Na2CO3 is used as an n-type dopant to improve the electro-optical properties of tris(8-hydroxyquinoline) aluminum (Alq(3))-based organic light-emitting diodes (OLEDs). Device properties such as the turn-on voltage, maximum luminance, and device efficiency were improved as Na2CO3 was doped. The higher mobility of Na2CO3-doped samples has been derived using space-charge-limited current measurements. Photoelectron spectroscopy results show that some electrons transfer from Na2CO3 into Alq(3), which moves the Fermi level close to the lowest unoccupied molecular orbital of Alq(3). Therefore, both the electron-transporting ability and electron-injection efficiency were enhanced, which improves the charge carrier balance in OLEDs and leads to better device efficiency. (C) 2012 Elsevier B. V. All rights reserved.