Efficient red perovskite quantum dots light-emitting diode fabricated by inkjet printing

Perovskite quantum dots (PeQDs) are considered potential display materials due to their high color purity, high photoluminescence quantum yield (PLQY), low cost and easy film casting. In this work, a novel electroluminescence (EL) device consisting of the interface layer of long alkyl-based oleylammonium bromide (OAmBr), which passivates the surface defects of PeQDs and adjusts the carrier transport properties, was designed. The PLQY of the OAmBr/PeQD bilayer was significantly improved. A high-performance EL device with the structure of indium tin oxide/poly(3,4-ethylenedioxythiophene) polystyrene sulfonate/poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine)/OAmBr/PeQDs/2,2^′,2^′′-(1,3,5-benzinetriyl)-tris(1-phenyl-1H benzimidazole)/LiF/Al was constructed using a spin-coating method. A peak external quantum efficiency (EQE) of 16.5% at the emission wavelength of 646 nm was obtained. Furthermore, an efficient matrix EL device was fabricated using an inkjet printing method. A high-quality PeQD matrix film was obtained by introducing small amounts of polybutene into the PeQDs to improve the printing process. The EQE reached 9.6% for the matrix device with 120 pixels per inch and the same device structure as that of the spin-coating one.