Poly(vinylidene fluoride)-passivated CsPbBr3 perovskite quantum dots with near-unity photoluminescence quantum yield and superior stability

Abstract

All inorganic perovskite quantum dots (QDs) have received great attention owing to their excellent performance in optoelectronic applications. However, they often suffer from defect-related photoluminescence (PL) quenching and phase transformation due to the loss of long-chain organic ligands, such as oleic acid (OA) and oleylamine (OAm). Here, we fabricated CsPbBr₃ QDs by a one-step microwave method, in the presence of α-phase poly(vinylidene fluoride) (PVDF) acing as the surface capping ligands. The PVDF-CsPbBr₃ QDs display a photoluminescence quantum yield (PLQY) of up to 98% (much higher than pristine QDs with OA/OAm as capping ligands), excellent stability in the desired cubic phase structure, and enhanced photoluminescence stability under ambient conditions. Using the as-prepared QDs as a light emitter, the efficient green perovskite quantum-dot light-emitting diode (QLED) with an external quantum efficiency (EQE) of 1.71% was prepared, exhibiting a peak luminance of 5711 cd m⁻² at 516 nm. Theoretical calculations indicate that there exists a much stronger interaction between the CsPbBr₃(001) surface and PVDF as compared to OA/OAm ligands, further explicating sufficient surface passivation with the introduced PVDF ligand.