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

Abstract

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 (>10000Cd∕m2 at 4V) and efficiency (7.2Cd∕A at 3.6V) was observed. Higher than required emission reaching 600Cd∕m2 at 6V can be observed after keeping the TiO2-free improved HOILED in air for 172h.