Metal halide hybrids have long celebrated their halometallate moieties as the luminescent center, leaving organic cations behind. Although the thermally activated delayed fluorescence (TADF) strategy has enabled efficient solid-state organic emitters, the complex molecular design required for TADF emitters has limited their facile integration into metal halide hybrid architectures. Here, we demonstrate a versatile strategy wherein a nonemissive organic moiety (benzyltributylammonium) is incorporated into a zero-dimensional disphenoidal Pb-halide hybrid, [(C19H34N)2PbCl4], resulting in efficient TADF-based dual-phase organic emission sensitized by halometallate units in the solid state (crystalline; amorphous). These materials exhibit strong PLQY (similar to 85%) and tunable organic luminescence (blue emission in crystalline phase; cyan emission in amorphous phase) modulated by the packing extent of organic moiety. [PbX4]2- units act as absorptive centers that sensitize organic cations showing TADF-based strong emission. Ground and excited state density functional theory calculations reveal the unique origin of sensitized TADF organic luminescence. Rheological measurements characterize relaxation dynamics of glass <-> supercooled liquid transitions, establishing correlations between molecular packing, phase, and emission characteristics. This first demonstration of dual-phase, sensitized TADF-based organic luminescence in lead halide hybrids establishes a new design paradigm that bridges molecular and solid-state photophysics, opening avenues for multifunctional applications in LEDs, optical thermometry, and security technologies.

Foreign