Fig. 1: Engineering and elucidation of flexible CBCN with circularly polarized luminescence.

a Concept and design of the CBCN composed of OHM and SLG. b Schematic image of the covalent bonding interface, generating a network topological structure. c Fabrication process of the CBCN, including two stages: I formation of OHM; II polymerization of the luminescent precursor with the surface of OHM. d Photographs showcasing the CBCN with different color emissions. Scale bar, 1 cm. e 3D-reconstruction images of the CBCN, viewed from the front (the left) and side (the right) directions. Scale bars, 150 μm. f Cross-sectional SEM image of the CBCN, showing a tightly bound interface. Scale bar, 10 μm. g FTIR spectra of the CBCN, demonstrating the formation of covalent bonds through the olefinic bonds disappearance of OHM and luminescent precursor. h Mechanical characterization of the CBCN-based film: the upper photographs illustrates its flexibility, while the lower graph depictes the tensile test result. Scale bar, 1 cm. i Simulated strain distribution within the CBCN model (top) and a physical-stacking bilayer model (bottom) conducted via finite element analysis. The models consist of a OHM layer and a SLG layer. Applying 50% strain to the OHM layer, the SLG will generate 50% strain in the CBCN model while failing to achieve in the physically stacked bilayer model, demonstrating the mechanical compliance and robust interface of CBCN.