Inverted CdSe-ZnS quantum dots light-emitting diode using low-work function organic material polyethylenimine ethoxylated

Abstract

Inverted quantum dot based light-emitting diodes (QDLED) were simply fabricated by an all solution processing. Polyethylenimine ethoxylated (PEIE) was used as a surface modifier in the device, to reduce the indium tin oxide (ITO) electrode work function below 3.08 eV. Based on transmission electron microscopy (TEM) results, CdSe-ZnS QDs with an 8 nm size were uniformly distributed to form a monolayer on a PEIE/ ITO glass substrate. In this inverted QDLED, hybrid polymers [poly(Nvinylcarbazole) + poly(N, N'-bis(4-butylphenyl)-N,N'-bis(phenyl) benzidine were adopted as a hole transporting layer (HTL) to enhance the hole transport property. At a low-operating voltage of 3 V, the device was turned on and emitted a spectrally red color light with a maximum luminance of 2900 cd m(-2) and a current efficacy of 0.35 cd A(-1).