Improving Efficiency of Blue Organic Light-Emitting Diode with Sulfobutylated Lignin Doped PEDOT as Anode Buffer Layer

Water-soluble alkyl chain sulfobutylated lignosulfonate (ASLS) doped PEDOT was prepared with lignin as raw material. Water processable PEDOT:ASLS was applied as hole injection layer (HIL) to modify ITO. Blue phosphorescent organic light-emitting diode plays a key role for full color display and are very challenging. With PEDOT:ASLS as HIL, a highly enhanced current efficiency of 37.65 cd/A was achieved. Considering our device structure, the result is even better than that of the control device using PEDOT:PSS as HIL. Compared with PSS with regular structure, strong aggregation and oxidation behavior of ASLS contribute to the hole injection capability of PEDOT:ASLS. Considering that ASLS is of disordered and amorphous structure, which is very different from poly(styrene sulfonic acid), it is exciting that ASLS might be of promising potential as a sustainable dopant of PEDOT. More importantly, this work will guide the design of dopant of PEDOT.