Effects of higher concentration of hole transport material on organic light emitting diode performance

The effects of higher hole transport material (HTM) composition on single emissive layer (EML) based organic light emitting diode (OLED) performance are investigated quantitatively. Due to higher ratio of HTM in EML, the turn-on voltage is reduced from 3.5 V to 2.7 V. In parallel, OLED luminescence and current efficiency also increased with higher HTM concentration. This improvement of OLED performance because of higher HTM concentration in mixture of transport materials has been explained in terms of charge transport, carrier recombination and charge balancing in EML.