title: Origin of Sub-Bandgap Electroluminescence in Organic Light-Emitting Diodes.
abstract: Sub-bandgap electroluminescence in organic light emitting diodes is a phenomenon in which the electroluminescence turn-on voltage is lower than the bandgap voltage of the emitter. Based on the results of transient electroluminescence (EL) and photoluminescence and electroabsorption spectroscopy measurements, it is concluded that in rubrene/C60 devices, charge transfer excitons are generated at the rubrene/C60 interface under sub-bandgap driving conditions, leading to the formation of triplet excitons, and sub-bandgap EL is the result of the subsequent triplet-triplet annihilation process.
authors: Department of Materials Science and Engineering, University of Florida, Gainesville, FL, 32611, USA.
authors: Chaoyu
authors: C
authors: Xiang
authors: Department of Materials Science and Engineering, University of Florida, Gainesville, FL, 32611, USA.
authors: Cheng
authors: C
authors: Peng
authors: Department of Materials Science and Engineering, University of Florida, Gainesville, FL, 32611, USA.
authors: Ying
authors: Y
authors: Chen
authors: Department of Materials Science and Engineering, University of Florida, Gainesville, FL, 32611, USA.
authors: Franky
authors: F
authors: So
keywords: OLEDs; charge transfer states; interfaces; organic light-emitting diodes; sub-bandgap electroluminescence; triplet-triplet annihilation