Origin of Sub-Bandgap Electroluminescence in Organic Light-Emitting Diodes

Chaoyu Xiang; Cheng Peng; Ying Chen; Franky So

doi:10.1002/smll.201501355

Origin of Sub-Bandgap Electroluminescence in Organic Light-Emitting Diodes

Small. 2015 Oct 28;11(40):5439-43. doi: 10.1002/smll.201501355. Epub 2015 Aug 27.

Authors

Chaoyu Xiang¹, Cheng Peng¹, Ying Chen¹, Franky So¹

Affiliation

¹ Department of Materials Science and Engineering, University of Florida, Gainesville, FL, 32611, USA.

PMID: 26312783
DOI: 10.1002/smll.201501355

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.

Keywords: OLEDs; charge transfer states; interfaces; organic light-emitting diodes; sub-bandgap electroluminescence; triplet-triplet annihilation.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.