  Charge-density wave (CDW) is one of the most fundamental quantum phenomena in
solids. Different from ordinary metals in which only single particle
excitations exist, CDW also has collective excitations and can carry electric
current in a collective fashion. Manipulating this collective condensation for
applications has long been a goal in the condensed matter and materials
community. Here we show that the CDW system of 1T-TaS2 is highly sensitive to
light directly from visible down to terahertz, with current responsivities
around the order of ~1 AW-1 at room temperature. Our findings open a new avenue
for realizing uncooled, ultrabroadband and sensitive photoelectronics
continuously down to terahertz spectral range.
