Assembling ultra-thick and crack-free colloidal crystals via an isothermal heating evaporation induced self-assembly method

Ultra-thick and crack-free colloidal crystals have many advantages in a number of existing and emerging applications. In this work, such systems are fabricated by a simple and reproducible method based on assembly of monodisperse silica particles by a crystalline layer assembly technique (CLAT). We find that high quality of colloidal crystals is obtained by using two simple processes: sintering of silica particles and thermal treatment of colloidal crystals. The crack-free colloidal crystal with a thickness of 100 μm is fabricated. The morphologies and microstructures of colloidal crystals are identified by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The reflection spectra are measured by UV-VIS spectrum measurement. The reflection spectra of the colloidal crystal with different thicknesses are calculated by using multiple scattering methods. When the thickness of the colloidal crystal is smaller than 60 μm, the reflection spectra of experimental measurements agree very well with that of theoretical calculations.