Boosting Stimulated Emission via a Hydrogen‐Bonded Co‐Crystallization Approach in Molecular Crystals

Stimulated emission (SE) of organic π‐conjugated molecule in solid state remains a significant challenge, mainly involving the mode of molecular stacking that invariably alters the photo‐physical processes. Herein, we successfully realized stimulated emission in molecular crystals using a hydrogen‐bonded co‐crystallization strategy. Two hydrogen‐bonded co‐crystals, obtained from 1,4‐bis‐ p ‐cyanostyrylbenzene (CNDSB) and two types of co‐formers, can boost stimulated emission and show decent amplified spontaneous emission (ASE), whereas the parent CNDSB crystal is not SE‐active. Crystal structural analysis demonstrated that the co‐crystallization eliminated excimer formation. The resulting higher k r and shorter excited lifetime led to a larger stimulated emission cross‐section, which benefited to the occurrence of ASE. Simultaneously, the uniaxial arrangements along the long axis of co‐crystal together contributed to highly polarized emission. This system presents very rare evidence of boosting stimulated emission by binary co‐crystallization, which enriches our insights into organic solid‐state lasers.