Broadly tunable deep blue laser based on a star-shaped oligofluorene truxene

We report amplified spontaneous emission (ASE) and optically pumped deep-blue-emitting distributed feedback (DFB) lasers based on a star-shaped oligofluorene truxene molecule. A low ASE threshold of 2.1 kW/cm2 at 439 nm was achieved. The material exhibits a high net gain of 38 cm−1 and also low optical loss coefficient of 3.5 cm−1. Second-order DFB lasers show tuning of the emission wavelength from 422 to 473 nm, and a minimum threshold density of 515 W/cm2. This is the broadest tuning range (51 nm) reported for organic deep-blue/blue lasing materials.