Overcoming the Limitations of MXene Electrodes for Solution-Processed Optoelectronic Devices.

MXenes constitute a rapidly growing family of 2D materials that are promising for optoelectronic applications because of numerous attractive properties, including high electrical conductivity. However, the most widely used titanium carbide (Ti 3 C 2 T x ) MXene transparent conductive electrode exhibits insufficient environmental stability and work function (WF), which impede practical applications Ti 3 C 2 T x electrodes in solution-processed optoelectronics. Herein, Ti 3 C 2 T x MXene film with a compact structure and a perfluorosulfonic acid (PFSA) barrier layer is presented as a promising electrode for organic light-emitting diodes (OLEDs). The electrode shows excellent environmental stability, high WF of 5.84 eV, and low sheet resistance R S of 97.4 Ω sq -1 . The compact Ti 3 C 2 T x structure after thermal annealing resists intercalation of moisture and environmental contaminants. In addition, the PFSA surface modification passivates interflake defects and modulates the WF. Thus, changes in the WF and R S are negligible even after 22 days of exposure to ambient air. The Ti 3 C 2 T x MXene is applied for large-area, 10 × 10 passive matrix flexible OLEDs on substrates measuring 6 × 6 cm. This work provides a simple but efficient strategy to overcome both the limited environmental stability and low WF of MXene electrodes for solution-processable optoelectronics.