Photoinduced phase transitions in two-dimensional charge-density-wave 1T-TaS₂

Charge-density-wave (CDW) materials with strongly correlated electrons have broadband light absorption and ultrafast response to light irradiation, and hence hold great potential in photodetection. 1T-TaS₂ is a typical CDW material with various thermodynamically CDW ground states at different temperatures and fertile out-of-equilibrium intermediate/hidden states. In particular, the light pulses can trigger melting of CDW ordering and also forms hidden states, which exhibits strikingly different electrical conductivity compared to the ground phase. Here, we review the recent research on phase transitions in 1T-TaS₂ and their potential applications in photodetection. We also discuss the ultrafast melting of CDW ordering by ultrafast laser irradiation and the out-of-equilibrium intermediate/hidden states by optical/electrical pulse. For photodetection, demonstrations of photoconductors and bolometers are introduced. Finally, we discuss some of the challenges that remain.