Amplified spontaneous emission in free-standing membranes incorporating star-shaped monodisperse π-conjugated truxene oligomers

A light-emitting photoresist comprising a vinyl-ether-based photosensitive polymer host doped with star-shaped π-conjugated truxene-core oligomers is shown to be a promising platform for the realization of soft-matter photonic devices. In particular, a simple process for the fabrication of free-standing membranes with no spin casting and peel-off steps is reported. The approach uses instead the hydrophobic nature of the nanocomposites. Membranes are fabricated, with a concentration of 20 mg ml−1 of the truxene oligomer denoted as T3, directly on deionized water by ultraviolet flood illumination. The resulting membrane is 94 μm thick on average with a diameter up to 50 mm. Amplified spontaneous emission developing around 435 nm above an ∼400 μJ cm−2 threshold is obtained by optical pulse pumping the sample at 355 nm in an edge-emitting photoluminescence configuration. These membranes form a versatile platform for flexible organic semiconductor lasers and optical amplifiers