperatures (190 {\deg}C) relative to the previous state of the art (250 {\deg}C), a temperature difference that makes the coating of different commodity plastic materials possible (e.g., Nafion, polyethersulfone, polyethylene naphthalate). These conditions enabled us to use combustion synthesis to spray coat uniform palladium films with conductivities approaching those of sputtered films. This work shows how self-driving laboratories can discover materials satisfying multiple objectives.