Combining nanoscale 3D printing with spark ablation to achieve novel nanostructured surfaces for photovoltaic applications

Laser polymerization has emerged as a direct writing technique allowing the fabrication of complex 3D structures with microscale resolution. The technique provides rapid prototyping capabilities for a broad range of applications, but to meet the growing interest in 3D nanoscale structures the resolution limits need to be pushed beyond the 100 nm benchmark, which is challenging in practical implementations. By using a two-photon polymerization process precise structures in the range of 40 to 50 nm can be achieved. Subsequent post-processing of the printed nanostructures by means of plasma etching or pyrolysis opens the possibilities to obtain even smaller 3D structures, only limited by the mechanical properties of the polymerize resist and the geometry. On the other hand, spark ablation recently emerged as a technique capable of preparing reproducibly sized and clean nanoparticles in a cost-effective manner. Here we employ the outcome of combining the abovementioned processes. Spark ablation process was used to decorate the printed 3D surface to yield specific surfaces with metal/metal oxide core-shell nanoparticles. Broad characterization was applied using microscopy (SEM, AFM), mechanical testing (in situ SEM mechanical testing), diffraction analysis (XRD), and electrical characterization (J/V)) before and after the assembly of complete solar cells. Namely, such formations were found to be prosperous for electron transport layers in perovskite solar cells.