Carbon Dot-Functionalized Colloidal Particles for Patterning and Controllable Layer-Structured Photonic Crystals Construction

The cracked morphology and iridescent properties of photonic crystal (PC) films have greatly limited their applications in the field of color pigments and optical instruments. Herein, we fabricated crack-free PC films with a controllable microscopic ordered structure by functionalizing carbon dots (CDs) onto poly(styrene-methyl methacylate-acrylic acid) (P(S-MMA-AA)) particles, enhancing the structural color contrast and saturation. Using the third-generation polyamidoamine (G3-PAMAM) dendrimer as a bridge, the CDs are coupled onto the P(S-MMA-AA) particles through the terminal amino groups of G3-PAMAM. The hydrogen bonds, derived from the grafted G3-PAMAM and CDs, effectively counteract the tensile stress of particle shrinkage during evaporation self-assembly, thereby enabling the formation of high-performance PC films. Moreover, due to the light absorption capacity and nanoscale effect of CDs, the CDs/P(S-MMA-AA) particles could be constructed to form robust PC films without the iridescence effect and effectively suppress the coffee-ring effect, which are developed to the colloidal PC ink for direct writing and patterning. Eventually, based on the Langmuir-Blodgett (LB) method, the CDs/P(S-MMA-AA) PC films with a controllable layer-structure are constructed, achieving the structural color regulation, which is expected to be applied to the design of smart windows.