• organic light-emitting diode;
  • size effect;
  • temperature dependence

In this paper, the effects of sample size, forward current, and temperature on the performance of organic light-emitting diodes (OLEDs) are discussed. It is found that the efficiency is inversely proportional to the sample size and current density due to the current spreading effect and limited carrier mobility of the organic material. The results demonstrate that both forward voltage and luminescent efficiency of all samples are functions of temperature. The voltage of devices decreases monotonously with temperature, while the efficiency shows the reverse trend. Carrier mobility, current injection efficiency, and the trap-recovery effect are regarded to be responsible for the temperature dependency.