Laser emission from solutions and films containing semiconducting polymer and titanium dioxide nanocrystals

We report laser emission from solutions and dilute blend films containing a semiconducting polymer, poly(2-methoxy,5-(2′-ethyl-hexyloxy)-1,4-phenylene-vinylene) (MEH-PPV), and titanium dioxide (TiO2) nanocrystals under pulsed optical excitation at 532 and 435 nm. The TiO2 nanoparticles multiply scatter photons in the active polymer medium such that gain exceeds loss above a critical excitation threshold. Above threshold, the emission spectrum narrows significantly. Solid state lasing is observed from free standing films of MEH-PPV and TiO2 in polystyrene. This is the first demonstration of lasing with a semiconducting polymer in the solid state as the active medium.