Device perfomance of a blue-emitting polyfluorene-based single-layer light-emitting diode are considerably enhanced by the inclusion of a A self-assembled monolayer (SAM) of a hole-A transporting material (see Figure). The SAM of CL silyl-functionalized triarylamine (TPD-Si-2) is inserted between the ITO anode and the active layer, offering improve hole injection, low visible absorption, and high stability.