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/cm(2) 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/cm(2). This is the broadest tuning range (51 nm) reported for organic deep-blue/blue lasing materials. (C) 2010 Elsevier B.V. All rights reserved.