Electrical and optical properties of blue organic light-emitting devices fabricated utilizing color conversion CdSe and CdSe/ZnS quantum dots embedded in a poly(N-vibyl carbazole) hole transport layer

Abstract

Blue organic light-emitting devices (OLEDs) with color conversion quantum dots (QDs) embedded in a poly(N-vinyl carbazole) (PVK) hole transport layer (HTL) were fabricated. The absorbance and the photoluminescence spectra for the CdSe and the CdSe/ZnS QDs showed dominant exciton peaks. Current densities as functions of the voltage showed enhanced hole trapping and a decreased hole current in the OLEDs containing CdSe and CdSe/ZnS QDs embedded in a HTL. The phenomena were intensified due to the existence of the ZnS shell. The luminance-voltage curve and the electroluminescence spectra showed that the brightness of the blue OLEDs fabricated utilizing the HTL based on CdSe and CdSe/ZnS QDs embedded in a PVK layer reached over 3,000 cd/m(2) and that the dominant exciton peak was shifted to longer wavelength.