Phosphomolybdic Acid-Modified Monolayer Graphene Anode for Efficient Organic and Perovskite Light-Emitting Diodes

Graphene is a promising flexible transparent electrode, and significant progress in graphene-based optoelectronic devices has been accomplished by reducing the sheet resistance and tuning the work function. Herein, phosphomolybdic acid (PMA) is proposed as a novel p-type chemical dopant for graphene, and the optical and electrical properties of graphene are investigated systematically. As a result, the monolayer graphene electrode with lower sheet resistance and work function are obtained while maintaining a high transmittance. The Raman spectrum proves the p-type doping effect of PMA on graphene, and the X-ray photoelectron spectroscopy results reveal the mechanism, which is that the electrons transfer from graphene to PMA through the Mo-O-C bond. Furthermore, using the PMA-doped graphene anode, organic and perovskite light-emitting diodes obtained the maximum efficiencies of 129.3 and 15.6 cd/A with an increase of 50.8 and 36.8% compared with the pristine counterparts, respectively. This work confirms that PMA is a potential p-type chemical dopant to achieve an ideal graphene electrode and demonstrates the feasibility of PMA-doped graphene in the practical application of next-generation displays and solid-state lighting.