One-dimensional (1D) van der Waals heterostructures (vdWHs) based on transition-metal dichalcogenides (TMDs) show great promise for next-generation optoelectronic devices, often surpassing their 2D counterparts. As a critical determinant of optoelectronic performance, exciton dynamics in 2D TMD vdWHs have been extensively studied, whereas they remain largely unexplored in 1D TMD vdWHs. In this study, we investigate the exciton dynamics in 1D $\mathrm{W}X{}_2/\mathrm{Mo}Y{}_2$ ($X, Y$ = S, Se) vdWHs using ab initio nonadiabatic molecular dynamics simulations. The high curvature in 1D vdWHs significantly modifies their band gaps and band alignment compared to their 2D counterparts, which possess zero curvature, resulting in carrier recombination three orders of magnitude faster than in 2D vdWHs. Notably, 1D ${\mathrm{WS}}_2/{\mathrm{MoSe}}_2$ exhibits phonon-assisted ultrafast intertube carrier transfer at 300 K, with timescale of 20 fs. The ultrafast electron transfer is dominated by the adiabatic (AD) mechanism, whereas the ultrafast hole transfer arises from comparable contributions of AD and nonadiabatic mechanisms. By analyzing phonon excitation and electron-phonon coupling at 100 K and 300 K, we reveal distinct intertube carrier transfer behaviors and their temperature-dependent variations across four 1D vdWHs. These atomic-level insights provide a critical foundation for the design of advanced optoelectronic devices utilizing 1D TMD vdWHs.

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• Carrier dynamics
• Ultrafast phenomena
• Heterostructures
• Nanotubes
• Transition metal dichalcogenides
• van der Waals systems
• Density functional theory
• First-principles calculations
• GGA
• Molecular dynamics
• Time-dependent DFT