Bridging Ionic and Excitonic Luminescence: Mn‐Mediated Size Control of CsPbBr ₃ Quantum Dots for Reconfigurable RGB Emission in a Single Glass Host via Composition–Thermal Processing

Achieving programmable and integrated multi‐color emission within a single monolithic material is a pivotal challenge for next‐generation photonic applications. This work reports a synergistic “composition–thermal processing” strategy in a Pb/Mn co‐doped borosilicate glass to realize reconfigurable RGB luminescence. The as‐made glasses maintain high transparency (>85%), where a Pb 2+ ‐related blue emission (∼460 nm) effectively sensitizes Mn 2+ through ionic energy transfer. As the Mn 2+ concentration increases, the blue emission is suppressed, whereas the Mn 2+ red emission is enhanced and undergoes a significant redshift from 567 to 612 nm, enabling a continuous color transition from blue to orange‐red. Upon controlled thermal treatment, the Mn 2+ concentration precisely tailors the QD dimensions from ∼22 down to ∼3 nm, which induces a significant ∼27 nm blue shift of the green emission (from 522 to 495 nm) through strong quantum confinement and local‐environment effects, where a newly established excitonic channel (CsPbBr 3 QD→Mn 2+ ) emerges and coexists with the residual ionic pathway. Furthermore, the glass exhibits a pronounced excitation‐dependent luminescent response, appearing wine red, pinkish white, and purplish red under 254, 365, and 410 nm illumination, respectively. This study establishes Mn‐mediated nanocrystal size engineering as a foundational paradigm for designing high‐integration and programmable intelligent luminescent materials.