title: Highly efficient red-emitting hybrid polymer light-emitting diodes via Förster resonance energy transfer based on homogeneous polymer blends with the same polyfluorene backbone.
abstract: Highly efficient inverted-type red-emitting hybrid polymeric light-emitting diodes (HyPLEDs) were successfully demonstrated via Förster resonance energy transfer (FRET) and interfacial engineering of metal oxide with a cationic conjugated polyelectrolyte (CPE). Similarly structured green- and red-emissive polyfluorene copolymers, F8BT and F8TBT, were homogeneously blended as a FRET donor (host) and acceptor (dopant). A cationic polyfluorene-based CPE was also used as an interfacial layer for optimizing the charge injection/transport and improving the contact problem between the hydrophilic ZnO and hydrophobic polymer layer. A long Förster radius (R0 = 5.32 nm) and high FRET efficiency (~80%) was calculated due to the almost-perfect spectral overlap between the emission of F8BT and the absorption of F8TBT. A HyPLED containing 2 wt % F8TBT showed a pure red emission (λmax = 640 nm) with a CIE coordinate of (0.62, 0.38), a maximum luminance of 26 400 cd/m(2) (at 12.8 V), a luminous efficiency of 7.14 cd/A (at 12.8 V), and a power efficiency of 1.75 lm/W (at 12.8 V). Our FRET-based HyPLED realized the one of the highest luminous efficiency values for pure red-emitting fluorescent polymeric light-emitting diodes reported so far.
authors.affiliation: School of Mechanical and Advanced Materials Engineering/Low Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology (UNIST), Banyeon-ri 100, Ulsan 689-798, Republic of Korea.
authors.forename: Bo Ram
authors.initials: BR
authors.lastname: Lee
authors.forename: Wonho
authors.initials: W
authors.lastname: Lee
authors.forename: Thanh Luan
authors.initials: TL
authors.lastname: Nguyen
authors.forename: Ji Sun
authors.initials: JS
authors.lastname: Park
authors.forename: Ji-Seon
authors.initials: JS
authors.lastname: Kim
authors.forename: Jin Young
authors.initials: JY
authors.lastname: Kim
authors.forename: Han Young
authors.initials: HY
authors.lastname: Woo
authors.forename: Myoung Hoon
authors.initials: MH
authors.lastname: Song