Organic light-emitting devices with double-block layer

We report on the fabrication of organic light-emitting devices (OLEDs) using double-block layers on the electron transport layer and emitting layer. The current efficiency of the organic light-emitting diode is improved by 43% to 9.16 cd A−1 as compared to the device with a single host of Alq3 as the electron transport layer. The maximum luminance is over 23 750 cd m−2 at the bias of 18 V and the current of 338.3 mA cm−2, which is 33% higher than the single host Alq3 device without block layer. Using a step-by-step procedure to smooth electron injection and transport, the energy levels introduced by the insertion layers are an effective method of improving the luminance characteristics.