Mechanical Programming of Carrier Flow by Band-Alignment Inversion in Two-Dimensional Heterostructures.

Controlling the direction of photogenerated carrier transfer in two-dimensional heterostructures is a longstanding challenge for optoelectronic logic and photocatalysis. Here we show that tensile strain can drive a complete inversion of band-edge alignment in type-II transition-metal dichalcogenide/transition-metal carbide (TMDC/MXene) heterostructures, reversing the carrier transfer direction without sacrificing efficient charge separation. This unusual behavior originates from opposite orbital responses of the two sublayers: strain lowers the band edges of weakly ionic TMDCs but raises those of strongly ionic MXenes, enabling strain-driven band-alignment inversion. In WSe/ZrCO heterostructures, this mechanism reverses both electron and hole transfer directions while preserving ultrafast femtosecond charge separation and nanosecond carrier lifetimes, as revealed by nonadiabatic molecular dynamics simulations. These results establish strain-driven band-alignment inversion as a general strategy for mechanically programmable control of carrier flow in van der Waals heterostructures.