Facile synthesis of solution-processed MoS2 nanosheets and their application in high-performance ultraviolet organic light-emitting diodes

Solution-processed aqueous molybdenum disulfide (MoS2) nanosheets with good dispersity and air stability were synthesized in a facile manner through liquid-phase exfoliation. MoS2 and corresponding composites of ultraviolet/ozone-treated MoS2 (MoS2-UVO) and MoS2-doped poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (MoS2+PEDOT:PSS) were characterized using atomic force microscopy and X-ray/ultraviolet photoelectron spectroscopy, confirming superior film morphology and exceptional electronic properties. High efficiencies of 8.1 cd A(-1) and 5.7 lm W-1 were demonstrated in visible organic light-emitting diode (OLED) with tris(8-hydroxy-quinolinato)aluminum as the emissive layer and MoS2+PEDOT:PSS as the hole-injection layer. Using 3-(4-biphenyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole as emitter and MoS2+PEDOT:PSS for hole-injection tuning, the fabricated ultraviolet OLED produced attractive short-wavelength electroluminescence of 376 nm with a full-width at half-maximum of 37 nm and improved stability. The radiance and external quantum efficiency reached 11.9 mW cm(-2) and 4.14%, respectively. Current-voltage characteristics and impedance spectroscopy confirmed that the hole-injection capacity increased in the order MoS2 < MoS2-UVO < MoS2+PEDOT:PSS. The extremely promoted hole injection of MoS2+PEDOT:PSS accounted for its outstanding device performance. Our results provide a novel approach for advancing MoS2 applications with solution processing and scalable manufacturing.