Layer-by-Layer Assembly-Based Heterointerfaces for Modulating the Electronic Properties of Ti₃C₂T MXene

Two-dimensional (2D) transition-metal carbides (MXenes) are emerging as promising materials for a wide range of applications owing to their intriguing electrical, optical, and optoelectronic properties. However, the modulation of metallic Ti₃C₂T MXene electronic properties is the key challenge to fabricate functional nanoelectronic devices. Here, we demonstrate a solution-processable route to fabricate Ti₃C₂T MXene/CuI nanoparticle heterointerfaces by employing a layer-by-layer assembly process. The charge transfer at the heterointerfacial assembly is monitored qualitatively from the quenched photoluminescence emission of CuI. The stable electrical conductivity and consistent Raman spectra of the 3-LBL assembly (three sequential stacks of CuI/MXene) signify the oxidation stability of Ti₃C₂T thin films even after exposure to the ambient environment for 2 months. Furthermore, the 3-LBL assembly exhibited a three-dimensional (3D) variable-range hopping-based electrical conduction in the temperature range 2 ≤ T < 100 K, contrary to the weak localized transport phenomenon in Ti₃C₂T MXene. The difference in charge transport mechanism is supported by distinct magnetoresistance (MR) of the Ti₃C₂T MXene (negative MR, -0.4%) and 3-LBL assembly (positive MR, 1.6%). Therefore, the modulated electrical transport and superior oxidation stability of the Ti₃C₂T MXene in the 3-LBL assembly have the potential to develop next-generation optoelectronic and memory devices.