Mechanically Flexible Organic Semiconductor Laser Array

We report the fabrication and characterization of a mechanically flexible 4 × 4 array of organic semiconductor lasers using blue-emitting tris(trifluorene)truxene oligomers as the gain medium. The device was fabricated entirely by soft lithography from the reproduction of a 1-D silica master grating. The grating array pattern was created directly on the master by a polymeric mask. Each element, or pixel, of the resulting laser array is made of a polymer mesa with embedded surface grating, and all the array elements are on the same mechanically flexible platform. Laser oscillation thresholds of individual photopumped laser pixels are as low as 75 nJ (70 μJ/cm² or 14 kW/cm²). The emission wavelength uniformity of the array is within ±3 nm with individual laser pixels emitting from 432 to 438 nm. On mechanical flexing of the array, a 10-nm tuning of the emission wavelength is achieved and is attributed to a change in the grating periodicity.