Effect of Water Vapor on the Operation and Stability of Tris(2,2‘-bipyridine)ruthenium(II)-Based Light-Emitting Electrochemical Cells

Abstract

Light-emitting electrochemical cells (LECs) based on Ru(bpy)3(ClO4)2 are thin-film solid-state devices that typically operate at low applied voltages and show relatively high efficiencies. They suffer, however, from poor operating lifetimes. A proposed source of lifetime degradation is water in the film. Previous studies have revealed a marked difference in operation performance between cells fabricated and tested inside a drybox and those made and tested under ambient conditions. This study further characterized the effect of water vapor on device operation. The role of water as solvent within the thin-film devices was found to increase the current and the initial light output, but at the expense of more rapid decay in light generation.

Luminescent Ionic Transition‐Metal Complexes for Light‐Emitting Electrochemical Cells

“…For instance, devices running in air exhibit shorter turn-on times than those in a nitrogen environment; [122] this is due to the presence of residual moisture and/or solvent in the iTMC layer, which increases the ionic mobility. [123,141,146] The use of complexes with counteranions smaller than [PF 6 À ], such as […”

“…1 wt %). One possible quencher was complex [Ru-(bpy) 2 (30), [141] probably as a result of the formation of 29.…”

Lumineszierende ionische Übergangsmetallkomplexe für leuchtende elektrochemische Zellen

“…So zeigen unter Stickstoff betriebene Einheiten längere Einschaltzeiten als an Luft betriebene, [122] bei denen Feuchtigkeits-und/oder Lçsungsmittelspuren in der iTMC-Schicht die Ionenbeweglichkeit erhçhen. [123,141,146] Der Einsatz von Komplexen mit kleineren Gegenionen als…”

“…Die ausführ-lichsten Studien zur Zersetzung des aktiven, lumineszierenden Materials in LECs liegen für Einheiten mit dem Komplex 3 vor. Auf der Grundlage früherer Arbeiten über den Zersetzungsmechanismus dieses iTMC in Lçsung [161,162,164] postulierten Kalyuzhny et al, [123] [141] was wahrscheinlich mit der Bildung von 29 zusammenhängt. [123] [143,144] .…”

The Design and Realization of Flexible, Long‐Lived Light‐Emitting Electrochemical Cells

“…However, the significant drawback of the current generation of LECs, which rationalizes the as-of-yet limited interest from academia and industry, is related to a nonadequate operational lifetime. [5,21,22] In this article, we demonstrate that it is possible to design and fabricate LECs with a record-long lifetime exceeding one month of uninterrupted operation at significant and efficient light emission. Our successful approach is based on a combination of a careful tuning of the composition of the active material and the employment of an appropriate operation protocol.…”