An Embedded Plasticization Strategy for Flexible Thermally Activated Delayed Fluorescence Polymers with High Luminance

Abstract Thermally activated delayed fluorescence (TADF) polymers offer the theoretical advantage of achieving 100% internal quantum efficiency. Together with their solution processability, TADF polymers are promising candidates for flexible display technologies. However, emissive polymers that simultaneously combine efficient TADF emission with mechanical flexibility remain rare. Here, we report an embedded plasticized linker strategy for mechanically compliant TADF polymers. Polyethylene glycol (PEG)-based flexible segments are covalently incorporated into acridine–benzophenone–carbazole polymer backbones. This “TADF unit + plasticized linker” design preserves the donor–acceptor electronic structure required for delayed fluorescence while introducing flexibility into the emissive polymer framework. The resulting polymers exhibit small singlet–triplet energy gaps, clear delayed fluorescence, and favorable film deformability. The deformation behavior of the neat polymer films was evaluated on PDMS substrates under an applied substrate strain of 75%. Notably, the optimized rigid organic light-emitting diode (OLED) based on PIDC(2,7)-EO achieves a maximum external quantum efficiency (EQE) of 20.1% and a high luminance of 85 988 cd m–2. This luminance value is among the highest reported for polymer-based TADF OLEDs. Flexible OLEDs fabricated on flexible substrates further deliver a maximum EQE of 14.7%. These results demonstrate efficient electroluminescence from flexible device architectures. This work establishes embedded plasticized linkers as an effective molecular design strategy for high-performance mechanically flexible TADF polymers. This strategy provides a promising route toward next-generation flexible OLED technologies.