%0 Journal Article %1 moghe2018ultrafast %A Moghe, Dhanashree A. %A Dey, Amrita %A Johnson, Kerr %A Lu, L.-P. %A Friend, Richard H. %A Kabra, Dinesh %D 2018 %J Applied Physics Letters %K OLED energy exciplex exciton organic photoluminescence polymer transfer %N 16 %P 163301 %R 10.1063/1.5020928 %T Ultrafast endothermic transfer of non-radiative exciplex state to radiative excitons in polyfluorene random copolymer for blue electroluminescence %U https://aip.scitation.org/doi/10.1063/1.5020928 %V 112 %X We report a blue-emitting random copolymer (termed modified Aryl-F8) consisting of three repeat units of polydioctylfluorene (F8), Aryl-polydioctylfluorene (Aryl-F8), and an aromatic amine comonomer unit, poly(bis-N,Ν′-(4-butylphenyl)-bis-N,N′-phenyl-1,4 phenylenediamine) chemically linked to get an improved charge carrier balance without compromising on the photoluminescence (PL) quantum yield with respect to the Aryl-F8 homo-polymer. The measured photoluminescence quantum efficiency (∼70%) of the blue-emitting polymer is comparable to or greater than the individual monomer units. The time resolved PL spectra from the modified Aryl-F8 are similar to those of Arylated-poly(9,9′-dioctylfluorene-co-bis-N,N′-(4-butylphenyl)-bis-N,N′-phenyl-1,4 phenylenediamine) (PFB) even at a time scale of 100–250 ps, indicating an ultrafast energy transfer from the (Aryl-F8 or F8):Arylated-PFB interface to Arylated-PFB, i.e., endothermic transfer of non-radiative exciplex to a radiative molecular exciton. Furthermore, the presence of non-radiative exciplex is confirmed by the photoluminescence decay profile and temperature dependent PL spectra. The luminance efficiency achieved for the modified Aryl-F8 polymer light-emitting diodes is ∼11 cd A−1 with an external quantum efficiency (EQE) of ∼4.5%, whereas it is 0.05 cd/A with an EQE of ∼0.025% for Aryl-F8. Almost two orders of higher efficiency is achieved due to the improved charge carrier balance from the random copolymer without compromising on the photoluminescence yield.

@article{moghe2018ultrafast, abstract = {We report a blue-emitting random copolymer (termed modified Aryl-F8) consisting of three repeat units of polydioctylfluorene (F8), Aryl-polydioctylfluorene (Aryl-F8), and an aromatic amine comonomer unit, poly(bis-N,Ν′-(4-butylphenyl)-bis-N,N′-phenyl-1,4 phenylenediamine) chemically linked to get an improved charge carrier balance without compromising on the photoluminescence (PL) quantum yield with respect to the Aryl-F8 homo-polymer. The measured photoluminescence quantum efficiency (∼70%) of the blue-emitting polymer is comparable to or greater than the individual monomer units. The time resolved PL spectra from the modified Aryl-F8 are similar to those of Arylated-poly(9,9′-dioctylfluorene-co-bis-N,N′-(4-butylphenyl)-bis-N,N′-phenyl-1,4 phenylenediamine) (PFB) even at a time scale of 100–250 ps, indicating an ultrafast energy transfer from the (Aryl-F8 or F8):Arylated-PFB interface to Arylated-PFB, i.e., endothermic transfer of non-radiative exciplex to a radiative molecular exciton. Furthermore, the presence of non-radiative exciplex is confirmed by the photoluminescence decay profile and temperature dependent PL spectra. The luminance efficiency achieved for the modified Aryl-F8 polymer light-emitting diodes is ∼11 cd A−1 with an external quantum efficiency (EQE) of ∼4.5%, whereas it is 0.05 cd/A with an EQE of ∼0.025% for Aryl-F8. Almost two orders of higher efficiency is achieved due to the improved charge carrier balance from the random copolymer without compromising on the photoluminescence yield.}, added-at = {2018-04-19T11:00:41.000+0200}, author = {Moghe, Dhanashree A. and Dey, Amrita and Johnson, Kerr and Lu, L.-P. and Friend, Richard H. and Kabra, Dinesh}, biburl = {https://www.bibsonomy.org/bibtex/2ee422572e2e738f6c6df0b8a1771ab36/masal}, doi = {10.1063/1.5020928}, interhash = {4a4dbed27f78da5484d22a8fd4aeefd4}, intrahash = {ee422572e2e738f6c6df0b8a1771ab36}, journal = {Applied Physics Letters}, keywords = {OLED energy exciplex exciton organic photoluminescence polymer transfer}, number = 16, pages = 163301, timestamp = {2018-04-19T11:00:41.000+0200}, title = {Ultrafast endothermic transfer of non-radiative exciplex state to radiative excitons in polyfluorene random copolymer for blue electroluminescence}, url = {https://aip.scitation.org/doi/10.1063/1.5020928}, volume = 112, year = 2018 }