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

ABSTRACT

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 (Ti3 C2 Tx ) MXene transparent conductive electrode exhibits insufficient environmental stability and work function (WF), which impede practical applications Ti3 C2 Tx electrodes in solution-processed optoelectronics. Herein, Ti3 C2 Tx 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 RS of 97.4 Ω sq-1 . The compact Ti3 C2 Tx 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 RS are negligible even after 22 days of exposure to ambient air. The Ti3 C2 Tx 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.