High‐Efficiency Intrinsically Thermoplastic Semiconducting Polymer with Excellent Strain‐Tolerance Capacity for Flexible Ultra‐Deep‐Blue Polymer Light‐Emitting Diodes

Complex internal stresses that appear in flexible thin-film electronic devices under long-term deformation operation are associated with incompatible mechanical properties of the multiple layers, which potentially cause intralayer fracture and separation. These defects may result in device instability, performance loss, and failure. Herein, a thermoplastic functional strategy is proposed for manufacturing high-performance stretchable semiconducting polymers with excellent strain-tolerance capacities for flexible electronic devices. Internal plasticization is used to obtain a thermoplastic light-emitting polymer (N2) that can suppress intralayer tensile fracture and compressive separation to enhance the deformation stability of flexible thin-film optoelectronic devices, enabling outstanding energy dissipation capacity under stress. The thermoplastic films exhibit stable and efficient ultra-deep-blue emission with a high efficiency of ≈90% and chromaticity coordinates of (0.16, 0.04). Moreover, the N2-based rigid and flexible polymer light-emitting diodes (PLEDs) exhibit stable ultra-deep-blue electroluminescence properties with high EQEs of ≈2.4% and 1.9%, respectively. Compared with devices based on brittle PODPF, flexible PLEDs based on thermoplastic films effectively suppress performance degradation after hundreds of cycles of bending fatigue, even under extremely rigid conditions. Introducing intrinsically thermoplastic semiconducting polymers in flexible electronic devices can thus substantially enhance their operational stability under deformation.