A New Kind of Electroluminescent Devices Containing Ultrathin Polyimide Langmuir-Blodgett Films as Insulators

Abstract

By utilizing ultrathin (100 and 200 Å) polyimide Langmuir-Blodgett (PI LB) films as insulating layers and Ta2O5 as an electron injection layer, a new kind of multilayered thin film EL device having a low operating voltage of less than 100 V has been developed. Without Ta2O5, the threshold voltages were typically 50 V, but the slope of the luminance-voltage characteristic was not steep enough. By introducing two Ta2O5 layers, the luminance-voltage characteristics have been improved, and an operating voltage of 90 V has been achieved. This operating voltage is 50 V lower than that of a device which contains SiO2 instead of PI LB films.