Stretchable Fluorescent Polyurethane Containing Fluorene-Based Trimer for Blue Polymer Light-Emitting Diodes

Intrinsically stretchable materials play a pivotal role in the advancement of flexible electronics. However, simultaneously achieving excellent mechanical stretchability and superior optoelectronic properties in light-emitting polymers remains a formidable challenge. Here, we present a novel fluorescent polyurethane (PU) synthesized by integrating a fluorene-based trimer (TrF) as the hard segment and polydimethylsiloxane (PDMS) as the soft segment. This molecular design imparts the polymer with a maximum elongation at a break of 125%, coupled with efficient deep-blue photoluminescence with a quantum yield of 50.2%. Besides, the interchain hydrogen bonds between urethane groups facilitate polymer solution gelation by forming noncovalent cross-linked networks. Polymer light-emitting diodes (PLEDs) based on this novel polymer were successfully fabricated, demonstrating a turn-on voltage of 3.8 V and a maximum luminance of 120 cd m–2. These results underscore the feasibility of integrating stretchability with optoelectronic functionality, emphasizing the critical balance between the mechanical flexibility and optoelectronic properties.