Stimulated Emission Properties of Sterically Modified Distyrylbenzene-Based H-Aggregate Single Crystals

J-aggregation has been shown to be beneficial for light amplification in single crystals of pi-conjugated organic molecules. In the case of H-aggregation, the criteria for such processes are still under debate. It has also been shown that H-aggregate arrangements with considerable pi-pi overlap are detrimental for light amplification. We show here that a proper alignment of the molecules in the crystal lattice, which minimizes pi-pi overlap between adjacent molecules, gives rise to (random) stimulated emission from cofacial arrangements similar to that of the herringbone aggregates.