Perovskites are known for their high yield photoluminescence and higher photovoltaic conversion efficiencies. To make them practically useful, the toxicity and stability issues need to be addressed. Herein, we report a less toxic and stable silver bismuth iodide quantum dot system, prepared by a modified ligand assisted reprecipitation (LARP) method. Three types of phase structures such as AgBiI 4 , Ag 2 BiI 5 , and AgBi 2 I 7 were obtained, and their structural and photophysical properties were investigated. By replacing lead (Pb), the toxicity would be reduced considerably and the optical properties persisted for more than six months at ambient conditions. The as-prepared silver bismuth iodide QDs were then used to construct photodetector devices, and the device performances were studied. The constructed photodetector devices have generated the photocurrent values of (AgBi 2 I 7 ∼ 0.12 and 0.32 mA), (Ag 2 BiI 5 ∼ 0.87 and 1.6 μA), and (AgBiI 4 ∼ 0.16 and 0.61 mA) at different biasing voltages of 0.1 and 0.2 V, respectively, under visible light irradiation. The AgBi 2 I 7 QD system generated higher photocurrent value and exhibited a better ON/OFF ratio of (I on /I off = 6.5 × 10 4 ). The silver bismuth iodide QDs based photodetectors are promising for ultraviolet photodetection.

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Constructing step scheme (S-scheme) heterojunctions makes it possible for promoting the separation and transfer of photoinduced carriers, as well as maintaining strong photoredox capacities. Herein, S-scheme Bi 2 S 3 /CdS heterojunctions were designed and constructed by the in situ substitution of Bi 3+ on CdS nanorods. The Sscheme 10%-Bi 2 S 3 /CdS heterojunction with intense interfacial contacts shows not only an optimal photoreduction rate toward Cr(VI) (3.18 and 7 times that of pure CdS and Bi 2 S 3 , respectively) but also a high photodegradation rate of ciprofloxacin (1.94 and 8.75 times that of pure CdS and Bi 2 S 3 , respectively). Meanwhile, the S-scheme 10%-Bi 2 S 3 /CdS heterojunction could efficiently prevent itself from photoetching. It is confirmed that the S-scheme 10%-Bi 2 S 3 /CdS heterojunction is produced by a built-in electric field between CdS and Bi 2 S 3 , which not only improves the charge transfer and separation efficiencies but also maintains strong redox capacities. The present study will provide distinguished insight into fabricating an S-scheme heterojunction with strong photoredox capabilities for the removal of pollutants.