An organic semiconductor laser based on star-shaped truxene-core oligomers for refractive index sensing

The sensing capabilities of an all-organic semiconductor distributed feedback laser based on star-shaped truxene-core molecules are described. Two assays are presented as a proof-of-principle demonstration. In the first, concentration changes in the range of 5-60% (v/v) glycerol solution in water were measured with a bulk detection sensitivity of 21 nm per refractive index unit. Secondly, layer-by-layer adsorption of polyelectrolytes to the laser surface, up to a thickness of ≈45 nm, was measured. The experimental results from both assays are compared to, and shown to agree with, a theoretical model. Organic semiconductor lasers of this type have a number of attractions including ease of large-scale fabrication, incorporation into existing assay equipment and no rigid optical alignment constraints for excitation and collection of emission, which makes them well-suited to sensing applications. Therefore, it is expected that this technology will be useful in biosensing applications where label-free samples are investigated.