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 WSe₂/Zr₂CO₂ 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.