Tailoring hole injection of graphene oxide doped PEDOT:PSS for assembling efficient near ultraviolet organic light-emitting diodes

Abstract

Tailoring hole injection plays a key role in near ultraviolet organic light-emitting diodes (NUV OLEDs) due to the wide band-gap and thus deep highest occupied molecular orbital level of emissive molecules. Solution-processed composite of graphene oxide doped poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS+GO) is facilely synthesized and served as hole injection layer of NUV OLEDs. The atomic force microscopy, ultraviolet photoelectron spectroscopy, impedance spectroscopy, Raman shift and infrared transmittance measurements confirm that PEDOT:PSS+GO shows superior film morphology and exceptional electronic properties such as enhanced surface work function, promoted hole injection capacity and improved device durability. With 9-(4′-(4,5-diphenyl-4 H-1,2,4-triazol-3-yl)-[1,1′-biphenyl]− 4-yl)− 9 H-carbazole as emissive molecule, the NUV OLED behaves superior short wavelength electroluminescence with emissive peak of 401 nm, maximum external quantum efficiency of 4.3 % and radiance of 14.3 mW/cm2, owing to the effective hole injection tailoring of PEDOT:PSS+GO and thus finely optimized carrier balance in the emissive layer. Our results pave an alternative approach for broadening GO applications and advancing short wavelength organic electroluminescence.