Tailored Iridescent Visual Appearance of Self-Assembled Correlated-Disordered Nanostructures

Disorder is often considered the opposite of order, lacking quantitative methods and being difficult to control. Disordered nanostructures can be conveniently prepared by bottom-up approaches, such as self-assembly, but their intrinsic randomness is often considered to lead to unpredictable results, impeding reproducibility and application. Here, we demonstrate that deterministic, angle-dependent visual appearances induced by specific correlated disorder can be achieved through bottom-up approaches, and reveal plenty of room for tailoring color appearance between order and random disorder. Two unprecedented iridescent visual appearances, backscattering iridescence (rainbow-like color transition covering more than five distinct colors at backscattering angles), and specular iridescent halo (gradual color changes in the visible light range around specular reflection direction), are proposed and demonstrated to be induced by correlated disorder at different degrees, which is regulated by interparticle distance. Besides elucidating the mechanism of iridescence generation, a comprehensive protocol for predicting the color appearance is established, and agrees well with experimental results. Combining bottom-up process, materials with low absorption, and tailored spatial disorder, we have endowed solar cells with colorful appearances, while maintaining the performance, which can serve as a solution for photovoltaic-integrated architectures and vehicles. This study advances the understanding of how disorder shapes color and angular appearance, and will find applications in energy photonics, dazzling arts, and anticounterfeiting.