High efficiency and stability in air of the encapsulation-free hybrid organic-inorganic light-emitting diode

High efficiency and stability in an encapsulation-free hybrid organic-inorganic light-emitting diode (HOILED) have been achieved by controlling the hole carrier concentration by the use of a cesium compound layer acting as a hole-blocking unit. The low efficiency and brightness of the conventional HOILED are caused by insufficient blocking on the titanium dioxide (TiO2) interface. Electroluminescence with high brightness (>10 000 Cd/m(2) at 4 V) and efficiency (7.2 Cd/A at 3.6 V) was observed. Higher than required emission reaching 600 Cd/m(2) at 6 V can be observed after keeping the TiO2-free improved HOILED in air for 172 h. (C) 2008 American Institute of Physics.