Abstract
We have investigated a performance of mixed single layer organic light emitting devices (OLED) by mixing of PyPySPyPy, Alq_3, α-NPD and dopant rubrene. For understanding the carrier injection characteristic of mixed single layer OLED, we have fabricated a hole-dominated device with a sandwich structure between Au/MoO_3 and an electron-dominated device with a sandwich structure between Al. The barrier height of carrier injection was estimated by measuring the temperature-dependence of current density-voltage (J-V) characteristics. The J-V characteristics between forward and reverse bias conditions were identical so the composition of organic materials in mixed layer was assumed to be uniform. Both of hole and electron injection mechanisms were explained to the Schottky thermionic emission with the barrier height of 0.25eV and 0.67eV, respectively. And the lowering of barrier height by dopant was confirmed.
