High‐Efficiency Blue Polymer Light‐Emitting Diodes with Neat Thermally Activated Delayed Fluorescence Polymer Films

Abstract Thermally activated delayed fluorescence (TADF) polymers have garnered considerable interest due to their promising application in solution‐processed large‐area displays. However, the realization of high‐performance blue TADF polymers remains limited compared to their green and red counterparts. In this study, two series of blue TADF polymers, denoted as PSiCATx and PMSiCATx, are introduced. Both polymers are characterized by the presence of the tetraphenylsilyl group, where PMSiCATx contains an additional methyl group on the tetraphenylsilane unit, which effectively limits the conjugation length of the backbone. These methyl‐modified polymers exhibit a photoluminescence quantum yield of ≈100% in the neat film. Bi‐layer organic light‐emitting diodes with solution‐processed emissive layers utilizing a hole injection layer modified by perfluorinated ionomers demonstrate excellent electroluminescence performance. The solution‐processed device based on polymer PMSiCAT20 achieves a high external quantum efficiency of 19.5%, a current efficiency of 40.9 cd A⁻¹ and a power efficiency of 30.6 lm W⁻¹, at a peak emission wavelength of 468 nm and with color coordinates of the Commission International de l’Eclairage of (0.16, 0.25).