Anisotropic Excitation‐Modulated Multi‐Color Three‐photon Excited Luminescence in Ln‐MOF Heterostructure
Hongjun Li, Yujie Cai, Lin Zhang, Enlai Hu, Jiaojiao Yang, Hai Guo, Yuanjing Cui, Banglin Chen, Guodong Qian
Abstract
Abstract Multi‐photon excited luminescence (MPEL) modulation is of great application value for optoelectronics, especially MPEL with the characteristics of multi‐color emission and optical anisotropy. However, it still suffers from the obstacles in highly‐integrating and orientedly‐assembly of various MPEL units. Herein, a hierarchical assembly‐in situ doping strategy is proposed to establish a novel lanthanide‐graded metal‐organic framework based heterostructure. Well‐designed ligand and Ln 3+ ions are respectively selected as the MPEL energy donor and acceptor units (MEDU and MEAU). Through utilizing the effective energy transfer between them, the as‐obtained triblock heterostructure displays multi‐dimensional three‐photon excited luminescence (3PEL) modulation, where the emission band and intensity can be switched by manipulating excited regions and excitation polarization based on a single pump source. This is attributed to the precise integration and orientation of photonic units. As a result, the heterostructure exhibits multi‐color 3PEL with a record‐high MPEL color gamut (>30% of sRGB area) in MOFs and high degree of linear polarization values (max ≈88.6%). Such anisotropic 3PEL modulation shows promising potential in nonlinear optical switches, programmable logic gates, and multi‐level optical barcodes. These findings open up an intriguing way to develop up‐conversion luminescent materials with functions on demand toward photonic modulation.