Hypothesis: Polymer photonic crystals have drawn a lot of interest due to cost-effective fabrication. Although tremendous efforts are tried, almost no large-size photonic crystal (PC) films can be obtained due to different kinds of reasons. The main issues are the tedious process and strict preparation conditions (like high temperature and solvents), sometimes the limitation of the machinery equipment, accordingly they are not conducive to preparation of subsequent large-scale PC films. Hence, there is an urgent desire to develop a technique that can assemble polymer PC films in a large scale at low temperature without solvent. Experiments: Through semi-continuous emulsion polymerization, core-interlayer-shell (CIS) colloidal particles (PS@PEA@P2EHA) were synthesized with the output of 240 g/h. After the successful production of polymer PC films in the laboratory at room temperature, industrial roll-to-roll process was used for large-scale production of the PC films. Findings: By introducing poly(2-ethylhexyl acrylate) which has quite low glass transition temperature (T-g) into the shell, we have successfully developed an energy-efficient technique for fabrication of large-area (over 100 m(2)) polymer PC films at ambient temperature for the first time. This technique has great potential to promote the industrial application of PC films, such as display, sensors, anti-counterfeiting and so on. (C) 2020 Elsevier Inc. All rights reserved.