Among blue fluorescent materials, polyfluorene derivatives have played the major role due to their high photoluminescence efficiency even if their application in polymer light-emitting diodes (PLEDs) has been limited by their poor color stability under operation lifetime. Many approaches have been successfully explored to overcome those drawbacks but the development of pure blue-emitting materials, with CIEy < 0.1 for definition, is still a challenge for full-color display application, or more interestingly, for blue light therapy. With this motivation, we propose an electroluminescent perfluorinated all-conjugated copolymer synthesized by a modified Suzuki cross-coupling [1] suitable for smart, wearable and ready-to-use blue light source for biomedical application. The perfluorination is an attractive strategy to improve thermal and oxidative stability (thanks to the high bond energy of the carbon-fluorine bond) [2] and simultaneously blue-shift both absorption and emission spectra (thanks both to the electron withdrawing nature and sterical demand of fluorine atom). High power PLED with a pure deep blue emission (405 nm peaked and CIEy = 0.06) is obtained and the performances are boosted above 3% quantum efficiency by insertion of exciton confinement polymeric layers (Polyvinylcarbazole and water/alcohol soluble polyfluorenes) in a fully solution-processed 3-layers architecture PLED. A deep investigation, both experimental and theoretical, about the effect of fluorination on the electronic levels of fluorene-based alternated and all-conjugated copolymers and on charge transport properties is in progress, as well as the test of effectiveness of the device in inhibiting bacteria activity.
Pure deep blue electroluminescent perfluorinated all-conjugated copolymer suitable for lighting applications and light therapy
Pasini M;Botta C;Galeotti F;Giovanella U
2013
Abstract
Among blue fluorescent materials, polyfluorene derivatives have played the major role due to their high photoluminescence efficiency even if their application in polymer light-emitting diodes (PLEDs) has been limited by their poor color stability under operation lifetime. Many approaches have been successfully explored to overcome those drawbacks but the development of pure blue-emitting materials, with CIEy < 0.1 for definition, is still a challenge for full-color display application, or more interestingly, for blue light therapy. With this motivation, we propose an electroluminescent perfluorinated all-conjugated copolymer synthesized by a modified Suzuki cross-coupling [1] suitable for smart, wearable and ready-to-use blue light source for biomedical application. The perfluorination is an attractive strategy to improve thermal and oxidative stability (thanks to the high bond energy of the carbon-fluorine bond) [2] and simultaneously blue-shift both absorption and emission spectra (thanks both to the electron withdrawing nature and sterical demand of fluorine atom). High power PLED with a pure deep blue emission (405 nm peaked and CIEy = 0.06) is obtained and the performances are boosted above 3% quantum efficiency by insertion of exciton confinement polymeric layers (Polyvinylcarbazole and water/alcohol soluble polyfluorenes) in a fully solution-processed 3-layers architecture PLED. A deep investigation, both experimental and theoretical, about the effect of fluorination on the electronic levels of fluorene-based alternated and all-conjugated copolymers and on charge transport properties is in progress, as well as the test of effectiveness of the device in inhibiting bacteria activity.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.