Approaching-unity PLQY and high stretchability in polymer emitters via molecular spacers

Stretchable organic light-emitting diodes (OLEDs) hold great promise for wearable displays and optical biointerfaces, yet progress is hindered by the intrinsic trade-off between mechanical stretchability and high emission efficiency. Here, we present a broadly applicable strategy to enhance both stretchability and light-emitting performance in thermally activated delayed fluorescence (TADF) polymers through the incorporation of optoelectronically inert small-molecule plasticizers. Using dioctyl phthalate (DOP) as a model additive, we show that plasticizers function as molecular spacers, expanding free volume to suppress triplet exciton quenching while facilitating stress-dissipative chain mobility. The resulting composites achieve approaching-unity photoluminescence quantum yield (PLQY), stretchability beyond 110% strain, and improved electroluminescent efficiency, with external quantum efficiency (EQE), reaching 12.6% in rigid devices and 3.05% in fully stretchable OLEDs. This strategy is effective across a range of TADF polymers, demonstrating plasticizer engineering as a simple, scalable design principle for intrinsically stretchable optoelectronic materials.