Solution-processed NiO tailoring hole injection and enhancing photoluminescence in light-emitting diodes

Solution-processed NiO mediating light-emitting diodes (LEDs) performance have been demonstrated. Using NiO-doped poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) tailoring hole injection, fantastic UV organic LEDs with maximum external quantum efficiency of 4.24 %, radiance of 3.9 mW/cm², and 375 nm short-wavelength emission are demonstrated. Using hybrid NiO-quantum dots/carbon dots dispersed in poly(methyl methacrylate) as composite fluorescence film, the 365-nm (and 395-nm) excited photoluminescent LEDs show high luminance of 22014 (and 23937) cd/m² at 100 mA (and 110 mA), power efficiency of 13.86 (and 13.00) lm/W, and yellow-green emission with spectra peak of about 555 nm and wide full width at half maximum of about 140 nm. Atomic force microscope, transmission electron microscope, X-ray/ultraviolet photoelectron spectroscopy, current-voltage, photoluminescence, impedance spectroscopy, and conductivity measurements confirm that NiO-doped poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) promotes hole injection in organic LEDs, NiO incorporation enhances photoluminescence of carbon dots, and accordingly contributing to superior device performance. Our experiments provide alternative methods for constructing fascinating LEDs and boosting NiO applications.