Multilayer Self‐Limiting Electrospray Deposition via Stepped Voltage Bias

The self‐limiting regime of electrospray deposition (SLED) is a highly adaptable means to coat complex 3D architectures and 2D templated surfaces. There are, however, drawbacks to this approach, including that (1) SLED coatings cannot be applied in multiple layers and (2) the generally micron‐scale thickness of SLED coatings is determined by the material and spray parameters, preventing nanoscale coatings such as those possible by atomic layer deposition or spin coating. This latter limitation can be circumvented by applying a secondary bias to the spray target, which reduces the SLED thickness and increases uniformity. Here, we demonstrate that the stepwise removal of bias can, in turn, result in the stepwise increase of the SLED thickness. We thereby demonstrate (i) tri‐layer polystyrene stacks with bias‐controlled thickness, (ii) uniform tri‐layer coatings on a complex geometry, and (iii) a mechanically robust nanocomposite using thermal capillary rise infiltration (CaRI) of electrosprayed bilayer films.