The lifetime improvement of organic light-emitting diodes with poly(3,4-ethylenedioxythiophene) polystyrene sulfonate on indium-tin-oxide surface and deuterated dopant in emitting layer

Abstract

In this study, the PEDOT:PSS conductive polymer material was spin-coated on the ITO surface to improve the surface roughness of the ITO and reduce the spikes on the ITO surface, so as to avoid the burning spots generated in the green organic light emitting diode (OLED) when the voltage was applied to light it up. The OLED emitting is successfully survived. Deuterium atoms (isotopes of hydrogen) with heavier atomic weights can strengthen C-D bonds, slow down the kinetic rate for unwarranted chemical reactions, and improve the performance and stability of OLEDs. In this study, deuterated D-Ir (mppy)₃ was employed as the dopant in the emitting layer of green OLED to replace the general Ir (mppy)₃ to improve the optoelectronic properties and extend the lifetime of green OLED. At a constant voltage of 4 V, the initial luminance and half lifetime of general Ir (mppy)₃ doped and deuterated D-Ir (mppy)₃ doped OLEDs are 188.1 cd/m², 7.2 h and 438.3 cd/m², 42.8 h, respectively. It is shown that doping the deuterated D-Ir (mppy)₃ material in the emitting layer has the effect of prolonging the lifetime of OLED. Compared with the general Ir (mppy)₃, the lifetime of deuterated D-Ir (mppy)₃ doped OLED achieved an extension by 5.9 times.