Photodoping-Modified Charge Density Wave Phase Transition in WS₂/1T-TaS₂ Heterostructure

Controlling collective electronic states hold great promise for development of innovative devices. Here, we experimentally detect the modification of the charge density wave (CDW) phase transition within a 1T-TaS₂ layer in a WS₂/1T-TaS₂ heterostructure using time-resolved ultrafast spectroscopy. Laser-induced charge transfer doping strongly suppresses the commensurate CDW phase, which results in a significant decrease in both the phase transition temperature (T_c) and phase transition stiffness. We interpret the phenomenon that photo-induced hole doping, when surpassing a critical threshold value of ∼ 10¹⁸ cm⁻³, sharply decreases the phase transition energy barrier. Our results provide new insights into controlling the CDW phase transition, paving the way for optical-controlled novel devices based on CDW materials.