In this letter, output luminance, current efficiency and power efficiency of the organic light emitting diodes (OLEDs) with N-2 doped hole transport layer (HTL) have been studied in detail. Experimental results show that the current efficiency and the power efficiency thus in turn the output luminance of OLEDs prepared with HTL evaporated in the optimum N-2 gas ambient pressure of 1 x 10(-4) Torr are improved about 13, 9 and 12 times, respectively, under 2.7 mA/ cm(2) driving current. The significant improving mechanism has been illustrated comprehensively with a series of schematic models. (C) 2003 Elsevier Science Ltd. All rights reserved.