Successive Passivation to Red Emissive Perovskite for Enhanced Photostability

ABSTRACT In recent years, perovskite nanocrystals (PNCs), an emerging class of fluorescent materials, exhibit exceptional optical properties. Nevertheless, PNCs (especially red PNCs) are susceptible to structural degradation, phase segregation, and fluorescence wavelength shifts upon ultraviolet light. In this work, we propose a dual passivation strategy using conjugated linoleic acid (CLA) and guanidinium iodide (GAI) to achieve the full‐process photostability of red PNCs. In the early stage of UV irradiation, GAI firmly binds to PNCs via the coordination between N atoms and Pb atoms to ensure the structural stability of PNCs, while the CLA gradually crosslinks and forms a polymer to encapsulate PNCs in the late stage of UV exposure. This sequential passivation approach effectively enhances the stability of PNCs. Finally, by incorporating several types of red PNCs with distinct photostabilities and color changes, a photo‐responsive and dynamic anti‐counterfeiting application is constructed. This work not only expands the passivation strategies for red PNCs, but also provides a new way for advanced anti‐counterfeiting applications.