Polarized Emission of Lanthanide Metal–Organic Framework (Ln‐MOF) Crystals for High‐Capacity Photonic Barcodes

Abstract Photonic barcodes hold great promise for applications in information storage and data encryption. However, the spectroscopic encoding of lanthanide‐based photonic barcodes reported thus far is exclusively manipulated by sophisticated external stimuli or spatially resolved lanthanide heterostructures, and still suffers from small coding space and low coding capacity. Herein, a facile approach to design high‐capacity photonic barcodes through manipulating the polarized emission of Eu³⁺ metal–organic framework is proposed. Thanks to the highly anisotropic crystal structure and low‐symmetry energy level splitting of Eu³⁺, the large degree of polarization (≈0.96) enables not only color‐tunable emission but also abundant well‐resolved sub‐barcodes. Such polarization‐sensitive emission of the crystals provides a smart encoding strategy to realize polarization‐covert sub‐barcodes, which can be further integrated into a large coding library of photonic barcodes toward high‐capacity data storage and advanced anti‐counterfeiting applications.