Controlled Growth of an Mo₂C-Graphene Hybrid Film as an Electrode in Self-Powered Two-Sided Mo₂C-Graphene/Sb₂SSe/TiO₂ Photodetectors.

The monotonic work function of graphene makes it difficult to meet the electrode requirements of every device with different band structures. Two-dimensional (2D) transition metal carbides (TMCs), such as carbides in MXene, are considered good candidates for electrodes as a complement to graphene. Carbides in MXene have been used to make electrodes for use in devices such as lithium batteries. However, the small lateral size and thermal instability of carbides in MXene, synthesized by the chemically etching method, limit its application in optoelectronic devices. The chemical vapor deposition (CVD) method provides a new way to obtain high-quality ultrathin TMCs without functional groups. However, the TMCs film prepared by the CVD method tends to grow vertically during the growth process, which is disadvantageous for its application in the transparent electrode. Herein, we prepared an ultrathin Mo₂C-graphene (Mo₂C-Gr) hybrid film by CVD to solve the above problem. The work function of Mo₂C-Gr is between that of graphene and a pure Mo₂C film. The Mo₂C-Gr hybrid film was selected as a transparent hole-transporting layer to fabricate novel Mo₂C-Gr/Sb₂SSe/TiO₂ two-sided photodetectors. The Mo₂C-Gr/Sb₂SSe/TiO₂/fluorine-doped tin oxide (FTO) device could detect light from both the FTO side and the Mo₂C-Gr side. The device could realize a short response time (0.084 ms) and recovery time (0.100 ms). This work is believed to provide a powerful method for preparing Mo₂C-graphene hybrid films and reveals its potential applications in optoelectronic devices.