Macroscopic Color Tuning by Selective Excitation of Electric and Magnetic Dipolar Mie‐Scattering of Silicon Nanospheres

ABSTRACT Silicon nanospheres (Si NSs) exhibit vivid structural colors originating from Mie resonances, but the coexistence of electric (ED) and magnetic (MD) dipole modes limits color saturation. Here, macroscopic color tuning of Si NS sub‐monolayers is achieved by selectively exciting the ED and MD modes with a dielectric spacer and a mirror, enabling broad color tuning at a fixed NS diameter. Based on the numerical simulations, Si NS sub‐monolayers with large interparticle separations are formed experimentally on a large‐size substrate made from an aluminum (Al) mirror and a silica (SiO 2 ) spacer by employing a colloidal suspension of polymer‐coated Si NSs as a precursor. Independent control of the ED and MD modes by varying the spacer thickness from 100 nm to 510 nm and nearly pure MD scattering from the system are demonstrated. Wide‐range color tuning is also achieved by varying the spacer thickness while keeping the Si NS size fixed. The colors remain stable for observation angles up to ∼40°, indicating non‐iridescent behavior advantageous for a variety of coloration applications. Finally, bicolor printing on a substrate is performed using single‐size Si NSs by patterning the spacer thickness.