Optically Pumped Lasing from Single Crystals of a Cyano‐Substituted Thiophene/Phenylene Co‐Oligomer

Room temperature optically pumped lasing is achieved for a new n-type molecular crystal of 2,5-bis(4′-cyanobiphenyl-4-yl)­thiophene (BP1T-CN). Efficient stimulated emission in the Fabry–Pérot crystal cavity is supported with a high group refractive index (4.18–4.98), Q factor (910–1860), material gain coefficient (120 cm-1), and a high stimulated emission rate demonstrated by pump–probe measurements.