High-Performance Red Transparent Quantum Dot Light-Emitting Diodes via Fully Solution-Processed MXene/Ag NWs Top Electrode

Abstract

The integration of high-performance transparent top electrodes with the functional layers of transparent quantum dot light-emitting diodes (T-QLEDs) poses a notable challenge. This study presents a composite transparent top electrode composed of MXene and Ag NWs. The composite electrode demonstrates exceptional transparency (84.6% at 620 nm) and low sheet resistance (16.07 Ω sq^-1), rendering it suitable for integration into T-QLEDs. The inclusion of MXene nanosheets in the composite electrode serves a dual role: adjusting the work function to enhance electron injection efficiency and enhancing the interface between Ag NWs and the emissive layer, thereby mitigating the common issue of interfacial resistance in conventional transparent electrodes. This strategic amalgamation results in notable improvements in device performance, yielding a maximum current efficiency of 23.12 cd A^-1, an external quantum efficiency of 13.98%, and a brightness of 21,015 cd m^-2. These performance metrics surpass those achieved by T-LEDs employing pristine Ag NW electrodes. This study offers valuable insights into T-QLED device advancement and provides a promising approach for transparent electrode fabrication in optoelectronic applications.

Keywords: MXene; interface engineering; organic light-emitting diodes; silver nanowires; transparent electrodes.

Figure 1

(a) Schematic diagram of preparation process of the MXene/Ag NWs composite electrode; SEM images of ZnO layer (b), 0.5 mg mL^–1, 1.0 mg mL^–1 and 2.0 mg mL^–1 MXene layers (c–e); Corresponding physical photos (f), and (g) Transmittance spectra of the thin films based on MXene at different concentrations; (h) SEM image of the MXene/Ag NWs coated on the ZnO layer.

Figure 2

(a) Schematic structure of the T-QLED device; (b) Energy level diagram of the functional layers within the device; (c) Current density–voltage, (d) Luminance–voltage; (e) Current efficiency-current density; (f) External quantum efficiency-current density curves of the T-QLED devices based on MXene at different concentrations.

Figure 3

Performance comparison of the T-QLED devices based on the MXene/Ag NWs and Ag NWs top electrodes. (a) Current density–voltage; (b) Luminance–voltage; (e) Current efficiency-current density; (f) External quantum efficiency-current density curves; The cross-section SEM images of T-QLED with an Ag NWs electrode (c), and T-QLED with a MXene/Ag NWs electrode (d).

Figure 4

(a) Electroluminescence (EL) spectra of the MXene/Ag NWs-based T-QLED device from both electrode sides; Electroluminescence spectra from the bottom electrode ITO side (b) and top electrode MXene/Ag NWs side at different voltages (c); (d) Transmittance curve of the MXene/Ag NWs-based T-QLED.