Tailoring optoelectronic properties of TMDs through atomic-scale solid–liquid interface engineering

Abstract Transition metal dichalcogenides hold immense promise in photoelectrochemical applications, yet the atomic-scale electron transfer dynamics at their aqueous interfaces remain elusive. Here, we systematically investigate the underlying physical principles for MoS₂, MoSe₂, and MoTe₂ contact with water using first-principles calculations. Our calculations reveal that interfacial charge transfer occurs exclusively between surface atoms and adjacent water molecules, with the directionality governed by the relative work functions and the external pressure from water. This interfacial charge redistribution triggers band gap narrowing through conduction band downshift, directly modulating the optical responses. In-depth evaluation of joint density of states and critical points reveal that aqueous contact induces new characteristic peaks, broadening the high-intensity region. These findings advance the fundamental understanding of solid–liquid interfacial electrochemistry and establish a theoretical framework for semiconductor-based interfacial electron transfer. Moreover, our work highlights the feasibility of tailoring optical properties at the atomic scale through precise solid–liquid interface engineering, offering transformative insights for next-generation optoelectronic devices.