Publication type: Article in scientific journal
Type of review: Not specified
Title: Optimized electrolyte loading and active film thickness for sandwich polymer light-emitting electrochemical cells
Authors : Diethelm, Matthias
Grossmann, Quirin
Schiller, Andreas
Knapp, Evelyne
Jenatsch, Sandra
Kawecki, Maciej
Nüesch, Frank
Hany, Roland
et. al : No
DOI : 10.1002/adom.201801278
Published in : Advanced Optical Materials
Volume(Issue) : 7
Issue : 3
Issue Date: 2018
Publisher / Ed. Institution : Wiley
ISSN: 2195-1071
Language : English
Subject (DDC) : 540: Chemistry
Abstract: Effects of ion concentration and active layer thickness play a critical role on the performance of light‐emitting electrochemical cells. Expanding on a pioneering materials system comprising the super yellow (SY) polymer and the electrolyte trimethylolpropane ethoxylate (TMPE)/Li+CF3SO3−, it is reported that a slightly lowered salt concentration and layer thickness result in a substantial efficiency increase, and that this increase is confined to a narrow concentration and thickness range. For a film thickness of 70 nm, a blend ratio SY:TMPE:Li+CF3SO3− = 1:0.075:0.0225, and a current of 7.7 mA cm−2 the current efficacy is 11.6 cd A−1, on a par with SY light‐emitting diodes. The optimized salt content can be explained by increased exciton quenching at higher concentrations and hindered carrier injection and conduction at lower concentrations, while the optical dependence on the layer thickness is due to weak microcavity effects. A comprehensive optical modeling study is presented, which includes the doping‐induced changes of the refractive indices and self‐absorption losses due the emission–absorption overlap of intrinsic and doped SY. The analysis indicates either a thickness‐independent emitter position (EP) close to the anode or a thickness‐dependent EP, shifted to the cathode for increased thicknesses.
Fulltext version : Published version
License (according to publishing contract) : Not specified
Departement: School of Engineering
Organisational Unit: Institute of Computational Physics (ICP)
Appears in Collections:Publikationen School of Engineering

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