Intrinsically stretchable and efficient cross-linked small molecular emitter for flexible organic light-emitting diodes

Abstract

Due to their rigid and plane conjugated skeletons, small molecular semiconductors always present irreversible brittle properties in the nano-film state, which is not conducive to deformation and operation stability in flexible optoelectronic devices. Herein, we proposed a universal side-chain cross-linkable strategy to construct a dynamic network structure of a small molecular semiconductor (F-3OCm) to improve the deformation tolerance for the fabrication of flexible optoelectronic devices. First, model F-3OCm cross-linked films were obtained by thermal annealing, which presented perfect solvent resistance. Compared to control F-3OEt, F-3OCm cross-linked films displayed viscoelastic behavior with low Young's modulus. Additionally, the tensile fracture rates of F-3OCm cross-linked films are enhanced to ∼20% without obvious cracks, indicating the excellent intrinsic stretchability with excellent deformation stability. In addition, these stretchable films present not only efficient emission behavior with a PLQY of ∼50% but also have deep-blue emission with tension-ratio-independent color purity. Finally, flexible organic light-emitting diodes (OLEDs) based on the F-3OCm cross-linked films present excellent deformation stability, associated with their intrinsically stretchabilty. Therefore, the side-chain cross-linkage strategy is a promising approach for designing intrinsically stretchable small molecular semiconductor films for flexible electronics.