Influence of buffer layer and doped electron transport layer on the luminance efficiency of organic light-emitting diode

We fabricated an organic light emitting diode (OLED) with MoO3 inserting in m-MTDATA/NPB interface as hole injection buffer layer, incorporating an ndoping transport layer which comprises 8-hydroxy-quinolinato lithium (Liq) doped into 4,7-diphyenyl-1, 10-phenanthroline (Bphen) aseolectron injection layer(ETL) By comparing the J-V curves of only devices, the doping rate was set as w(Bphen)∶w(Liq)=65∶35. The device performance was enhanced significantly after using Liq and MoO3. However, the performance was saturated when the thickness was over 1Its the use of MoO3 and n-doping in ETL that facilitated the hole injection and electron injection and transport respectively, reached effective carrier balance in emission zone and improved the device luminance efficiency greatly. The current efficiency, power efficiency and luminance of the devices were improved by about 62%, about 98% and about 60%，with the voltage reduced by about 28%.