Stabilizing the optical properties of PFO through addition of a non-volatile low molecular weight aromatic etherElectronic supplementary information (ESI) available: Green : blue integrated intensity ratios for annealed films in Fig. 5 and 6, AFM, PLM, SEM and AES images of thin films cast from the various solutions mentioned in this paper, PL spectra of a 25 hour anneal of PFO and 1-1 blend, and PLED device fabrication details. See DOI: 10.1039/c0jm01615b

New composites consisting of poly(9,9′-dioctylfluorene) (PFO) and polyphenyl ether (PPE) were prepared, cast into thin films, and their optical, thermal, and device properties were evaluated. The incorporation of PPE allowed facile formation of PFO β-phase domains and provided a new method of achieving this structure. In addition, the PPE/PFO composites exhibited notably improved spectral stability over pure PFO. Prototype polymer light-emitting diodes based upon PFO/PPE composite thin films were fabricated and their device response was directly compared to equivalent PFO devices revealing no obvious performance degradation. Blending polyphenyl ether (PPE) with poly(9,9′-dioctylfluorene) (PFO) mitigates deleterious effects arising from thermal or device stressing resulting in markedly improved spectral stability without compromising PLED device response.