We demonstrated a fabrication technique to reduce the driving voltage, increase the current efficiency, and extend the operating lifetime of an organic light-emitting diode (OLED) by simply controlling the deposition rate of bis(10-hydroxybenzo[h]qinolinato) beryllium (Bebq 2 ) used as the emitting layer and the electron-transport layer. In our optimized device, 55 nm of Bebq 2 was first deposited at a faster deposition rate of 1.3 nm/s, followed by the deposition of a thin Bebq 2 (5 nm) layer at a slower rate of 0.03 nm/s. The Bebq 2 layer with the faster deposition rate exhibited higher photoluminescence efficiency and was suitable for use in light emission. The thin Bebq 2 layer with the slower deposition rate was used to modify the interface between the Bebq 2 and cathode and hence improve the injection efficiency and lower the driving voltage. The operating lifetime of such a two-step deposition OLED was 1.92 and 4.6 times longer than that of devices with a single deposition rate, that is, 1.3 and 0.03 nm/s cases, respectively
