Precisely voltage tunable polymeric light emitting diodes by controlling polymer chemical oxidation and adding inorganic semiconducting nanoparticles. From blue to red stopping at white in the same device

We present a detailed study and experimental recipes to tune the outcoming light of single layer polymeric diodes fabricated with commercially available polyfluorene. The standard blue emission peaking at 440 nm can be tuned to obtain even white emission by controlling the deliberate oxidation of the material. Furthermore, with the addition of inorganic quantum dots was not only possible to redshift the emission as a function of the blend composition but also a fine tuning of the emitted light as a function of the external applied voltage. Merging these two effects we fabricated PFO and PFO:QD light emitting diodes that practically cover the entire visible spectrum. The same device exhibits emission from blue to red depending on the applied bias, from blue to green depending on the oxidation degree of the polymer and from white to blue and/or red combining both. The door is already open to cover the whole color gamut with solely one device.