Sandwich‐Like Encapsulation of a Highly Luminescent Copper(I) Complex

A small molecular weight cationic copper(I) complex showing high luminescence quantum yield based on a thermally activated delayed fluorescence mechanism is immobilized between two 1 nm thin silicate layers. Partial ion exchange of the emitter into a synthetic layered silicate (fluorohectorite) yields an ordered heterostructure with two types of strictly alternating interlayers: a monolayer of the cationic emitter and a monolayer of hydrated Na+ cations. Osmotic swelling of the latter produces dispersions of double‐stacks in which the emitter monolayer is encapsulated between two silicate layers. The electrostatic attraction of the emitter interlayer with the oppositely charged silicate layers exerts electrostatic pressure on the emitter. Compared to crystalline salt, rigid confinement for the encapsulated emitter provides improved thermal stability and increased emission quantum yield at ambient temperature. The suspension of delaminated, micrometer‐sized double‐stacks of 3.9 nm thickness allows for easy solution processing of low‐cost optoelectronic devices, such as light‐emitting electrochemical cells and organic light‐emitting diodes. Encapsulation of thermally activated delayed fluorescence emitter improves thermal stability and increases luminescence quantum yields at ambient temperature. Synthesis route involves delamination of regularly ordered interstratifications yielding dispersible double‐stacks of densely packed emitter interlayers encapsulated between silicate layers. Immobilization of low molecular weight emitters enables the application of luminescent compounds suitable for optoelectronic devices preventing their diffusion across the device.