text. Here is reported a printing technology that enables the functionalization of photoconducting materials with an arbitrary user-defined pattern of nanocrystals. Two sets of information can be encoded into the same unit area; control over the polyhedral shape of individual nanocrystals and high lateral resolution (micrometre scale) for large 2D patterns (millimetre scale) of Cu2O that were grown over unstructured amorphous silicon. Key to this new technology is a parallel modulation of both the electrode kinetics at the silicon/electrolyte interface as well as the light-assisted control of adsorption of halide ions on the growing Cu2O particles. This is achieved using local pixelation of a visible light stimuli by means of adapting to the field of photoelectrochemistry the instrumental tools for spatial light modulation more often used in super resolution microscopy. Any user-defined pattern (i.e., any arbitrary bitmap image file or a sequence of images) is converted within seconds into an array of nanoparticles. The process does not rely on the use of physical masks Received: ((will be filled in by the editorial staff)) Revised: ((will be filled in by the editorial staff))