as a Janus Material for Energy Generation and Storage*

An approach to designing solar absorber materials based on intercalation-induced metal-to-semiconductor transition has been proposed. Using hybrid density functional calculation, Al-intercalated Chevrel phase Mo₆S₈ with end product Al_4/3Mo₆S₈ is predicted to be a semiconductor with a 1.18 eV indirect band gap. Compared with GaAs and Si, Al_4/3Mo₆S₈ shows significantly higher optical absorption over the solar spectrum as a result of the parallel bands across the band gap with direct transitions around 1.35 eV, nearly ideal for an absorber material in a solar cell. Chevrel phase Mo₆S₈ has recently been explored as a cathode material in rechargeable Al-ion batteries. Thus, Al_4/3Mo₆S₈ is a potential dual-function (or Janus) material for both energy generation and storage.