In Situ Coordinative Ligand Displacement Creates Electron Channels for Highly Photostable Carbon-Based Phosphors

Abstract

The practical application of carbon quantum dots (CQDs) as superior carbon-based phosphors in light-emitting devices is severely hindered by their photodegradation, which originates from photochemical free radicals generated by the accumulation of redundant photogenerated electrons. Metal–organic frameworks (MOFs) can offer abundant electron-withdrawing metal nodes that can serve as perfect acceptors to capture these harmful electrons for a nonrecombination transfer pathway. The construction of electron transfer channels between CQDs and MOFs can fundamentally inhibit the generation of photochemical radicals. A size match between the MOF pores and the diameter of CQDs is a prerequisite for establishing the high-speed electron transfer pathway. In this study, we propose an in situ coordinative ligand displacement strategy, in which CQDs serve as ligand units to partially displace multifunctional organic ligands within the MOF structure. Through the in situ reaction, the Zr–O–C bond between UiO-66 and CQDs creates a high-speed electron transfer channel to partially transfer electrons (lifetime: 2.98 ns), thereby inhibiting the generation of photochemical free radicals. The resulting CQDs@UiO-66 exhibits antiphotodegradation ability (120 h UV aging, retaining 85% intensity). This work provides a strategy to inhibit photochemical free radicals, thereby enabling the development of carbon-based phosphors with antiphotodegradation ability and high photostability.