Optimizing the Eu3+ Concentration in Novel Eu‐Doped TPU Films for the Development of Highly Emissive Red Flexible Material

New flexible red emitting materials have been prepared based on the thermoplastic polyurethane (TPU) and Eu(TTA)₃bipy (Eu), as doping europium(III) species. The films were achieved by slow evaporation of the mixture of the complex species and TPU in dichloromethane/dimethylformamide (DCM/DMF), and were characterized by FTIR, TGA, powder X‐ray diffraction, SEM‐EDS, and AFM. Considering the whole characterization dataset, it was possible to identify main interactions of the complex with the polymeric host which are responsible of the properties of the obtained film. When exciting at 394 nm, a QY 17.2% was obtained of for a 1% concentration of europium(III) ion, which is an excellent performance considering the high dilution of Eu in the matrix. Furthermore, the material retains a transparency comparable to that of pristine TPU. The QY values for films with higher concentration such as 4 and 10% are close to those of the pristine Eu (36‐41% using 394 nm excitation source) and preserves a well‐resolved Stark Splitting for all transitions (5D0 → 7F0‐4). Therefore, this work highlights a new flexible material with a low content of europium(III) ion with excellent emissive properties.