Fig. 1: High-efficiency solid–solution emission in SBFs-based fluorophores.

a SBFs-based SSSE-active organic fluorophores, demonstrating highly emissive properties in both solution and solid phases as developed in this work. b In solution, schematic surface energy diagram for excited state deactivation through an invariant CI, giving rise to the Inverted Energy Gap Law (IEGL). c In solid state, DFT optimisation indicates that the bulky Glu (side group) oriented perpendicularly prevents trapping and conserves the high fluorescence quantum yield (ΦF).