LEDs Benefit from Interface Engineering

A research group from the UK, Germany and Singapore describes the production of efficient polymer LEDs by molecular-scale interface engineering in the March 30 issue of Nature.A series of green-emitting devices displayed an external forward efficiency of 6 percent at a luminance of 1600 cd/m² at 5 V.

The researchers assembled the LEDs by alternately depositing 1- to 1.5-nm-thick layers of polyanions and polycations on indium tin oxide to facilitate carrier-hopping and then spin casting a calcium cathode on the structure. They suggest that optimization by cathode engineering and improved adhesion could lead to devices of higher diode current and luminance.