Intercalated Chevrel Phase Mo₆S₈ as a Janus Material for Energy Generation and Storage

An approach to designing solar absorber materials based on an intercalation-induced metal-to-semiconductor transition has been proposed. Using a hybrid density functional calculation, Al-intercalated Chevrel phase Mo 6 S 8 with end product Al 4/3 Mo 6 S 8 is predicted to be a semiconductor with a 1.18 eV indirect band gap. Compared with GaAs and Si, Al 4/3 Mo 6 S 8 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 Mo 6 S 8 has recently been explored as a cathode material in rechargeable Al-ion batteries. Thus, Al 4/3 Mo 6 S 8 is a potential dual-function (or Janus) material for both energy generation and storage. A possible device structure utilizing this unique property has been proposed.