This paper describes the mechanism of energy transfer and charge trapping in dye-doped organic light-emitting diodes with two dopants, rubrene and coumarin-6. The current efficiency is found to improve significantly compared to undoped cell, which reaches 6.4 cd/A anal 9.0 cd/A at 100 mA/cm(2) for the rubrene and coumarin-6 doped cells, respectively. The dopant concentration affects the device performance by changing the location, of recombination zone and self-quenching effect. Transient, response of pulsed cells shows that, carrier trapping changes the detection tinge of electroluminescence significantly at low voltage. The potential application of doped organic cells in optic-electric conversion is developed.