Solution-processed MnOx mediated hole injection and carbon dots fluorescence in high-performance light-emitting diodes

Solution-processed MnO_x has been facilely synthesized from hydrothermal method. High-performance organic light-emitting diodes (OLEDs) are demonstrated with MnO_x mediated hole injection. Using single MnO_x as hole injection layer, the OLED shows radiance of 4.46 mW cm⁻² at 16 V and external quantum efficiency (EQE) of 2.42 %. With MnO_x-doped poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) tailoring hole injection, the OLED achieves satisfactory EQE of 3.83 % and maximum radiance of 12.77 mW cm⁻² at 14 V. High-performance photoluminescent LEDs from MnO_x mediated carbon dots (CDs) are realized. Using 395-nm (410-nm) chips excited composite MnO_x-CDs fluorescence, the photoluminescent LEDs achieve maximum luminance of 56945 cd m⁻² (85669 cd m⁻²) and power efficiency of 2.27 lm W⁻¹ (1.76 lm W⁻¹). Our works provide some novel insights into broadening MnO_x applications and advancing LEDs.