Photoemission from Bi‐doped calcium aluminate glasses similar to sunlight

Abstract

AbstractLight sources as the substitution for sunlight play an important role due to their practical applications in aircraft, medicine, and agriculture. Bi3+ ions show tunable emission from ultraviolet to deep red depending on local crystal field, presenting great potential in mimicking sunlight. However, these emissions are mainly limited to crystals. To stabilize Bi3+ ions inside photonic glasses with desirable emission and excellent physical properties remains challenging. Here, we managed to stabilize Bi3+ with ultrabroad and tunable emission inside glasses at air atmosphere. This emission spans the whole visible range of 350‐780 nm and matches well with the sunlight spectra. For the first time, an external quantum efficiency of 34% was obtained from Bi‐doped photonic glasses without optimizing glass composition. We find that the local oxidation atmosphere from super‐oxide ions and proper crystal field formed by AlO4 are responsible for this unique luminescence, which is revealed by the detailed comparison on the optical and structural properties of calcium aluminate glasses and Ca12Al14O33 crystals with the same composition. Moreover, glasses with distortion structure further results in multiluminescent centers of Bi3+ so as to broaden the emission band. This work provides new insights into the luminescent behaviors of Bi ions in luminescent materials, and should contribute to designing new photonic glasses in future.