White light emission generated by two stacking patterns of a single organic molecular crystal

Dual emission by monomers and excimers is expected for single-molecule white light emitters. However, in the case of a system with an ideal excimer in a single conformation, it is very difficult to achieve their dual emission unless they have multiple chromophores in the molecule. Here, we report single-chromophore white light emission based on dual emission from the aggregation/crystallization of oxidative photocyclization condensates of diarylethene. These condensates form distinct pi-pi stacking by aggregation/crystallization and show structureless yellow emission due to the excited multimer in addition to blue monomer emission. Especially in the crystalline state, white light emission was observed at the International Commission on Illumination (CIE) 1931 coordinates of (0.31, 0.30). Experimental and theoretical studies have shown that white light emission is based on a balanced dual emission produced by two different stacking patterns having different overlapping areas in the crystal.