Carbonized Polymer Dots‐Based Spectrally Adaptable Photonic Microbarcodes

Abstract Carbonized polymer dots (CPDs) are versatile nanomaterials with remarkable optical properties that enable their use in a wide range of photonics applications. CPDs exhibit excitation‐wavelength‐dependent tunable emissions that span the visible to near‐infrared (NIR) spectrum. In this study, whispering‐gallery‐mode (WGM) emission achieved using CPDs‐coated monodisperse polystyrene (PS) microbeads (CPDs@PS) are used to develop wavelength‐adaptable photonic barcodes by leveraging the excitation‐dependent photoluminescence of CPDs. Each resonant emission peak acts as a unique fingerprint of photonics barcodes related to the corresponding microresonator caused by WGM emission. These photonic barcodes can be easily disguised and then authenticated by varying the excitation wavelength. WGM‐based barcodes can exhibit a large number of encoding capacities by adjusting the resonator diameter. Monodisperse CPDs@PS microbeads (3, 4.5, and 6 µm) are used to demonstrate adaptable photonic barcodes, which can improve the readability and reproducibility of spectral patterns for the reliable tagging and identification of commodities. Unlike traditional semiconductor quantum dots or dye‐doped microresonators, this adaptive resonant emission does not require structural or chemical modifications, making it an ideal candidate for multiplexed assays, cell tagging and tracking, anti‐counterfeiting, and for ensuring the integrity and authenticity of products in various high‐value sectors.