Issue 37, 2024

Achieving 9% EQE in light-emitting electrochemical cells via a TADF-sensitized fluorescence strategy

Abstract

Light-emitting electrochemical cells (LECs) are appealing for cost-effective, large-area emission applications; however, their luminescence efficiency is significantly limited by exciton annihilation caused by high concentration polarons. Here, we present thermally activated delayed fluorescence (TADF) sensitized fluorescence LECs (TSF-LECs) that achieve a record 9% EQE. The TADF sensitizers with rapid reverse intersystem crossing (RISC) rates can effectively convert triplet excitons to singlet excitons in LECs, thereby establishing a more efficient overall energy transfer pathway. Importantly, magneto-electroluminescence measurements indicate that the additional RISC route in TSF-LECs significantly suppresses the annihilation of triplet excitons and thus reduces exciton loss under high concentration polaron conditions. Compared to LECs without a sensitizer, TSF-LECs exhibit improved EQE and luminance, extended operational lifetimes, and suppressed efficiency roll-off. A flexible display prototype based on TSF-LECs was further fabricated, capable of stably displaying high-brightness preset patterns for extended periods. The exploration of the exciton dynamics in high concentration polaron environments offers valuable insights for future developments in high-efficiency LEC technology.

Graphical abstract: Achieving 9% EQE in light-emitting electrochemical cells via a TADF-sensitized fluorescence strategy

Supplementary files

Article information

Article type
Paper
Submitted
15 Jul 2024
Accepted
04 Sep 2024
First published
05 Sep 2024
This article is Open Access
Creative Commons BY-NC license

Phys. Chem. Chem. Phys., 2024,26, 24498-24505

Achieving 9% EQE in light-emitting electrochemical cells via a TADF-sensitized fluorescence strategy

Z. Zhou, Q. Chang, R. Chen, P. Jin, B. Yin, C. Zhang and J. Yao, Phys. Chem. Chem. Phys., 2024, 26, 24498 DOI: 10.1039/D4CP02801E

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