An Inverted Layer-by-Layer Process to Enable Ultrasmooth MXene–Ag Nanowire Hybrid Electrode for Organic Photovoltaics

To realize flexible and wearable electronic devices in the future, it is important to develop flexible transparent electrodes while replacing indium tin oxide-based transparent electrodes. Herein, a highly conductive transparent electrode based on hybrid materials of MXene nanosheet films and Ag nanowires (AgNWs) is reported, which synergistically combines the advantageous properties of each material. MXene/AgNW/colorless polyimide (cPI) hybrid electrode is prepared utilizing reverse sequential processing of MXene nanosheets and AgNWs and exhibits significantly improved conductivity and transmittance compared with the MXene/cPI electrode. Furthermore, owing to the abundant hydrophilic termination groups (-O and -OH) on the MXene surface, the MXene/AgNW/cPI hybrid electrode shows hydrophilic surface properties and a highly uniform film. Therefore, the MXene/AgNW/cPI hybrid electrode exhibits higher transmittance at 550 nm to 79% than MXene/cPI electrode (59%) and considerably lower sheet resistance (13.08 ohm sq⁻¹) than MXene/cPI electrode (113.6 ohm sq⁻¹). Flexible organic photovoltaic devices fabricated with MXene/AgNW/cPI hybrid electrode achieve higher power conversion efficiency of 10.3% compared with 6.70% of the corresponding MXene/cPI electrode. These results provide the great potential of Ti₃C₂-based MXene hybrid electrode as a flexible transparent electrode, paving the way for various and wider range of applications include solar cells and light-emitting diodes.