Tailoring Interlayer Interaction for Enhancing Thermoelectric Properties of Two-Dimensional 2H–Mo_1–xNb_xS₂ Compounds

Tuning interlayer interactions plays a crucial role in discovery and modulation of novel quantum states in two-dimensional layered materials. Herein, we realize that the interlayer interactions in hexagonal-type MoS 2 (2H–MoS 2 ) can be effectively regulated via isovalent doping with niobium (Nb). Doping with Nb enhances the interlayer bonding strength and mitigates the “anti-spring” properties of the interlayer Mo–S bond in comparison with that of a undoped MoS 2 sample. This modification of the chemical bonding leads to a stronger interlayer interaction and a notable stiffening of low-frequency optical and acoustic phonon modes. Moreover, Nb doping drives the Fermi level deeper into the valence band, resulting in a significant increase in the carrier concentration and effective mass upon doping with isovalent substitution. Additionally, the strengthened interlayer interactions prolong the carrier relaxation time, thereby boosting carrier mobility. Ultimately, by doping Nb in 2H–MoS 2, a dramatic improvement is achieved in the dimensionless figure of merit ( ZT ) by approximately a factor of 26 times in comparison to a undoped MoS 2 polycrystalline compound. The discovery provides a new perspective on the modulation of phonon and electron transport by tailoring interlayer interactions through doping strategies.