Key Ionic Electrolytes for Highly Self-Stable Light-Emitting Electrochemical Cells Based on Ir(III) Complexes

Elisa Fresta, Miguel A. Monclús, Morten Bertz, Cintia Ezquerro, Jon M. Molina-Aldareguia, Jesús R. Berenguer, Masahiro Kunimoto, Takayuki Homma, Rubén D. Costa

Research output: Contribution to journalArticle

Abstract

Self-stability in light-emitting electrochemical cells (LECs) based on Ir(III) ionic transition metal complexes (Ir-iTMC) has been long overlooked. Herein, it is demonstrated that the nature of the active layer blending an archetype Ir-iTMC as emitter and ionic electrolytes—ionic liquid (IL) or ionic polyelectrolyte (IP)—is paramount for the storage and mechanical stability of rigid/flexible LECs. Strikingly, devices with ionic polyelectrolytes (IPs) stand out compared to those with traditional configurations with or without ILs. They exhibit i) superior brightness and efficiencies in rigid/flexible devices due to the higher photoluminescence quantum yield, ii) the best performance at pulsed current driving mode under inert/ambient operation conditions due to a slower growth of the doped regions, iii) enhanced device stabilities upon ambient/inert storage, resulting in <10% performance loss after 1 month of aging, and iv) the smallest performance loss (<10%) upon bending stress, since IPs prevent mechanically induced damage, preserving morphological and spectroscopic features. These findings are supported by steady-state and time-resolved emission spectroscopy, electrochemical impedance spectroscopy, microscopic and mechanical assays, along with the analysis of fresh and aged devices driven at different modes under inert/ambient conditions. Overall, this work highlights the need of revisiting new emitter:electrolyte combinations toward realizing highly self-stable LECs.

Original languageEnglish
Article number2000295
JournalAdvanced Optical Materials
Volume8
Issue number12
DOIs
Publication statusPublished - 2020 Jun 1

Keywords

  • ionic electrolytes
  • light-emitting electrochemical cells
  • mechanical stability
  • self-stable devices
  • storage stability

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics

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