Mechanical Interlocking Integrated TADF Polyrotaxane With Intrinsic Stretchability for Deformable Organic Light‐Emitting Diodes

ABSTRACT

Intrinsically stretchable organic light‐emitting diodes (OLEDs) have long suffered from the irreconcilable trade‐off between mechanical flexibility and optoelectronic efficiency. Herein, we propose an integrated mechanically interlocked design strategy, and construct a series of novel stretchable thermally activated delayed fluorescence (TADF) polyrotaxanes (ROXσBN) using high‐efficiency TADF luminescent macrocycles as the functional wheels and flexible polyurethane chains as the axes. These materials efficiently dissipate deformation stress via macrocycle sliding along axles, and simultaneously build a complete charge carrier transport network through the continuous packing of TADF macrocycles. The TADF polyrotaxane can simultaneously achieve balanced mechanical and optoelectronic properties, which maintains a high photoluminescence quantum yield (PLQY = 73%) at an elongation at break of 39%. The OLED based on polyrotaxane achieves a high external quantum efficiency (EQE _max ) of 23.5% with luminance up to 12587 cd·m ^{− 2} . Notably, the luminance of flexible device based on ROX30BN retains more than 90% of its initial value after 100 cycles of repeated bending or stretching. This work realizes the molecular‐level integration of TADF luminescent function and the mechanically interlocked topology of polyrotaxanes for the first time, which opens up a brand‐new molecular design direction for the development of stretchable optoelectronic materials.