The light-emitting electrochemical cell promises cost-efficient, large-area emissive applications, as its characteristic in-situ doping enables use of air-stabile electrodes and a solution-processed single-layer active material. However, mutual exclusion of high efficiency and high brightness has proven a seemingly fundamental problem. Here we present a generic approach that overcomes this critical issue, and report on devices equipped with air-stabile electrodes and outcoupling structure that deliver a record-high efficiency of 99.2 cd A at a bright luminance of 1910 cd m. This device significantly outperforms the corresponding optimized organic light-emitting diode despite the latter employing calcium as the cathode. The key to this achievement is the design of the host-guest active material, in which tailored traps suppress exciton diffusion and quenching in the central recombination zone, allowing efficient triplet emission. Simultaneously, the traps do not significantly hamper electron and hole transport, as essentially all traps in the transport regions are filled by doping.
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http://dx.doi.org/10.1038/s41467-017-01339-0 | DOI Listing |
Nat Commun
January 2025
The Organic Photonics and Electronics Group, Department of Physics, Umeå University, Umeå, Sweden.
The attainment of white emission from a light-emitting electrochemical cell (LEC) is important, since it enables illumination and facile color conversion from devices that can be cost-efficient and sustainable. However, a drawback with current white LECs is that they either employ non-sustainable metals as an emitter constituent or are intrinsically efficiency limited by that the emitter only converts singlet excitons to photons. Organic compounds that emit by thermally activated delayed fluorescence (TADF) can address these issues since they can harvest all excitons for light emission while being metal free.
View Article and Find Full Text PDFJ Colloid Interface Sci
January 2025
MOE Key Laboratory for UV Light-Emitting Materials and Technology, Department of Physics, Northeast Normal University, Changchun, Jilin 130024, PR China; Faculty of Chemistry, Northeast Normal University, Changchun, Jilin 130024, PR China. Electronic address:
Considering factors such as crustal reserves, atomic mass, redox potential and energy density, sodium-ion batteries (SIBs) are regarded as the most promising alternative to lithium-ion batteries (LIBs). Transition metal-based layered oxides, especially typical NaMnO, stand out among cathode materials due to their low cost and high energy density. However, NaMnO cathodes face several challenges, including Jahn-Teller distortion, manganese dissolution, structural collapse, irreversible phase transition and significant capacity loss.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
The Organic Photonics and Electronics Group, Department of Physics, Umeå University, SE-90187 Umeå, Sweden.
Light-emitting electrochemical cells (LECs) are promising candidates for fully solution-processed lighting applications because they can comprise a single active-material layer and air-stable electrodes. While their performance is often claimed to be independent of the electrode material selection due to the in situ formation of electric double layers (EDLs), we demonstrate conceptually and experimentally that this understanding needs to be modified. Specifically, the exciton generation zone is observed to be affected by the electrode work function.
View Article and Find Full Text PDFMolecules
November 2024
Department of Chemical Engineering, National Chung Hsing University, Taichung 40227, Taiwan.
In this study, a three-dimensional (3D) interconnected porous Ni/SiC skeleton (3D Ni/SiC) was synthesized by binder-free hydrogen bubble template-assisted electrodeposition in an electrolyte containing Ni ions and SiC nanopowders. This 3D Ni/SiC skeleton served as a substrate for directly synthesizing nickel-cobalt layered double hydroxide (LDH) nanosheets via electrodeposition, allowing the formation of a nickel-cobalt LDH nanosheet-decorated 3D Ni/SiC skeleton (NiCo@3D Ni/SiC). The multiscale hierarchical structure of NiCo@3D Ni/SiC was attributed to the synergistic interaction between the pseudocapacitor (3D Ni skeleton and Ni-Co LDH) and electrochemical double-layer capacitor (SiC nanopowders).
View Article and Find Full Text PDFChem Sci
December 2024
MOE Key Laboratory for UV Light-Emitting Materials and Technology, Northeast Normal University Changchun Jilin 130024 China
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