UV-vis/X-ray/thermo-induced synthesis and UV-SWIR photoresponsive property of a mixed-valence viologen molybdate semiconductor

A new design strategy through the synergy of Mo(VI)–Mo(V) intervalence charge transfer and π(radical)–π(radical/cation) interactions is proposed to obtain semiconductors with photoresponsive ranges covering the whole UV–SWIR (ultraviolet–shortwave near-infrared; ca. 250–3000 nm) region. With this strategy, a viologen-based molybdate semiconductor with a UV–SWIR photoresponsive range was obtained through UV/X-ray irradiation or thermal annealing. The thermally annealed semiconductor has the highest conversion and the best photocurrent response in the range of 355–2400 nm.